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Diffstat (limited to 'lib/libspl/backtrace.c')
| -rw-r--r-- | lib/libspl/backtrace.c | 303 |
1 files changed, 0 insertions, 303 deletions
diff --git a/lib/libspl/backtrace.c b/lib/libspl/backtrace.c deleted file mode 100644 index c4a7006a9692..000000000000 --- a/lib/libspl/backtrace.c +++ /dev/null @@ -1,303 +0,0 @@ -// SPDX-License-Identifier: CDDL-1.0 -/* - * CDDL HEADER START - * - * The contents of this file are subject to the terms of the - * Common Development and Distribution License (the "License"). - * You may not use this file except in compliance with the License. - * - * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE - * or https://opensource.org/licenses/CDDL-1.0. - * See the License for the specific language governing permissions - * and limitations under the License. - * - * When distributing Covered Code, include this CDDL HEADER in each - * file and include the License file at usr/src/OPENSOLARIS.LICENSE. - * If applicable, add the following below this CDDL HEADER, with the - * fields enclosed by brackets "[]" replaced with your own identifying - * information: Portions Copyright [yyyy] [name of copyright owner] - * - * CDDL HEADER END - */ -/* - * Copyright (c) 2024, Rob Norris <robn@despairlabs.com> - * Copyright (c) 2024, Klara Inc. - */ - -#include <sys/backtrace.h> -#include <sys/types.h> -#include <sys/debug.h> -#include <unistd.h> - -/* - * Output helpers. libspl_backtrace() must not block, must be thread-safe and - * must be safe to call from a signal handler. At least, that means not having - * printf, so we end up having to call write() directly on the fd. That's - * awkward, as we always have to pass through a length, and some systems will - * complain if we don't consume the return. So we have some macros to make - * things a little more palatable. - */ -#define spl_bt_write_n(fd, s, n) \ - do { ssize_t r __maybe_unused = write(fd, s, n); } while (0) -#define spl_bt_write(fd, s) spl_bt_write_n(fd, s, sizeof (s)-1) - -#ifdef HAVE_LIBUNWIND -/* - * libunwind-gcc and libunwind-llvm both list registers using an enum, - * unw_regnum_t, however they indicate the highest numbered register for - * a given architecture in different ways. We can check which one is defined - * and mark which libunwind is in use - */ -#ifdef IS_LIBUNWIND_LLVM -#include <libunwind.h> -#define LAST_REG_INDEX _LIBUNWIND_HIGHEST_DWARF_REGISTER -#else -/* - * Need to define UNW_LOCAL_ONLY before importing libunwind.h - * if using libgcc libunwind. - */ -#define UNW_LOCAL_ONLY -#include <libunwind.h> -#define LAST_REG_INDEX UNW_TDEP_LAST_REG -#endif - - -/* - * Convert `v` to ASCII hex characters. The bottom `n` nybbles (4-bits ie one - * hex digit) will be written, up to `buflen`. The buffer will not be - * null-terminated. Returns the number of digits written. - */ -static size_t -spl_bt_u64_to_hex_str(uint64_t v, size_t n, char *buf, size_t buflen) -{ - static const char hexdigits[] = { - '0', '1', '2', '3', '4', '5', '6', '7', - '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' - }; - - size_t pos = 0; - boolean_t want = (n == 0); - for (int i = 15; i >= 0; i--) { - const uint64_t d = v >> (i * 4) & 0xf; - if (!want && (d != 0 || n > i)) - want = B_TRUE; - if (want) { - buf[pos++] = hexdigits[d]; - if (pos == buflen) - break; - } - } - return (pos); -} - -void -libspl_backtrace(int fd) -{ - unw_context_t uc; - unw_cursor_t cp; - unw_word_t v; - char buf[128]; - size_t n; - int err; - - /* Snapshot the current frame and state. */ - unw_getcontext(&uc); - - /* - * TODO: walk back to the frame that tripped the assertion / the place - * where the signal was recieved. - */ - - /* - * Register dump. We're going to loop over all the registers in the - * top frame, and show them, with names, in a nice three-column - * layout, which keeps us within 80 columns. - */ - spl_bt_write(fd, "Registers:\n"); - - /* Initialise a frame cursor, starting at the current frame */ - unw_init_local(&cp, &uc); - - /* - * Iterate over all registers for the architecture. We've figured - * out the highest number above, however, not all register numbers in - * this range are defined by the architecture, and not all defined - * registers will be present on every implementation of that - * architecture. Moreover, libunwind provides nice names for most, but - * not all registers, but these are hardcoded; a name being available - * does not mean that register is available. - * - * So, we have to pull this all together here. We try to get the value - * of every possible register. If we get a value for it, then the - * register must exist, and so we get its name. If libunwind has no - * name for it, we synthesize something. These cases should be rare, - * and they're usually for uninteresting or niche registers, so it - * shouldn't really matter. We can see the value, and that's the main - * thing. - */ - uint_t cols = 0; - for (uint_t regnum = 0; regnum <= LAST_REG_INDEX; regnum++) { - /* - * Get the value. Any error probably means the register - * doesn't exist, and we skip it. LLVM libunwind iterates over - * fp registers in the same list, however they have to be - * accessed using unw_get_fpreg instead. Here, we just ignore - * them. - */ -#ifdef IS_LIBUNWIND_LLVM - if (unw_is_fpreg(&cp, regnum) || - unw_get_reg(&cp, regnum, &v) < 0) - continue; -#else - if (unw_get_reg(&cp, regnum, &v) < 0) - continue; -#endif - - /* - * Register name. If GCC libunwind doesn't have a name for it, - * it will return "???". As a shortcut, we just treat '?' - * is an alternate end-of-string character. LLVM libunwind will - * return the string 'unknown register', which we detect by - * checking if the register name is longer than 5 characters. - */ -#ifdef IS_LIBUNWIND_LLVM - const char *name = unw_regname(&cp, regnum); -#else - const char *name = unw_regname(regnum); -#endif - for (n = 0; name[n] != '\0' && name[n] != '?'; n++) {} - if (n == 0 || n > 5) { - /* - * No valid name, or likely llvm_libunwind returned - * unknown_register, so make one of the form "?xx", - * where "xx" is the two-char hex of libunwind's - * register number. - */ - buf[0] = '?'; - n = spl_bt_u64_to_hex_str(regnum, 2, - &buf[1], sizeof (buf)-1) + 1; - name = buf; - } - - /* - * Two spaces of padding before each column, plus extra - * spaces to align register names shorter than three chars. - */ - spl_bt_write_n(fd, " ", 5-MIN(n, 3)); - - /* Register name and column punctuation */ - spl_bt_write_n(fd, name, n); - spl_bt_write(fd, ": 0x"); - - /* - * Convert register value (from unw_get_reg()) to hex. We're - * assuming that all registers are 64-bits wide, which is - * probably fine for any general-purpose registers on any - * machine currently in use. A more generic way would be to - * look at the width of unw_word_t, but that would also - * complicate the column code a bit. This is fine. - */ - n = spl_bt_u64_to_hex_str(v, 16, buf, sizeof (buf)); - spl_bt_write_n(fd, buf, n); - - /* Every third column, emit a newline */ - if (!(++cols % 3)) - spl_bt_write(fd, "\n"); - } - - /* If we finished before the third column, emit a newline. */ - if (cols % 3) - spl_bt_write(fd, "\n"); - - /* Now the main event, the backtrace. */ - spl_bt_write(fd, "Call trace:\n"); - - /* Reset the cursor to the top again. */ - unw_init_local(&cp, &uc); - - do { - /* - * Getting the IP should never fail; libunwind handles it - * specially, because its used a lot internally. Still, no - * point being silly about it, as the last thing we want is - * our crash handler to crash. So if it ever does fail, we'll - * show an error line, but keep going to the next frame. - */ - if (unw_get_reg(&cp, UNW_REG_IP, &v) < 0) { - spl_bt_write(fd, " [couldn't get IP register; " - "corrupt frame?]"); - continue; - } - - /* IP & punctuation */ - n = spl_bt_u64_to_hex_str(v, 16, buf, sizeof (buf)); - spl_bt_write(fd, " [0x"); - spl_bt_write_n(fd, buf, n); - spl_bt_write(fd, "] "); - - /* - * Function ("procedure") name for the current frame. `v` - * receives the offset from the named function to the IP, which - * we show as a "+offset" suffix. - * - * If libunwind can't determine the name, we just show "???" - * instead. We've already displayed the IP above; that will - * have to do. - * - * unw_get_proc_name() will return ENOMEM if the buffer is too - * small, instead truncating the name. So we treat that as a - * success and use whatever is in the buffer. - */ - err = unw_get_proc_name(&cp, buf, sizeof (buf), &v); - if (err == 0 || err == -UNW_ENOMEM) { - for (n = 0; n < sizeof (buf) && buf[n] != '\0'; n++) {} - spl_bt_write_n(fd, buf, n); - - /* Offset from proc name */ - spl_bt_write(fd, "+0x"); - n = spl_bt_u64_to_hex_str(v, 2, buf, sizeof (buf)); - spl_bt_write_n(fd, buf, n); - } else - spl_bt_write(fd, "???"); - -#ifdef HAVE_LIBUNWIND_ELF - /* - * Newer libunwind has unw_get_elf_filename(), which gets - * the name of the ELF object that the frame was executing in. - * Like `unw_get_proc_name()`, `v` recieves the offset within - * the file, and UNW_ENOMEM indicates that a truncate filename - * was left in the buffer. - */ - err = unw_get_elf_filename(&cp, buf, sizeof (buf), &v); - if (err == 0 || err == -UNW_ENOMEM) { - for (n = 0; n < sizeof (buf) && buf[n] != '\0'; n++) {} - spl_bt_write(fd, " (in "); - spl_bt_write_n(fd, buf, n); - - /* Offset within file */ - spl_bt_write(fd, " +0x"); - n = spl_bt_u64_to_hex_str(v, 2, buf, sizeof (buf)); - spl_bt_write_n(fd, buf, n); - spl_bt_write(fd, ")"); - } -#endif - spl_bt_write(fd, "\n"); - } while (unw_step(&cp) > 0); -} -#elif defined(HAVE_BACKTRACE) -#include <execinfo.h> - -void -libspl_backtrace(int fd) -{ - void *btptrs[64]; - size_t nptrs = backtrace(btptrs, 64); - spl_bt_write(fd, "Call trace:\n"); - backtrace_symbols_fd(btptrs, nptrs, fd); -} -#else -void -libspl_backtrace(int fd __maybe_unused) -{ -} -#endif |