This is a note to let you know that I've just added the patch titled
selftests/vDSO: fix clang build errors and warnings
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-vdso-fix-clang-build-errors-and-warnings.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit caaeb678840a778b3476a087486c51e2198c09ca
Author: John Hubbard <jhubbard@xxxxxxxxxx>
Date: Fri Jul 5 09:57:34 2024 -1000
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: Carlos Llamas <cmllamas@xxxxxxxxxx>
Reviewed-by: Edward Liaw <edliaw@xxxxxxxxxx>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Tested-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 413f75620a35b..4ae417372e9eb 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 8a44ff973ee17..27f6fdf119691 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;
