Re: Improved backtrace for s390*.

Re: Improved backtrace for s390*.

[Martin Schwidefsky]

> > 2003-12-05  Martin Schwidefsky  <schwidefsky@de.ibm.com>
> >
> >          * sysdeps/s390/s390-32/backtrace.c (trace_arg): New structure.
> >          (unwind_backtrace, unwind_getip): New variables.
> >          (init, __backchain_backtrace, backtrace_helper): New
functions.
> >          (__backtrace): Use unwind info for backtrace instead of
backchain
> >          walking if the unwind functions can be found.
> >          * sysdeps/s390/s390-64/backtrace.c: Likewise.
>
> I assume you tested it.  Applied.  Thanks,

Yes, I did.

blue skies,
   Martin

Linux/390 Design & Development, IBM Deutschland Entwicklung GmbH
Schönaicherstr. 220, D-71032 Böblingen, Telefon: 49 - (0)7031 - 16-2247
E-Mail: schwidefsky@de.ibm.com

Re: Improved backtrace for s390*.

[Jakub Jelinek]

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On Mon, Dec 08, 2003 at 02:26:00PM +0100, Martin Schwidefsky wrote:
> 
> > > 2003-12-05  Martin Schwidefsky  <schwidefsky@de.ibm.com>
> > >
> > >          * sysdeps/s390/s390-32/backtrace.c (trace_arg): New structure.
> > >          (unwind_backtrace, unwind_getip): New variables.
> > >          (init, __backchain_backtrace, backtrace_helper): New
> functions.
> > >          (__backtrace): Use unwind info for backtrace instead of
> backchain
> > >          walking if the unwind functions can be found.
> > >          * sysdeps/s390/s390-64/backtrace.c: Likewise.
> >
> > I assume you tested it.  Applied.  Thanks,
> 
> Yes, I did.

Also with GCC 3.2 or earlier compiled code (which had no
-fasynchronous-unwind-tables by default)?

I think you need something similar to following (which is for IA-32,
not for s390*):

	Jakub

[-- Attachment #2: backtrace.c --]
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/* Return backtrace of current program state.
   Copyright (C) 2003 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.

   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <bits/libc-lock.h>
#include <dlfcn.h>
#include <execinfo.h>
#include <stdlib.h>
#include <unwind.h>

struct trace_arg
{
  void **array;
  int cnt, size;
  void *lastebp, *lastesp;
};

static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
static _Unwind_Ptr (*unwind_getcfa) (struct _Unwind_Context *);
static _Unwind_Ptr (*unwind_getgr) (struct _Unwind_Context *, int);

static void
init (void)
{
  void *handle = __libc_dlopen ("libgcc_s.so.1");

  if (handle == NULL)
    return;

  unwind_backtrace = __libc_dlsym (handle, "_Unwind_Backtrace");
  unwind_getip = __libc_dlsym (handle, "_Unwind_GetIP");
  unwind_getcfa = __libc_dlsym (handle, "_Unwind_GetCFA");
  unwind_getgr = __libc_dlsym (handle, "_Unwind_GetGR");
  if (unwind_getip == NULL || unwind_getgr == NULL || unwind_getcfa == NULL)
    unwind_backtrace = NULL;
}

static _Unwind_Reason_Code
backtrace_helper (struct _Unwind_Context *ctx, void *a)
{
  struct trace_arg *arg = a;

  /* We are first called with address in the __backtrace function.
     Skip it.  */
  if (arg->cnt != -1)
    arg->array[arg->cnt] = (void *) unwind_getip (ctx);
  if (++arg->cnt == arg->size)
    return _URC_END_OF_STACK;

  /* %ebp is DWARF2 register 5 on IA-32.  */
  arg->lastebp = (void *) unwind_getgr (ctx, 5);
  arg->lastesp = (void *) unwind_getcfa (ctx);
  return _URC_NO_REASON;
}


/* This is a global variable set at program start time.  It marks the
   highest used stack address.  */
extern void *__libc_stack_end;


/* This is the stack layout we see with every stack frame
   if not compiled without frame pointer.

            +-----------------+        +-----------------+
    %ebp -> | %ebp last frame--------> | %ebp last frame--->...
            |                 |        |                 |
            | return address  |        | return address  |
            +-----------------+        +-----------------+

   First try as far to get as far as possible using
   _Unwind_Backtrace which handles -fomit-frame-pointer
   as well, but requires .eh_frame info.  Then fall back to
   walking the stack manually.  */

struct layout
{
  struct layout *ebp;
  void *ret;
};


int
__backtrace (array, size)
     void **array;
     int size;
{
  struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
  __libc_once_define (static, once);

  __libc_once (once, init);
  if (unwind_backtrace == NULL)
    return 0;

  if (size >= 1)
    unwind_backtrace (backtrace_helper, &arg);

  if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
    --arg.cnt;
  else if (arg.cnt < size)
    {
      struct layout *ebp = (struct layout *) arg.lastebp;

      while (arg.cnt < size)
	{
	  /* Check for out of range.  */
	  if ((void *) ebp < arg.lastesp || (void *) ebp > __libc_stack_end
	      || ((long) ebp & 3))
	    break;

	  array[arg.cnt++] = ebp->ret;
	  ebp = ebp->ebp;
	}
    }
  return arg.cnt != -1 ? arg.cnt : 0;
}
weak_alias (__backtrace, backtrace)

Re: Improved backtrace for s390*.

[Ulrich Drepper]

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Hash: SHA1

Martin Schwidefsky wrote:

> 2003-12-05  Martin Schwidefsky  <schwidefsky@de.ibm.com>
> 
> 	* sysdeps/s390/s390-32/backtrace.c (trace_arg): New structure.
> 	(unwind_backtrace, unwind_getip): New variables.
> 	(init, __backchain_backtrace, backtrace_helper): New functions.
> 	(__backtrace): Use unwind info for backtrace instead of backchain
> 	walking if the unwind functions can be found.
> 	* sysdeps/s390/s390-64/backtrace.c: Likewise.

I assume you tested it.  Applied.  Thanks,

- -- 
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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Improved backtrace for s390*.

[Martin Schwidefsky]

Hi
this patch makes the s390* version of backtrace use the _Unwind_Backtrace
and _Unwind_GetIP functions from the libgcc to do the job. They work
even with -fomit-frame-pointer (thanks Jakub for the blueprint :-).

blue skies,
  Martin.

2003-12-05  Martin Schwidefsky  <schwidefsky@de.ibm.com>

	* sysdeps/s390/s390-32/backtrace.c (trace_arg): New structure.
	(unwind_backtrace, unwind_getip): New variables.
	(init, __backchain_backtrace, backtrace_helper): New functions.
	(__backtrace): Use unwind info for backtrace instead of backchain
	walking if the unwind functions can be found.
	* sysdeps/s390/s390-64/backtrace.c: Likewise.

diff -urN libc/sysdeps/s390/s390-32/backtrace.c libc-s390/sysdeps/s390/s390-32/backtrace.c
--- libc/sysdeps/s390/s390-32/backtrace.c	2003-03-28 14:25:36.000000000 +0100
+++ libc-s390/sysdeps/s390/s390-32/backtrace.c	2003-11-13 15:33:24.000000000 +0100
@@ -1,5 +1,5 @@
 /* Return backtrace of current program state.
-   Copyright (C) 2000, 2001 Free Software Foundation, Inc.
+   Copyright (C) 2000, 2001, 2003 Free Software Foundation, Inc.
    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
    This file is part of the GNU C Library.
 
@@ -18,8 +18,12 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
+#include <bits/libc-lock.h>
+#include <dlfcn.h>
 #include <execinfo.h>
 #include <stddef.h>
+#include <stdlib.h>
+#include <unwind.h>
 
 /* This is a global variable set at program start time.  It marks the
    highest used stack address.  */
@@ -51,10 +55,31 @@
   int empty[2];
 };
 
-int
-__backtrace (array, size)
-     void **array;
-     int size;
+struct trace_arg
+{
+  void **array;
+  int cnt, size;
+};
+
+static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
+static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
+
+static void
+init (void)
+{
+  void *handle = __libc_dlopen ("libgcc_s.so.1");
+
+  if (handle == NULL)
+    return;
+
+  unwind_backtrace = __libc_dlsym (handle, "_Unwind_Backtrace");
+  unwind_getip = __libc_dlsym (handle, "_Unwind_GetIP");
+  if (unwind_getip == NULL)
+    unwind_backtrace = NULL;
+}
+
+static int
+__backchain_backtrace (void **array, int size)
 {
   /* We assume that all the code is generated with frame pointers set.  */
   struct layout *stack;
@@ -71,11 +96,42 @@
 	   out of range.  */
 	break;
 
-      array[cnt++] = stack->save_grps[8] & 0x7fffffff;
+      array[cnt++] = (void *) (stack->save_grps[8] & 0x7fffffff);
 
       stack = (struct layout *) stack->back_chain;
     }
 
   return cnt;
 }
+
+static _Unwind_Reason_Code
+backtrace_helper (struct _Unwind_Context *ctx, void *a)
+{
+  struct trace_arg *arg = a;
+
+  /* We are first called with address in the __backtrace function.
+     Skip it.  */
+  if (arg->cnt != -1)
+    arg->array[arg->cnt] = (void *) unwind_getip (ctx);
+  if (++arg->cnt == arg->size)
+    return _URC_END_OF_STACK;
+  return _URC_NO_REASON;
+}
+
+int
+__backtrace (void **array, int size)
+{
+  struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+  __libc_once_define (static, once);
+
+  __libc_once (once, init);
+  if (unwind_backtrace == NULL)
+    return __backchain_backtrace (array, size);
+
+  if (size >= 1)
+    unwind_backtrace (backtrace_helper, &arg);
+
+  return arg.cnt != -1 ? arg.cnt : 0;
+}
+
 weak_alias (__backtrace, backtrace)
diff -urN libc/sysdeps/s390/s390-64/backtrace.c libc-s390/sysdeps/s390/s390-64/backtrace.c
--- libc/sysdeps/s390/s390-64/backtrace.c	2003-05-06 10:05:46.000000000 +0200
+++ libc-s390/sysdeps/s390/s390-64/backtrace.c	2003-11-13 15:33:24.000000000 +0100
@@ -1,5 +1,5 @@
 /* Return backtrace of current program state.  64 bit S/390 version.
-   Copyright (C) 2001 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2003 Free Software Foundation, Inc.
    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
    This file is part of the GNU C Library.
 
@@ -18,8 +18,12 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
+#include <bits/libc-lock.h>
+#include <dlfcn.h>
 #include <execinfo.h>
 #include <stddef.h>
+#include <stdlib.h>
+#include <unwind.h>
 
 
 /* This is a global variable set at program start time.  It marks the
@@ -50,10 +54,31 @@
   long empty[2];
 };
 
+struct trace_arg
+{
+  void **array;
+  int cnt, size;
+};
+
+static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
+static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
+
+static void
+init (void)
+{
+  void *handle = __libc_dlopen ("libgcc_s.so.1");
+
+  if (handle == NULL)
+    return;
+
+  unwind_backtrace = __libc_dlsym (handle, "_Unwind_Backtrace");
+  unwind_getip = __libc_dlsym (handle, "_Unwind_GetIP");
+  if (unwind_getip == NULL)
+    unwind_backtrace = NULL;
+}
+
 int
-__backtrace (array, size)
-     void **array;
-     int size;
+__backchain_backtrace (void **array, int size)
 {
   /* We assume that all the code is generated with frame pointers set.  */
   struct layout *stack;
@@ -77,4 +102,35 @@
 
   return cnt;
 }
+
+static _Unwind_Reason_Code
+backtrace_helper (struct _Unwind_Context *ctx, void *a)
+{
+  struct trace_arg *arg = a;
+
+  /* We are first called with address in the __backtrace function.
+     Skip it.  */
+  if (arg->cnt != -1)
+    arg->array[arg->cnt] = (void *) unwind_getip (ctx);
+  if (++arg->cnt == arg->size)
+    return _URC_END_OF_STACK;
+  return _URC_NO_REASON;
+}
+
+int
+__backtrace (void **array, int size)
+{
+  struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
+  __libc_once_define (static, once);
+
+  __libc_once (once, init);
+  if (unwind_backtrace == NULL)
+    return __backchain_backtrace (array, size);
+
+  if (size >= 1)
+    unwind_backtrace (backtrace_helper, &arg);
+
+  return arg.cnt != -1 ? arg.cnt : 0;
+}
+
 weak_alias (__backtrace, backtrace)