diff options
Diffstat (limited to 'debug')
| -rw-r--r-- | debug/backtrace.c | 158 |
1 files changed, 101 insertions, 57 deletions
diff --git a/debug/backtrace.c b/debug/backtrace.c index 60d4a15232..d423cc053a 100644 --- a/debug/backtrace.c +++ b/debug/backtrace.c @@ -1,7 +1,7 @@ -/* Return backtrace of current program state. Generic version. - Copyright (C) 1998-2018 Free Software Foundation, Inc. +/* Return backtrace of current program state. + Copyright (C) 2003-2018 Free Software Foundation, Inc. This file is part of the GNU C Library. - Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998. + 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 @@ -17,74 +17,118 @@ License along with the GNU C Library; if not, see <http://www.gnu.org/licenses/>. */ +#include <libc-lock.h> +#include <dlfcn.h> #include <execinfo.h> -#include <signal.h> -#include <frame.h> -#include <sigcontextinfo.h> -#include <ldsodefs.h> - -/* This implementation assumes a stack layout that matches the defaults - used by gcc's `__builtin_frame_address' and `__builtin_return_address' - (FP is the frame pointer register): - - +-----------------+ +-----------------+ - FP -> | previous FP --------> | previous FP ------>... - | | | | - | return address | | return address | - +-----------------+ +-----------------+ - - */ - -/* Get some notion of the current stack. Need not be exactly the top - of the stack, just something somewhere in the current frame. */ -#ifndef CURRENT_STACK_FRAME -# define CURRENT_STACK_FRAME ({ char __csf; &__csf; }) -#endif +#include <gnu/lib-names.h> +#include <stdlib.h> +#include <unwind.h> -/* By default we assume that the stack grows downward. */ -#ifndef INNER_THAN -# define INNER_THAN < -#endif +struct trace_arg +{ + void **array; + _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; +} -/* By default assume the `next' pointer in struct layout points to the - next struct layout. */ -#ifndef ADVANCE_STACK_FRAME -# define ADVANCE_STACK_FRAME(next) ((struct layout *) (next)) -#endif -/* By default, the frame pointer is just what we get from gcc. */ -#ifndef FIRST_FRAME_POINTER -# define FIRST_FRAME_POINTER __builtin_frame_address (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) +{ + 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); + + /* Check whether we make any progress. */ + _Unwind_Word cfa = unwind_getcfa (ctx); + + if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt] + && cfa == arg->cfa) + return _URC_END_OF_STACK; + arg->cfa = cfa; + } + if (++arg->cnt == arg->size) + return _URC_END_OF_STACK; + return _URC_NO_REASON; +} + int __backtrace (void **array, int size) { - struct layout *current; - void *top_frame; - void *top_stack; - int cnt = 0; + struct trace_arg arg = { .array = array, .cfa = 0, .size = size, .cnt = -1 }; - top_frame = FIRST_FRAME_POINTER; - top_stack = CURRENT_STACK_FRAME; + if (size <= 0) + return 0; - /* We skip the call to this function, it makes no sense to record it. */ - current = ((struct layout *) top_frame); - while (cnt < size) - { - if ((void *) current INNER_THAN top_stack - || !((void *) current INNER_THAN __libc_stack_end)) - /* This means the address is out of range. Note that for the - toplevel we see a frame pointer with value NULL which clearly is - out of range. */ - break; +#ifdef SHARED + __libc_once_define (static, once); - array[cnt++] = current->return_address; + __libc_once (once, init); + if (unwind_backtrace == NULL) + return 0; +#endif - current = ADVANCE_STACK_FRAME (current->next); - } + unwind_backtrace (backtrace_helper, &arg); - return cnt; + /* _Unwind_Backtrace seems to put NULL address above + _start. Fix it up here. */ + if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL) + --arg.cnt; + return arg.cnt != -1 ? arg.cnt : 0; } 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 |