[commit] Remove unused function in ppc-linux-nat.c

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[commit] Remove unused function in ppc-linux-nat.c

Ulrich Weigand
Hello,

this patch removes the never-used ppc_linux_in_sigtramp routine and
its subroutines.  This has been superseded by sigtramp frame sniffers.

Tested on powerpc-linux.  Committed to mainline.

Bye,
Ulrich

ChangeLog:

        * ppc-linux-tdep.c (INSTR_SC, INSTR_LI_R0_0x6666, INSTR_LI_R0_0x7777,
        INSTR_LI_R0_NR_sigreturn, INSTR_LI_R0_NR_rt_sigreturn): Remove.
        (PPC_LINUX_SIGNAL_FRAMESIZE, PPC_LINUX_REGS_PTR_OFFSET,
        PPC_LINUX_HANDLER_PTR_OFFSET): Remove.
        (ppc_linux_in_sigtramp, insn_is_sigreturn,
        ppc_linux_at_sigtramp_return_path): Remove.


diff -urNp gdb-orig/gdb/ppc-linux-tdep.c gdb-head/gdb/ppc-linux-tdep.c
--- gdb-orig/gdb/ppc-linux-tdep.c 2007-05-14 17:01:20.000000000 +0200
+++ gdb-head/gdb/ppc-linux-tdep.c 2007-05-15 20:19:36.131691396 +0200
@@ -40,33 +40,6 @@
 #include "frame-unwind.h"
 #include "tramp-frame.h"
 
-/* The following instructions are used in the signal trampoline code
-   on GNU/Linux PPC. The kernel used to use magic syscalls 0x6666 and
-   0x7777 but now uses the sigreturn syscalls.  We check for both.  */
-#define INSTR_LI_R0_0x6666 0x38006666
-#define INSTR_LI_R0_0x7777 0x38007777
-#define INSTR_LI_R0_NR_sigreturn 0x38000077
-#define INSTR_LI_R0_NR_rt_sigreturn 0x380000AC
-
-#define INSTR_SC 0x44000002
-
-/* Since the *-tdep.c files are platform independent (i.e, they may be
-   used to build cross platform debuggers), we can't include system
-   headers.  Therefore, details concerning the sigcontext structure
-   must be painstakingly rerecorded.  What's worse, if these details
-   ever change in the header files, they'll have to be changed here
-   as well. */
-
-/* __SIGNAL_FRAMESIZE from <asm/ptrace.h> */
-#define PPC_LINUX_SIGNAL_FRAMESIZE 64
-
-/* From <asm/sigcontext.h>, offsetof(struct sigcontext_struct, regs) == 0x1c */
-#define PPC_LINUX_REGS_PTR_OFFSET (PPC_LINUX_SIGNAL_FRAMESIZE + 0x1c)
-
-/* From <asm/sigcontext.h>,
-   offsetof(struct sigcontext_struct, handler) == 0x14 */
-#define PPC_LINUX_HANDLER_PTR_OFFSET (PPC_LINUX_SIGNAL_FRAMESIZE + 0x14)
-
 /* From <asm/ptrace.h>, values for PT_NIP, PT_R1, and PT_LNK */
 #define PPC_LINUX_PT_R0 0
 #define PPC_LINUX_PT_R1 1
@@ -111,116 +84,6 @@
 #define PPC_LINUX_PT_FPR31 (PPC_LINUX_PT_FPR0 + 2*31)
 #define PPC_LINUX_PT_FPSCR (PPC_LINUX_PT_FPR0 + 2*32 + 1)
 
-static int ppc_linux_at_sigtramp_return_path (CORE_ADDR pc);
-
-/* Determine if pc is in a signal trampoline...
-
-   Ha!  That's not what this does at all.  wait_for_inferior in
-   infrun.c calls get_frame_type() in order to detect entry into a
-   signal trampoline just after delivery of a signal.  But on
-   GNU/Linux, signal trampolines are used for the return path only.
-   The kernel sets things up so that the signal handler is called
-   directly.
-
-   If we use in_sigtramp2() in place of in_sigtramp() (see below)
-   we'll (often) end up with stop_pc in the trampoline and prev_pc in
-   the (now exited) handler.  The code there will cause a temporary
-   breakpoint to be set on prev_pc which is not very likely to get hit
-   again.
-
-   If this is confusing, think of it this way...  the code in
-   wait_for_inferior() needs to be able to detect entry into a signal
-   trampoline just after a signal is delivered, not after the handler
-   has been run.
-
-   So, we define in_sigtramp() below to return 1 if the following is
-   true:
-
-   1) The previous frame is a real signal trampoline.
-
-   - and -
-
-   2) pc is at the first or second instruction of the corresponding
-   handler.
-
-   Why the second instruction?  It seems that wait_for_inferior()
-   never sees the first instruction when single stepping.  When a
-   signal is delivered while stepping, the next instruction that
-   would've been stepped over isn't, instead a signal is delivered and
-   the first instruction of the handler is stepped over instead.  That
-   puts us on the second instruction.  (I added the test for the first
-   instruction long after the fact, just in case the observed behavior
-   is ever fixed.)  */
-
-int
-ppc_linux_in_sigtramp (CORE_ADDR pc, char *func_name)
-{
-  CORE_ADDR lr;
-  CORE_ADDR sp;
-  CORE_ADDR tramp_sp;
-  gdb_byte buf[4];
-  CORE_ADDR handler;
-
-  lr = read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum);
-  if (!ppc_linux_at_sigtramp_return_path (lr))
-    return 0;
-
-  sp = read_register (SP_REGNUM);
-
-  if (target_read_memory (sp, buf, sizeof (buf)) != 0)
-    return 0;
-
-  tramp_sp = extract_unsigned_integer (buf, 4);
-
-  if (target_read_memory (tramp_sp + PPC_LINUX_HANDLER_PTR_OFFSET, buf,
-  sizeof (buf)) != 0)
-    return 0;
-
-  handler = extract_unsigned_integer (buf, 4);
-
-  return (pc == handler || pc == handler + 4);
-}
-
-static int
-insn_is_sigreturn (unsigned long pcinsn)
-{
-  switch(pcinsn)
-    {
-    case INSTR_LI_R0_0x6666:
-    case INSTR_LI_R0_0x7777:
-    case INSTR_LI_R0_NR_sigreturn:
-    case INSTR_LI_R0_NR_rt_sigreturn:
-      return 1;
-    default:
-      return 0;
-    }
-}
-
-/*
- * The signal handler trampoline is on the stack and consists of exactly
- * two instructions.  The easiest and most accurate way of determining
- * whether the pc is in one of these trampolines is by inspecting the
- * instructions.  It'd be faster though if we could find a way to do this
- * via some simple address comparisons.
- */
-static int
-ppc_linux_at_sigtramp_return_path (CORE_ADDR pc)
-{
-  gdb_byte buf[12];
-  unsigned long pcinsn;
-  if (target_read_memory (pc - 4, buf, sizeof (buf)) != 0)
-    return 0;
-
-  /* extract the instruction at the pc */
-  pcinsn = extract_unsigned_integer (buf + 4, 4);
-
-  return (
-   (insn_is_sigreturn (pcinsn)
-    && extract_unsigned_integer (buf + 8, 4) == INSTR_SC)
-   ||
-   (pcinsn == INSTR_SC
-    && insn_is_sigreturn (extract_unsigned_integer (buf, 4))));
-}
 
 static CORE_ADDR
 ppc_linux_skip_trampoline_code (CORE_ADDR pc)
--
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  [hidden email]