From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- tools/perf/util/addr2line.c | 436 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 436 insertions(+) create mode 100644 tools/perf/util/addr2line.c (limited to 'tools/perf/util/addr2line.c') diff --git a/tools/perf/util/addr2line.c b/tools/perf/util/addr2line.c new file mode 100644 index 000000000..4b0d349ed --- /dev/null +++ b/tools/perf/util/addr2line.c @@ -0,0 +1,436 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "addr2line.h" +#include "debug.h" +#include "dso.h" +#include "string2.h" +#include "srcline.h" +#include "symbol.h" +#include "symbol_conf.h" + +#include +#include +#include + +#include +#include +#include +#include + +#define MAX_INLINE_NEST 1024 + +static int filename_split(char *filename, unsigned int *line_nr) +{ + char *sep; + + sep = strchr(filename, '\n'); + if (sep) + *sep = '\0'; + + if (!strcmp(filename, "??:0")) + return 0; + + sep = strchr(filename, ':'); + if (sep) { + *sep++ = '\0'; + *line_nr = strtoul(sep, NULL, 0); + return 1; + } + pr_debug("addr2line missing ':' in filename split\n"); + return 0; +} + +static void addr2line_subprocess_cleanup(struct child_process *a2l) +{ + if (a2l->pid != -1) { + kill(a2l->pid, SIGKILL); + finish_command(a2l); /* ignore result, we don't care */ + a2l->pid = -1; + close(a2l->in); + close(a2l->out); + } + + free(a2l); +} + +static struct child_process *addr2line_subprocess_init(const char *addr2line_path, + const char *binary_path) +{ + const char *argv[] = { + addr2line_path ?: "addr2line", + "-e", binary_path, + "-a", "-i", "-f", NULL + }; + struct child_process *a2l = zalloc(sizeof(*a2l)); + int start_command_status = 0; + + if (a2l == NULL) { + pr_err("Failed to allocate memory for addr2line"); + return NULL; + } + + a2l->pid = -1; + a2l->in = -1; + a2l->out = -1; + a2l->no_stderr = 1; + + a2l->argv = argv; + start_command_status = start_command(a2l); + a2l->argv = NULL; /* it's not used after start_command; avoid dangling pointers */ + + if (start_command_status != 0) { + pr_warning("could not start addr2line (%s) for %s: start_command return code %d\n", + addr2line_path, binary_path, start_command_status); + addr2line_subprocess_cleanup(a2l); + return NULL; + } + + return a2l; +} + +enum cmd_a2l_style { + BROKEN, + GNU_BINUTILS, + LLVM, +}; + +static enum cmd_a2l_style cmd_addr2line_configure(struct child_process *a2l, const char *dso_name) +{ + static bool cached; + static enum cmd_a2l_style style; + + if (!cached) { + char buf[128]; + struct io io; + int ch; + int lines; + + if (write(a2l->in, ",\n", 2) != 2) + return BROKEN; + + io__init(&io, a2l->out, buf, sizeof(buf)); + ch = io__get_char(&io); + if (ch == ',') { + style = LLVM; + cached = true; + lines = 1; + pr_debug3("Detected LLVM addr2line style\n"); + } else if (ch == '0') { + style = GNU_BINUTILS; + cached = true; + lines = 3; + pr_debug3("Detected binutils addr2line style\n"); + } else { + if (!symbol_conf.addr2line_disable_warn) { + char *output = NULL; + size_t output_len; + + io__getline(&io, &output, &output_len); + pr_warning("%s %s: addr2line configuration failed\n", + __func__, dso_name); + pr_warning("\t%c%s", ch, output); + } + pr_debug("Unknown/broken addr2line style\n"); + return BROKEN; + } + while (lines) { + ch = io__get_char(&io); + if (ch <= 0) + break; + if (ch == '\n') + lines--; + } + /* Ignore SIGPIPE in the event addr2line exits. */ + signal(SIGPIPE, SIG_IGN); + } + return style; +} + +static int read_addr2line_record(struct io *io, + enum cmd_a2l_style style, + const char *dso_name, + u64 addr, + bool first, + char **function, + char **filename, + unsigned int *line_nr) +{ + /* + * Returns: + * -1 ==> error + * 0 ==> sentinel (or other ill-formed) record read + * 1 ==> a genuine record read + */ + char *line = NULL; + size_t line_len = 0; + unsigned int dummy_line_nr = 0; + int ret = -1; + + if (function != NULL) + zfree(function); + + if (filename != NULL) + zfree(filename); + + if (line_nr != NULL) + *line_nr = 0; + + /* + * Read the first line. Without an error this will be: + * - for the first line an address like 0x1234, + * - the binutils sentinel 0x0000000000000000, + * - the llvm-addr2line the sentinel ',' character, + * - the function name line for an inlined function. + */ + if (io__getline(io, &line, &line_len) < 0 || !line_len) + goto error; + + pr_debug3("%s %s: addr2line read address for sentinel: %s", __func__, dso_name, line); + if (style == LLVM && line_len == 2 && line[0] == ',') { + /* Found the llvm-addr2line sentinel character. */ + zfree(&line); + return 0; + } else if (style == GNU_BINUTILS && (!first || addr != 0)) { + int zero_count = 0, non_zero_count = 0; + /* + * Check for binutils sentinel ignoring it for the case the + * requested address is 0. + */ + + /* A given address should always start 0x. */ + if (line_len >= 2 || line[0] != '0' || line[1] != 'x') { + for (size_t i = 2; i < line_len; i++) { + if (line[i] == '0') + zero_count++; + else if (line[i] != '\n') + non_zero_count++; + } + if (!non_zero_count) { + int ch; + + if (first && !zero_count) { + /* Line was erroneous just '0x'. */ + goto error; + } + /* + * Line was 0x0..0, the sentinel for binutils. Remove + * the function and filename lines. + */ + zfree(&line); + do { + ch = io__get_char(io); + } while (ch > 0 && ch != '\n'); + do { + ch = io__get_char(io); + } while (ch > 0 && ch != '\n'); + return 0; + } + } + } + /* Read the second function name line (if inline data then this is the first line). */ + if (first && (io__getline(io, &line, &line_len) < 0 || !line_len)) + goto error; + + pr_debug3("%s %s: addr2line read line: %s", __func__, dso_name, line); + if (function != NULL) + *function = strdup(strim(line)); + + zfree(&line); + line_len = 0; + + /* Read the third filename and line number line. */ + if (io__getline(io, &line, &line_len) < 0 || !line_len) + goto error; + + pr_debug3("%s %s: addr2line filename:number : %s", __func__, dso_name, line); + if (filename_split(line, line_nr == NULL ? &dummy_line_nr : line_nr) == 0 && + style == GNU_BINUTILS) { + ret = 0; + goto error; + } + + if (filename != NULL) + *filename = strdup(line); + + zfree(&line); + line_len = 0; + + return 1; + +error: + free(line); + if (function != NULL) + zfree(function); + if (filename != NULL) + zfree(filename); + return ret; +} + +static int inline_list__append_record(struct dso *dso, + struct inline_node *node, + struct symbol *sym, + const char *function, + const char *filename, + unsigned int line_nr) +{ + struct symbol *inline_sym = new_inline_sym(dso, sym, function); + + return inline_list__append(inline_sym, srcline_from_fileline(filename, line_nr), node); +} + +int cmd__addr2line(const char *dso_name, u64 addr, + char **file, unsigned int *line_nr, + struct dso *dso, + bool unwind_inlines, + struct inline_node *node, + struct symbol *sym __maybe_unused) +{ + struct child_process *a2l = dso__a2l(dso); + char *record_function = NULL; + char *record_filename = NULL; + unsigned int record_line_nr = 0; + int record_status = -1; + int ret = 0; + size_t inline_count = 0; + int len; + char buf[128]; + ssize_t written; + struct io io = { .eof = false }; + enum cmd_a2l_style cmd_a2l_style; + + if (!a2l) { + if (!filename__has_section(dso_name, ".debug_line")) + goto out; + + dso__set_a2l(dso, + addr2line_subprocess_init(symbol_conf.addr2line_path, dso_name)); + a2l = dso__a2l(dso); + } + + if (a2l == NULL) { + if (!symbol_conf.addr2line_disable_warn) + pr_warning("%s %s: addr2line_subprocess_init failed\n", __func__, dso_name); + goto out; + } + cmd_a2l_style = cmd_addr2line_configure(a2l, dso_name); + if (cmd_a2l_style == BROKEN) + goto out; + + /* + * Send our request and then *deliberately* send something that can't be + * interpreted as a valid address to ask addr2line about (namely, + * ","). This causes addr2line to first write out the answer to our + * request, in an unbounded/unknown number of records, and then to write + * out the lines "0x0...0", "??" and "??:0", for GNU binutils, or "," + * for llvm-addr2line, so that we can detect when it has finished giving + * us anything useful. + */ + len = snprintf(buf, sizeof(buf), "%016"PRIx64"\n,\n", addr); + written = len > 0 ? write(a2l->in, buf, len) : -1; + if (written != len) { + if (!symbol_conf.addr2line_disable_warn) + pr_warning("%s %s: could not send request\n", __func__, dso_name); + goto out; + } + io__init(&io, a2l->out, buf, sizeof(buf)); + io.timeout_ms = symbol_conf.addr2line_timeout_ms; + switch (read_addr2line_record(&io, cmd_a2l_style, dso_name, addr, /*first=*/true, + &record_function, &record_filename, &record_line_nr)) { + case -1: + if (!symbol_conf.addr2line_disable_warn) + pr_warning("%s %s: could not read first record\n", __func__, dso_name); + goto out; + case 0: + /* + * The first record was invalid, so return failure, but first + * read another record, since we sent a sentinel ',' for the + * sake of detected the last inlined function. Treat this as the + * first of a record as the ',' generates a new start with GNU + * binutils, also force a non-zero address as we're no longer + * reading that record. + */ + switch (read_addr2line_record(&io, cmd_a2l_style, dso_name, + /*addr=*/1, /*first=*/true, + NULL, NULL, NULL)) { + case -1: + if (!symbol_conf.addr2line_disable_warn) + pr_warning("%s %s: could not read sentinel record\n", + __func__, dso_name); + break; + case 0: + /* The sentinel as expected. */ + break; + default: + if (!symbol_conf.addr2line_disable_warn) + pr_warning("%s %s: unexpected record instead of sentinel", + __func__, dso_name); + break; + } + goto out; + default: + /* First record as expected. */ + break; + } + + if (file) { + *file = strdup(record_filename); + ret = 1; + } + if (line_nr) + *line_nr = record_line_nr; + + if (unwind_inlines) { + if (node && inline_list__append_record(dso, node, sym, + record_function, + record_filename, + record_line_nr)) { + ret = 0; + goto out; + } + } + + /* + * We have to read the records even if we don't care about the inline + * info. This isn't the first record and force the address to non-zero + * as we're reading records beyond the first. + */ + while ((record_status = read_addr2line_record(&io, + cmd_a2l_style, + dso_name, + /*addr=*/1, + /*first=*/false, + &record_function, + &record_filename, + &record_line_nr)) == 1) { + if (unwind_inlines && node && inline_count++ < MAX_INLINE_NEST) { + if (inline_list__append_record(dso, node, sym, + record_function, + record_filename, + record_line_nr)) { + ret = 0; + goto out; + } + ret = 1; /* found at least one inline frame */ + } + } + +out: + free(record_function); + free(record_filename); + if (io.eof) { + dso__set_a2l(dso, NULL); + addr2line_subprocess_cleanup(a2l); + } + return ret; +} + +void dso__free_a2l(struct dso *dso) +{ + struct child_process *a2l = dso__a2l(dso); + + if (!a2l) + return; + + addr2line_subprocess_cleanup(a2l); + + dso__set_a2l(dso, NULL); +} -- cgit v1.3.1