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/fdarray.c | 163 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 163 insertions(+) create mode 100644 tools/perf/tests/fdarray.c (limited to 'tools/perf/tests/fdarray.c') diff --git a/tools/perf/tests/fdarray.c b/tools/perf/tests/fdarray.c new file mode 100644 index 000000000..40983c357 --- /dev/null +++ b/tools/perf/tests/fdarray.c @@ -0,0 +1,163 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include "util/debug.h" +#include "tests/tests.h" + +static void fdarray__init_revents(struct fdarray *fda, short revents) +{ + int fd; + + fda->nr = fda->nr_alloc; + + for (fd = 0; fd < fda->nr; ++fd) { + fda->entries[fd].fd = fda->nr - fd; + fda->entries[fd].events = revents; + fda->entries[fd].revents = revents; + } +} + +static int fdarray__fprintf_prefix(struct fdarray *fda, const char *prefix, FILE *fp) +{ + int printed = 0; + + if (verbose <= 0) + return 0; + + printed += fprintf(fp, "\n%s: ", prefix); + return printed + fdarray__fprintf(fda, fp); +} + +static int test__fdarray__filter(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ + int nr_fds, err = TEST_FAIL; + struct fdarray *fda = fdarray__new(5, 5); + + if (fda == NULL) { + pr_debug("\nfdarray__new() failed!"); + goto out; + } + + fdarray__init_revents(fda, POLLIN); + nr_fds = fdarray__filter(fda, POLLHUP, NULL, NULL); + if (nr_fds != fda->nr_alloc) { + pr_debug("\nfdarray__filter()=%d != %d shouldn't have filtered anything", + nr_fds, fda->nr_alloc); + goto out_delete; + } + + fdarray__init_revents(fda, POLLHUP); + nr_fds = fdarray__filter(fda, POLLHUP, NULL, NULL); + if (nr_fds != 0) { + pr_debug("\nfdarray__filter()=%d != %d, should have filtered all fds", + nr_fds, fda->nr_alloc); + goto out_delete; + } + + fdarray__init_revents(fda, POLLHUP); + fda->entries[2].revents = POLLIN; + + pr_debug("\nfiltering all but fda->entries[2]:"); + fdarray__fprintf_prefix(fda, "before", stderr); + nr_fds = fdarray__filter(fda, POLLHUP, NULL, NULL); + fdarray__fprintf_prefix(fda, " after", stderr); + if (nr_fds != 1) { + pr_debug("\nfdarray__filter()=%d != 1, should have left just one event", nr_fds); + goto out_delete; + } + + fdarray__init_revents(fda, POLLHUP); + fda->entries[0].revents = POLLIN; + fda->entries[3].revents = POLLIN; + + pr_debug("\nfiltering all but (fda->entries[0], fda->entries[3]):"); + fdarray__fprintf_prefix(fda, "before", stderr); + nr_fds = fdarray__filter(fda, POLLHUP, NULL, NULL); + fdarray__fprintf_prefix(fda, " after", stderr); + if (nr_fds != 2) { + pr_debug("\nfdarray__filter()=%d != 2, should have left just two events", + nr_fds); + goto out_delete; + } + + pr_debug("\n"); + + err = 0; +out_delete: + fdarray__delete(fda); +out: + return err; +} + +static int test__fdarray__add(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ + int err = TEST_FAIL; + struct fdarray *fda = fdarray__new(2, 2); + + if (fda == NULL) { + pr_debug("\nfdarray__new() failed!"); + goto out; + } + +#define FDA_CHECK(_idx, _fd, _revents) \ + if (fda->entries[_idx].fd != _fd) { \ + pr_debug("\n%d: fda->entries[%d](%d) != %d!", \ + __LINE__, _idx, fda->entries[1].fd, _fd); \ + goto out_delete; \ + } \ + if (fda->entries[_idx].events != (_revents)) { \ + pr_debug("\n%d: fda->entries[%d].revents(%d) != %d!", \ + __LINE__, _idx, fda->entries[_idx].fd, _revents); \ + goto out_delete; \ + } + +#define FDA_ADD(_idx, _fd, _revents, _nr) \ + if (fdarray__add(fda, _fd, _revents, fdarray_flag__default) < 0) { \ + pr_debug("\n%d: fdarray__add(fda, %d, %d) failed!", \ + __LINE__,_fd, _revents); \ + goto out_delete; \ + } \ + if (fda->nr != _nr) { \ + pr_debug("\n%d: fdarray__add(fda, %d, %d)=%d != %d", \ + __LINE__,_fd, _revents, fda->nr, _nr); \ + goto out_delete; \ + } \ + FDA_CHECK(_idx, _fd, _revents) + + FDA_ADD(0, 1, POLLIN, 1); + FDA_ADD(1, 2, POLLERR, 2); + + fdarray__fprintf_prefix(fda, "before growing array", stderr); + + FDA_ADD(2, 35, POLLHUP, 3); + + if (fda->entries == NULL) { + pr_debug("\nfdarray__add(fda, 35, POLLHUP) should have allocated fda->pollfd!"); + goto out_delete; + } + + fdarray__fprintf_prefix(fda, "after 3rd add", stderr); + + FDA_ADD(3, 88, POLLIN | POLLOUT, 4); + + fdarray__fprintf_prefix(fda, "after 4th add", stderr); + + FDA_CHECK(0, 1, POLLIN); + FDA_CHECK(1, 2, POLLERR); + FDA_CHECK(2, 35, POLLHUP); + FDA_CHECK(3, 88, POLLIN | POLLOUT); + +#undef FDA_ADD +#undef FDA_CHECK + + pr_debug("\n"); + + err = 0; +out_delete: + fdarray__delete(fda); +out: + return err; +} + +DEFINE_SUITE("Filter fds with revents mask in a fdarray", fdarray__filter); +DEFINE_SUITE("Add fd to a fdarray, making it autogrow", fdarray__add); -- cgit v1.3.1