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 --- lib/tests/test_fprobe.c | 327 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 327 insertions(+) create mode 100644 lib/tests/test_fprobe.c (limited to 'lib/tests/test_fprobe.c') diff --git a/lib/tests/test_fprobe.c b/lib/tests/test_fprobe.c new file mode 100644 index 000000000..108c7aa33 --- /dev/null +++ b/lib/tests/test_fprobe.c @@ -0,0 +1,327 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * test_fprobe.c - simple sanity test for fprobe + */ + +#include +#include +#include +#include + +#define div_factor 3 + +static struct kunit *current_test; + +static u32 rand1, entry_only_val, entry_val, exit_val; +static u32 entry_only_count, entry_count, exit_count; + +/* Use indirect calls to avoid inlining the target functions */ +static u32 (*target)(u32 value); +static u32 (*target2)(u32 value); +static unsigned long target_ip; +static unsigned long target2_ip; +static int entry_return_value; + +static noinline u32 fprobe_selftest_target(u32 value) +{ + return (value / div_factor); +} + +static noinline u32 fprobe_selftest_target2(u32 value) +{ + return (value / div_factor) + 1; +} + +static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, void *data) +{ + KUNIT_EXPECT_FALSE(current_test, preemptible()); + /* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */ + if (ip != target_ip) + KUNIT_EXPECT_EQ(current_test, ip, target2_ip); + entry_val = (rand1 / div_factor); + if (fp->entry_data_size) { + KUNIT_EXPECT_NOT_NULL(current_test, data); + if (data) + *(u32 *)data = entry_val; + } else + KUNIT_EXPECT_NULL(current_test, data); + + return entry_return_value; +} + +static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, void *data) +{ + unsigned long ret = ftrace_regs_get_return_value(fregs); + + KUNIT_EXPECT_FALSE(current_test, preemptible()); + if (ip != target_ip) { + KUNIT_EXPECT_EQ(current_test, ip, target2_ip); + KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor) + 1); + } else + KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor)); + KUNIT_EXPECT_EQ(current_test, entry_val, (rand1 / div_factor)); + exit_val = entry_val + div_factor; + if (fp->entry_data_size) { + KUNIT_EXPECT_NOT_NULL(current_test, data); + if (data) + KUNIT_EXPECT_EQ(current_test, *(u32 *)data, entry_val); + } else + KUNIT_EXPECT_NULL(current_test, data); +} + +/* Test entry only (no rethook) */ +static void test_fprobe_entry(struct kunit *test) +{ + struct fprobe fp_entry = { + .entry_handler = fp_entry_handler, + }; + + current_test = test; + + /* Before register, unregister should be failed. */ + KUNIT_EXPECT_NE(test, 0, unregister_fprobe(&fp_entry)); + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp_entry, "fprobe_selftest_target*", NULL)); + + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, 0, exit_val); + + entry_val = 0; + exit_val = 0; + target2(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, 0, exit_val); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp_entry)); +} + +static void test_fprobe(struct kunit *test) +{ + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target*", NULL)); + + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + entry_val = 0; + exit_val = 0; + target2(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +static void test_fprobe_syms(struct kunit *test) +{ + static const char *syms[] = {"fprobe_selftest_target", "fprobe_selftest_target2"}; + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe_syms(&fp, syms, 2)); + + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + entry_val = 0; + exit_val = 0; + target2(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, entry_val + div_factor, exit_val); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +/* Test private entry_data */ +static void test_fprobe_data(struct kunit *test) +{ + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + .entry_data_size = sizeof(u32), + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target", NULL)); + + target(rand1); + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +static void test_fprobe_skip(struct kunit *test) +{ + struct fprobe fp = { + .entry_handler = fp_entry_handler, + .exit_handler = fp_exit_handler, + }; + + current_test = test; + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target", NULL)); + + entry_return_value = 1; + entry_val = 0; + exit_val = 0; + target(rand1); + KUNIT_EXPECT_NE(test, 0, entry_val); + KUNIT_EXPECT_EQ(test, 0, exit_val); + KUNIT_EXPECT_EQ(test, 0, fp.nmissed); + entry_return_value = 0; + + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp)); +} + +/* Handler for fprobe entry only case */ +static notrace int entry_only_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, void *data) +{ + KUNIT_EXPECT_FALSE(current_test, preemptible()); + KUNIT_EXPECT_EQ(current_test, ip, target_ip); + + entry_only_count++; + entry_only_val = (rand1 / div_factor); + + return 0; +} + +static notrace int fprobe_entry_multi_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, + void *data) +{ + KUNIT_EXPECT_FALSE(current_test, preemptible()); + KUNIT_EXPECT_EQ(current_test, ip, target_ip); + + entry_count++; + entry_val = (rand1 / div_factor); + + return 0; +} + +static notrace void fprobe_exit_multi_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, + void *data) +{ + unsigned long ret = ftrace_regs_get_return_value(fregs); + + KUNIT_EXPECT_FALSE(current_test, preemptible()); + KUNIT_EXPECT_EQ(current_test, ip, target_ip); + KUNIT_EXPECT_EQ(current_test, ret, (rand1 / div_factor)); + + exit_count++; + exit_val = ret; +} + +static void check_fprobe_multi(struct kunit *test) +{ + entry_only_count = entry_count = exit_count = 0; + entry_only_val = entry_val = exit_val = 0; + + target(rand1); + + /* Verify all handlers were called */ + KUNIT_EXPECT_EQ(test, 1, entry_only_count); + KUNIT_EXPECT_EQ(test, 1, entry_count); + KUNIT_EXPECT_EQ(test, 1, exit_count); + + /* Verify values are correct */ + KUNIT_EXPECT_EQ(test, (rand1 / div_factor), entry_only_val); + KUNIT_EXPECT_EQ(test, (rand1 / div_factor), entry_val); + KUNIT_EXPECT_EQ(test, (rand1 / div_factor), exit_val); +} + +/* Test multiple fprobes hooking the same target function */ +static void test_fprobe_multi(struct kunit *test) +{ + struct fprobe fp1 = { + .entry_handler = fprobe_entry_multi_handler, + .exit_handler = fprobe_exit_multi_handler, + }; + struct fprobe fp2 = { + .entry_handler = entry_only_handler, + }; + + current_test = test; + + /* Test Case 1: Register in order 1 -> 2 */ + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp1, "fprobe_selftest_target", NULL)); + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp2, "fprobe_selftest_target", NULL)); + + check_fprobe_multi(test); + + /* Unregister all */ + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp1)); + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp2)); + + /* Test Case 2: Register in order 2 -> 1 */ + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp2, "fprobe_selftest_target", NULL)); + KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp1, "fprobe_selftest_target", NULL)); + + check_fprobe_multi(test); + + /* Unregister all */ + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp1)); + KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp2)); +} + +static unsigned long get_ftrace_location(void *func) +{ + unsigned long size, addr = (unsigned long)func; + + if (!kallsyms_lookup_size_offset(addr, &size, NULL) || !size) + return 0; + + return ftrace_location_range(addr, addr + size - 1); +} + +static int fprobe_test_init(struct kunit *test) +{ + rand1 = get_random_u32_above(div_factor); + target = fprobe_selftest_target; + target2 = fprobe_selftest_target2; + target_ip = get_ftrace_location(target); + target2_ip = get_ftrace_location(target2); + + return 0; +} + +static struct kunit_case fprobe_testcases[] = { + KUNIT_CASE(test_fprobe_entry), + KUNIT_CASE(test_fprobe), + KUNIT_CASE(test_fprobe_syms), + KUNIT_CASE(test_fprobe_data), + KUNIT_CASE(test_fprobe_skip), + KUNIT_CASE(test_fprobe_multi), + {} +}; + +static struct kunit_suite fprobe_test_suite = { + .name = "fprobe_test", + .init = fprobe_test_init, + .test_cases = fprobe_testcases, +}; + +kunit_test_suites(&fprobe_test_suite); + -- cgit v1.3.1