| /* |
| * Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com> |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "defs.h" |
| #include <limits.h> |
| #include <libunwind-ptrace.h> |
| |
| /* |
| * Кeep a sorted array of cache entries, |
| * so that we can binary search through it. |
| */ |
| struct mmap_cache_t { |
| /** |
| * example entry: |
| * 7fabbb09b000-7fabbb09f000 r--p 00179000 fc:00 1180246 /lib/libc-2.11.1.so |
| * |
| * start_addr is 0x7fabbb09b000 |
| * end_addr is 0x7fabbb09f000 |
| * mmap_offset is 0x179000 |
| * binary_filename is "/lib/libc-2.11.1.so" |
| */ |
| unsigned long start_addr; |
| unsigned long end_addr; |
| unsigned long mmap_offset; |
| char* binary_filename; |
| }; |
| |
| static unw_addr_space_t libunwind_as; |
| |
| void |
| init_unwind_addr_space(void) |
| { |
| libunwind_as = unw_create_addr_space(&_UPT_accessors, 0); |
| if (!libunwind_as) |
| error_msg_and_die("failed to create address space for stack tracing"); |
| } |
| |
| void |
| init_libunwind_ui(struct tcb *tcp) |
| { |
| tcp->libunwind_ui = _UPT_create(tcp->pid); |
| if (!tcp->libunwind_ui) |
| die_out_of_memory(); |
| } |
| |
| void |
| free_libunwind_ui(struct tcb *tcp) |
| { |
| _UPT_destroy(tcp->libunwind_ui); |
| tcp->libunwind_ui = NULL; |
| } |
| |
| /* |
| * caching of /proc/ID/maps for each process to speed up stack tracing |
| * |
| * The cache must be refreshed after some syscall: mmap, mprotect, munmap, execve |
| */ |
| static void |
| alloc_mmap_cache(struct tcb* tcp) |
| { |
| unsigned long start_addr, end_addr, mmap_offset; |
| char filename[sizeof ("/proc/0123456789/maps")]; |
| char buffer[PATH_MAX + 80]; |
| char binary_path[PATH_MAX]; |
| struct mmap_cache_t *cur_entry, *prev_entry; |
| /* start with a small dynamically-allocated array and then expand it */ |
| size_t cur_array_size = 10; |
| struct mmap_cache_t *cache_head; |
| FILE *fp; |
| |
| sprintf(filename, "/proc/%d/maps", tcp->pid); |
| fp = fopen(filename, "r"); |
| if (!fp) { |
| perror_msg("fopen: %s", filename); |
| return; |
| } |
| |
| cache_head = calloc(cur_array_size, sizeof(*cache_head)); |
| if (!cache_head) |
| die_out_of_memory(); |
| |
| while (fgets(buffer, sizeof(buffer), fp) != NULL) { |
| binary_path[0] = '\0'; // 'reset' it just to be paranoid |
| |
| sscanf(buffer, "%lx-%lx %*c%*c%*c%*c %lx %*x:%*x %*d %[^\n]", |
| &start_addr, &end_addr, &mmap_offset, binary_path); |
| |
| /* ignore special 'fake files' like "[vdso]", "[heap]", "[stack]", */ |
| if (binary_path[0] == '[') { |
| continue; |
| } |
| |
| if (binary_path[0] == '\0') { |
| continue; |
| } |
| |
| if (end_addr < start_addr) |
| perror_msg_and_die("%s: unrecognized maps file format", |
| filename); |
| |
| cur_entry = &cache_head[tcp->mmap_cache_size]; |
| cur_entry->start_addr = start_addr; |
| cur_entry->end_addr = end_addr; |
| cur_entry->mmap_offset = mmap_offset; |
| cur_entry->binary_filename = strdup(binary_path); |
| |
| /* |
| * sanity check to make sure that we're storing |
| * non-overlapping regions in ascending order |
| */ |
| if (tcp->mmap_cache_size > 0) { |
| prev_entry = &cache_head[tcp->mmap_cache_size - 1]; |
| if (prev_entry->start_addr >= cur_entry->start_addr) |
| perror_msg_and_die("Overlaying memory region in %s", |
| filename); |
| if (prev_entry->end_addr > cur_entry->start_addr) |
| perror_msg_and_die("Overlaying memory region in %s", |
| filename); |
| } |
| tcp->mmap_cache_size++; |
| |
| /* resize doubling its size */ |
| if (tcp->mmap_cache_size >= cur_array_size) { |
| cur_array_size *= 2; |
| cache_head = realloc(cache_head, cur_array_size * sizeof(*cache_head)); |
| if (!cache_head) |
| die_out_of_memory(); |
| } |
| } |
| fclose(fp); |
| tcp->mmap_cache = cache_head; |
| } |
| |
| /* deleting the cache */ |
| void |
| delete_mmap_cache(struct tcb* tcp) |
| { |
| unsigned int i; |
| for (i = 0; i < tcp->mmap_cache_size; i++) { |
| free(tcp->mmap_cache[i].binary_filename); |
| tcp->mmap_cache[i].binary_filename = NULL; |
| } |
| free(tcp->mmap_cache); |
| tcp->mmap_cache = NULL; |
| tcp->mmap_cache_size = 0; |
| } |
| |
| /* use libunwind to unwind the stack and print a backtrace */ |
| void |
| print_stacktrace(struct tcb* tcp) |
| { |
| unw_word_t ip; |
| unw_cursor_t cursor; |
| unw_word_t function_off_set; |
| int stack_depth = 0, ret_val; |
| /* these are used for the binary search through the mmap_chace */ |
| unsigned int lower, upper, mid; |
| size_t symbol_name_size = 40; |
| char * symbol_name; |
| struct mmap_cache_t* cur_mmap_cache; |
| unsigned long true_offset; |
| |
| if (!tcp->mmap_cache) |
| alloc_mmap_cache(tcp); |
| if (!tcp->mmap_cache || !tcp->mmap_cache_size) |
| return; |
| |
| symbol_name = malloc(symbol_name_size); |
| if (!symbol_name) |
| die_out_of_memory(); |
| |
| if (unw_init_remote(&cursor, libunwind_as, tcp->libunwind_ui) < 0) |
| perror_msg_and_die("Can't initiate libunwind"); |
| |
| do { |
| /* looping on the stack frame */ |
| if (unw_get_reg(&cursor, UNW_REG_IP, &ip) < 0) { |
| perror_msg("Can't walk the stack of process %d", tcp->pid); |
| break; |
| } |
| |
| lower = 0; |
| upper = tcp->mmap_cache_size - 1; |
| |
| while (lower <= upper) { |
| /* find the mmap_cache and print the stack frame */ |
| mid = (upper + lower) / 2; |
| cur_mmap_cache = &tcp->mmap_cache[mid]; |
| |
| if (ip >= cur_mmap_cache->start_addr && |
| ip < cur_mmap_cache->end_addr) { |
| for (;;) { |
| symbol_name[0] = '\0'; |
| ret_val = unw_get_proc_name(&cursor, symbol_name, |
| symbol_name_size, &function_off_set); |
| if (ret_val != -UNW_ENOMEM) |
| break; |
| symbol_name_size *= 2; |
| symbol_name = realloc(symbol_name, symbol_name_size); |
| if (!symbol_name) |
| die_out_of_memory(); |
| } |
| |
| true_offset = ip - cur_mmap_cache->start_addr + |
| cur_mmap_cache->mmap_offset; |
| if (symbol_name[0]) { |
| /* |
| * we want to keep the format used by backtrace_symbols from the glibc |
| * |
| * ./a.out() [0x40063d] |
| * ./a.out() [0x4006bb] |
| * ./a.out() [0x4006c6] |
| * /lib64/libc.so.6(__libc_start_main+0xed) [0x7fa2f8a5976d] |
| * ./a.out() [0x400569] |
| */ |
| tprintf(" > %s(%s+0x%lx) [0x%lx]\n", |
| cur_mmap_cache->binary_filename, |
| symbol_name, function_off_set, true_offset); |
| } else { |
| tprintf(" > %s() [0x%lx]\n", |
| cur_mmap_cache->binary_filename, true_offset); |
| } |
| line_ended(); |
| break; /* stack frame printed */ |
| } |
| else if (mid == 0) { |
| /* |
| * there is a bug in libunwind >= 1.0 |
| * after a set_tid_address syscall |
| * unw_get_reg returns IP == 0 |
| */ |
| if(ip) |
| tprintf(" > backtracing_error\n"); |
| line_ended(); |
| goto ret; |
| } |
| else if (ip < cur_mmap_cache->start_addr) |
| upper = mid; |
| else |
| lower = mid + 1; |
| |
| } |
| if (lower > upper) { |
| tprintf(" > backtracing_error [0x%lx]\n", ip); |
| line_ended(); |
| goto ret; |
| } |
| |
| ret_val = unw_step(&cursor); |
| |
| if (++stack_depth > 255) { |
| tprintf("> too many stack frames\n"); |
| line_ended(); |
| break; |
| } |
| } while (ret_val > 0); |
| ret: |
| free(symbol_name); |
| } |