When building with clang, via:

make LLVM=1 -C tools/testing/selftests

...there are several warnings, and an error. This fixes all of those and allows these tests to run and pass.

1. Fix linker error (undefined reference to memcpy) by providing a local version of memcpy.

2. clang complains about using this form:

if (g = h & 0xf0000000)

...so factor out the assignment into a separate step.

3. The code is passing a signed const char* to elf_hash(), which expects a const unsigned char *. There are several callers, so fix this at the source by allowing the function to accept a signed argument, and then converting to unsigned operations, once inside the function.

4. clang doesn't have __attribute__((externally_visible)) and generates a warning to that effect. Fortunately, gcc 12 and gcc 13 do not seem to require that attribute in order to build, run and pass tests here, so remove it.

Reviewed-by: Carlos Llamas cmllamas@google.com Reviewed-by: Edward Liaw edliaw@google.com Reviewed-by: Muhammad Usama Anjum usama.anjum@collabora.com Tested-by: Muhammad Usama Anjum usama.anjum@collabora.com Signed-off-by: John Hubbard jhubbard@nvidia.com --- tools/testing/selftests/vDSO/parse_vdso.c | 16 +++++++++++----- .../selftests/vDSO/vdso_standalone_test_x86.c | 18 ++++++++++++++++-- 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c index 413f75620a35..4ae417372e9e 100644 --- a/tools/testing/selftests/vDSO/parse_vdso.c +++ b/tools/testing/selftests/vDSO/parse_vdso.c @@ -55,14 +55,20 @@ static struct vdso_info ELF(Verdef) *verdef; } vdso_info;

-/* Straight from the ELF specification. */ -static unsigned long elf_hash(const unsigned char *name) +/* + * Straight from the ELF specification...and then tweaked slightly, in order to + * avoid a few clang warnings. + */ +static unsigned long elf_hash(const char *name) { unsigned long h = 0, g; - while (*name) + const unsigned char *uch_name = (const unsigned char *)name; + + while (*uch_name) { - h = (h << 4) + *name++; - if (g = h & 0xf0000000) + h = (h << 4) + *uch_name++; + g = h & 0xf0000000; + if (g) h ^= g >> 24; h &= ~g; } diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c index 8a44ff973ee1..27f6fdf11969 100644 --- a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c +++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c @@ -18,7 +18,7 @@

#include "parse_vdso.h"

-/* We need a libc functions... */ +/* We need some libc functions... */ int strcmp(const char *a, const char *b) { /* This implementation is buggy: it never returns -1. */ @@ -34,6 +34,20 @@ int strcmp(const char *a, const char *b) return 0; }

+/* + * The clang build needs this, although gcc does not. + * Stolen from lib/string.c. + */ +void *memcpy(void *dest, const void *src, size_t count) +{ + char *tmp = dest; + const char *s = src; + + while (count--) + *tmp++ = *s++; + return dest; +} + /* ...and two syscalls. This is x86-specific. */ static inline long x86_syscall3(long nr, long a0, long a1, long a2) { @@ -70,7 +84,7 @@ void to_base10(char *lastdig, time_t n) } }

-__attribute__((externally_visible)) void c_main(void **stack) +void c_main(void **stack) { /* Parse the stack */ long argc = (long)*stack;

The Makefile open-codes compiler invocations that ../lib.mk already provides.

Avoid this by using a Make feature that allows setting per-target variables, which in this case are: CFLAGS and LDFLAGS. This approach generates the exact same compiler invocations as before, but removes all of the code duplication, along with the quirky mangled variable names. So now the Makefile is smaller, less unusual, and easier to read.

The new dependencies are listed after including lib.mk, in order to let lib.mk provide the first target ("all:"), and are grouped together with their respective source file dependencies, for visual clarity.

Signed-off-by: John Hubbard jhubbard@nvidia.com --- tools/testing/selftests/vDSO/Makefile | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile index 209ede5de208..98d8ba2afa00 100644 --- a/tools/testing/selftests/vDSO/Makefile +++ b/tools/testing/selftests/vDSO/Makefile @@ -12,8 +12,7 @@ endif TEST_GEN_PROGS += vdso_test_correctness

CFLAGS := -std=gnu99 -CFLAGS_vdso_standalone_test_x86 := -nostdlib -fno-asynchronous-unwind-tables -fno-stack-protector -LDFLAGS_vdso_test_correctness := -ldl + ifeq ($(CONFIG_X86_32),y) LDLIBS += -lgcc_s endif @@ -23,12 +22,9 @@ $(OUTPUT)/vdso_test_gettimeofday: parse_vdso.c vdso_test_gettimeofday.c $(OUTPUT)/vdso_test_getcpu: parse_vdso.c vdso_test_getcpu.c $(OUTPUT)/vdso_test_abi: parse_vdso.c vdso_test_abi.c $(OUTPUT)/vdso_test_clock_getres: vdso_test_clock_getres.c + $(OUTPUT)/vdso_standalone_test_x86: vdso_standalone_test_x86.c parse_vdso.c - $(CC) $(CFLAGS) $(CFLAGS_vdso_standalone_test_x86) \ - vdso_standalone_test_x86.c parse_vdso.c \ - -o $@ +$(OUTPUT)/vdso_standalone_test_x86: CFLAGS +=-nostdlib -fno-asynchronous-unwind-tables -fno-stack-protector + $(OUTPUT)/vdso_test_correctness: vdso_test_correctness.c - $(CC) $(CFLAGS) \ - vdso_test_correctness.c \ - -o $@ \ - $(LDFLAGS_vdso_test_correctness) +$(OUTPUT)/vdso_test_correctness: LDFLAGS += -ldl