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/help-unknown-cmd.c | 122 +++++++++++++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) create mode 100644 tools/perf/util/help-unknown-cmd.c (limited to 'tools/perf/util/help-unknown-cmd.c') diff --git a/tools/perf/util/help-unknown-cmd.c b/tools/perf/util/help-unknown-cmd.c new file mode 100644 index 000000000..a0a46e34f --- /dev/null +++ b/tools/perf/util/help-unknown-cmd.c @@ -0,0 +1,122 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "cache.h" +#include "config.h" +#include +#include +#include +#include +#include "../builtin.h" +#include "levenshtein.h" +#include + +static int autocorrect; + +static int perf_unknown_cmd_config(const char *var, const char *value, + void *cb __maybe_unused) +{ + if (!strcmp(var, "help.autocorrect")) + return perf_config_int(&autocorrect, var,value); + + return 0; +} + +static int levenshtein_compare(const void *p1, const void *p2) +{ + const struct cmdname *const *c1 = p1, *const *c2 = p2; + const char *s1 = (*c1)->name, *s2 = (*c2)->name; + int l1 = (*c1)->len; + int l2 = (*c2)->len; + return l1 != l2 ? l1 - l2 : strcmp(s1, s2); +} + +static int add_cmd_list(struct cmdnames *cmds, struct cmdnames *old) +{ + unsigned int i, nr = cmds->cnt + old->cnt; + void *tmp; + + if (nr > cmds->alloc) { + /* Choose bigger one to alloc */ + if (alloc_nr(cmds->alloc) < nr) + cmds->alloc = nr; + else + cmds->alloc = alloc_nr(cmds->alloc); + tmp = realloc(cmds->names, cmds->alloc * sizeof(*cmds->names)); + if (!tmp) + return -1; + cmds->names = tmp; + } + for (i = 0; i < old->cnt; i++) + cmds->names[cmds->cnt++] = old->names[i]; + zfree(&old->names); + old->cnt = 0; + return 0; +} + +const char *help_unknown_cmd(const char *cmd, struct cmdnames *main_cmds) +{ + unsigned int i, n = 0, best_similarity = 0; + struct cmdnames other_cmds; + + memset(&other_cmds, 0, sizeof(other_cmds)); + + perf_config(perf_unknown_cmd_config, NULL); + + load_command_list("perf-", main_cmds, &other_cmds); + + if (add_cmd_list(main_cmds, &other_cmds) < 0) { + fprintf(stderr, "ERROR: Failed to allocate command list for unknown command.\n"); + goto end; + } + qsort(main_cmds->names, main_cmds->cnt, + sizeof(main_cmds->names), cmdname_compare); + uniq(main_cmds); + + if (main_cmds->cnt) { + /* This reuses cmdname->len for similarity index */ + for (i = 0; i < main_cmds->cnt; ++i) { + main_cmds->names[i]->len = + levenshtein(cmd, main_cmds->names[i]->name, + /*swap_penalty=*/0, + /*substition_penality=*/2, + /*insertion_penality=*/1, + /*deletion_penalty=*/1); + } + qsort(main_cmds->names, main_cmds->cnt, + sizeof(*main_cmds->names), levenshtein_compare); + + best_similarity = main_cmds->names[0]->len; + n = 1; + while (n < main_cmds->cnt && best_similarity == main_cmds->names[n]->len) + ++n; + } + + if (autocorrect && n == 1) { + const char *assumed = main_cmds->names[0]->name; + + main_cmds->names[0] = NULL; + clean_cmdnames(&other_cmds); + fprintf(stderr, "WARNING: You called a perf program named '%s', " + "which does not exist.\n" + "Continuing under the assumption that you meant '%s'\n", + cmd, assumed); + if (autocorrect > 0) { + fprintf(stderr, "in %0.1f seconds automatically...\n", + (float)autocorrect/10.0); + poll(NULL, 0, autocorrect * 100); + } + return assumed; + } + + fprintf(stderr, "perf: '%s' is not a perf-command. See 'perf --help'.\n", cmd); + + if (main_cmds->cnt && best_similarity < 6) { + fprintf(stderr, "\nDid you mean %s?\n", + n < 2 ? "this": "one of these"); + + for (i = 0; i < n; i++) + fprintf(stderr, "\t%s\n", main_cmds->names[i]->name); + } +end: + clean_cmdnames(&other_cmds); + return NULL; +} -- cgit v1.3.1