[rfc] Improve NetBSD/i386 signal trampoline detection

[rfc] Improve NetBSD/i386 signal trampoline detection

[Nick Hudson]

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Hi,

I put together this patch to improve NetBSD/i386 signal trampoline detection. 
I believe tramp_frame is a better and preferred method.

I think I need to add the instructions for when the setcontext/sigreturn fails 
as well. Is this correct?

Any/all comments appreciated.

Thanks,
Nick

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Index: gdb/i386nbsd-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/i386nbsd-tdep.c,v
retrieving revision 1.33
diff -u -p -u -r1.33 i386nbsd-tdep.c
--- gdb/i386nbsd-tdep.c	23 Aug 2007 18:08:34 -0000	1.33
+++ gdb/i386nbsd-tdep.c	2 Oct 2007 10:39:21 -0000
@@ -26,6 +26,8 @@
 #include "regset.h"
 #include "osabi.h"
 #include "symtab.h"
+#include "trad-frame.h"
+#include "tramp-frame.h"
 
 #include "gdb_assert.h"
 #include "gdb_string.h"
@@ -91,109 +93,6 @@ i386nbsd_aout_regset_from_core_section (
   return NULL;
 }
 
-/* Under NetBSD/i386, signal handler invocations can be identified by the
-   designated code sequence that is used to return from a signal handler.
-   In particular, the return address of a signal handler points to the
-   following code sequence:
-
-	leal	0x10(%esp), %eax
-	pushl	%eax
-	pushl	%eax
-	movl	$0x127, %eax		# __sigreturn14
-	int	$0x80
-
-   Each instruction has a unique encoding, so we simply attempt to match
-   the instruction the PC is pointing to with any of the above instructions.
-   If there is a hit, we know the offset to the start of the designated
-   sequence and can then check whether we really are executing in the
-   signal trampoline.  If not, -1 is returned, otherwise the offset from the
-   start of the return sequence is returned.  */
-#define RETCODE_INSN1		0x8d
-#define RETCODE_INSN2		0x50
-#define RETCODE_INSN3		0x50
-#define RETCODE_INSN4		0xb8
-#define RETCODE_INSN5		0xcd
-
-#define RETCODE_INSN2_OFF	4
-#define RETCODE_INSN3_OFF	5
-#define RETCODE_INSN4_OFF	6
-#define RETCODE_INSN5_OFF	11
-
-static const unsigned char sigtramp_retcode[] =
-{
-  RETCODE_INSN1, 0x44, 0x24, 0x10,
-  RETCODE_INSN2,
-  RETCODE_INSN3,
-  RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
-  RETCODE_INSN5, 0x80,
-};
-
-static LONGEST
-i386nbsd_sigtramp_offset (struct frame_info *next_frame)
-{
-  CORE_ADDR pc = frame_pc_unwind (next_frame);
-  unsigned char ret[sizeof(sigtramp_retcode)], insn;
-  LONGEST off;
-  int i;
-
-  if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
-    return -1;
-
-  switch (insn)
-    {
-    case RETCODE_INSN1:
-      off = 0;
-      break;
-
-    case RETCODE_INSN2:
-      /* INSN2 and INSN3 are the same.  Read at the location of PC+1
-	 to determine if we're actually looking at INSN2 or INSN3.  */
-      if (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
-	return -1;
-
-      if (insn == RETCODE_INSN3)
-	off = RETCODE_INSN2_OFF;
-      else
-	off = RETCODE_INSN3_OFF;
-      break;
-
-    case RETCODE_INSN4:
-      off = RETCODE_INSN4_OFF;
-      break;
-
-    case RETCODE_INSN5:
-      off = RETCODE_INSN5_OFF;
-      break;
-
-    default:
-      return -1;
-    }
-
-  pc -= off;
-
-  if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
-    return -1;
-
-  if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
-    return off;
-
-  return -1;
-}
-
-/* Return whether the frame preceding NEXT_FRAME corresponds to a
-   NetBSD sigtramp routine.  */
-
-static int
-i386nbsd_sigtramp_p (struct frame_info *next_frame)
-{
-  CORE_ADDR pc = frame_pc_unwind (next_frame);
-  char *name;
-
-  find_pc_partial_function (pc, &name, NULL, NULL);
-  return (nbsd_pc_in_sigtramp (pc, name)
-	  || i386nbsd_sigtramp_offset (next_frame) >= 0);
-}
-
 /* From <machine/signal.h>.  */
 int i386nbsd_sc_reg_offset[] =
 {
@@ -215,31 +114,176 @@ int i386nbsd_sc_reg_offset[] =
   0 * 4				/* %gs */
 };
 
+/* From <machine/mcontext.h>.  */
+int i386nbsd_mc_reg_offset[] =
+{
+  11 * 4,			/* %eax */
+  10 * 4,			/* %ecx */
+  9 * 4,			/* %edx */
+  8 * 4,			/* %ebx */
+  7 * 4,			/* %esp */
+  6 * 4,			/* %ebp */
+  5 * 4,			/* %esi */
+  4 * 4,			/* %edi */
+  14 * 4,			/* %eip */
+  16 * 4,			/* %eflags */
+  15 * 4,			/* %cs */
+  18 * 4,			/* %ss */
+  3 * 4,			/* %ds */
+  2 * 4,			/* %es */
+  1 * 4,			/* %fs */
+  0 * 4				/* %gs */
+};
+
+
+static void
+i386nbsd_sigtramp_cache_init (const struct tramp_frame *,
+			     struct frame_info *,
+			     struct trad_frame_cache *,
+			     CORE_ADDR);
+
+static const struct tramp_frame i386nbsd_sigtramp1 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x10, -1 },
+			/* leal  0x10(%esp), %eax */
+    { 0x50, -1 },	/* pushl %eax */
+    { 0x50, -1 },	/* pushl %eax */
+    { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x127, %eax		# __sigreturn14 */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+static const struct tramp_frame i386nbsd_sigtramp2 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x0c, -1 },
+			/* leal  0x0c(%esp), %eax */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x127, %eax		# __sigreturn14 */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+static const struct tramp_frame i386nbsd_sigtramp3 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8b, -1}, { 0x44, -1}, { 0x24, -1}, { 0x08, -1},
+			/* movl  8(%esp),%eax */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* movl  $0x134, %eax            # setcontext */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    /* more... */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+
+static const struct tramp_frame i386nbsd_sigtramp4 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
+        { 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* leal  0x8c(%esp), %eax */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* movl  $0x134, %eax            # setcontext */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    /* more... */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+static void
+i386nbsd_sigtramp_cache_init (const struct tramp_frame *self,
+			     struct frame_info *next_frame,
+			     struct trad_frame_cache *this_cache,
+			     CORE_ADDR func)
+{
+  struct gdbarch *gdbarch = get_frame_arch (next_frame);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  CORE_ADDR sp = frame_unwind_register_unsigned (next_frame, I386_ESP_REGNUM);
+  CORE_ADDR base;
+  int *reg_offset;
+  int num_regs;
+  int i;
+
+  if (self == &i386nbsd_sigtramp1 || self == &i386nbsd_sigtramp2)
+    {
+      reg_offset = i386nbsd_sc_reg_offset;
+      num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
+
+      /* Read in the sigcontext address */
+      base = read_memory_unsigned_integer (sp + 8, 4);
+    }
+  else
+    {
+      reg_offset = i386nbsd_mc_reg_offset;
+      num_regs = ARRAY_SIZE (i386nbsd_mc_reg_offset);
+
+      /* Read in the ucontext address */
+      base = read_memory_unsigned_integer (sp + 8, 4);
+      /* offsetof(ucontext_t, uc_mcontext) == 36 */
+      base += 36;
+    }
+
+  for (i = 0; i < num_regs; i++)
+    if (reg_offset[i] != -1)
+      trad_frame_set_reg_addr (this_cache, i, base + reg_offset[i]);
+
+  /* Construct the frame ID using the function start.  */
+  trad_frame_set_id (this_cache, frame_id_build (sp, func));
+}
+
 static void 
 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 
-  /* Obviously NetBSD is BSD-based.  */
-  i386bsd_init_abi (info, gdbarch);
-
   /* NetBSD has a different `struct reg'.  */
   tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
   tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
   tdep->sizeof_gregset = 16 * 4;
 
-  /* NetBSD has different signal trampoline conventions.  */
-  tdep->sigtramp_start = 0;
-  tdep->sigtramp_end = 0;
-  tdep->sigtramp_p = i386nbsd_sigtramp_p;
-
   /* NetBSD uses -freg-struct-return by default.  */
   tdep->struct_return = reg_struct_return;
 
-  /* NetBSD has a `struct sigcontext' that's different from the
-     original 4.3 BSD.  */
-  tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
-  tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
+  /* NetBSD uses tramp_frame sniffers for signal trampolines. */
+  tdep->sigcontext_addr = 0;
+  tdep->sigtramp_start = 0;
+  tdep->sigtramp_end = 0;
+  tdep->sigtramp_p = 0;
+  tdep->sc_reg_offset = 0;
+  tdep->sc_num_regs = 0;
+
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp1);
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp2);
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp3);
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp4);
 }
 
 /* NetBSD a.out.  */
Index: gdb/tramp-frame.h
===================================================================
RCS file: /cvs/src/src/gdb/tramp-frame.h,v
retrieving revision 1.9
diff -u -p -u -r1.9 tramp-frame.h
--- gdb/tramp-frame.h	23 Aug 2007 18:08:46 -0000	1.9
+++ gdb/tramp-frame.h	2 Oct 2007 10:39:23 -0000
@@ -62,7 +62,7 @@ struct tramp_frame
   {
     ULONGEST bytes;
     ULONGEST mask;
-  } insn[16];
+  } insn[32];
   /* Initialize a trad-frame cache corresponding to the tramp-frame.
      FUNC is the address of the instruction TRAMP[0] in memory.  */
   void (*init) (const struct tramp_frame *self,

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Daniel Jacobowitz]

On Tue, Oct 02, 2007 at 12:07:15PM +0100, Nick Hudson wrote:
> Hi,
> 
> I put together this patch to improve NetBSD/i386 signal trampoline detection. 
> I believe tramp_frame is a better and preferred method.
> 
> I think I need to add the instructions for when the setcontext/sigreturn fails 
> as well. Is this correct?
> 
> Any/all comments appreciated.

Trivial comments: you've added #includes so Makefile.in needs an
update (maybe I'll do automatic dependencies sometime soon); please
include a ChangeLog with all patches; do you have a copyright
assignment?

Does this fix a problem, or are you just cleaning up?

As for the patch itself I'm hoping Mark Kettenis can look at it; he's
both the i386 port and FreeBSD maintainer, which is not all that close
to an i386-netbsd maintainer but it's the closest we have.

-- 
Daniel Jacobowitz
CodeSourcery

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Nick Hudson]

On Thursday 11 October 2007 19:04:28 Daniel Jacobowitz wrote:
> On Tue, Oct 02, 2007 at 12:07:15PM +0100, Nick Hudson wrote:
> > Hi,
> >
> > I put together this patch to improve NetBSD/i386 signal trampoline
> > detection. I believe tramp_frame is a better and preferred method.
> >
> > I think I need to add the instructions for when the setcontext/sigreturn
> > fails as well. Is this correct?
> >
> > Any/all comments appreciated.
>
> Trivial comments: you've added #includes so Makefile.in needs an
> update (maybe I'll do automatic dependencies sometime soon);

I'll fix this

> please include a ChangeLog with all patches;

sure, but I was mostly checking I was going the right way.

> do you have a copyright assignment?

Yep.

> Does this fix a problem, or are you just cleaning up?

Both really. gdb doesn't understand the signal trampolines used by newer 
versions of NetBSD.

> As for the patch itself I'm hoping Mark Kettenis can look at it; he's
> both the i386 port and FreeBSD maintainer, which is not all that close
> to an i386-netbsd maintainer but it's the closest we have.

OK, thanks for the comments.

I'll post a new patch after I get Mark's comments.

Cheers,
Nick

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Mark Kettenis]

> From: Nick Hudson <nick.hudson@dsl.pipex.com>
> Date: Tue, 2 Oct 2007 12:07:15 +0100
> 
> Hi,
> 
> I put together this patch to improve NetBSD/i386 signal trampoline
> detection.  I believe tramp_frame is a better and preferred method.

I've been hesitant using tramp_frame on i386, since it doesn't have
fixed-length instructions.  This means that there is a chance of false
matches, because you're forced to set the instruction length to 1 byte
(like you do in your diff).

That said, the sequences in your diff are probably long enough to make
the chance of getting a false positive pretty slim.

> I think I need to add the instructions for when the
> setcontext/sigreturn fails as well. Is this correct?

Probably a good idea, since it makes the false positives even less
likely.

> 
> Any/all comments appreciated.

By not calling i386bsd_init_abi(), tdep->jb_pc_offset is no longer
set.  You could initialize tdep->jb_pc_offset in i386nbsd_init_abi(),
but I'd prefer leaving in the i386bsd_init_abi() call, because it
shows the inheritance structure a bit more clearly.

It'd also be nice to have some documentation about what versions of
NetBSD use which sigtramp code (best to stick to official releases
here).  Perhaps that information could be used to give somewhat more
meaningfull names to the tramp_frame varaibles.

> Index: gdb/i386nbsd-tdep.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/i386nbsd-tdep.c,v
> retrieving revision 1.33
> diff -u -p -u -r1.33 i386nbsd-tdep.c
> --- gdb/i386nbsd-tdep.c	23 Aug 2007 18:08:34 -0000	1.33
> +++ gdb/i386nbsd-tdep.c	2 Oct 2007 10:39:21 -0000
> @@ -26,6 +26,8 @@
>  #include "regset.h"
>  #include "osabi.h"
>  #include "symtab.h"
> +#include "trad-frame.h"
> +#include "tramp-frame.h"
>  
>  #include "gdb_assert.h"
>  #include "gdb_string.h"
> @@ -91,109 +93,6 @@ i386nbsd_aout_regset_from_core_section (
>    return NULL;
>  }
>  
> -/* Under NetBSD/i386, signal handler invocations can be identified by the
> -   designated code sequence that is used to return from a signal handler.
> -   In particular, the return address of a signal handler points to the
> -   following code sequence:
> -
> -	leal	0x10(%esp), %eax
> -	pushl	%eax
> -	pushl	%eax
> -	movl	$0x127, %eax		# __sigreturn14
> -	int	$0x80
> -
> -   Each instruction has a unique encoding, so we simply attempt to match
> -   the instruction the PC is pointing to with any of the above instructions.
> -   If there is a hit, we know the offset to the start of the designated
> -   sequence and can then check whether we really are executing in the
> -   signal trampoline.  If not, -1 is returned, otherwise the offset from the
> -   start of the return sequence is returned.  */
> -#define RETCODE_INSN1		0x8d
> -#define RETCODE_INSN2		0x50
> -#define RETCODE_INSN3		0x50
> -#define RETCODE_INSN4		0xb8
> -#define RETCODE_INSN5		0xcd
> -
> -#define RETCODE_INSN2_OFF	4
> -#define RETCODE_INSN3_OFF	5
> -#define RETCODE_INSN4_OFF	6
> -#define RETCODE_INSN5_OFF	11
> -
> -static const unsigned char sigtramp_retcode[] =
> -{
> -  RETCODE_INSN1, 0x44, 0x24, 0x10,
> -  RETCODE_INSN2,
> -  RETCODE_INSN3,
> -  RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
> -  RETCODE_INSN5, 0x80,
> -};
> -
> -static LONGEST
> -i386nbsd_sigtramp_offset (struct frame_info *next_frame)
> -{
> -  CORE_ADDR pc = frame_pc_unwind (next_frame);
> -  unsigned char ret[sizeof(sigtramp_retcode)], insn;
> -  LONGEST off;
> -  int i;
> -
> -  if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
> -    return -1;
> -
> -  switch (insn)
> -    {
> -    case RETCODE_INSN1:
> -      off = 0;
> -      break;
> -
> -    case RETCODE_INSN2:
> -      /* INSN2 and INSN3 are the same.  Read at the location of PC+1
> -	 to determine if we're actually looking at INSN2 or INSN3.  */
> -      if (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
> -	return -1;
> -
> -      if (insn == RETCODE_INSN3)
> -	off = RETCODE_INSN2_OFF;
> -      else
> -	off = RETCODE_INSN3_OFF;
> -      break;
> -
> -    case RETCODE_INSN4:
> -      off = RETCODE_INSN4_OFF;
> -      break;
> -
> -    case RETCODE_INSN5:
> -      off = RETCODE_INSN5_OFF;
> -      break;
> -
> -    default:
> -      return -1;
> -    }
> -
> -  pc -= off;
> -
> -  if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
> -    return -1;
> -
> -  if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
> -    return off;
> -
> -  return -1;
> -}
> -
> -/* Return whether the frame preceding NEXT_FRAME corresponds to a
> -   NetBSD sigtramp routine.  */
> -
> -static int
> -i386nbsd_sigtramp_p (struct frame_info *next_frame)
> -{
> -  CORE_ADDR pc = frame_pc_unwind (next_frame);
> -  char *name;
> -
> -  find_pc_partial_function (pc, &name, NULL, NULL);
> -  return (nbsd_pc_in_sigtramp (pc, name)
> -	  || i386nbsd_sigtramp_offset (next_frame) >= 0);
> -}
> -
>  /* From <machine/signal.h>.  */
>  int i386nbsd_sc_reg_offset[] =
>  {
> @@ -215,31 +114,176 @@ int i386nbsd_sc_reg_offset[] =
>    0 * 4				/* %gs */
>  };
>  
> +/* From <machine/mcontext.h>.  */
> +int i386nbsd_mc_reg_offset[] =
> +{
> +  11 * 4,			/* %eax */
> +  10 * 4,			/* %ecx */
> +  9 * 4,			/* %edx */
> +  8 * 4,			/* %ebx */
> +  7 * 4,			/* %esp */
> +  6 * 4,			/* %ebp */
> +  5 * 4,			/* %esi */
> +  4 * 4,			/* %edi */
> +  14 * 4,			/* %eip */
> +  16 * 4,			/* %eflags */
> +  15 * 4,			/* %cs */
> +  18 * 4,			/* %ss */
> +  3 * 4,			/* %ds */
> +  2 * 4,			/* %es */
> +  1 * 4,			/* %fs */
> +  0 * 4				/* %gs */
> +};
> +
> +
> +static void
> +i386nbsd_sigtramp_cache_init (const struct tramp_frame *,
> +			     struct frame_info *,
> +			     struct trad_frame_cache *,
> +			     CORE_ADDR);
> +
> +static const struct tramp_frame i386nbsd_sigtramp1 =
> +{
> +  SIGTRAMP_FRAME,
> +  1,
> +  {
> +    { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x10, -1 },
> +			/* leal  0x10(%esp), %eax */
> +    { 0x50, -1 },	/* pushl %eax */
> +    { 0x50, -1 },	/* pushl %eax */
> +    { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
> +			/* movl  $0x127, %eax		# __sigreturn14 */
> +    { 0xcd, -1 }, { 0x80, -1},
> +			/* int   $0x80 */
> +    { TRAMP_SENTINEL_INSN, -1 }
> +  },
> +  i386nbsd_sigtramp_cache_init
> +};
> +
> +static const struct tramp_frame i386nbsd_sigtramp2 =
> +{
> +  SIGTRAMP_FRAME,
> +  1,
> +  {
> +    { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x0c, -1 },
> +			/* leal  0x0c(%esp), %eax */
> +    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
> +			/* movl  %eax, 0x4(%esp) */
> +    { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
> +			/* movl  $0x127, %eax		# __sigreturn14 */
> +    { 0xcd, -1 }, { 0x80, -1},
> +			/* int   $0x80 */
> +    { TRAMP_SENTINEL_INSN, -1 }
> +  },
> +  i386nbsd_sigtramp_cache_init
> +};
> +
> +static const struct tramp_frame i386nbsd_sigtramp3 =
> +{
> +  SIGTRAMP_FRAME,
> +  1,
> +  {
> +    { 0x8b, -1}, { 0x44, -1}, { 0x24, -1}, { 0x08, -1},
> +			/* movl  8(%esp),%eax */
> +    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
> +			/* movl  %eax, 0x4(%esp) */
> +    { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
> +			/* movl  $0x134, %eax            # setcontext */
> +    { 0xcd, -1 }, { 0x80, -1},
> +			/* int   $0x80 */
> +    /* more... */
> +    { TRAMP_SENTINEL_INSN, -1 }
> +  },
> +  i386nbsd_sigtramp_cache_init
> +};
> +
> +
> +static const struct tramp_frame i386nbsd_sigtramp4 =
> +{
> +  SIGTRAMP_FRAME,
> +  1,
> +  {
> +    { 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
> +        { 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
> +			/* leal  0x8c(%esp), %eax */
> +    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
> +			/* movl  %eax, 0x4(%esp) */
> +    { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
> +			/* movl  $0x134, %eax            # setcontext */
> +    { 0xcd, -1 }, { 0x80, -1},
> +			/* int   $0x80 */
> +    /* more... */
> +    { TRAMP_SENTINEL_INSN, -1 }
> +  },
> +  i386nbsd_sigtramp_cache_init
> +};
> +
> +static void
> +i386nbsd_sigtramp_cache_init (const struct tramp_frame *self,
> +			     struct frame_info *next_frame,
> +			     struct trad_frame_cache *this_cache,
> +			     CORE_ADDR func)
> +{
> +  struct gdbarch *gdbarch = get_frame_arch (next_frame);
> +  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
> +  CORE_ADDR sp = frame_unwind_register_unsigned (next_frame, I386_ESP_REGNUM);
> +  CORE_ADDR base;
> +  int *reg_offset;
> +  int num_regs;
> +  int i;
> +
> +  if (self == &i386nbsd_sigtramp1 || self == &i386nbsd_sigtramp2)
> +    {
> +      reg_offset = i386nbsd_sc_reg_offset;
> +      num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
> +
> +      /* Read in the sigcontext address */
> +      base = read_memory_unsigned_integer (sp + 8, 4);
> +    }
> +  else
> +    {
> +      reg_offset = i386nbsd_mc_reg_offset;
> +      num_regs = ARRAY_SIZE (i386nbsd_mc_reg_offset);
> +
> +      /* Read in the ucontext address */
> +      base = read_memory_unsigned_integer (sp + 8, 4);
> +      /* offsetof(ucontext_t, uc_mcontext) == 36 */
> +      base += 36;
> +    }
> +
> +  for (i = 0; i < num_regs; i++)
> +    if (reg_offset[i] != -1)
> +      trad_frame_set_reg_addr (this_cache, i, base + reg_offset[i]);
> +
> +  /* Construct the frame ID using the function start.  */
> +  trad_frame_set_id (this_cache, frame_id_build (sp, func));
> +}
> +
>  static void 
>  i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
>  {
>    struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
>  
> -  /* Obviously NetBSD is BSD-based.  */
> -  i386bsd_init_abi (info, gdbarch);
> -
>    /* NetBSD has a different `struct reg'.  */
>    tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
>    tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
>    tdep->sizeof_gregset = 16 * 4;
>  
> -  /* NetBSD has different signal trampoline conventions.  */
> -  tdep->sigtramp_start = 0;
> -  tdep->sigtramp_end = 0;
> -  tdep->sigtramp_p = i386nbsd_sigtramp_p;
> -
>    /* NetBSD uses -freg-struct-return by default.  */
>    tdep->struct_return = reg_struct_return;
>  
> -  /* NetBSD has a `struct sigcontext' that's different from the
> -     original 4.3 BSD.  */
> -  tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
> -  tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
> +  /* NetBSD uses tramp_frame sniffers for signal trampolines. */
> +  tdep->sigcontext_addr = 0;
> +  tdep->sigtramp_start = 0;
> +  tdep->sigtramp_end = 0;
> +  tdep->sigtramp_p = 0;
> +  tdep->sc_reg_offset = 0;
> +  tdep->sc_num_regs = 0;
> +
> +  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp1);
> +  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp2);
> +  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp3);
> +  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp4);
>  }
>  
>  /* NetBSD a.out.  */
> Index: gdb/tramp-frame.h
> ===================================================================
> RCS file: /cvs/src/src/gdb/tramp-frame.h,v
> retrieving revision 1.9
> diff -u -p -u -r1.9 tramp-frame.h
> --- gdb/tramp-frame.h	23 Aug 2007 18:08:46 -0000	1.9
> +++ gdb/tramp-frame.h	2 Oct 2007 10:39:23 -0000
> @@ -62,7 +62,7 @@ struct tramp_frame
>    {
>      ULONGEST bytes;
>      ULONGEST mask;
> -  } insn[16];
> +  } insn[32];
>    /* Initialize a trad-frame cache corresponding to the tramp-frame.
>       FUNC is the address of the instruction TRAMP[0] in memory.  */
>    void (*init) (const struct tramp_frame *self,
> 
> --Boundary-00=_kZiAH4vl3ZRjugd--
> 

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Nick Hudson]

[-- Attachment #1: Type: text/plain, Size: 1325 bytes --]

I've put together a new patch.

On Thursday 11 October 2007 19:04:28 Daniel Jacobowitz wrote:
> Trivial comments: you've added #includes so Makefile.in needs an
> update (maybe I'll do automatic dependencies sometime soon); please
> include a ChangeLog with all patches;

Both done.

On Thursday 11 October 2007 20:13:14 Mark Kettenis wrote:
> > From: Nick Hudson <nick.hudson@dsl.pipex.com>
> > I think I need to add the instructions for when the
> > setcontext/sigreturn fails as well. Is this correct?
>
> Probably a good idea, since it makes the false positives even less
> likely.

Done.

> By not calling i386bsd_init_abi(), tdep->jb_pc_offset is no longer
> set.  You could initialize tdep->jb_pc_offset in i386nbsd_init_abi(),
> but I'd prefer leaving in the i386bsd_init_abi() call, because it
> shows the inheritance structure a bit more clearly.

OK, no problems - I've put it back.

> It'd also be nice to have some documentation about what versions of
> NetBSD use which sigtramp code (best to stick to official releases
> here).  Perhaps that information could be used to give somewhat more
> meaningfull names to the tramp_frame varaibles.

Each variable is numbered with the NetBSD dot release that the code was first 
seen.

You'll have to forgive the ChangeLog as it's completely alien to me.

Thanks,
Nick

[-- Attachment #2: diff --]
[-- Type: text/x-diff, Size: 12092 bytes --]

Index: gdb/Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.939
diff -u -p -u -r1.939 Makefile.in
--- gdb/Makefile.in	27 Sep 2007 18:48:32 -0000	1.939
+++ gdb/Makefile.in	18 Oct 2007 19:57:10 -0000
@@ -2130,7 +2130,7 @@ i386nbsd-nat.o: i386nbsd-nat.c $(defs_h)
 i386nbsd-tdep.o: i386nbsd-tdep.c $(defs_h) $(arch_utils_h) $(frame_h) \
 	$(gdbcore_h) $(regcache_h) $(regset_h) $(osabi_h) $(symtab_h) \
 	$(gdb_assert_h) $(gdb_string_h) $(i386_tdep_h) $(i387_tdep_h) \
-	$(nbsd_tdep_h) $(solib_svr4_h)
+	$(nbsd_tdep_h) $(solib_svr4_h) $(trad_frame_h) $(tramp_frame_h)
 i386-nto-tdep.o: i386-nto-tdep.c $(defs_h) $(frame_h) $(osabi_h) \
 	$(regcache_h) $(target_h) $(gdb_assert_h) $(gdb_string_h) \
 	$(i386_tdep_h) $(i387_tdep_h) $(nto_tdep_h) $(solib_svr4_h)
Index: gdb/i386nbsd-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/i386nbsd-tdep.c,v
retrieving revision 1.33
diff -u -p -u -r1.33 i386nbsd-tdep.c
--- gdb/i386nbsd-tdep.c	23 Aug 2007 18:08:34 -0000	1.33
+++ gdb/i386nbsd-tdep.c	18 Oct 2007 19:57:10 -0000
@@ -26,6 +26,8 @@
 #include "regset.h"
 #include "osabi.h"
 #include "symtab.h"
+#include "trad-frame.h"
+#include "tramp-frame.h"
 
 #include "gdb_assert.h"
 #include "gdb_string.h"
@@ -91,109 +93,6 @@ i386nbsd_aout_regset_from_core_section (
   return NULL;
 }
 
-/* Under NetBSD/i386, signal handler invocations can be identified by the
-   designated code sequence that is used to return from a signal handler.
-   In particular, the return address of a signal handler points to the
-   following code sequence:
-
-	leal	0x10(%esp), %eax
-	pushl	%eax
-	pushl	%eax
-	movl	$0x127, %eax		# __sigreturn14
-	int	$0x80
-
-   Each instruction has a unique encoding, so we simply attempt to match
-   the instruction the PC is pointing to with any of the above instructions.
-   If there is a hit, we know the offset to the start of the designated
-   sequence and can then check whether we really are executing in the
-   signal trampoline.  If not, -1 is returned, otherwise the offset from the
-   start of the return sequence is returned.  */
-#define RETCODE_INSN1		0x8d
-#define RETCODE_INSN2		0x50
-#define RETCODE_INSN3		0x50
-#define RETCODE_INSN4		0xb8
-#define RETCODE_INSN5		0xcd
-
-#define RETCODE_INSN2_OFF	4
-#define RETCODE_INSN3_OFF	5
-#define RETCODE_INSN4_OFF	6
-#define RETCODE_INSN5_OFF	11
-
-static const unsigned char sigtramp_retcode[] =
-{
-  RETCODE_INSN1, 0x44, 0x24, 0x10,
-  RETCODE_INSN2,
-  RETCODE_INSN3,
-  RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
-  RETCODE_INSN5, 0x80,
-};
-
-static LONGEST
-i386nbsd_sigtramp_offset (struct frame_info *next_frame)
-{
-  CORE_ADDR pc = frame_pc_unwind (next_frame);
-  unsigned char ret[sizeof(sigtramp_retcode)], insn;
-  LONGEST off;
-  int i;
-
-  if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
-    return -1;
-
-  switch (insn)
-    {
-    case RETCODE_INSN1:
-      off = 0;
-      break;
-
-    case RETCODE_INSN2:
-      /* INSN2 and INSN3 are the same.  Read at the location of PC+1
-	 to determine if we're actually looking at INSN2 or INSN3.  */
-      if (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
-	return -1;
-
-      if (insn == RETCODE_INSN3)
-	off = RETCODE_INSN2_OFF;
-      else
-	off = RETCODE_INSN3_OFF;
-      break;
-
-    case RETCODE_INSN4:
-      off = RETCODE_INSN4_OFF;
-      break;
-
-    case RETCODE_INSN5:
-      off = RETCODE_INSN5_OFF;
-      break;
-
-    default:
-      return -1;
-    }
-
-  pc -= off;
-
-  if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
-    return -1;
-
-  if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
-    return off;
-
-  return -1;
-}
-
-/* Return whether the frame preceding NEXT_FRAME corresponds to a
-   NetBSD sigtramp routine.  */
-
-static int
-i386nbsd_sigtramp_p (struct frame_info *next_frame)
-{
-  CORE_ADDR pc = frame_pc_unwind (next_frame);
-  char *name;
-
-  find_pc_partial_function (pc, &name, NULL, NULL);
-  return (nbsd_pc_in_sigtramp (pc, name)
-	  || i386nbsd_sigtramp_offset (next_frame) >= 0);
-}
-
 /* From <machine/signal.h>.  */
 int i386nbsd_sc_reg_offset[] =
 {
@@ -215,6 +114,196 @@ int i386nbsd_sc_reg_offset[] =
   0 * 4				/* %gs */
 };
 
+/* From <machine/mcontext.h>.  */
+int i386nbsd_mc_reg_offset[] =
+{
+  11 * 4,			/* %eax */
+  10 * 4,			/* %ecx */
+  9 * 4,			/* %edx */
+  8 * 4,			/* %ebx */
+  7 * 4,			/* %esp */
+  6 * 4,			/* %ebp */
+  5 * 4,			/* %esi */
+  4 * 4,			/* %edi */
+  14 * 4,			/* %eip */
+  16 * 4,			/* %eflags */
+  15 * 4,			/* %cs */
+  18 * 4,			/* %ss */
+  3 * 4,			/* %ds */
+  2 * 4,			/* %es */
+  1 * 4,			/* %fs */
+  0 * 4				/* %gs */
+};
+
+static void
+i386nbsd_sigtramp_cache_init (const struct tramp_frame *,
+			     struct frame_info *,
+			     struct trad_frame_cache *,
+			     CORE_ADDR);
+
+static const struct tramp_frame i386nbsd_sigtramp_sc16 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x10, -1 },
+			/* leal  0x10(%esp), %eax */
+    { 0x50, -1 },	/* pushl %eax */
+    { 0x50, -1 },	/* pushl %eax */
+    { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x127, %eax		# __sigreturn14 */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x1, %eax		# exit */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+static const struct tramp_frame i386nbsd_sigtramp_sc2 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x0c, -1 },
+			/* leal  0x0c(%esp), %eax */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x127, %eax		# __sigreturn14 */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x1, %eax */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+static const struct tramp_frame i386nbsd_sigtramp_si2 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8b, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x08, -1 },
+			/* movl  8(%esp),%eax */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* movl  $0x134, %eax            # setcontext */
+    { 0xcd, -1 }, { 0x80, -1 },
+			/* int   $0x80 */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* movl  $0x1, %eax */
+    { 0xcd, -1 }, { 0x80, -1 },
+			/* int   $0x80 */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+static const struct tramp_frame i386nbsd_sigtramp_si31 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
+        { 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* leal  0x8c(%esp), %eax */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* movl  $0x134, %eax            # setcontext */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x1, %eax */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+static const struct tramp_frame i386nbsd_sigtramp_si4 =
+{
+  SIGTRAMP_FRAME,
+  1,
+  {
+    { 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
+        { 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* leal  0x8c(%esp), %eax */
+    { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+			/* movl  %eax, 0x4(%esp) */
+    { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
+			/* movl  $0x134, %eax            # setcontext */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { 0xc7, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
+        { 0xff, -1 }, { 0xff, -1 }, { 0xff, -1 }, { 0xff, -1 },
+			/* movl   $0xffffffff,0x4(%esp) */
+    { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
+			/* movl  $0x1, %eax */
+    { 0xcd, -1 }, { 0x80, -1},
+			/* int   $0x80 */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  i386nbsd_sigtramp_cache_init
+};
+
+
+static void
+i386nbsd_sigtramp_cache_init (const struct tramp_frame *self,
+			     struct frame_info *next_frame,
+			     struct trad_frame_cache *this_cache,
+			     CORE_ADDR func)
+{
+  struct gdbarch *gdbarch = get_frame_arch (next_frame);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  CORE_ADDR sp = frame_unwind_register_unsigned (next_frame, I386_ESP_REGNUM);
+  CORE_ADDR base;
+  int *reg_offset;
+  int num_regs;
+  int i;
+
+  if (self == &i386nbsd_sigtramp_sc16 || self == &i386nbsd_sigtramp_sc2)
+    {
+      reg_offset = i386nbsd_sc_reg_offset;
+      num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
+
+      /* Read in the sigcontext address */
+      base = read_memory_unsigned_integer (sp + 8, 4);
+    }
+  else
+    {
+      reg_offset = i386nbsd_mc_reg_offset;
+      num_regs = ARRAY_SIZE (i386nbsd_mc_reg_offset);
+
+      /* Read in the ucontext address */
+      base = read_memory_unsigned_integer (sp + 8, 4);
+      /* offsetof(ucontext_t, uc_mcontext) == 36 */
+      base += 36;
+    }
+
+  for (i = 0; i < num_regs; i++)
+    if (reg_offset[i] != -1)
+      trad_frame_set_reg_addr (this_cache, i, base + reg_offset[i]);
+
+  /* Construct the frame ID using the function start.  */
+  trad_frame_set_id (this_cache, frame_id_build (sp, func));
+}
+
 static void 
 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -228,18 +317,22 @@ i386nbsd_init_abi (struct gdbarch_info i
   tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
   tdep->sizeof_gregset = 16 * 4;
 
-  /* NetBSD has different signal trampoline conventions.  */
-  tdep->sigtramp_start = 0;
-  tdep->sigtramp_end = 0;
-  tdep->sigtramp_p = i386nbsd_sigtramp_p;
-
   /* NetBSD uses -freg-struct-return by default.  */
   tdep->struct_return = reg_struct_return;
 
-  /* NetBSD has a `struct sigcontext' that's different from the
-     original 4.3 BSD.  */
-  tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
-  tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
+  /* NetBSD uses tramp_frame sniffers for signal trampolines. */
+  tdep->sigcontext_addr= 0;
+  tdep->sigtramp_start = 0;
+  tdep->sigtramp_end = 0;
+  tdep->sigtramp_p = 0;
+  tdep->sc_reg_offset = 0;
+  tdep->sc_num_regs = 0;
+
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_sc16);
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_sc2);
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si2);
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si31);
+  tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si4);
 }
 
 /* NetBSD a.out.  */
Index: gdb/tramp-frame.h
===================================================================
RCS file: /cvs/src/src/gdb/tramp-frame.h,v
retrieving revision 1.9
diff -u -p -u -r1.9 tramp-frame.h
--- gdb/tramp-frame.h	23 Aug 2007 18:08:46 -0000	1.9
+++ gdb/tramp-frame.h	18 Oct 2007 19:57:11 -0000
@@ -62,7 +62,7 @@ struct tramp_frame
   {
     ULONGEST bytes;
     ULONGEST mask;
-  } insn[16];
+  } insn[48];
   /* Initialize a trad-frame cache corresponding to the tramp-frame.
      FUNC is the address of the instruction TRAMP[0] in memory.  */
   void (*init) (const struct tramp_frame *self,

[-- Attachment #3: ChangeLog --]
[-- Type: text/plain, Size: 605 bytes --]

	* i386nbsd-tdep.c: Include "trad-frame.h" and "tramp-frame.h"
	(sigtramp_retcode, i386nbsd_sigtramp_offset, i386nbsd_sigtramp_p):
	Remove
	(i386nbsd_mc_reg_offset): New array.
	(i386nbsd_sigtramp_cache_init): New function.
	(i386nbsd_sigtramp_sc16, i386nbsd_sigtramp_sc2, i386nbsd_sigtramp_si2)
	(i386nbsd_sigtramp_si31, i386nbsd_sigtramp_si4): New signal trampoline
	frame descriptions.
	(i386nbsd_init_abi): Override ABI sigcontext defaults and register
	new signal frame unwinders
	* Makefile.in (i386nbsd-tdep.o): Update dependencies.
	* tramp-frame.h (struct tramp_frame): Allow for 48 instructions

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Nick Hudson]

On Thursday 18 October 2007 21:20:18 Nick Hudson wrote:
> I've put together a new patch.
[snip]

Is this patch OK?

If so, can someone commit it or give me access to commit it?

Thanks,
Nick

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Daniel Jacobowitz]

On Fri, Nov 02, 2007 at 08:02:37AM +0000, Nick Hudson wrote:
> On Thursday 18 October 2007 21:20:18 Nick Hudson wrote:
> > I've put together a new patch.
> [snip]
> 
> Is this patch OK?
> 
> If so, can someone commit it or give me access to commit it?

Mark, did you see the updated patch?

  http://sourceware.org/ml/gdb-patches/2007-10/msg00447.html

-- 
Daniel Jacobowitz
CodeSourcery

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Mark Kettenis]

> Date: Sun, 16 Dec 2007 13:52:09 -0500
> From: Daniel Jacobowitz <drow@false.org>
> 
> On Fri, Nov 02, 2007 at 08:02:37AM +0000, Nick Hudson wrote:
> > On Thursday 18 October 2007 21:20:18 Nick Hudson wrote:
> > > I've put together a new patch.
> > [snip]
> > 
> > Is this patch OK?
> > 
> > If so, can someone commit it or give me access to commit it?
> 
> Mark, did you see the updated patch?
> 
>   http://sourceware.org/ml/gdb-patches/2007-10/msg00447.html

I think I looked at it, but it got burried under lots of other mail.
I'll try to get it committed next week.  Does Nick have a copyright
assignment in place?

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Daniel Jacobowitz]

On Sun, Dec 16, 2007 at 09:08:33PM +0100, Mark Kettenis wrote:
> I think I looked at it, but it got burried under lots of other mail.
> I'll try to get it committed next week.  Does Nick have a copyright
> assignment in place?

Yes, he does.

-- 
Daniel Jacobowitz
CodeSourcery

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Mark Kettenis]

> From: Nick Hudson <nick.hudson@dsl.pipex.com>
> Date: Thu, 18 Oct 2007 21:20:18 +0100
>
> 	* i386nbsd-tdep.c: Include "trad-frame.h" and "tramp-frame.h"
> 	(sigtramp_retcode, i386nbsd_sigtramp_offset, i386nbsd_sigtramp_p):
> 	Remove
> 	(i386nbsd_mc_reg_offset): New array.
> 	(i386nbsd_sigtramp_cache_init): New function.
> 	(i386nbsd_sigtramp_sc16, i386nbsd_sigtramp_sc2, i386nbsd_sigtramp_si2)
> 	(i386nbsd_sigtramp_si31, i386nbsd_sigtramp_si4): New signal trampoline
> 	frame descriptions.
> 	(i386nbsd_init_abi): Override ABI sigcontext defaults and register
> 	new signal frame unwinders
> 	* Makefile.in (i386nbsd-tdep.o): Update dependencies.
> 	* tramp-frame.h (struct tramp_frame): Allow for 48 instructions

I've comitted this now (sorry for the delay), with a small fix to make
the prototype for i386nbsd_sigtramp_cache_init not start in column
zero.

Daniel, I think that makes Nick qualify for "Write After Approval".
Can you set him up for that?

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Daniel Jacobowitz]

On Sat, Dec 29, 2007 at 06:05:18PM +0100, Mark Kettenis wrote:
> Daniel, I think that makes Nick qualify for "Write After Approval".
> Can you set him up for that?

You can, actually :-)

Nick, I'm assuming you don't have a sourceware account already.
There's a web form on the front page of http://sourceware.org to
request an account; list Mark or me as approving it.

-- 
Daniel Jacobowitz
CodeSourcery

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Nick Hudson]

On Sunday 30 December 2007 00:30:37 Daniel Jacobowitz wrote:
> On Sat, Dec 29, 2007 at 06:05:18PM +0100, Mark Kettenis wrote:
> > Daniel, I think that makes Nick qualify for "Write After Approval".
> > Can you set him up for that?
>
> You can, actually :-)
>
> Nick, I'm assuming you don't have a sourceware account already.
> There's a web form on the front page of http://sourceware.org to
> request an account; list Mark or me as approving it.

Actually I do have an account. It's "skrll".

Cheers,
Nick

Re: [rfc] Improve NetBSD/i386 signal trampoline detection

[Daniel Jacobowitz]

On Sun, Dec 30, 2007 at 11:24:43AM +0000, Nick Hudson wrote:
> Actually I do have an account. It's "skrll".

OK.  Looks like you already have write access to the GDB repository;
feel free to add yourself to MAINTAINERS in write-after-approval (and
post the patch).

-- 
Daniel Jacobowitz
CodeSourcery