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/crypto/tests/test-utils.h | 111 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 111 insertions(+) create mode 100644 lib/crypto/tests/test-utils.h (limited to 'lib/crypto/tests/test-utils.h') diff --git a/lib/crypto/tests/test-utils.h b/lib/crypto/tests/test-utils.h new file mode 100644 index 000000000..73ca21f91 --- /dev/null +++ b/lib/crypto/tests/test-utils.h @@ -0,0 +1,111 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Test utility functions shared by the crypto library tests. + * + * For now this is simply a header that's included into the KUnit test suites + * that need it. If this gets too large it could be made its own translation + * unit and libcrypto_test_utils module, but that seems overkill for now. + */ +#ifndef LIB_CRYPTO_TEST_UTILS_H +#define LIB_CRYPTO_TEST_UTILS_H + +#include +#include +#include +#include +#include + +static u64 random_seed; + +static __maybe_unused void action_free_guarded_buf(void *buf) +{ + vfree(buf); +} + +/* + * Allocate a KUnit-managed buffer that has length @size bytes (> 0) immediately + * followed by an unmapped page, and assert that the allocation succeeds. + */ +static __maybe_unused void *alloc_guarded_buf(struct kunit *test, size_t size) +{ + size_t full_size = round_up(size, PAGE_SIZE); + void *buf = vmalloc(full_size); + + KUNIT_ASSERT_NOT_NULL(test, buf); + KUNIT_ASSERT_EQ(test, 0, + kunit_add_action_or_reset(test, action_free_guarded_buf, + buf)); + return buf + full_size - size; +} + +static __maybe_unused void *alloc_buf(struct kunit *test, size_t size) +{ + void *buf = kunit_kmalloc(test, size, GFP_KERNEL); + + KUNIT_ASSERT_NOT_NULL(test, buf); + return buf; +} + +static __maybe_unused void *memdup_buf(struct kunit *test, const void *src, + size_t size) +{ + void *dst = alloc_buf(test, size); + + return memcpy(dst, src, size); +} + +/* + * This is a simple linear congruential generator. It is used only for testing, + * which does not require cryptographically secure random numbers. A hard-coded + * algorithm is used instead of so that it matches the + * algorithm used by the test vector generation script. This allows the input + * data in random test vectors to be concisely stored as just the seed. + */ +static __maybe_unused u32 rand32(void) +{ + random_seed = (random_seed * 25214903917 + 11) & ((1ULL << 48) - 1); + return random_seed >> 16; +} + +static __maybe_unused void rand_bytes(u8 *out, size_t len) +{ + for (size_t i = 0; i < len; i++) + out[i] = rand32(); +} + +static __maybe_unused void rand_bytes_seeded_from_len(u8 *out, size_t len) +{ + random_seed = len; + rand_bytes(out, len); +} + +static __maybe_unused bool rand_bool(void) +{ + return rand32() % 2; +} + +/* Generate a random length, preferring small lengths. */ +static __maybe_unused size_t rand_length(size_t max_len) +{ + size_t len; + + switch (rand32() % 3) { + case 0: + len = rand32() % 128; + break; + case 1: + len = rand32() % 3072; + break; + default: + len = rand32(); + break; + } + return len % (max_len + 1); +} + +static __maybe_unused size_t rand_offset(size_t max_offset) +{ + return min(rand32() % 128, max_offset); +} + +#endif /* LIB_CRYPTO_TEST_UTILS_H */ -- cgit v1.3.1