1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or https://opensource.org/licenses/CDDL-1.0. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright (c) 2024, Rob Norris <robn@despairlabs.com> 23 * Copyright (c) 2024, Klara Inc. 24 */ 25 26 #include <sys/backtrace.h> 27 #include <sys/types.h> 28 #include <unistd.h> 29 30 /* 31 * libspl_backtrace() must be safe to call from inside a signal hander. This 32 * mostly means it must not allocate, and so we can't use things like printf. 33 */ 34 35 #if defined(HAVE_LIBUNWIND) 36 #define UNW_LOCAL_ONLY 37 #include <libunwind.h> 38 39 static size_t 40 libspl_u64_to_hex_str(uint64_t v, size_t digits, char *buf, size_t buflen) 41 { 42 static const char hexdigits[] = { 43 '0', '1', '2', '3', '4', '5', '6', '7', 44 '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' 45 }; 46 47 size_t pos = 0; 48 boolean_t want = (digits == 0); 49 for (int i = 15; i >= 0; i--) { 50 const uint64_t d = v >> (i * 4) & 0xf; 51 if (!want && (d != 0 || digits > i)) 52 want = B_TRUE; 53 if (want) { 54 buf[pos++] = hexdigits[d]; 55 if (pos == buflen) 56 break; 57 } 58 } 59 return (pos); 60 } 61 62 void 63 libspl_backtrace(int fd) 64 { 65 ssize_t ret __attribute__((unused)); 66 unw_context_t uc; 67 unw_cursor_t cp; 68 unw_word_t loc; 69 char buf[128]; 70 size_t n; 71 72 ret = write(fd, "Call trace:\n", 12); 73 unw_getcontext(&uc); 74 unw_init_local(&cp, &uc); 75 while (unw_step(&cp) > 0) { 76 unw_get_reg(&cp, UNW_REG_IP, &loc); 77 ret = write(fd, " [0x", 5); 78 n = libspl_u64_to_hex_str(loc, 10, buf, sizeof (buf)); 79 ret = write(fd, buf, n); 80 ret = write(fd, "] ", 2); 81 unw_get_proc_name(&cp, buf, sizeof (buf), &loc); 82 for (n = 0; n < sizeof (buf) && buf[n] != '\0'; n++) {} 83 ret = write(fd, buf, n); 84 ret = write(fd, "+0x", 3); 85 n = libspl_u64_to_hex_str(loc, 2, buf, sizeof (buf)); 86 ret = write(fd, buf, n); 87 #ifdef HAVE_LIBUNWIND_ELF 88 ret = write(fd, " (in ", 5); 89 unw_get_elf_filename(&cp, buf, sizeof (buf), &loc); 90 for (n = 0; n < sizeof (buf) && buf[n] != '\0'; n++) {} 91 ret = write(fd, buf, n); 92 ret = write(fd, " +0x", 4); 93 n = libspl_u64_to_hex_str(loc, 2, buf, sizeof (buf)); 94 ret = write(fd, buf, n); 95 ret = write(fd, ")", 1); 96 #endif 97 ret = write(fd, "\n", 1); 98 } 99 } 100 #elif defined(HAVE_BACKTRACE) 101 #include <execinfo.h> 102 103 void 104 libspl_backtrace(int fd) 105 { 106 ssize_t ret __attribute__((unused)); 107 void *btptrs[64]; 108 size_t nptrs = backtrace(btptrs, 64); 109 ret = write(fd, "Call trace:\n", 12); 110 backtrace_symbols_fd(btptrs, nptrs, fd); 111 } 112 #else 113 #include <sys/debug.h> 114 115 void 116 libspl_backtrace(int fd __maybe_unused) 117 { 118 } 119 #endif 120