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Commit d5e9dddd authored by John Hubbard's avatar John Hubbard Committed by Greg Kroah-Hartman
Browse files

selftests/vDSO: fix clang build errors and warnings 



[ Upstream commit 73810cd45b99c6c418e1c6a487b52c1e74edb20d ]

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: default avatarCarlos Llamas <cmllamas@google.com>
Reviewed-by: default avatarEdward Liaw <edliaw@google.com>
Reviewed-by: default avatarMuhammad Usama Anjum <usama.anjum@collabora.com>
Tested-by: default avatarMuhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: default avatarShuah Khan <skhan@linuxfoundation.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 4f5e56dd

tools/testing/selftests/vDSO/parse_vdso.c

+11 −5
Original line number Diff line number Diff line
@@ -77,14 +77,20 @@ 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;

	}

tools/testing/selftests/vDSO/vdso_standalone_test_x86.c

+16 −2
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ extern void *vdso_sym(const char *version, const char *name); 
extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);

extern void vdso_init_from_auxv(void *auxv);



/* 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. */
@@ -36,6 +36,20 @@ 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)

{
@@ -72,7 +86,7 @@ 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;