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/wp.c | 214 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 214 insertions(+) create mode 100644 tools/perf/tests/wp.c (limited to 'tools/perf/tests/wp.c') diff --git a/tools/perf/tests/wp.c b/tools/perf/tests/wp.c new file mode 100644 index 000000000..69b31f00e --- /dev/null +++ b/tools/perf/tests/wp.c @@ -0,0 +1,214 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include "tests.h" +#include "debug.h" +#include "event.h" +#include "cloexec.h" +#include "../perf-sys.h" + +#define WP_TEST_ASSERT_VAL(fd, text, val) \ +do { \ + long long count; \ + wp_read(fd, &count, sizeof(long long)); \ + TEST_ASSERT_VAL(text, count == val); \ +} while (0) + +#ifdef __i386__ +/* Only breakpoint length less-than 8 has hardware support on i386. */ +static volatile u32 data1; +#else +static volatile u64 data1; +#endif +static volatile u8 data2[3]; + +#ifndef __s390x__ +static int wp_read(int fd, long long *count, int size) +{ + int ret = read(fd, count, size); + + if (ret != size) { + pr_debug("failed to read: %d\n", ret); + return -1; + } + return 0; +} + +static void get__perf_event_attr(struct perf_event_attr *attr, int wp_type, + void *wp_addr, unsigned long wp_len) +{ + memset(attr, 0, sizeof(struct perf_event_attr)); + attr->type = PERF_TYPE_BREAKPOINT; + attr->size = sizeof(struct perf_event_attr); + attr->config = 0; + attr->bp_type = wp_type; + attr->bp_addr = (unsigned long)wp_addr; + attr->bp_len = wp_len; + attr->sample_period = 1; + attr->sample_type = PERF_SAMPLE_IP; + attr->exclude_kernel = 1; + attr->exclude_hv = 1; +} + +static int __event(int wp_type, void *wp_addr, unsigned long wp_len) +{ + int fd; + struct perf_event_attr attr; + + get__perf_event_attr(&attr, wp_type, wp_addr, wp_len); + fd = sys_perf_event_open(&attr, 0, -1, -1, + perf_event_open_cloexec_flag()); + if (fd < 0) { + fd = -errno; + pr_debug("failed opening event %x\n", attr.bp_type); + } + + return fd; +} +#endif + +static int test__wp_ro(struct test_suite *test __maybe_unused, + int subtest __maybe_unused) +{ +#if defined(__s390x__) || defined(__x86_64__) || defined(__i386__) + return TEST_SKIP; +#else + int fd; + unsigned long tmp, tmp1 = rand(); + + fd = __event(HW_BREAKPOINT_R, (void *)&data1, sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + tmp = data1; + WP_TEST_ASSERT_VAL(fd, "RO watchpoint", 1); + + data1 = tmp1 + tmp; + WP_TEST_ASSERT_VAL(fd, "RO watchpoint", 1); + + close(fd); + return 0; +#endif +} + +static int test__wp_wo(struct test_suite *test __maybe_unused, + int subtest __maybe_unused) +{ +#if defined(__s390x__) + return TEST_SKIP; +#else + int fd; + unsigned long tmp, tmp1 = rand(); + + fd = __event(HW_BREAKPOINT_W, (void *)&data1, sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + tmp = data1; + WP_TEST_ASSERT_VAL(fd, "WO watchpoint", 0); + + data1 = tmp1 + tmp; + WP_TEST_ASSERT_VAL(fd, "WO watchpoint", 1); + + close(fd); + return 0; +#endif +} + +static int test__wp_rw(struct test_suite *test __maybe_unused, + int subtest __maybe_unused) +{ +#if defined(__s390x__) + return TEST_SKIP; +#else + int fd; + unsigned long tmp, tmp1 = rand(); + + fd = __event(HW_BREAKPOINT_R | HW_BREAKPOINT_W, (void *)&data1, + sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + tmp = data1; + WP_TEST_ASSERT_VAL(fd, "RW watchpoint", 1); + + data1 = tmp1 + tmp; + WP_TEST_ASSERT_VAL(fd, "RW watchpoint", 2); + + close(fd); + return 0; +#endif +} + +static int test__wp_modify(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ +#if defined(__s390x__) + return TEST_SKIP; +#else + int fd, ret; + unsigned long tmp = rand(); + struct perf_event_attr new_attr; + + fd = __event(HW_BREAKPOINT_W, (void *)&data1, sizeof(data1)); + if (fd < 0) + return fd == -ENODEV ? TEST_SKIP : -1; + + data1 = tmp; + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 1); + + /* Modify watchpoint with disabled = 1 */ + get__perf_event_attr(&new_attr, HW_BREAKPOINT_W, (void *)&data2[0], + sizeof(u8) * 2); + new_attr.disabled = 1; + ret = ioctl(fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &new_attr); + if (ret < 0) { + if (errno == ENOTTY) { + test->test_cases[subtest].skip_reason = "missing kernel support"; + ret = TEST_SKIP; + } + + pr_debug("ioctl(PERF_EVENT_IOC_MODIFY_ATTRIBUTES) failed\n"); + close(fd); + return ret; + } + + data2[1] = tmp; /* Not Counted */ + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 1); + + /* Enable the event */ + ioctl(fd, PERF_EVENT_IOC_ENABLE, 0); + if (ret < 0) { + pr_debug("Failed to enable event\n"); + close(fd); + return ret; + } + + data2[1] = tmp; /* Counted */ + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 2); + + data2[2] = tmp; /* Not Counted */ + WP_TEST_ASSERT_VAL(fd, "Modify watchpoint", 2); + + close(fd); + return 0; +#endif +} + +static struct test_case wp_tests[] = { + TEST_CASE_REASON("Read Only Watchpoint", wp_ro, "missing hardware support"), + TEST_CASE_REASON("Write Only Watchpoint", wp_wo, "missing hardware support"), + TEST_CASE_REASON("Read / Write Watchpoint", wp_rw, "missing hardware support"), + TEST_CASE_REASON("Modify Watchpoint", wp_modify, "missing hardware support"), + { .name = NULL, } +}; + +struct test_suite suite__wp = { + .desc = "Watchpoint", + .test_cases = wp_tests, +}; -- cgit v1.3.1