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backtrace: Implement on top of <unwind-link.h>

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This reimplements the generic version of backtrace.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer 2021-03-01 15:56:36 +01:00
parent 9fc813e1a3
commit e164d95abf
1 changed files with 16 additions and 66 deletions
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82
debug/backtrace.c
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@ -17,10 +17,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <libc-lock.h>
#include <dlfcn.h>
#include <execinfo.h>
#include <gnu/lib-names.h>
#include <stdlib.h>
#include <unwind.h>
#include <unwind-link.h>
@ -28,47 +25,12 @@
struct trace_arg
{
void **array;
struct unwind_link *unwind_link;
_Unwind_Word cfa;
int cnt;
int size;
};
#ifdef SHARED
static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
static _Unwind_Word (*unwind_getcfa) (struct _Unwind_Context *);
static void *libgcc_handle;
/* Dummy version in case libgcc_s does not contain the real code. */
static _Unwind_Word
dummy_getcfa (struct _Unwind_Context *ctx __attribute__ ((unused)))
{
return 0;
}
static void
init (void)
{
libgcc_handle = __libc_dlopen (LIBGCC_S_SO);
if (libgcc_handle == NULL)
return;
unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP");
if (unwind_getip == NULL)
unwind_backtrace = NULL;
unwind_getcfa = (__libc_dlsym (libgcc_handle, "_Unwind_GetCFA")
?: dummy_getcfa);
}
#else
# define unwind_backtrace _Unwind_Backtrace
# define unwind_getip _Unwind_GetIP
# define unwind_getcfa _Unwind_GetCFA
#endif
static _Unwind_Reason_Code
backtrace_helper (struct _Unwind_Context *ctx, void *a)
{
@ -78,14 +40,16 @@ backtrace_helper (struct _Unwind_Context *ctx, void *a)
Skip it. */
if (arg->cnt != -1)
{
arg->array[arg->cnt] = (void *) unwind_getip (ctx);
arg->array[arg->cnt]
= (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetIP) (ctx);
if (arg->cnt > 0)
arg->array[arg->cnt]
= unwind_arch_adjustment (arg->array[arg->cnt - 1],
arg->array[arg->cnt]);
/* Check whether we make any progress. */
_Unwind_Word cfa = unwind_getcfa (ctx);
_Unwind_Word cfa
= UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetCFA) (ctx);
if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt]
&& cfa == arg->cfa)
@ -100,20 +64,20 @@ backtrace_helper (struct _Unwind_Context *ctx, void *a)
int
__backtrace (void **array, int size)
{
struct trace_arg arg = { .array = array, .cfa = 0, .size = size, .cnt = -1 };
struct trace_arg arg =
{
.array = array,
.unwind_link = __libc_unwind_link_get (),
.cfa = 0,
.size = size,
.cnt = -1
};
if (size <= 0)
if (size <= 0 || arg.unwind_link == NULL)
return 0;
#ifdef SHARED
__libc_once_define (static, once);
__libc_once (once, init);
if (unwind_backtrace == NULL)
return 0;
#endif
unwind_backtrace (backtrace_helper, &arg);
UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
(backtrace_helper, &arg);
/* _Unwind_Backtrace seems to put NULL address above
_start. Fix it up here. */
@ -123,17 +87,3 @@ __backtrace (void **array, int size)
}
weak_alias (__backtrace, backtrace)
libc_hidden_def (__backtrace)
#ifdef SHARED
/* Free all resources if necessary. */
libc_freeres_fn (free_mem)
{
unwind_backtrace = NULL;
if (libgcc_handle != NULL)
{
__libc_dlclose (libgcc_handle);
libgcc_handle = NULL;
}
}
#endif