2004-06-22  Andrew Cagney  <cagney@gnu.org>

	* rs6000-tdep.c (struct rs6000_framedata): Add field "func_start".

	(skip_prologue): Delete local variable "orig_pc", use

	"func_start".  Add local variable "num_skip_linux_syscall_insn",

	use to skip over first half of a GNU/Linux syscall and update

	"func_start".

Index: ./gdb/rs6000-tdep.c

===================================================================

RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v

retrieving revision 1.215

diff -p -u -r1.215 rs6000-tdep.c

--- ./gdb/rs6000-tdep.c	20 Jun 2004 17:18:06 -0000	1.215

+++ ./gdb/rs6000-tdep.c	22 Jun 2004 19:06:46 -0000

@@ -71,6 +71,7 @@

 struct rs6000_framedata

   {

+    CORE_ADDR func_start;	/* True function start.  */

     int offset;			/* total size of frame --- the distance

 				   by which we decrement sp to allocate

 				   the frame */

@@ -694,7 +695,6 @@ store_param_on_stack_p (unsigned long op

 static CORE_ADDR

 skip_prologue (CORE_ADDR pc, CORE_ADDR lim_pc, struct rs6000_framedata *fdata)

 {

-  CORE_ADDR orig_pc = pc;

   CORE_ADDR last_prologue_pc = pc;

   CORE_ADDR li_found_pc = 0;

   char buf[4];

@@ -712,6 +712,7 @@ skip_prologue (CORE_ADDR pc, CORE_ADDR l

   int minimal_toc_loaded = 0;

   int prev_insn_was_prologue_insn = 1;

   int num_skip_non_prologue_insns = 0;

+  int num_skip_ppc64_gnu_linux_syscall_insn = 0;

   int r0_contains_arg = 0;

   const struct bfd_arch_info *arch_info = gdbarch_bfd_arch_info (current_gdbarch);

   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);

@@ -732,6 +733,7 @@ skip_prologue (CORE_ADDR pc, CORE_ADDR l

     lim_pc = refine_prologue_limit (pc, lim_pc);

   memset (fdata, 0, sizeof (struct rs6000_framedata));

+  fdata->func_start = pc;

   fdata->saved_gpr = -1;

   fdata->saved_fpr = -1;

   fdata->saved_vr = -1;

@@ -760,6 +762,55 @@ skip_prologue (CORE_ADDR pc, CORE_ADDR l

 	break;

       op = extract_signed_integer (buf, 4);

+      /* A PPC64 GNU/Linux system call function is split into two

+	 sub-functions: a non-threaded fast-path (__NAME_nocancel)

+	 which does not use a frame; and a threaded slow-path

+	 (Lpseudo_cancel) that does create a frame.  Ref:

+	 nptl/sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep-cancel.h

+

+	 *INDENT-OFF*

+	 NAME:

+	 	SINGLE_THREAD_P

+	 	bne- .Lpseudo_cancel

+	 __NAME_nocancel:

+	 	li r0,162

+	 	sc

+	 	bnslr+

+	 	b 0x7fe014ef64 <.__syscall_error>

+	 Lpseudo_cancel:

+	 	stdu r1,-128(r1)

+	 	...

+	 *INDENT-ON*

+

+	 Unfortunatly, because the latter case uses a local label (not

+	 in the symbol table) a PC in "Lpseudo_cancel" appears to be

+	 in "__NAME_nocancel".  The following code recognizes this,

+	 adjusting FUNC_START to point to where "Lpseudo_cancel"

+	 should be, and parsing the prologue sequence as if

+	 "Lpseudo_cancel" was the entry point.  */

+

+      if (((op & 0xffff0000) == 0x38000000 /* li r0,N */

+	   && pc == fdata->func_start + 0

+	   && num_skip_ppc64_gnu_linux_syscall_insn == 0)

+	  || (op == 0x44000002 /* sc */

+	      && pc == fdata->func_start + 4

+	      && num_skip_ppc64_gnu_linux_syscall_insn == 1)

+	  || (op == 0x4ca30020 /* bnslr+ */

+	      && pc == fdata->func_start + 8

+	      && num_skip_ppc64_gnu_linux_syscall_insn == 2))

+	{

+	  num_skip_ppc64_gnu_linux_syscall_insn++;

+	  continue;

+	}

+      else if ((op & 0xfc000003) == 0x48000000 /* b __syscall_error */

+	       && pc == fdata->func_start + 12

+	       && num_skip_ppc64_gnu_linux_syscall_insn == 3)

+	{

+	  num_skip_ppc64_gnu_linux_syscall_insn = -1;

+	  fdata->func_start = pc;

+	  continue;

+	}

+

       if ((op & 0xfc1fffff) == 0x7c0802a6)

 	{			/* mflr Rx */

 	  /* Since shared library / PIC code, which needs to get its

@@ -913,7 +964,7 @@ skip_prologue (CORE_ADDR pc, CORE_ADDR l

 	  fdata->frameless = 0;

 	  /* Don't skip over the subroutine call if it is not within

 	     the first three instructions of the prologue.  */

-	  if ((pc - orig_pc) > 8)

+	  if ((pc - fdata->func_start) > 8)

 	    break;

 	  op = read_memory_integer (pc + 4, 4);