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/tests/task-exit.c | 161 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 tools/perf/tests/task-exit.c (limited to 'tools/perf/tests/task-exit.c') diff --git a/tools/perf/tests/task-exit.c b/tools/perf/tests/task-exit.c new file mode 100644 index 000000000..4053ff281 --- /dev/null +++ b/tools/perf/tests/task-exit.c @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "debug.h" +#include "evlist.h" +#include "evsel.h" +#include "target.h" +#include "thread_map.h" +#include "tests.h" +#include "util/mmap.h" + +#include +#include +#include +#include +#include +#include + +static int exited; +static int nr_exit; + +static void sig_handler(int sig __maybe_unused) +{ + exited = 1; +} + +/* + * evlist__prepare_workload will send a SIGUSR1 if the fork fails, since + * we asked by setting its exec_error to this handler. + */ +static void workload_exec_failed_signal(int signo __maybe_unused, + siginfo_t *info __maybe_unused, + void *ucontext __maybe_unused) +{ + exited = 1; + nr_exit = -1; +} + +/* + * This test will start a workload that does nothing then it checks + * if the number of exit event reported by the kernel is 1 or not + * in order to check the kernel returns correct number of event. + */ +static int test__task_exit(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ + int err = -1; + union perf_event *event; + struct evsel *evsel; + struct evlist *evlist; + struct target target = { + .uses_mmap = true, + }; + const char *argv[] = { "true", NULL }; + char sbuf[STRERR_BUFSIZE]; + struct perf_cpu_map *cpus; + struct perf_thread_map *threads; + struct mmap *md; + int retry_count = 0; + + signal(SIGCHLD, sig_handler); + + evlist = evlist__new_dummy(); + if (evlist == NULL) { + pr_debug("evlist__new_dummy\n"); + return -1; + } + + /* + * Create maps of threads and cpus to monitor. In this case + * we start with all threads and cpus (-1, -1) but then in + * evlist__prepare_workload we'll fill in the only thread + * we're monitoring, the one forked there. + */ + cpus = perf_cpu_map__new_any_cpu(); + threads = thread_map__new_by_tid(-1); + if (!cpus || !threads) { + err = -ENOMEM; + pr_debug("Not enough memory to create thread/cpu maps\n"); + goto out_delete_evlist; + } + + perf_evlist__set_maps(&evlist->core, cpus, threads); + + err = evlist__prepare_workload(evlist, &target, argv, false, workload_exec_failed_signal); + if (err < 0) { + pr_debug("Couldn't run the workload!\n"); + goto out_delete_evlist; + } + + evsel = evlist__first(evlist); + evsel->core.attr.task = 1; +#ifdef __s390x__ + evsel->core.attr.sample_freq = 1000000; +#else + evsel->core.attr.sample_freq = 1; +#endif + evsel->core.attr.inherit = 0; + evsel->core.attr.watermark = 0; + evsel->core.attr.wakeup_events = 1; + evsel->core.attr.exclude_kernel = 1; + + err = evlist__open(evlist); + if (err < 0) { + pr_debug("Couldn't open the evlist: %s\n", + str_error_r(-err, sbuf, sizeof(sbuf))); + goto out_delete_evlist; + } + + if (evlist__mmap(evlist, 128) < 0) { + pr_debug("failed to mmap events: %d (%s)\n", errno, + str_error_r(errno, sbuf, sizeof(sbuf))); + err = -1; + goto out_delete_evlist; + } + + evlist__start_workload(evlist); + +retry: + md = &evlist->mmap[0]; + if (perf_mmap__read_init(&md->core) < 0) + goto out_init; + + while ((event = perf_mmap__read_event(&md->core)) != NULL) { + if (event->header.type == PERF_RECORD_EXIT) + nr_exit++; + + perf_mmap__consume(&md->core); + } + perf_mmap__read_done(&md->core); + +out_init: + if (!exited || !nr_exit) { + evlist__poll(evlist, -1); + + if (retry_count++ > 1000) { + pr_debug("Failed after retrying 1000 times\n"); + err = -1; + goto out_delete_evlist; + } + + goto retry; + } + + if (nr_exit != 1) { + pr_debug("received %d EXIT records\n", nr_exit); + err = -1; + } + +out_delete_evlist: + perf_cpu_map__put(cpus); + perf_thread_map__put(threads); + evlist__delete(evlist); + return err; +} + +struct test_case tests__task_exit[] = { + TEST_CASE_EXCLUSIVE("Number of exit events of a simple workload", task_exit), + { .name = NULL, } +}; +struct test_suite suite__task_exit = { + .desc = "Number of exit events of a simple workload", + .test_cases = tests__task_exit, +}; -- cgit v1.3.1