From 75738c297badd8ef64075f9aebcb5aaef9e03c24 Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@linux-m68k.org>
Date: Tue, 26 Feb 2002 22:12:49 +0000
Subject: 	* config/m68k/tm-linux.h (FRAME_SAVED_PC): Define as 
 m68k_linux_frame_saved_pc. 	(IN_SIGTRAMP): Define as
 m68k_linux_in_sigtramp instead of 	in_sigtramp. 
 (SIGCONTEXT_PC_OFFSET): Remove. 	* m68klinux-nat.c
 (m68k_linux_frame_saved_pc, 	m68k_linux_sigtramp_saved_pc): New functions. 
 (IS_SIGTRAMP, IS_RT_SIGTRAMP): Define. 	(SIGCONTEXT_PC_OFFSET): Moved
 here from config/m68k/tm-linux.h. 	(UCONTEXT_PC_OFFSET): Define. 
 (m68k_linux_in_sigtramp): Renamed from in_sigtramp, handle both 	non-RT
 and RT signal trampolines.

---
 gdb/m68klinux-nat.c | 102 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 82 insertions(+), 20 deletions(-)

(limited to 'gdb/m68klinux-nat.c')

diff --git a/gdb/m68klinux-nat.c b/gdb/m68klinux-nat.c
index ffb5532..10f4a19 100644
--- a/gdb/m68klinux-nat.c
+++ b/gdb/m68klinux-nat.c
@@ -594,40 +594,102 @@ kernel_u_size (void)
   return (sizeof (struct user));
 }
 
-/* Return non-zero if PC points into the signal trampoline.  */
+/* Check whether insn1 and insn2 are parts of a signal trampoline.  */
+
+#define IS_SIGTRAMP(insn1, insn2)					\
+  (/* addaw #20,sp; moveq #119,d0; trap #0 */				\
+   (insn1 == 0xdefc0014 && insn2 == 0x70774e40)				\
+   /* moveq #119,d0; trap #0 */						\
+   || insn1 == 0x70774e40)
+
+#define IS_RT_SIGTRAMP(insn1, insn2)					\
+  (/* movel #173,d0; trap #0 */						\
+   (insn1 == 0x203c0000 && insn2 == 0x00ad4e40)				\
+   /* moveq #82,d0; notb d0; trap #0 */					\
+   || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
+
+/* Return non-zero if PC points into the signal trampoline.  For the sake
+   of m68k_linux_frame_saved_pc we also distinguish between non-RT and RT
+   signal trampolines.  */
 
 int
-in_sigtramp (CORE_ADDR pc)
+m68k_linux_in_sigtramp (CORE_ADDR pc)
 {
   CORE_ADDR sp;
-  char buf[TARGET_SHORT_BIT / TARGET_CHAR_BIT];
-  int insn;
+  char buf[12];
+  unsigned long insn0, insn1, insn2;
 
-  sp = read_register (SP_REGNUM);
-  if (pc - 2 < sp)
+  if (read_memory_nobpt (pc - 4, buf, sizeof (buf)))
     return 0;
+  insn1 = extract_unsigned_integer (buf + 4, 4);
+  insn2 = extract_unsigned_integer (buf + 8, 4);
+  if (IS_SIGTRAMP (insn1, insn2))
+    return 1;
+  if (IS_RT_SIGTRAMP (insn1, insn2))
+    return 2;
 
-  if (read_memory_nobpt (pc, buf, sizeof (buf)))
-    return 0;
-  insn = extract_unsigned_integer (buf, sizeof (buf));
-  if (insn == 0xdefc		/* addaw #,sp */
-      || insn == 0x7077		/* moveq #119,d0 */
-      || insn == 0x4e40		/* trap #0 */
-      || insn == 0x203c /* movel #,d0 */ )
+  insn0 = extract_unsigned_integer (buf, 4);
+  if (IS_SIGTRAMP (insn0, insn1))
     return 1;
+  if (IS_RT_SIGTRAMP (insn0, insn1))
+    return 2;
 
-  if (read_memory_nobpt (pc - 2, buf, sizeof (buf)))
-    return 0;
-  insn = extract_unsigned_integer (buf, sizeof (buf));
-  if (insn == 0xdefc		/* addaw #,sp */
-      || insn == 0x7077		/* moveq #119,d0 */
-      || insn == 0x4e40		/* trap #0 */
-      || insn == 0x203c /* movel #,d0 */ )
+  insn0 = (insn0 << 16) | (insn1 >> 16);
+  insn1 = (insn1 << 16) | (insn2 >> 16);
+  if (IS_SIGTRAMP (insn0, insn1))
     return 1;
+  if (IS_RT_SIGTRAMP (insn0, insn1))
+    return 2;
 
   return 0;
 }
 
+/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
+#define SIGCONTEXT_PC_OFFSET 26
+
+/* Offset to saved PC in ucontext, from <asm/ucontext.h>.  */
+#define UCONTEXT_PC_OFFSET 88
+
+/* Get saved user PC for sigtramp from sigcontext or ucontext.  */
+
+static CORE_ADDR
+m68k_linux_sigtramp_saved_pc (struct frame_info *frame)
+{
+  CORE_ADDR sigcontext_addr;
+  char buf[TARGET_PTR_BIT / TARGET_CHAR_BIT];
+  int ptrbytes = TARGET_PTR_BIT / TARGET_CHAR_BIT;
+  int sigcontext_offs = (2 * TARGET_INT_BIT) / TARGET_CHAR_BIT;
+
+  /* Get sigcontext address, it is the third parameter on the stack.  */
+  if (frame->next)
+    sigcontext_addr = read_memory_integer (FRAME_ARGS_ADDRESS (frame->next)
+					   + FRAME_ARGS_SKIP
+					   + sigcontext_offs,
+					   ptrbytes);
+  else
+    sigcontext_addr = read_memory_integer (read_register (SP_REGNUM)
+					   + sigcontext_offs,
+					   ptrbytes);
+
+  /* Don't cause a memory_error when accessing sigcontext in case the
+     stack layout has changed or the stack is corrupt.  */
+  if (m68k_linux_in_sigtramp (frame->pc) == 2)
+    target_read_memory (sigcontext_addr + UCONTEXT_PC_OFFSET, buf, ptrbytes);
+  else
+    target_read_memory (sigcontext_addr + SIGCONTEXT_PC_OFFSET, buf, ptrbytes);
+  return extract_unsigned_integer (buf, ptrbytes);
+}
+
+/* Return the saved program counter for FRAME.  */
+
+CORE_ADDR
+m68k_linux_frame_saved_pc (struct frame_info *frame)
+{
+  if (frame->signal_handler_caller)
+    return m68k_linux_sigtramp_saved_pc (frame);
+
+  return read_memory_integer (frame->frame + 4, 4);
+}
 
 /* Register that we are able to handle GNU/Linux ELF core file
    formats.  */
-- 
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