286 lines
7.5 KiB
C
286 lines
7.5 KiB
C
/*
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* Copyright (C) 2009 Internet Systems Consortium, Inc. ("ISC")
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/* $Id: backtrace.c,v 1.3 2009/09/02 23:48:02 tbox Exp $ */
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/*! \file */
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#include "config.h"
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#include <string.h>
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#include <stdlib.h>
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#ifdef HAVE_LIBCTRACE
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#include <execinfo.h>
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#endif
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#include <isc/backtrace.h>
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#include <isc/result.h>
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#include <isc/util.h>
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#ifdef ISC_PLATFORM_USEBACKTRACE
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/*
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* Getting a back trace of a running process is tricky and highly platform
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* dependent. Our current approach is as follows:
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* 1. If the system library supports the "backtrace()" function, use it.
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* 2. Otherwise, if the compiler is gcc and the architecture is x86_64 or IA64,
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* then use gcc's (hidden) Unwind_Backtrace() function. Note that this
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* function doesn't work for C programs on many other architectures.
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* 3. Otherwise, if the architecture x86 or x86_64, try to unwind the stack
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* frame following frame pointers. This assumes the executable binary
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* compiled with frame pointers; this is not always true for x86_64 (rather,
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* compiler optimizations often disable frame pointers). The validation
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* checks in getnextframeptr() hopefully rejects bogus values stored in
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* the RBP register in such a case. If the backtrace function itself crashes
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* due to this problem, the whole package should be rebuilt with
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* --disable-backtrace.
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*/
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#ifdef HAVE_LIBCTRACE
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#define BACKTRACE_LIBC
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#elif defined(__GNUC__) && (defined(__x86_64__) || defined(__ia64__))
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#define BACKTRACE_GCC
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#elif defined(__x86_64__) || defined(__i386__)
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#define BACKTRACE_X86STACK
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#else
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#define BACKTRACE_DISABLED
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#endif /* HAVE_LIBCTRACE */
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#else /* !ISC_PLATFORM_USEBACKTRACE */
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#define BACKTRACE_DISABLED
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#endif /* ISC_PLATFORM_USEBACKTRACE */
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#ifdef BACKTRACE_LIBC
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isc_result_t
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isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
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int n;
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/*
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* Validate the arguments: intentionally avoid using REQUIRE().
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* See notes in backtrace.h.
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*/
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if (addrs == NULL || nframes == NULL)
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return (ISC_R_FAILURE);
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/*
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* backtrace(3) includes this function itself in the address array,
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* which should be eliminated from the returned sequence.
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*/
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n = backtrace(addrs, maxaddrs);
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if (n < 2)
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return (ISC_R_NOTFOUND);
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n--;
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memmove(addrs, &addrs[1], sizeof(void *) * n);
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*nframes = n;
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return (ISC_R_SUCCESS);
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}
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#elif defined(BACKTRACE_GCC)
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extern int _Unwind_Backtrace(void* fn, void* a);
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extern void* _Unwind_GetIP(void* ctx);
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typedef struct {
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void **result;
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int max_depth;
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int skip_count;
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int count;
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} trace_arg_t;
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static int
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btcallback(void *uc, void *opq) {
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trace_arg_t *arg = (trace_arg_t *)opq;
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if (arg->skip_count > 0)
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arg->skip_count--;
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else
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arg->result[arg->count++] = (void *)_Unwind_GetIP(uc);
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if (arg->count == arg->max_depth)
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return (5); /* _URC_END_OF_STACK */
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return (0); /* _URC_NO_REASON */
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}
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isc_result_t
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isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
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trace_arg_t arg;
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/* Argument validation: see above. */
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if (addrs == NULL || nframes == NULL)
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return (ISC_R_FAILURE);
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arg.skip_count = 1;
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arg.result = addrs;
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arg.max_depth = maxaddrs;
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arg.count = 0;
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_Unwind_Backtrace(btcallback, &arg);
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*nframes = arg.count;
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return (ISC_R_SUCCESS);
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}
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#elif defined(BACKTRACE_X86STACK)
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#ifdef __x86_64__
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static unsigned long
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getrbp() {
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__asm("movq %rbp, %rax\n");
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}
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#endif
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static void **
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getnextframeptr(void **sp) {
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void **newsp = (void **)*sp;
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/*
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* Perform sanity check for the new frame pointer, derived from
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* google glog. This can actually be bogus depending on compiler.
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*/
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/* prohibit the stack frames from growing downwards */
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if (newsp <= sp)
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return (NULL);
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/* A heuristics to reject "too large" frame: this actually happened. */
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if ((char *)newsp - (char *)sp > 100000)
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return (NULL);
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/*
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* Not sure if other checks used in glog are needed at this moment.
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* For our purposes we don't have to consider non-contiguous frames,
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* for example.
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*/
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return (newsp);
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}
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isc_result_t
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isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
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int i = 0;
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void **sp;
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/* Argument validation: see above. */
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if (addrs == NULL || nframes == NULL)
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return (ISC_R_FAILURE);
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#ifdef __x86_64__
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sp = (void **)getrbp();
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if (sp == NULL)
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return (ISC_R_NOTFOUND);
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/*
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* sp is the frame ptr of this function itself due to the call to
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* getrbp(), so need to unwind one frame for consistency.
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*/
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sp = getnextframeptr(sp);
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#else
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/*
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* i386: the frame pointer is stored 2 words below the address for the
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* first argument. Note that the body of this function cannot be
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* inlined since it depends on the address of the function argument.
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*/
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sp = (void **)&addrs - 2;
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#endif
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while (sp != NULL && i < maxaddrs) {
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addrs[i++] = *(sp + 1);
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sp = getnextframeptr(sp);
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}
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*nframes = i;
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return (ISC_R_SUCCESS);
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}
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#elif defined(BACKTRACE_DISABLED)
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isc_result_t
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isc_backtrace_gettrace(void **addrs, int maxaddrs, int *nframes) {
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/* Argument validation: see above. */
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if (addrs == NULL || nframes == NULL)
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return (ISC_R_FAILURE);
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UNUSED(maxaddrs);
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return (ISC_R_NOTIMPLEMENTED);
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}
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#endif
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isc_result_t
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isc_backtrace_getsymbolfromindex(int idx, const void **addrp,
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const char **symbolp)
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{
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REQUIRE(addrp != NULL && *addrp == NULL);
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REQUIRE(symbolp != NULL && *symbolp == NULL);
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if (idx < 0 || idx >= isc__backtrace_nsymbols)
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return (ISC_R_RANGE);
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*addrp = isc__backtrace_symtable[idx].addr;
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*symbolp = isc__backtrace_symtable[idx].symbol;
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return (ISC_R_SUCCESS);
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}
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static int
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symtbl_compare(const void *addr, const void *entryarg) {
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const isc_backtrace_symmap_t *entry = entryarg;
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const isc_backtrace_symmap_t *end =
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&isc__backtrace_symtable[isc__backtrace_nsymbols - 1];
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if (isc__backtrace_nsymbols == 1 || entry == end) {
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if (addr >= entry->addr) {
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/*
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* If addr is equal to or larger than that of the last
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* entry of the table, we cannot be sure if this is
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* within a valid range so we consider it valid.
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*/
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return (0);
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}
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return (-1);
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}
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/* entry + 1 is a valid entry from now on. */
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if (addr < entry->addr)
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return (-1);
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else if (addr >= (entry + 1)->addr)
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return (1);
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return (0);
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}
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isc_result_t
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isc_backtrace_getsymbol(const void *addr, const char **symbolp,
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unsigned long *offsetp)
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{
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isc_result_t result = ISC_R_SUCCESS;
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isc_backtrace_symmap_t *found;
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/*
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* Validate the arguments: intentionally avoid using REQUIRE().
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* See notes in backtrace.h.
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*/
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if (symbolp == NULL || *symbolp != NULL || offsetp == NULL)
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return (ISC_R_FAILURE);
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if (isc__backtrace_nsymbols < 1)
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return (ISC_R_NOTFOUND);
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/*
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* Search the table for the entry that meets:
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* entry.addr <= addr < next_entry.addr.
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*/
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found = bsearch(addr, isc__backtrace_symtable, isc__backtrace_nsymbols,
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sizeof(isc__backtrace_symtable[0]), symtbl_compare);
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if (found == NULL)
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result = ISC_R_NOTFOUND;
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else {
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*symbolp = found->symbol;
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*offsetp = (const char *)addr - (char *)found->addr;
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}
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return (result);
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}
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