589 lines
14 KiB
C
589 lines
14 KiB
C
/*
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* Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "defs.h"
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#include <limits.h>
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#include <libunwind-ptrace.h>
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#ifdef _LARGEFILE64_SOURCE
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# ifdef HAVE_FOPEN64
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# define fopen_for_input fopen64
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# else
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# define fopen_for_input fopen
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# endif
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#else
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# define fopen_for_input fopen
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#endif
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#define DPRINTF(F, A, ...) if (debug_flag) error_msg("[unwind(" A ")] " F, __VA_ARGS__)
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/*
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* Кeep a sorted array of cache entries,
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* so that we can binary search through it.
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*/
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struct mmap_cache_t {
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/**
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* example entry:
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* 7fabbb09b000-7fabbb09f000 r-xp 00179000 fc:00 1180246 /lib/libc-2.11.1.so
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*
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* start_addr is 0x7fabbb09b000
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* end_addr is 0x7fabbb09f000
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* mmap_offset is 0x179000
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* binary_filename is "/lib/libc-2.11.1.so"
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*/
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unsigned long start_addr;
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unsigned long end_addr;
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unsigned long mmap_offset;
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char *binary_filename;
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};
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/*
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* Type used in stacktrace walker
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*/
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typedef void (*call_action_fn)(void *data,
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const char *binary_filename,
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const char *symbol_name,
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unw_word_t function_offset,
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unsigned long true_offset);
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typedef void (*error_action_fn)(void *data,
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const char *error,
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unsigned long true_offset);
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/*
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* Type used in stacktrace capturing
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*/
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struct call_t {
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struct call_t* next;
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char *output_line;
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};
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struct queue_t {
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struct call_t *tail;
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struct call_t *head;
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};
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static void queue_print(struct queue_t *queue);
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static void delete_mmap_cache(struct tcb *tcp, const char *caller);
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static unw_addr_space_t libunwind_as;
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static unsigned int mmap_cache_generation;
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void
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unwind_init(void)
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{
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libunwind_as = unw_create_addr_space(&_UPT_accessors, 0);
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if (!libunwind_as)
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error_msg_and_die("failed to create address space for stack tracing");
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unw_set_caching_policy(libunwind_as, UNW_CACHE_GLOBAL);
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}
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void
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unwind_tcb_init(struct tcb *tcp)
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{
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if (tcp->libunwind_ui)
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return;
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tcp->libunwind_ui = _UPT_create(tcp->pid);
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if (!tcp->libunwind_ui)
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die_out_of_memory();
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tcp->queue = xmalloc(sizeof(*tcp->queue));
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tcp->queue->head = NULL;
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tcp->queue->tail = NULL;
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}
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void
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unwind_tcb_fin(struct tcb *tcp)
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{
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queue_print(tcp->queue);
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free(tcp->queue);
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tcp->queue = NULL;
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delete_mmap_cache(tcp, __FUNCTION__);
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_UPT_destroy(tcp->libunwind_ui);
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tcp->libunwind_ui = NULL;
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}
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/*
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* caching of /proc/ID/maps for each process to speed up stack tracing
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*
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* The cache must be refreshed after syscalls that affect memory mappings,
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* e.g. mmap, mprotect, munmap, execve.
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*/
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static void
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build_mmap_cache(struct tcb* tcp)
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{
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FILE *fp;
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struct mmap_cache_t *cache_head;
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/* start with a small dynamically-allocated array and then expand it */
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size_t cur_array_size = 10;
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char filename[sizeof("/proc/4294967296/maps")];
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char buffer[PATH_MAX + 80];
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unw_flush_cache(libunwind_as, 0, 0);
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sprintf(filename, "/proc/%u/maps", tcp->pid);
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fp = fopen_for_input(filename, "r");
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if (!fp) {
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perror_msg("fopen: %s", filename);
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return;
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}
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cache_head = xcalloc(cur_array_size, sizeof(*cache_head));
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while (fgets(buffer, sizeof(buffer), fp) != NULL) {
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struct mmap_cache_t *entry;
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unsigned long start_addr, end_addr, mmap_offset;
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char exec_bit;
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char binary_path[PATH_MAX];
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if (sscanf(buffer, "%lx-%lx %*c%*c%c%*c %lx %*x:%*x %*d %[^\n]",
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&start_addr, &end_addr, &exec_bit,
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&mmap_offset, binary_path) != 5)
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continue;
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/* ignore mappings that have no PROT_EXEC bit set */
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if (exec_bit != 'x')
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continue;
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if (end_addr < start_addr) {
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error_msg("%s: unrecognized file format", filename);
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break;
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}
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/*
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* sanity check to make sure that we're storing
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* non-overlapping regions in ascending order
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*/
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if (tcp->mmap_cache_size > 0) {
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entry = &cache_head[tcp->mmap_cache_size - 1];
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if (entry->start_addr == start_addr &&
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entry->end_addr == end_addr) {
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/* duplicate entry, e.g. [vsyscall] */
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continue;
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}
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if (start_addr <= entry->start_addr ||
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start_addr < entry->end_addr) {
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error_msg("%s: overlapping memory region",
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filename);
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continue;
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}
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}
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if (tcp->mmap_cache_size >= cur_array_size) {
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cur_array_size *= 2;
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cache_head = xreallocarray(cache_head, cur_array_size,
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sizeof(*cache_head));
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}
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entry = &cache_head[tcp->mmap_cache_size];
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entry->start_addr = start_addr;
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entry->end_addr = end_addr;
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entry->mmap_offset = mmap_offset;
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entry->binary_filename = xstrdup(binary_path);
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tcp->mmap_cache_size++;
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}
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fclose(fp);
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tcp->mmap_cache = cache_head;
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tcp->mmap_cache_generation = mmap_cache_generation;
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DPRINTF("tgen=%u, ggen=%u, tcp=%p, cache=%p",
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"cache-build",
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tcp->mmap_cache_generation,
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mmap_cache_generation,
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tcp, tcp->mmap_cache);
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}
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/* deleting the cache */
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static void
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delete_mmap_cache(struct tcb *tcp, const char *caller)
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{
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unsigned int i;
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DPRINTF("tgen=%u, ggen=%u, tcp=%p, cache=%p, caller=%s",
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"cache-delete",
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tcp->mmap_cache_generation,
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mmap_cache_generation,
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tcp, tcp->mmap_cache, caller);
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for (i = 0; i < tcp->mmap_cache_size; i++) {
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free(tcp->mmap_cache[i].binary_filename);
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tcp->mmap_cache[i].binary_filename = NULL;
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}
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free(tcp->mmap_cache);
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tcp->mmap_cache = NULL;
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tcp->mmap_cache_size = 0;
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}
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static bool
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rebuild_cache_if_invalid(struct tcb *tcp, const char *caller)
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{
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if ((tcp->mmap_cache_generation != mmap_cache_generation)
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&& tcp->mmap_cache)
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delete_mmap_cache(tcp, caller);
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if (!tcp->mmap_cache)
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build_mmap_cache(tcp);
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if (!tcp->mmap_cache || !tcp->mmap_cache_size)
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return false;
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else
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return true;
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}
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void
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unwind_cache_invalidate(struct tcb* tcp)
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{
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#if SUPPORTED_PERSONALITIES > 1
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if (tcp->currpers != DEFAULT_PERSONALITY) {
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/* disable strack trace */
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return;
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}
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#endif
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mmap_cache_generation++;
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DPRINTF("tgen=%u, ggen=%u, tcp=%p, cache=%p", "increment",
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tcp->mmap_cache_generation,
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mmap_cache_generation,
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tcp,
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tcp->mmap_cache);
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}
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static void
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get_symbol_name(unw_cursor_t *cursor, char **name,
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size_t *size, unw_word_t *offset)
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{
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for (;;) {
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int rc = unw_get_proc_name(cursor, *name, *size, offset);
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if (rc == 0)
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break;
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if (rc != -UNW_ENOMEM) {
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**name = '\0';
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*offset = 0;
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break;
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}
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*name = xreallocarray(*name, 2, *size);
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*size *= 2;
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}
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}
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static int
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print_stack_frame(struct tcb *tcp,
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call_action_fn call_action,
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error_action_fn error_action,
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void *data,
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unw_cursor_t *cursor,
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char **symbol_name,
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size_t *symbol_name_size)
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{
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unw_word_t ip;
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int lower = 0;
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int upper = (int) tcp->mmap_cache_size - 1;
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if (unw_get_reg(cursor, UNW_REG_IP, &ip) < 0) {
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perror_msg("Can't walk the stack of process %d", tcp->pid);
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return -1;
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}
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while (lower <= upper) {
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struct mmap_cache_t *cur_mmap_cache;
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int mid = (upper + lower) / 2;
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cur_mmap_cache = &tcp->mmap_cache[mid];
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if (ip >= cur_mmap_cache->start_addr &&
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ip < cur_mmap_cache->end_addr) {
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unsigned long true_offset;
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unw_word_t function_offset;
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get_symbol_name(cursor, symbol_name, symbol_name_size,
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&function_offset);
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true_offset = ip - cur_mmap_cache->start_addr +
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cur_mmap_cache->mmap_offset;
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call_action(data,
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cur_mmap_cache->binary_filename,
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*symbol_name,
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function_offset,
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true_offset);
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return 0;
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}
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else if (ip < cur_mmap_cache->start_addr)
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upper = mid - 1;
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else
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lower = mid + 1;
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}
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/*
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* there is a bug in libunwind >= 1.0
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* after a set_tid_address syscall
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* unw_get_reg returns IP == 0
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*/
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if(ip)
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error_action(data, "unexpected_backtracing_error", ip);
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return -1;
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}
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/*
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* walking the stack
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*/
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static void
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stacktrace_walk(struct tcb *tcp,
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call_action_fn call_action,
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error_action_fn error_action,
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void *data)
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{
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char *symbol_name;
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size_t symbol_name_size = 40;
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unw_cursor_t cursor;
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int stack_depth;
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if (!tcp->mmap_cache)
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error_msg_and_die("bug: mmap_cache is NULL");
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if (tcp->mmap_cache_size == 0)
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error_msg_and_die("bug: mmap_cache is empty");
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symbol_name = xmalloc(symbol_name_size);
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if (unw_init_remote(&cursor, libunwind_as, tcp->libunwind_ui) < 0)
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perror_msg_and_die("Can't initiate libunwind");
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for (stack_depth = 0; stack_depth < 256; ++stack_depth) {
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if (print_stack_frame(tcp, call_action, error_action, data,
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&cursor, &symbol_name, &symbol_name_size) < 0)
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break;
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if (unw_step(&cursor) <= 0)
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break;
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}
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if (stack_depth >= 256)
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error_action(data, "too many stack frames", 0);
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free(symbol_name);
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}
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/*
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* printing an entry in stack to stream or buffer
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*/
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/*
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* we want to keep the format used by backtrace_symbols from the glibc
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*
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* ./a.out() [0x40063d]
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* ./a.out() [0x4006bb]
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* ./a.out() [0x4006c6]
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* /lib64/libc.so.6(__libc_start_main+0xed) [0x7fa2f8a5976d]
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* ./a.out() [0x400569]
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*/
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#define STACK_ENTRY_SYMBOL_FMT \
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" > %s(%s+0x%lx) [0x%lx]\n", \
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binary_filename, \
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symbol_name, \
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(unsigned long) function_offset, \
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true_offset
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#define STACK_ENTRY_NOSYMBOL_FMT \
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" > %s() [0x%lx]\n", \
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binary_filename, true_offset
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#define STACK_ENTRY_BUG_FMT \
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" > BUG IN %s\n"
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#define STACK_ENTRY_ERROR_WITH_OFFSET_FMT \
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" > %s [0x%lx]\n", error, true_offset
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#define STACK_ENTRY_ERROR_FMT \
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" > %s\n", error
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static void
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print_call_cb(void *dummy,
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const char *binary_filename,
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const char *symbol_name,
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unw_word_t function_offset,
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unsigned long true_offset)
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{
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if (symbol_name && (symbol_name[0] != '\0'))
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tprintf(STACK_ENTRY_SYMBOL_FMT);
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else if (binary_filename)
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tprintf(STACK_ENTRY_NOSYMBOL_FMT);
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else
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tprintf(STACK_ENTRY_BUG_FMT, __FUNCTION__);
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line_ended();
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}
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static void
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print_error_cb(void *dummy,
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const char *error,
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unsigned long true_offset)
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{
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if (true_offset)
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tprintf(STACK_ENTRY_ERROR_WITH_OFFSET_FMT);
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else
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tprintf(STACK_ENTRY_ERROR_FMT);
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line_ended();
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}
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static char *
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sprint_call_or_error(const char *binary_filename,
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const char *symbol_name,
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unw_word_t function_offset,
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unsigned long true_offset,
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const char *error)
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{
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char *output_line = NULL;
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int n;
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if (symbol_name)
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n = asprintf(&output_line, STACK_ENTRY_SYMBOL_FMT);
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else if (binary_filename)
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n = asprintf(&output_line, STACK_ENTRY_NOSYMBOL_FMT);
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else if (error)
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n = true_offset
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? asprintf(&output_line, STACK_ENTRY_ERROR_WITH_OFFSET_FMT)
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: asprintf(&output_line, STACK_ENTRY_ERROR_FMT);
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else
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n = asprintf(&output_line, STACK_ENTRY_BUG_FMT, __FUNCTION__);
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if (n < 0)
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error_msg_and_die("error in asprintf");
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return output_line;
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}
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/*
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* queue manipulators
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*/
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static void
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queue_put(struct queue_t *queue,
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const char *binary_filename,
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const char *symbol_name,
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unw_word_t function_offset,
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unsigned long true_offset,
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const char *error)
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{
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struct call_t *call;
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call = xmalloc(sizeof(*call));
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call->output_line = sprint_call_or_error(binary_filename,
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symbol_name,
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function_offset,
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true_offset,
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error);
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call->next = NULL;
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if (!queue->head) {
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queue->head = call;
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queue->tail = call;
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} else {
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queue->tail->next = call;
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queue->tail = call;
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}
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}
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static void
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queue_put_call(void *queue,
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const char *binary_filename,
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const char *symbol_name,
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unw_word_t function_offset,
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unsigned long true_offset)
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{
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queue_put(queue,
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binary_filename,
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symbol_name,
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function_offset,
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true_offset,
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NULL);
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}
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static void
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queue_put_error(void *queue,
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const char *error,
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unsigned long ip)
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{
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queue_put(queue, NULL, NULL, 0, ip, error);
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}
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static void
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queue_print(struct queue_t *queue)
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{
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struct call_t *call, *tmp;
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queue->tail = NULL;
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call = queue->head;
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queue->head = NULL;
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while (call) {
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tmp = call;
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call = call->next;
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tprints(tmp->output_line);
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line_ended();
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free(tmp->output_line);
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tmp->output_line = NULL;
|
||
tmp->next = NULL;
|
||
free(tmp);
|
||
}
|
||
}
|
||
|
||
/*
|
||
* printing stack
|
||
*/
|
||
void
|
||
unwind_print_stacktrace(struct tcb* tcp)
|
||
{
|
||
#if SUPPORTED_PERSONALITIES > 1
|
||
if (tcp->currpers != DEFAULT_PERSONALITY) {
|
||
/* disable strack trace */
|
||
return;
|
||
}
|
||
#endif
|
||
if (tcp->queue->head) {
|
||
DPRINTF("tcp=%p, queue=%p", "queueprint", tcp, tcp->queue->head);
|
||
queue_print(tcp->queue);
|
||
}
|
||
else if (rebuild_cache_if_invalid(tcp, __FUNCTION__)) {
|
||
DPRINTF("tcp=%p, queue=%p", "stackprint", tcp, tcp->queue->head);
|
||
stacktrace_walk(tcp, print_call_cb, print_error_cb, NULL);
|
||
}
|
||
}
|
||
|
||
/*
|
||
* capturing stack
|
||
*/
|
||
void
|
||
unwind_capture_stacktrace(struct tcb *tcp)
|
||
{
|
||
#if SUPPORTED_PERSONALITIES > 1
|
||
if (tcp->currpers != DEFAULT_PERSONALITY) {
|
||
/* disable strack trace */
|
||
return;
|
||
}
|
||
#endif
|
||
if (tcp->queue->head)
|
||
error_msg_and_die("bug: unprinted entries in queue");
|
||
|
||
if (rebuild_cache_if_invalid(tcp, __FUNCTION__)) {
|
||
stacktrace_walk(tcp, queue_put_call, queue_put_error,
|
||
tcp->queue);
|
||
DPRINTF("tcp=%p, queue=%p", "captured", tcp, tcp->queue->head);
|
||
}
|
||
}
|