| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | #include "stacktrace-common.h" |
| 4 | |
| 5 | #if defined(USE_LIBUNWIND) |
| 6 | #if !defined(STATIC_BUILD) |
| 7 | #define UNW_LOCAL_ONLY |
| 8 | #endif |
| 9 | #include <libunwind.h> |
| 10 | #include <dlfcn.h> |
| 11 | |
| 12 | const char *stacktrace_backend(void) { |
| 13 | return "libunwind"; |
| 14 | } |
| 15 | |
| 16 | void impl_stacktrace_init(void) { |
| 17 | unw_set_caching_policy(unw_local_addr_space, UNW_CACHE_NONE); |
| 18 | } |
| 19 | |
| 20 | void stacktrace_flush(void) { |
| 21 | unw_flush_cache(unw_local_addr_space, 0, 0); |
| 22 | } |
| 23 | |
| 24 | bool stacktrace_capture_is_async_signal_safe(void) { |
| 25 | #if defined(STATIC_BUILD) |
| 26 | return false; |
| 27 | #else |
| 28 | return true; |
| 29 | #endif |
| 30 | } |
| 31 | |
| 32 | bool stacktrace_available(void) { |
| 33 | return true; |
| 34 | } |
| 35 | |
| 36 | NEVER_INLINE |
| 37 | void stacktrace_capture(BUFFER *wb) { |
| 38 | // this function is async-signal-safe, if the buffer has enough space to hold the stack trace |
| 39 | |
| 40 | root_cause_function[0] = '\0'; |
| 41 | |
| 42 | unw_cursor_t cursor; |
| 43 | unw_context_t context; |
| 44 | size_t frames = 0; |
| 45 | |
| 46 | // Initialize context for current thread |
| 47 | unw_getcontext(&context); |
| 48 | unw_init_local(&cursor, &context); |
| 49 | |
| 50 | // Skip one frame to hide stacktrace_capture() itself |
| 51 | unw_step(&cursor); |
| 52 | |
| 53 | size_t added = 0; |
| 54 | bool found_signal_handler = false; |
| 55 | |
| 56 | while (unw_step(&cursor) > 0) { |
| 57 | unw_word_t offset, pc; |
| 58 | char sym[256]; |
| 59 | |
| 60 | unw_get_reg(&cursor, UNW_REG_IP, &pc); |
| 61 | if (!pc) |
| 62 | break; |
| 63 | |
| 64 | const char *name = sym; |
| 65 | if (unw_get_proc_name(&cursor, sym, sizeof(sym), &offset) != 0) { |
| 66 | name = "<unknown>"; |
| 67 | offset = 0; |
| 68 | } |
| 69 | |
| 70 | // Check if we found the signal handler frame |
| 71 | if (!found_signal_handler && stacktrace_is_signal_handler_function(name)) { |
| 72 | // We found the signal handler, reset the buffer |
| 73 | buffer_flush(wb); |
| 74 | added = 0; |
| 75 | frames = 0; |
| 76 | found_signal_handler = true; |
| 77 | continue; // Skip adding the signal handler itself |
| 78 | } |
| 79 | |
| 80 | // Check for logging functions, but only if we haven't found a signal handler yet |
| 81 | if (!found_signal_handler && stacktrace_is_logging_function(name)) { |
| 82 | // Found a logging function, reset the buffer |
| 83 | buffer_flush(wb); |
| 84 | added = 0; |
| 85 | frames = 0; |
| 86 | // continue to add the function to the stack trace |
| 87 | } |
| 88 | |
| 89 | if (frames++) |
| 90 | buffer_putc(wb, '\n'); |
| 91 | |
| 92 | buffer_putc(wb, '#'); |
| 93 | buffer_print_uint64(wb, added); |
| 94 | buffer_putc(wb, ' '); |
| 95 | buffer_strcat(wb, name); |
| 96 | |
| 97 | if(offset) { |
| 98 | buffer_putc(wb, '+'); |
| 99 | buffer_print_uint64_hex(wb, offset); |
| 100 | } |
| 101 | |
| 102 | added++; |
| 103 | } |
| 104 | |
| 105 | if (!added) |
| 106 | buffer_strcat(wb, NO_STACK_TRACE_PREFIX "libunwind reports no frames"); |
| 107 | } |
| 108 | |
| 109 | // Collect frames using libunwind |
| 110 | static int collect_frames_libunwind(void **frames, int max_frames, int skip) { |
| 111 | unw_cursor_t cursor; |
| 112 | unw_context_t context; |
| 113 | |
| 114 | unw_getcontext(&context); |
| 115 | unw_init_local(&cursor, &context); |
| 116 | |
| 117 | // Collect all frames first, including the ones we'll skip |
| 118 | // This way we ensure we capture all frames, including inlined ones |
| 119 | void *all_frames[150]; // Allocate a larger buffer to hold all frames |
| 120 | int total_frames = 0; |
| 121 | |
| 122 | // Collect as many frames as possible |
| 123 | while (total_frames < 150 && unw_step(&cursor) > 0) { |
| 124 | unw_word_t pc; |
| 125 | unw_get_reg(&cursor, UNW_REG_IP, &pc); |
| 126 | if (!pc) |
| 127 | break; |
| 128 | |
| 129 | all_frames[total_frames++] = (void *)pc; |
| 130 | } |
| 131 | |
| 132 | // Now copy the frames we want, skipping the requested number |
| 133 | int frame_count = 0; |
| 134 | for (int i = skip; i < total_frames && frame_count < max_frames; i++) { |
| 135 | frames[frame_count++] = all_frames[i]; |
| 136 | } |
| 137 | |
| 138 | return frame_count; |
| 139 | } |
| 140 | |
| 141 | // Implementation-specific function to collect stack trace frames |
| 142 | int impl_stacktrace_get_frames(void **frames, int max_frames, int skip_frames) { |
| 143 | if (!frames || max_frames <= 0) |
| 144 | return 0; |
| 145 | |
| 146 | // Add 1 to skip_frames to also skip this function itself |
| 147 | return collect_frames_libunwind(frames, max_frames, skip_frames + 1); |
| 148 | } |
| 149 | |
| 150 | // Implementation-specific function to convert a stacktrace to a buffer |
| 151 | void impl_stacktrace_to_buffer(STACKTRACE trace, BUFFER *wb) { |
| 152 | struct stacktrace *st = (struct stacktrace *)trace; |
| 153 | |
| 154 | // Format each frame |
| 155 | for (int i = 0; i < st->frame_count; i++) { |
| 156 | if (i > 0) |
| 157 | buffer_putc(wb, '\n'); |
| 158 | |
| 159 | buffer_putc(wb, '#'); |
| 160 | buffer_print_uint64(wb, i); |
| 161 | buffer_putc(wb, ' '); |
| 162 | |
| 163 | // Try to resolve symbol name |
| 164 | unw_cursor_t cursor; |
| 165 | unw_context_t context; |
| 166 | char sym[256] = "<unknown>"; |
| 167 | unw_word_t offset = 0; |
| 168 | |
| 169 | // We don't have the context anymore, so do the best we can |
| 170 | // Try to resolve the address to a symbol name |
| 171 | if (dladdr(st->frames[i], (Dl_info *)sym) == 0) { |
| 172 | buffer_strcat(wb, "<unknown>"); |
| 173 | } else { |
| 174 | Dl_info *info = (Dl_info *)sym; |
| 175 | if (info->dli_sname) |
| 176 | buffer_strcat(wb, info->dli_sname); |
| 177 | else |
| 178 | buffer_strcat(wb, "<unknown>"); |
| 179 | } |
| 180 | |
| 181 | buffer_strcat(wb, " ["); |
| 182 | buffer_print_uint64_hex(wb, (uint64_t)st->frames[i]); |
| 183 | buffer_putc(wb, ']'); |
| 184 | } |
| 185 | } |
| 186 | |
| 187 | #endif // USE_LIBUNWIND |