[PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

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[PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Florian Weimer-5
This change is desirable for a rework of the statically linked startup
code to remove the generic ROP trampoline in it (bug 23323).

I verified that the *crt*.o files are unchanged by this change after
stripping (although my binutils dispatcher fails to determine the
correct ABI for some of the MIPS gcrt1.o files, so those have not been
checked).

Thanks,
Florian
8<------------------------------------------------------------------8<

This supersedes the init_array sysdeps directory.  It allows us to
check for ELF_INITFINI in both C and assembler code, and skip DT_INIT
and DT_FINI processing completely on newer architectures.

A new header file is needed because <dl-machine.h> is incompatible
with assembler code.  <sysdep.h> is compatible with assembler code,
but it cannot be included in all assembler files because on some
architectures, it redefines register names, and some assembler files
conflict with that.

<elf-initfini.h> is replicated for legacy architectures which need
DT_INIT/DT_FINI support.  New architectures follow the generic default
and disable it.

-----
 csu/elf-init.c                                     |  7 ++--
 csu/gmon-start.c                                   |  8 +++++
 elf/dl-fini.c                                      |  5 +--
 elf/dl-init.c                                      |  8 ++---
 nptl/pt-crti.S                                     | 13 +++++--
 .../pt-crti.S => aarch64/elf-initfini.h}           | 13 +++----
 sysdeps/alpha/elf-initfini.h                       | 20 +++++++++++
 sysdeps/arm/elf-initfini.h                         | 20 +++++++++++
 sysdeps/csky/Implies                               |  1 -
 sysdeps/{init_array => generic}/crti.S             | 12 +++++--
 sysdeps/{init_array => generic}/crtn.S             |  6 ++++
 sysdeps/generic/elf-initfini.h                     | 24 +++++++++++++
 sysdeps/hppa/elf-initfini.h                        | 20 +++++++++++
 sysdeps/ia64/elf-initfini.h                        | 20 +++++++++++
 sysdeps/init_array/elf-init.c                      | 37 -------------------
 sysdeps/init_array/gmon-start.c                    | 41 ----------------------
 sysdeps/m68k/elf-initfini.h                        | 20 +++++++++++
 sysdeps/microblaze/elf-initfini.h                  | 20 +++++++++++
 sysdeps/mips/elf-initfini.h                        | 20 +++++++++++
 sysdeps/nios2/elf-initfini.h                       | 20 +++++++++++
 sysdeps/powerpc/elf-initfini.h                     | 20 +++++++++++
 sysdeps/riscv/Implies                              |  2 --
 sysdeps/s390/elf-initfini.h                        | 20 +++++++++++
 sysdeps/sh/elf-initfini.h                          | 20 +++++++++++
 sysdeps/sparc/elf-initfini.h                       | 20 +++++++++++
 sysdeps/x86/elf-initfini.h                         | 20 +++++++++++
 26 files changed, 331 insertions(+), 106 deletions(-)

diff --git a/csu/elf-init.c b/csu/elf-init.c
index 6112dca379..c16029aa08 100644
--- a/csu/elf-init.c
+++ b/csu/elf-init.c
@@ -34,6 +34,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <stddef.h>
+#include <elf-initfini.h>
 
 
 /* These magic symbols are provided by the linker.  */
@@ -49,7 +50,7 @@ extern void (*__fini_array_start []) (void) attribute_hidden;
 extern void (*__fini_array_end []) (void) attribute_hidden;
 
 
-#ifndef NO_INITFINI
+#if ELF_INITFINI
 /* These function symbols are provided for the .init/.fini section entry
    points automagically by the linker.  */
 extern void _init (void);
@@ -79,7 +80,7 @@ __libc_csu_init (int argc, char **argv, char **envp)
   }
 #endif
 
-#ifndef NO_INITFINI
+#if ELF_INITFINI
   _init ();
 #endif
 
@@ -99,7 +100,7 @@ __libc_csu_fini (void)
   while (i-- > 0)
     (*__fini_array_start [i]) ();
 
-# ifndef NO_INITFINI
+# if ELF_INITFINI
   _fini ();
 # endif
 #endif
diff --git a/csu/gmon-start.c b/csu/gmon-start.c
index 9e427342df..1a4fc655ba 100644
--- a/csu/gmon-start.c
+++ b/csu/gmon-start.c
@@ -37,6 +37,7 @@
 #include <sys/gmon.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <elf-initfini.h>
 #define __ASSEMBLY__
 #include <entry.h>
 
@@ -59,6 +60,13 @@ extern char etext[];
 # endif
 #endif
 
+#if !ELF_INITFINI
+/* Instead of defining __gmon_start__ globally in gcrt1.o, we make it
+   static and just put a pointer to it into the .preinit_array
+   section.  */
+# define GMON_START_ARRAY_SECTION ".preinit_array"
+#endif
+
 #ifdef GMON_START_ARRAY_SECTION
 static void __gmon_start__ (void);
 static void (*const gmon_start_initializer) (void)
diff --git a/elf/dl-fini.c b/elf/dl-fini.c
index 70e7346304..e33cf4db96 100644
--- a/elf/dl-fini.c
+++ b/elf/dl-fini.c
@@ -19,6 +19,7 @@
 #include <assert.h>
 #include <string.h>
 #include <ldsodefs.h>
+#include <elf-initfini.h>
 
 
 /* Type of the constructor functions.  */
@@ -117,7 +118,7 @@ _dl_fini (void)
 
   /* Is there a destructor function?  */
   if (l->l_info[DT_FINI_ARRAY] != NULL
-      || l->l_info[DT_FINI] != NULL)
+      || (ELF_INITFINI && l->l_info[DT_FINI] != NULL))
     {
       /* When debugging print a message first.  */
       if (__builtin_expect (GLRO(dl_debug_mask)
@@ -139,7 +140,7 @@ _dl_fini (void)
  }
 
       /* Next try the old-style destructor.  */
-      if (l->l_info[DT_FINI] != NULL)
+      if (ELF_INITFINI && l->l_info[DT_FINI] != NULL)
  DL_CALL_DT_FINI
   (l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
     }
diff --git a/elf/dl-init.c b/elf/dl-init.c
index 3721bca81e..9ac8bafdf9 100644
--- a/elf/dl-init.c
+++ b/elf/dl-init.c
@@ -18,6 +18,7 @@
 
 #include <stddef.h>
 #include <ldsodefs.h>
+#include <elf-initfini.h>
 
 
 /* Type of the initializer.  */
@@ -40,11 +41,6 @@ call_init (struct link_map *l, int argc, char **argv, char **env)
       && l->l_type == lt_executable)
     return;
 
-  /* Are there any constructors?  */
-  if (l->l_info[DT_INIT] == NULL
-      && __builtin_expect (l->l_info[DT_INIT_ARRAY] == NULL, 1))
-    return;
-
   /* Print a debug message if wanted.  */
   if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS))
     _dl_debug_printf ("\ncalling init: %s\n\n",
@@ -54,7 +50,7 @@ call_init (struct link_map *l, int argc, char **argv, char **env)
      - the one named by DT_INIT
      - the others in the DT_INIT_ARRAY.
   */
-  if (l->l_info[DT_INIT] != NULL)
+  if (ELF_INITFINI && l->l_info[DT_INIT] != NULL)
     DL_CALL_DT_INIT(l, l->l_addr + l->l_info[DT_INIT]->d_un.d_ptr, argc, argv, env);
 
   /* Next see whether there is an array with initialization functions.  */
diff --git a/nptl/pt-crti.S b/nptl/pt-crti.S
index b389442a15..ef006a0437 100644
--- a/nptl/pt-crti.S
+++ b/nptl/pt-crti.S
@@ -33,11 +33,18 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <elf-initfini.h>
+
 /* Arrange for __pthread_initialize_minimal_internal to be called at
    libpthread startup, instead of conditionally calling
    __gmon_start__.  */
 
-#define PREINIT_FUNCTION __pthread_initialize_minimal_internal
-#define PREINIT_FUNCTION_WEAK 0
+#if ELF_INITFINI
+# define PREINIT_FUNCTION __pthread_initialize_minimal_internal
+# define PREINIT_FUNCTION_WEAK 0
 
-#include <crti.S>
+# include <crti.S>
+#else
+ .section .init_array,"a",%init_array
+ .dc.a __pthread_initialize_minimal_internal
+#endif
diff --git a/sysdeps/init_array/pt-crti.S b/sysdeps/aarch64/elf-initfini.h
similarity index 67%
rename from sysdeps/init_array/pt-crti.S
rename to sysdeps/aarch64/elf-initfini.h
index 3955298eca..660964ccda 100644
--- a/sysdeps/init_array/pt-crti.S
+++ b/sysdeps/aarch64/elf-initfini.h
@@ -1,5 +1,5 @@
-/* Special initializer support for libpthread.
-   Copyright (C) 2015-2019 Free Software Foundation, Inc.
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  AArch64 version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -14,10 +14,7 @@
 
    You should have received a copy of the GNU Lesser General Public
    License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
+   <http://www.gnu.org/licenses/>.  */
 
-/* This arranges for libpthread.so's special initializer to be called as
-   soon as the library is loaded.  */
-
- .section .init_array,"a",%init_array
- .dc.a __pthread_initialize_minimal_internal
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/alpha/elf-initfini.h b/sysdeps/alpha/elf-initfini.h
new file mode 100644
index 0000000000..f3203cf173
--- /dev/null
+++ b/sysdeps/alpha/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  Alpha version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/arm/elf-initfini.h b/sysdeps/arm/elf-initfini.h
new file mode 100644
index 0000000000..b4406f1003
--- /dev/null
+++ b/sysdeps/arm/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  Arm version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/csky/Implies b/sysdeps/csky/Implies
index fd80b4826e..f8c3a7586e 100644
--- a/sysdeps/csky/Implies
+++ b/sysdeps/csky/Implies
@@ -1,4 +1,3 @@
-init_array
 wordsize-32
 # C-SKY uses IEEE 754 floating point.
 ieee754/flt-32
diff --git a/sysdeps/init_array/crti.S b/sysdeps/generic/crti.S
similarity index 80%
rename from sysdeps/init_array/crti.S
rename to sysdeps/generic/crti.S
index 145c918f93..82d6dc0d91 100644
--- a/sysdeps/init_array/crti.S
+++ b/sysdeps/generic/crti.S
@@ -12,11 +12,17 @@
    toolchains without .init_array support can use this to avoid the
    superfluous .init and .fini boilerplate code.  */
 
+#include <elf-initfini.h>
+
+#if ELF_INITFINI
+# error Cannot use default crti.S because it lacks _init code
+#endif
+
 #ifdef PREINIT_FUNCTION
 
-#if PREINIT_FUNCTION_WEAK
-# error PREINIT_FUNCTION_WEAK is unsupported
-#endif
+# if PREINIT_FUNCTION_WEAK
+#  error PREINIT_FUNCTION_WEAK is unsupported
+# endif
 
 /* This arranges for PREINIT_FUNCTION to be called upon loading a library that
    contains crti.o.  */
diff --git a/sysdeps/init_array/crtn.S b/sysdeps/generic/crtn.S
similarity index 82%
rename from sysdeps/init_array/crtn.S
rename to sysdeps/generic/crtn.S
index 6f70e77160..d92b07dd0b 100644
--- a/sysdeps/init_array/crtn.S
+++ b/sysdeps/generic/crtn.S
@@ -11,3 +11,9 @@
    But new configurations without compatibility concerns for
    toolchains without .init_array support can use this to avoid the
    superfluous .init and .fini boilerplate code.  */
+
+#include <elf-initfini.h>
+
+#if ELF_INITFINI
+# error Cannot use genetric crtn.S because it lacks _fini code
+#endif
diff --git a/sysdeps/generic/elf-initfini.h b/sysdeps/generic/elf-initfini.h
new file mode 100644
index 0000000000..2f4d172765
--- /dev/null
+++ b/sysdeps/generic/elf-initfini.h
@@ -0,0 +1,24 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Legacy platforms define this to 1.  If 0, the dynamic linker
+   ignores the DT_INIT and DT_FINI tags, and static binaries will not
+   call the _init or _fini functions.  If 1, the old constructor
+   mechanisms are used in addition to the initarray/finiarray
+   support.  */
+#define ELF_INITFINI 0
diff --git a/sysdeps/hppa/elf-initfini.h b/sysdeps/hppa/elf-initfini.h
new file mode 100644
index 0000000000..18e3df5aff
--- /dev/null
+++ b/sysdeps/hppa/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  HPPA version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/ia64/elf-initfini.h b/sysdeps/ia64/elf-initfini.h
new file mode 100644
index 0000000000..9b45ce3c7e
--- /dev/null
+++ b/sysdeps/ia64/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  IA64 version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/init_array/elf-init.c b/sysdeps/init_array/elf-init.c
deleted file mode 100644
index d928e6997c..0000000000
--- a/sysdeps/init_array/elf-init.c
+++ /dev/null
@@ -1,37 +0,0 @@
-/* Startup support for ELF initializers/finalizers in the main executable.
-   Copyright (C) 2013-2019 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   In addition to the permissions in the GNU Lesser General Public
-   License, the Free Software Foundation gives you unlimited
-   permission to link the compiled version of this file with other
-   programs, and to distribute those programs without any restriction
-   coming from the use of this file. (The GNU Lesser General Public
-   License restrictions do apply in other respects; for example, they
-   cover modification of the file, and distribution when not linked
-   into another program.)
-
-   Note that people who make modified versions of this file are not
-   obligated to grant this special exception for their modified
-   versions; it is their choice whether to do so. The GNU Lesser
-   General Public License gives permission to release a modified
-   version without this exception; this exception also makes it
-   possible to release a modified version which carries forward this
-   exception.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define NO_INITFINI
-#include <csu/elf-init.c>
diff --git a/sysdeps/init_array/gmon-start.c b/sysdeps/init_array/gmon-start.c
deleted file mode 100644
index 9ea40b44b6..0000000000
--- a/sysdeps/init_array/gmon-start.c
+++ /dev/null
@@ -1,41 +0,0 @@
-/* gmon startup hook using .preinit_array.
-   Copyright (C) 2013-2019 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   In addition to the permissions in the GNU Lesser General Public
-   License, the Free Software Foundation gives you unlimited
-   permission to link the compiled version of this file with other
-   programs, and to distribute those programs without any restriction
-   coming from the use of this file.  (The GNU Lesser General Public
-   License restrictions do apply in other respects; for example, they
-   cover modification of the file, and distribution when not linked
-   into another program.)
-
-   Note that people who make modified versions of this file are not
-   obligated to grant this special exception for their modified
-   versions; it is their choice whether to do so.  The GNU Lesser
-   General Public License gives permission to release a modified
-   version without this exception; this exception also makes it
-   possible to release a modified version which carries forward this
-   exception.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-/* Instead of defining __gmon_start__ globally in gcrt1.o, we make it
-   static and just put a pointer to it into the .preinit_array section.  */
-
-#define GMON_START_ARRAY_SECTION ".preinit_array"
-
-#include <csu/gmon-start.c>
diff --git a/sysdeps/m68k/elf-initfini.h b/sysdeps/m68k/elf-initfini.h
new file mode 100644
index 0000000000..6ae56c16c3
--- /dev/null
+++ b/sysdeps/m68k/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  m68k version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/microblaze/elf-initfini.h b/sysdeps/microblaze/elf-initfini.h
new file mode 100644
index 0000000000..e36e664762
--- /dev/null
+++ b/sysdeps/microblaze/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader, for Microblaze.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/mips/elf-initfini.h b/sysdeps/mips/elf-initfini.h
new file mode 100644
index 0000000000..83fe8025b7
--- /dev/null
+++ b/sysdeps/mips/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  MIPS version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/nios2/elf-initfini.h b/sysdeps/nios2/elf-initfini.h
new file mode 100644
index 0000000000..56c510da71
--- /dev/null
+++ b/sysdeps/nios2/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  nios2 version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/powerpc/elf-initfini.h b/sysdeps/powerpc/elf-initfini.h
new file mode 100644
index 0000000000..c1c38efe1f
--- /dev/null
+++ b/sysdeps/powerpc/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader, for powerpc.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/riscv/Implies b/sysdeps/riscv/Implies
index c88325b8be..1945b1f4bb 100644
--- a/sysdeps/riscv/Implies
+++ b/sysdeps/riscv/Implies
@@ -1,5 +1,3 @@
-init_array
-
 ieee754/ldbl-128
 ieee754/dbl-64
 ieee754/flt-32
diff --git a/sysdeps/s390/elf-initfini.h b/sysdeps/s390/elf-initfini.h
new file mode 100644
index 0000000000..b300881236
--- /dev/null
+++ b/sysdeps/s390/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  S/390 version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/sh/elf-initfini.h b/sysdeps/sh/elf-initfini.h
new file mode 100644
index 0000000000..de44d0bb6a
--- /dev/null
+++ b/sysdeps/sh/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  SH version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/sparc/elf-initfini.h b/sysdeps/sparc/elf-initfini.h
new file mode 100644
index 0000000000..9a983c5501
--- /dev/null
+++ b/sysdeps/sparc/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  SPARC version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1
diff --git a/sysdeps/x86/elf-initfini.h b/sysdeps/x86/elf-initfini.h
new file mode 100644
index 0000000000..ba4b5a5b47
--- /dev/null
+++ b/sysdeps/x86/elf-initfini.h
@@ -0,0 +1,20 @@
+/* Determine DT_INIT/DT_FINI support in the dynamic loader.  x86 version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Enable DT_INIT/DT_FINI support.  */
+#define ELF_INITFINI 1

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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Adhemerval Zanella-2


On 20/12/2019 11:23, Florian Weimer wrote:

> This change is desirable for a rework of the statically linked startup
> code to remove the generic ROP trampoline in it (bug 23323).
>
> I verified that the *crt*.o files are unchanged by this change after
> stripping (although my binutils dispatcher fails to determine the
> correct ABI for some of the MIPS gcrt1.o files, so those have not been
> checked).
>
> Thanks,
> Florian
> 8<------------------------------------------------------------------8<
>
> This supersedes the init_array sysdeps directory.  It allows us to
> check for ELF_INITFINI in both C and assembler code, and skip DT_INIT
> and DT_FINI processing completely on newer architectures.
>
> A new header file is needed because <dl-machine.h> is incompatible
> with assembler code.  <sysdep.h> is compatible with assembler code,
> but it cannot be included in all assembler files because on some
> architectures, it redefines register names, and some assembler files
> conflict with that.
>
> <elf-initfini.h> is replicated for legacy architectures which need
> DT_INIT/DT_FINI support.  New architectures follow the generic default
> and disable it.

LGTM, with only a small clarification below.

Reviewed-by: Adhemerval Zanella <[hidden email]>

>
> -----
>  csu/elf-init.c                                     |  7 ++--
>  csu/gmon-start.c                                   |  8 +++++
>  elf/dl-fini.c                                      |  5 +--
>  elf/dl-init.c                                      |  8 ++---
>  nptl/pt-crti.S                                     | 13 +++++--
>  .../pt-crti.S => aarch64/elf-initfini.h}           | 13 +++----
>  sysdeps/alpha/elf-initfini.h                       | 20 +++++++++++
>  sysdeps/arm/elf-initfini.h                         | 20 +++++++++++
>  sysdeps/csky/Implies                               |  1 -
>  sysdeps/{init_array => generic}/crti.S             | 12 +++++--
>  sysdeps/{init_array => generic}/crtn.S             |  6 ++++
>  sysdeps/generic/elf-initfini.h                     | 24 +++++++++++++
>  sysdeps/hppa/elf-initfini.h                        | 20 +++++++++++
>  sysdeps/ia64/elf-initfini.h                        | 20 +++++++++++
>  sysdeps/init_array/elf-init.c                      | 37 -------------------
>  sysdeps/init_array/gmon-start.c                    | 41 ----------------------
>  sysdeps/m68k/elf-initfini.h                        | 20 +++++++++++
>  sysdeps/microblaze/elf-initfini.h                  | 20 +++++++++++
>  sysdeps/mips/elf-initfini.h                        | 20 +++++++++++
>  sysdeps/nios2/elf-initfini.h                       | 20 +++++++++++
>  sysdeps/powerpc/elf-initfini.h                     | 20 +++++++++++
>  sysdeps/riscv/Implies                              |  2 --
>  sysdeps/s390/elf-initfini.h                        | 20 +++++++++++
>  sysdeps/sh/elf-initfini.h                          | 20 +++++++++++
>  sysdeps/sparc/elf-initfini.h                       | 20 +++++++++++
>  sysdeps/x86/elf-initfini.h                         | 20 +++++++++++
>  26 files changed, 331 insertions(+), 106 deletions(-)
>
> diff --git a/csu/elf-init.c b/csu/elf-init.c
> index 6112dca379..c16029aa08 100644
> --- a/csu/elf-init.c
> +++ b/csu/elf-init.c
> @@ -34,6 +34,7 @@
>     <https://www.gnu.org/licenses/>.  */
>  
>  #include <stddef.h>
> +#include <elf-initfini.h>
>  
>  
>  /* These magic symbols are provided by the linker.  */

Ok.

> @@ -49,7 +50,7 @@ extern void (*__fini_array_start []) (void) attribute_hidden;
>  extern void (*__fini_array_end []) (void) attribute_hidden;
>  
>  
> -#ifndef NO_INITFINI
> +#if ELF_INITFINI
>  /* These function symbols are provided for the .init/.fini section entry
>     points automagically by the linker.  */
>  extern void _init (void);
> @@ -79,7 +80,7 @@ __libc_csu_init (int argc, char **argv, char **envp)
>    }
>  #endif
>  
> -#ifndef NO_INITFINI
> +#if ELF_INITFINI
>    _init ();
>  #endif
>  

Ok.

> @@ -99,7 +100,7 @@ __libc_csu_fini (void)
>    while (i-- > 0)
>      (*__fini_array_start [i]) ();
>  
> -# ifndef NO_INITFINI
> +# if ELF_INITFINI
>    _fini ();
>  # endif
>  #endif

Ok.

> diff --git a/csu/gmon-start.c b/csu/gmon-start.c
> index 9e427342df..1a4fc655ba 100644
> --- a/csu/gmon-start.c
> +++ b/csu/gmon-start.c
> @@ -37,6 +37,7 @@
>  #include <sys/gmon.h>
>  #include <stdlib.h>
>  #include <unistd.h>
> +#include <elf-initfini.h>
>  #define __ASSEMBLY__
>  #include <entry.h>
>  
> @@ -59,6 +60,13 @@ extern char etext[];
>  # endif
>  #endif
>  
> +#if !ELF_INITFINI
> +/* Instead of defining __gmon_start__ globally in gcrt1.o, we make it
> +   static and just put a pointer to it into the .preinit_array
> +   section.  */
> +# define GMON_START_ARRAY_SECTION ".preinit_array"
> +#endif
> +
>  #ifdef GMON_START_ARRAY_SECTION
>  static void __gmon_start__ (void);
>  static void (*const gmon_start_initializer) (void)
> diff --git a/elf/dl-fini.c b/elf/dl-fini.c
> index 70e7346304..e33cf4db96 100644
> --- a/elf/dl-fini.c
> +++ b/elf/dl-fini.c
> @@ -19,6 +19,7 @@
>  #include <assert.h>
>  #include <string.h>
>  #include <ldsodefs.h>
> +#include <elf-initfini.h>
>  
>  
>  /* Type of the constructor functions.  */
> @@ -117,7 +118,7 @@ _dl_fini (void)
>  
>    /* Is there a destructor function?  */
>    if (l->l_info[DT_FINI_ARRAY] != NULL
> -      || l->l_info[DT_FINI] != NULL)
> +      || (ELF_INITFINI && l->l_info[DT_FINI] != NULL))
>      {
>        /* When debugging print a message first.  */
>        if (__builtin_expect (GLRO(dl_debug_mask)
> @@ -139,7 +140,7 @@ _dl_fini (void)
>   }
>  
>        /* Next try the old-style destructor.  */
> -      if (l->l_info[DT_FINI] != NULL)
> +      if (ELF_INITFINI && l->l_info[DT_FINI] != NULL)
>   DL_CALL_DT_FINI
>    (l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
>      }
> diff --git a/elf/dl-init.c b/elf/dl-init.c
> index 3721bca81e..9ac8bafdf9 100644
> --- a/elf/dl-init.c
> +++ b/elf/dl-init.c
> @@ -18,6 +18,7 @@
>  
>  #include <stddef.h>
>  #include <ldsodefs.h>
> +#include <elf-initfini.h>
>  
>  
>  /* Type of the initializer.  */
> @@ -40,11 +41,6 @@ call_init (struct link_map *l, int argc, char **argv, char **env)
>        && l->l_type == lt_executable)
>      return;
>  
> -  /* Are there any constructors?  */
> -  if (l->l_info[DT_INIT] == NULL
> -      && __builtin_expect (l->l_info[DT_INIT_ARRAY] == NULL, 1))
> -    return;
> -

Is the idea of removing the early return to always print the debug
message below?

>    /* Print a debug message if wanted.  */
>    if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS))
>      _dl_debug_printf ("\ncalling init: %s\n\n",
> @@ -54,7 +50,7 @@ call_init (struct link_map *l, int argc, char **argv, char **env)
>       - the one named by DT_INIT
>       - the others in the DT_INIT_ARRAY.
>    */
> -  if (l->l_info[DT_INIT] != NULL)
> +  if (ELF_INITFINI && l->l_info[DT_INIT] != NULL)
>      DL_CALL_DT_INIT(l, l->l_addr + l->l_info[DT_INIT]->d_un.d_ptr, argc, argv, env);
>  
>    /* Next see whether there is an array with initialization functions.  */

Ok.

> diff --git a/nptl/pt-crti.S b/nptl/pt-crti.S
> index b389442a15..ef006a0437 100644
> --- a/nptl/pt-crti.S
> +++ b/nptl/pt-crti.S
> @@ -33,11 +33,18 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> +#include <elf-initfini.h>
> +
>  /* Arrange for __pthread_initialize_minimal_internal to be called at
>     libpthread startup, instead of conditionally calling
>     __gmon_start__.  */
>  
> -#define PREINIT_FUNCTION __pthread_initialize_minimal_internal
> -#define PREINIT_FUNCTION_WEAK 0
> +#if ELF_INITFINI
> +# define PREINIT_FUNCTION __pthread_initialize_minimal_internal
> +# define PREINIT_FUNCTION_WEAK 0
>  
> -#include <crti.S>
> +# include <crti.S>
> +#else
> + .section .init_array,"a",%init_array
> + .dc.a __pthread_initialize_minimal_internal
> +#endif

Ok.

> diff --git a/sysdeps/init_array/pt-crti.S b/sysdeps/aarch64/elf-initfini.h
> similarity index 67%
> rename from sysdeps/init_array/pt-crti.S
> rename to sysdeps/aarch64/elf-initfini.h
> index 3955298eca..660964ccda 100644
> --- a/sysdeps/init_array/pt-crti.S
> +++ b/sysdeps/aarch64/elf-initfini.h
> @@ -1,5 +1,5 @@
> -/* Special initializer support for libpthread.
> -   Copyright (C) 2015-2019 Free Software Foundation, Inc.
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  AArch64 version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
>     This file is part of the GNU C Library.
>  
>     The GNU C Library is free software; you can redistribute it and/or
> @@ -14,10 +14,7 @@
>  
>     You should have received a copy of the GNU Lesser General Public
>     License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> +   <http://www.gnu.org/licenses/>.  */
>  
> -/* This arranges for libpthread.so's special initializer to be called as
> -   soon as the library is loaded.  */
> -
> - .section .init_array,"a",%init_array
> - .dc.a __pthread_initialize_minimal_internal
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

Ok.

> diff --git a/sysdeps/alpha/elf-initfini.h b/sysdeps/alpha/elf-initfini.h
> new file mode 100644
> index 0000000000..f3203cf173
> --- /dev/null
> +++ b/sysdeps/alpha/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  Alpha version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

Ok.

> diff --git a/sysdeps/arm/elf-initfini.h b/sysdeps/arm/elf-initfini.h
> new file mode 100644
> index 0000000000..b4406f1003
> --- /dev/null
> +++ b/sysdeps/arm/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  Arm version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

Ok.

> diff --git a/sysdeps/csky/Implies b/sysdeps/csky/Implies
> index fd80b4826e..f8c3a7586e 100644
> --- a/sysdeps/csky/Implies
> +++ b/sysdeps/csky/Implies
> @@ -1,4 +1,3 @@
> -init_array
>  wordsize-32
>  # C-SKY uses IEEE 754 floating point.
>  ieee754/flt-32

Ok.

> diff --git a/sysdeps/init_array/crti.S b/sysdeps/generic/crti.S
> similarity index 80%
> rename from sysdeps/init_array/crti.S
> rename to sysdeps/generic/crti.S
> index 145c918f93..82d6dc0d91 100644
> --- a/sysdeps/init_array/crti.S
> +++ b/sysdeps/generic/crti.S
> @@ -12,11 +12,17 @@
>     toolchains without .init_array support can use this to avoid the
>     superfluous .init and .fini boilerplate code.  */
>  
> +#include <elf-initfini.h>
> +
> +#if ELF_INITFINI
> +# error Cannot use default crti.S because it lacks _init code
> +#endif
> +

Ok.

>  #ifdef PREINIT_FUNCTION
>  
> -#if PREINIT_FUNCTION_WEAK
> -# error PREINIT_FUNCTION_WEAK is unsupported
> -#endif
> +# if PREINIT_FUNCTION_WEAK
> +#  error PREINIT_FUNCTION_WEAK is unsupported
> +# endif
>  
>  /* This arranges for PREINIT_FUNCTION to be called upon loading a library that
>     contains crti.o.  */

Ok.

> diff --git a/sysdeps/init_array/crtn.S b/sysdeps/generic/crtn.S
> similarity index 82%
> rename from sysdeps/init_array/crtn.S
> rename to sysdeps/generic/crtn.S
> index 6f70e77160..d92b07dd0b 100644
> --- a/sysdeps/init_array/crtn.S
> +++ b/sysdeps/generic/crtn.S
> @@ -11,3 +11,9 @@
>     But new configurations without compatibility concerns for
>     toolchains without .init_array support can use this to avoid the
>     superfluous .init and .fini boilerplate code.  */
> +
> +#include <elf-initfini.h>
> +
> +#if ELF_INITFINI
> +# error Cannot use genetric crtn.S because it lacks _fini code
> +#endif

Ok.

> diff --git a/sysdeps/generic/elf-initfini.h b/sysdeps/generic/elf-initfini.h
> new file mode 100644
> index 0000000000..2f4d172765
> --- /dev/null
> +++ b/sysdeps/generic/elf-initfini.h
> @@ -0,0 +1,24 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Legacy platforms define this to 1.  If 0, the dynamic linker
> +   ignores the DT_INIT and DT_FINI tags, and static binaries will not
> +   call the _init or _fini functions.  If 1, the old constructor
> +   mechanisms are used in addition to the initarray/finiarray
> +   support.  */
> +#define ELF_INITFINI 0

Ok.

> diff --git a/sysdeps/hppa/elf-initfini.h b/sysdeps/hppa/elf-initfini.h
> new file mode 100644
> index 0000000000..18e3df5aff
> --- /dev/null
> +++ b/sysdeps/hppa/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  HPPA version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

Ok.

> diff --git a/sysdeps/ia64/elf-initfini.h b/sysdeps/ia64/elf-initfini.h
> new file mode 100644
> index 0000000000..9b45ce3c7e
> --- /dev/null
> +++ b/sysdeps/ia64/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  IA64 version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

Ok.

> diff --git a/sysdeps/init_array/elf-init.c b/sysdeps/init_array/elf-init.c
> deleted file mode 100644
> index d928e6997c..0000000000
> --- a/sysdeps/init_array/elf-init.c
> +++ /dev/null
> @@ -1,37 +0,0 @@
> -/* Startup support for ELF initializers/finalizers in the main executable.
> -   Copyright (C) 2013-2019 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   In addition to the permissions in the GNU Lesser General Public
> -   License, the Free Software Foundation gives you unlimited
> -   permission to link the compiled version of this file with other
> -   programs, and to distribute those programs without any restriction
> -   coming from the use of this file. (The GNU Lesser General Public
> -   License restrictions do apply in other respects; for example, they
> -   cover modification of the file, and distribution when not linked
> -   into another program.)
> -
> -   Note that people who make modified versions of this file are not
> -   obligated to grant this special exception for their modified
> -   versions; it is their choice whether to do so. The GNU Lesser
> -   General Public License gives permission to release a modified
> -   version without this exception; this exception also makes it
> -   possible to release a modified version which carries forward this
> -   exception.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#define NO_INITFINI
> -#include <csu/elf-init.c>

Ok.

> diff --git a/sysdeps/init_array/gmon-start.c b/sysdeps/init_array/gmon-start.c
> deleted file mode 100644
> index 9ea40b44b6..0000000000
> --- a/sysdeps/init_array/gmon-start.c
> +++ /dev/null
> @@ -1,41 +0,0 @@
> -/* gmon startup hook using .preinit_array.
> -   Copyright (C) 2013-2019 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   In addition to the permissions in the GNU Lesser General Public
> -   License, the Free Software Foundation gives you unlimited
> -   permission to link the compiled version of this file with other
> -   programs, and to distribute those programs without any restriction
> -   coming from the use of this file.  (The GNU Lesser General Public
> -   License restrictions do apply in other respects; for example, they
> -   cover modification of the file, and distribution when not linked
> -   into another program.)
> -
> -   Note that people who make modified versions of this file are not
> -   obligated to grant this special exception for their modified
> -   versions; it is their choice whether to do so.  The GNU Lesser
> -   General Public License gives permission to release a modified
> -   version without this exception; this exception also makes it
> -   possible to release a modified version which carries forward this
> -   exception.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -/* Instead of defining __gmon_start__ globally in gcrt1.o, we make it
> -   static and just put a pointer to it into the .preinit_array section.  */
> -
> -#define GMON_START_ARRAY_SECTION ".preinit_array"
> -
> -#include <csu/gmon-start.c>

Ok.

> diff --git a/sysdeps/m68k/elf-initfini.h b/sysdeps/m68k/elf-initfini.h
> new file mode 100644
> index 0000000000..6ae56c16c3
> --- /dev/null
> +++ b/sysdeps/m68k/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  m68k version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

Ok.

> diff --git a/sysdeps/microblaze/elf-initfini.h b/sysdeps/microblaze/elf-initfini.h
> new file mode 100644
> index 0000000000..e36e664762
> --- /dev/null
> +++ b/sysdeps/microblaze/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader, for Microblaze.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

Ok.

> diff --git a/sysdeps/mips/elf-initfini.h b/sysdeps/mips/elf-initfini.h
> new file mode 100644
> index 0000000000..83fe8025b7
> --- /dev/null
> +++ b/sysdeps/mips/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  MIPS version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

OK.

> diff --git a/sysdeps/nios2/elf-initfini.h b/sysdeps/nios2/elf-initfini.h
> new file mode 100644
> index 0000000000..56c510da71
> --- /dev/null
> +++ b/sysdeps/nios2/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  nios2 version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

OK.

> diff --git a/sysdeps/powerpc/elf-initfini.h b/sysdeps/powerpc/elf-initfini.h
> new file mode 100644
> index 0000000000..c1c38efe1f
> --- /dev/null
> +++ b/sysdeps/powerpc/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader, for powerpc.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1
OK.

> diff --git a/sysdeps/riscv/Implies b/sysdeps/riscv/Implies
> index c88325b8be..1945b1f4bb 100644
> --- a/sysdeps/riscv/Implies
> +++ b/sysdeps/riscv/Implies
> @@ -1,5 +1,3 @@
> -init_array
> -
>  ieee754/ldbl-128
>  ieee754/dbl-64
>  ieee754/flt-32

OK.

> diff --git a/sysdeps/s390/elf-initfini.h b/sysdeps/s390/elf-initfini.h
> new file mode 100644
> index 0000000000..b300881236
> --- /dev/null
> +++ b/sysdeps/s390/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  S/390 version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1
OK.

> diff --git a/sysdeps/sh/elf-initfini.h b/sysdeps/sh/elf-initfini.h
> new file mode 100644
> index 0000000000..de44d0bb6a
> --- /dev/null
> +++ b/sysdeps/sh/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  SH version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1
OK.

> diff --git a/sysdeps/sparc/elf-initfini.h b/sysdeps/sparc/elf-initfini.h
> new file mode 100644
> index 0000000000..9a983c5501
> --- /dev/null
> +++ b/sysdeps/sparc/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  SPARC version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1

OK.

> diff --git a/sysdeps/x86/elf-initfini.h b/sysdeps/x86/elf-initfini.h
> new file mode 100644
> index 0000000000..ba4b5a5b47
> --- /dev/null
> +++ b/sysdeps/x86/elf-initfini.h
> @@ -0,0 +1,20 @@
> +/* Determine DT_INIT/DT_FINI support in the dynamic loader.  x86 version.
> +   Copyright (C) 2019 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Enable DT_INIT/DT_FINI support.  */
> +#define ELF_INITFINI 1
>
OK.
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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Florian Weimer
* Adhemerval Zanella:

>> @@ -40,11 +41,6 @@ call_init (struct link_map *l, int argc, char **argv, char **env)
>>        && l->l_type == lt_executable)
>>      return;
>>  
>> -  /* Are there any constructors?  */
>> -  if (l->l_info[DT_INIT] == NULL
>> -      && __builtin_expect (l->l_info[DT_INIT_ARRAY] == NULL, 1))
>> -    return;
>> -
>
> Is the idea of removing the early return to always print the debug
> message below?

Yes, I think this message is helpful to show what is going on,
although like so many dynamic linker log messages, its wording could
probably be improved.

I do not think it matters today because every object linked by current
GCC contains an ELF constructor (the _ITM_registerTMCloneTable stuff).
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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Florian Weimer-5
In reply to this post by Adhemerval Zanella-2
* Adhemerval Zanella:

> On 20/12/2019 11:23, Florian Weimer wrote:
>> This change is desirable for a rework of the statically linked startup
>> code to remove the generic ROP trampoline in it (bug 23323).
>>
>> I verified that the *crt*.o files are unchanged by this change after
>> stripping (although my binutils dispatcher fails to determine the
>> correct ABI for some of the MIPS gcrt1.o files, so those have not been
>> checked).
>>
>> Thanks,
>> Florian
>> 8<------------------------------------------------------------------8<
>>
>> This supersedes the init_array sysdeps directory.  It allows us to
>> check for ELF_INITFINI in both C and assembler code, and skip DT_INIT
>> and DT_FINI processing completely on newer architectures.
>>
>> A new header file is needed because <dl-machine.h> is incompatible
>> with assembler code.  <sysdep.h> is compatible with assembler code,
>> but it cannot be included in all assembler files because on some
>> architectures, it redefines register names, and some assembler files
>> conflict with that.
>>
>> <elf-initfini.h> is replicated for legacy architectures which need
>> DT_INIT/DT_FINI support.  New architectures follow the generic default
>> and disable it.
>
> LGTM, with only a small clarification below.
>
> Reviewed-by: Adhemerval Zanella <[hidden email]>

I've fixed up the years and URLs and pushed this.

Thanks,
Florian

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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Andreas Schwab
In reply to this post by Florian Weimer-5
This breaks riscv64.

Andreas.

--
Andreas Schwab, SUSE Labs, [hidden email]
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."
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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Florian Weimer-5
* Andreas Schwab:

> This breaks riscv64.

How so?

Thanks,
Florian

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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Andreas Schwab
On Feb 20 2020, Florian Weimer wrote:

> * Andreas Schwab:
>
>> This breaks riscv64.
>
> How so?

It crashes.

Andreas.

--
Andreas Schwab, SUSE Labs, [hidden email]
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."
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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Andreas Schwab
In reply to this post by Florian Weimer-5
environ is empty.

Andreas.

--
Andreas Schwab, SUSE Labs, [hidden email]
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."
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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Florian Weimer-5
* Andreas Schwab:

> environ is empty.

That's because libc.so.6 still has DT_INIT, from which _environ and
other variables are set up.  I assumed binutils would convert that into
DT_INITARRAY because the architecture is not supposed to have DT_INIT.
Without that, it's hard to declare that there is no DT_INIT, and the
patch essentially breaks ABI (because DT_INIT processing is gone).

This should fix the breakage:

Subject: Use ELF constructor instead of _init in libc.so

On !ELF_INITFINI architectures, _init is no longer called by the dynamic
linker.  We can use an ELF constructor instead because the constructor
order does not matter.  (The other constructors are used to set up libio
vtable bypasses and do not depend on this initialization routine.)

diff --git a/csu/init-first.c b/csu/init-first.c
index 1cd8a75098..1fa1633657 100644
--- a/csu/init-first.c
+++ b/csu/init-first.c
@@ -46,9 +46,8 @@ __libc_init_first (int argc, char **argv, char **envp)
   /* For DSOs we do not need __libc_init_first but instead _init.  */
 }
 
-void
-attribute_hidden
-_init (int argc, char **argv, char **envp)
+static void __attribute__ ((constructor))
+init (int argc, char **argv, char **envp)
 {
 #endif
 

But I'm no longer sure if RISC-V is actually an !ELF_INITFINI
architecture.

Thanks,
Florian

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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Jim Wilson-2
On Thu, Feb 20, 2020 at 10:53 AM Florian Weimer <[hidden email]> wrote:
> That's because libc.so.6 still has DT_INIT, from which _environ and
> other variables are set up.  I assumed binutils would convert that into
> DT_INITARRAY because the architecture is not supposed to have DT_INIT.
> Without that, it's hard to declare that there is no DT_INIT, and the
> patch essentially breaks ABI (because DT_INIT processing is gone).

DT_INIT is a function address.  DT_INITARRAY is a pointer to a table
of addresses.  I don't see how the linker can easily convert between
them.  We would have to increase the size of the init_array table at
link time, and I don't think we have any linker support for that.
Maybe we could modify the startfiles to put a weak reference to _init
at the end of init_array, right before the zero that normally ends the
list, and fix the linker to stop creating DT_INIT for _init.  But that
sounds a little risky, and defeats the purpose of dropping support for
_init to reduce code size.  I would prefer that glibc not create an
_init function in the first place.

> But I'm no longer sure if RISC-V is actually an !ELF_INITFINI
> architecture.

gcc will not create .init sections.  Newlib does not create them or
run them in the startfiles.  The linux kernel does not run DT_INIT.
That is probably why your patch failed for Andreas.

But there is a problem with GNU ld which automatically creates DT_INIT
when it sees a function called _init.  We missed that.  This is in
target dependent code.  The default function name can be overridden
but that isn't quite right for RISC-V either.  Maybe we should give a
linker error if someone gives a _init or _fini function to the linker?
 That way they get a link time error instead of a run-time error.

Jim
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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Florian Weimer-5
* Jim Wilson:

> On Thu, Feb 20, 2020 at 10:53 AM Florian Weimer <[hidden email]> wrote:
>> That's because libc.so.6 still has DT_INIT, from which _environ and
>> other variables are set up.  I assumed binutils would convert that into
>> DT_INITARRAY because the architecture is not supposed to have DT_INIT.
>> Without that, it's hard to declare that there is no DT_INIT, and the
>> patch essentially breaks ABI (because DT_INIT processing is gone).
>
> DT_INIT is a function address.  DT_INITARRAY is a pointer to a table
> of addresses.  I don't see how the linker can easily convert between
> them.  We would have to increase the size of the init_array table at
> link time, and I don't think we have any linker support for that.
> Maybe we could modify the startfiles to put a weak reference to _init
> at the end of init_array, right before the zero that normally ends the
> list, and fix the linker to stop creating DT_INIT for _init.  But that
> sounds a little risky, and defeats the purpose of dropping support for
> _init to reduce code size.  I would prefer that glibc not create an
> _init function in the first place.

I'm not worried about glibc here.  It's easy to make glibc consistent
with itself.  The patch I posted seems to do the trick, without
regressing anywhere else.

What I don't know is whether this binutils bug has resulted in DT_INIT
being used *elsewhere*.  I don't have a RISC-V distribution to analyze,
so I really don't know.  Fedora RISC-V seems dead, this hasn't been
updated in a while:

  <https://dl.fedoraproject.org/pub/alt/risc-v/repo/fedora/rawhide/latest/riscv64/>

(I have existing tools for RPM-based distributions, so having one would
be most useful to me to check for DT_INIT references.)

>> But I'm no longer sure if RISC-V is actually an !ELF_INITFINI
>> architecture.
>
> gcc will not create .init sections.  Newlib does not create them or
> run them in the startfiles.  The linux kernel does not run DT_INIT.

The kernel never runs DT_INIT on any architecture as far as I know, but
currently released glibc does, even on RISC-V.

> That is probably why your patch failed for Andreas.

Yes, looks like it.

> But there is a problem with GNU ld which automatically creates DT_INIT
> when it sees a function called _init.  We missed that.  This is in
> target dependent code.  The default function name can be overridden
> but that isn't quite right for RISC-V either.  Maybe we should give a
> linker error if someone gives a _init or _fini function to the linker?
>  That way they get a link time error instead of a run-time error.

I would expect the toolchain to treat _init just like any other
function, so without DT_INIT support, it would turn into dead code.

Thanks,
Florian

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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Florian Weimer-5
* Florian Weimer:

> * Jim Wilson:
>
>> On Thu, Feb 20, 2020 at 10:53 AM Florian Weimer <[hidden email]> wrote:
>>> That's because libc.so.6 still has DT_INIT, from which _environ and
>>> other variables are set up.  I assumed binutils would convert that into
>>> DT_INITARRAY because the architecture is not supposed to have DT_INIT.
>>> Without that, it's hard to declare that there is no DT_INIT, and the
>>> patch essentially breaks ABI (because DT_INIT processing is gone).
>>
>> DT_INIT is a function address.  DT_INITARRAY is a pointer to a table
>> of addresses.  I don't see how the linker can easily convert between
>> them.  We would have to increase the size of the init_array table at
>> link time, and I don't think we have any linker support for that.
>> Maybe we could modify the startfiles to put a weak reference to _init
>> at the end of init_array, right before the zero that normally ends the
>> list, and fix the linker to stop creating DT_INIT for _init.  But that
>> sounds a little risky, and defeats the purpose of dropping support for
>> _init to reduce code size.  I would prefer that glibc not create an
>> _init function in the first place.
>
> I'm not worried about glibc here.  It's easy to make glibc consistent
> with itself.  The patch I posted seems to do the trick, without
> regressing anywhere else.
>
> What I don't know is whether this binutils bug has resulted in DT_INIT
> being used *elsewhere*.  I don't have a RISC-V distribution to analyze,
> so I really don't know.  Fedora RISC-V seems dead, this hasn't been
> updated in a while:
>
>   <https://dl.fedoraproject.org/pub/alt/risc-v/repo/fedora/rawhide/latest/riscv64/>
>
> (I have existing tools for RPM-based distributions, so having one would
> be most useful to me to check for DT_INIT references.)

I loaded the repository

  <http://fedora.riscv.rocks/repos/rawhide/latest/riscv64/>

and ran this query:

SELECT symboldb.nevra(package), file.name
  FROM symboldb.elf_dynamic dt
    JOIN symboldb.elf_file hdr USING (contents_id)
    JOIN symboldb.file USING (contents_id)
    JOIN symboldb.package USING (package_id)
  WHERE hdr.e_machine = 243 AND dt.tag = 12 ORDER BY 1, 2;

                     nevra                     |                        name                        
-----------------------------------------------+----------------------------------------------------
 glibc-2.30.9000-31.fc32.riscv64               | /lib64/libc-2.30.9000.so
 jamin-0.97.16-19.20111031cvs.fc31.riscv64     | /usr/lib64/ladspa/jamincont_1912.so
 ladspa-1.13-23.fc31.riscv64                   | /usr/lib64/ladspa/amp.so
 ladspa-1.13-23.fc31.riscv64                   | /usr/lib64/ladspa/delay.so
 ladspa-1.13-23.fc31.riscv64                   | /usr/lib64/ladspa/filter.so
 ladspa-1.13-23.fc31.riscv64                   | /usr/lib64/ladspa/noise.so
 ladspa-autotalent-plugins-0.2-20.fc31.riscv64 | /usr/lib64/ladspa/autotalent.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/adsr_1653.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/adsr_1680.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/amp_1654.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/blop_files/parabola_1649_data.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/blop_files/sawtooth_1641_data.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/blop_files/square_1643_data.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/branch_1673.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/dahdsr_2021.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/difference_2030.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/fmod_1656.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/interpolator_1660.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/lp4pole_1671.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/product_1668.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/pulse_1645.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/quantiser100_2029.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/quantiser20_2027.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/quantiser50_2028.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/random_1661.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/ratio_2034.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/sawtooth_1641.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/sequencer16_1677.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/sequencer32_1676.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/sequencer64_1675.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/square_1643.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/sum_1665.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/sync_pulse_2023.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/sync_square_1678.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/tracker_2025.so
 ladspa-blop-plugins-0.2.8-26.fc31.riscv64     | /usr/lib64/ladspa/triangle_1649.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_autopan.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_chorusflanger.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_deesser.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_doubler.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_dynamics_m.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_dynamics_st.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_echo.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_eq.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_eqbw.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_limiter.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_pinknoise.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_pitch.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_reflector.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_reverb.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_rotspeak.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_sigmoid.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_tremolo.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_tubewarmth.so
 ladspa-tap-plugins-0.7.0-24.fc31.riscv64      | /usr/lib64/ladspa/tap_vibrato.so
 ladspa-wasp-plugins-0.9.7-10.fc31.riscv64     | /usr/lib64/ladspa/libwasp_booster.so
 ladspa-wasp-plugins-0.9.7-10.fc31.riscv64     | /usr/lib64/ladspa/libwasp_noisifier.so
 ladspa-wasp-plugins-0.9.7-10.fc31.riscv64     | /usr/lib64/ladspa/libwasp_xshaper.so
 nekobee-dssi-0.1.7-22.fc31.riscv64            | /usr/lib64/dssi/nekobee.so
 numactl-libs-2.0.12-3.fc32.riscv64            | /usr/lib64/libnuma.so.1.0.0
 sblim-cmpi-rpm-1.0.1-25.fc31.riscv64          | /usr/lib64/libcimrpm.so.0.0.0
 sblim-cmpi-rpm-1.0.1-25.fc31.riscv64          | /usr/lib64/libcimrpmv4.so.0.0.0
(62 rows)

So there are a few packages which have been built in such a way that
they have a DT_INIT tag.

I don't know if this qualifies as use, and I haven't disassembled the
objects to see if the init routine does anything meaningful.

Thoughts?  Should we still label RISC-V as an !ELF_INITFINI
architecture?

Thanks,
Florian

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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

Jim Wilson-2
On Fri, Feb 21, 2020 at 10:34 AM Florian Weimer <[hidden email]> wrote:
> So there are a few packages which have been built in such a way that
> they have a DT_INIT tag.

I looked at numactl.  In the Makefile.am I see
    -Wl,-init,numa_init -Wl,-fini,numa_fini
So the DT_INIT and DT_FINI are doing something useful, but can be
fixed by porting the package to use init_array/fini_array instead, or
maybe adding some trickiness to the linker.  But I'd rather the
package be fixed, and that the linker should give an error when -init
or -fini are used.

It is at least the intent that we don't have init/fini support for
RISC-V, and we should drop DT_INIT if we can do so without causing an
ABI break.  It looks like glibc is the only important package with
DT_INIT so maybe that is the only one we have to worry about.

> Thoughts?  Should we still label RISC-V as an !ELF_INITFINI
> architecture?

I created an ABI issue to start a discussion with other RISC-V developers
    https://github.com/riscv/riscv-elf-psabi-doc/issues/132

Jim
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Re: [PATCH] Introduce <elf-initfini.h> and ELF_INITFINI for all architectures

David Abdurachmanov-2
In reply to this post by Florian Weimer-5
On Fri, Feb 21, 2020 at 2:42 PM Florian Weimer <[hidden email]> wrote:

>
> * Jim Wilson:
>
> > On Thu, Feb 20, 2020 at 10:53 AM Florian Weimer <[hidden email]> wrote:
> >> That's because libc.so.6 still has DT_INIT, from which _environ and
> >> other variables are set up.  I assumed binutils would convert that into
> >> DT_INITARRAY because the architecture is not supposed to have DT_INIT.
> >> Without that, it's hard to declare that there is no DT_INIT, and the
> >> patch essentially breaks ABI (because DT_INIT processing is gone).
> >
> > DT_INIT is a function address.  DT_INITARRAY is a pointer to a table
> > of addresses.  I don't see how the linker can easily convert between
> > them.  We would have to increase the size of the init_array table at
> > link time, and I don't think we have any linker support for that.
> > Maybe we could modify the startfiles to put a weak reference to _init
> > at the end of init_array, right before the zero that normally ends the
> > list, and fix the linker to stop creating DT_INIT for _init.  But that
> > sounds a little risky, and defeats the purpose of dropping support for
> > _init to reduce code size.  I would prefer that glibc not create an
> > _init function in the first place.
>
> I'm not worried about glibc here.  It's easy to make glibc consistent
> with itself.  The patch I posted seems to do the trick, without
> regressing anywhere else.
>
> What I don't know is whether this binutils bug has resulted in DT_INIT
> being used *elsewhere*.  I don't have a RISC-V distribution to analyze,
> so I really don't know.  Fedora RISC-V seems dead, this hasn't been
> updated in a while:
>
>   <https://dl.fedoraproject.org/pub/alt/risc-v/repo/fedora/rawhide/latest/riscv64/>
>

We are still alive, but the mirroring of the repository to
dl.fedoraproject.org was disabled.
I will look into enabling it again.