The following commit has been merged into the timers/vdso branch of tip:
Commit-ID: 8770a9183fe18442c7cfbb56bb7e006462775a91
Gitweb: https://git.kernel.org/tip/8770a9183fe18442c7cfbb56bb7e006462775a91
Author: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
AuthorDate: Wed, 26 Feb 2025 12:44:55 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 03 Mar 2025 20:00:13 +01:00
selftests: vDSO: vdso_standalone_test_x86: Switch to nolibc
vdso_standalone_test_x86 provides its own ASM syscall wrappers and
_start() implementation. The in-tree nolibc library already provides
this functionality for multiple architectures. By making use of nolibc,
the standalone testcase can be built from the exact same codebase as the
non-standalone version.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Acked-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-16-28e14e031ed8@xxxxxxxxxxxxx
---
tools/testing/selftests/vDSO/Makefile | 8 +-
tools/testing/selftests/vDSO/vdso_standalone_test_x86.c | 175 +------
2 files changed, 39 insertions(+), 144 deletions(-)
diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
index bc8ca18..12a0614 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -22,13 +22,17 @@ include ../lib.mk
CFLAGS += $(TOOLS_INCLUDES)
+CFLAGS_NOLIBC := -nostdlib -nostdinc -ffreestanding -fno-asynchronous-unwind-tables \
+ -fno-stack-protector -include $(top_srcdir)/tools/include/nolibc/nolibc.h \
+ -I$(top_srcdir)/tools/include/nolibc/ $(KHDR_INCLUDES)
+
$(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
-$(OUTPUT)/vdso_standalone_test_x86: CFLAGS +=-nostdlib -fno-asynchronous-unwind-tables -fno-stack-protector
+$(OUTPUT)/vdso_standalone_test_x86: vdso_standalone_test_x86.c parse_vdso.c | headers
+$(OUTPUT)/vdso_standalone_test_x86: CFLAGS:=$(CFLAGS_NOLIBC) $(CFLAGS)
$(OUTPUT)/vdso_test_correctness: vdso_test_correctness.c
$(OUTPUT)/vdso_test_correctness: LDFLAGS += -ldl
diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
index 500608f..9ce795b 100644
--- a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
+++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
@@ -1,167 +1,58 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
- * vdso_test.c: Sample code to test parse_vdso.c on x86
- * Copyright (c) 2011-2014 Andy Lutomirski
+ * vdso_test_gettimeofday.c: Sample code to test parse_vdso.c and
+ * vDSO gettimeofday()
+ * Copyright (c) 2014 Andy Lutomirski
*
- * You can amuse yourself by compiling with:
- * gcc -std=gnu99 -nostdlib
- * -Os -fno-asynchronous-unwind-tables -flto -lgcc_s
- * vdso_standalone_test_x86.c parse_vdso.c
- * to generate a small binary. On x86_64, you can omit -lgcc_s
- * if you want the binary to be completely standalone.
+ * Compile with:
+ * gcc -std=gnu99 vdso_test_gettimeofday.c parse_vdso_gettimeofday.c
+ *
+ * Tested on x86, 32-bit and 64-bit. It may work on other architectures, too.
*/
-#include <sys/syscall.h>
+#include <stdio.h>
+#ifndef NOLIBC
+#include <sys/auxv.h>
#include <sys/time.h>
-#include <unistd.h>
-#include <stdint.h>
-#include <linux/auxvec.h>
-
-#include "parse_vdso.h"
-
-/* We need some libc functions... */
-int strcmp(const char *a, const char *b)
-{
- /* This implementation is buggy: it never returns -1. */
- while (*a || *b) {
- if (*a != *b)
- return 1;
- if (*a == 0 || *b == 0)
- return 1;
- a++;
- 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)
-{
- long ret;
-#ifdef __x86_64__
- asm volatile ("syscall" : "=a" (ret) : "a" (nr),
- "D" (a0), "S" (a1), "d" (a2) :
- "cc", "memory", "rcx",
- "r8", "r9", "r10", "r11" );
-#else
- asm volatile ("int $0x80" : "=a" (ret) : "a" (nr),
- "b" (a0), "c" (a1), "d" (a2) :
- "cc", "memory" );
#endif
- return ret;
-}
-
-static inline long linux_write(int fd, const void *data, size_t len)
-{
- return x86_syscall3(__NR_write, fd, (long)data, (long)len);
-}
-static inline void linux_exit(int code)
-{
- x86_syscall3(__NR_exit, code, 0, 0);
-}
-
-void to_base10(char *lastdig, time_t n)
-{
- while (n) {
- *lastdig = (n % 10) + '0';
- n /= 10;
- lastdig--;
- }
-}
+#include "../kselftest.h"
+#include "parse_vdso.h"
+#include "vdso_config.h"
+#include "vdso_call.h"
-unsigned long getauxval(const unsigned long *auxv, unsigned long type)
+int main(int argc, char **argv)
{
- unsigned long ret;
-
- if (!auxv)
- return 0;
-
- while (1) {
- if (!auxv[0] && !auxv[1]) {
- ret = 0;
- break;
- }
+ const char *version = versions[VDSO_VERSION];
+ const char **name = (const char **)&names[VDSO_NAMES];
- if (auxv[0] == type) {
- ret = auxv[1];
- break;
- }
-
- auxv += 2;
+ unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
+ if (!sysinfo_ehdr) {
+ printf("AT_SYSINFO_EHDR is not present!\n");
+ return KSFT_SKIP;
}
- return ret;
-}
-
-void c_main(void **stack)
-{
- /* Parse the stack */
- long argc = (long)*stack;
- stack += argc + 2;
-
- /* Now we're pointing at the environment. Skip it. */
- while(*stack)
- stack++;
- stack++;
-
- /* Now we're pointing at auxv. Initialize the vDSO parser. */
- vdso_init_from_sysinfo_ehdr(getauxval((unsigned long *)stack, AT_SYSINFO_EHDR));
+ vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
/* Find gettimeofday. */
typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
- gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
+ gtod_t gtod = (gtod_t)vdso_sym(version, name[0]);
- if (!gtod)
- linux_exit(1);
+ if (!gtod) {
+ printf("Could not find %s\n", name[0]);
+ return KSFT_SKIP;
+ }
struct timeval tv;
- long ret = gtod(&tv, 0);
+ long ret = VDSO_CALL(gtod, 2, &tv, 0);
if (ret == 0) {
- char buf[] = "The time is .000000\n";
- to_base10(buf + 31, tv.tv_sec);
- to_base10(buf + 38, tv.tv_usec);
- linux_write(1, buf, sizeof(buf) - 1);
+ printf("The time is %lld.%06lld\n",
+ (long long)tv.tv_sec, (long long)tv.tv_usec);
} else {
- linux_exit(ret);
+ printf("%s failed\n", name[0]);
+ return KSFT_FAIL;
}
- linux_exit(0);
+ return 0;
}
-
-/*
- * This is the real entry point. It passes the initial stack into
- * the C entry point.
- */
-asm (
- ".text\n"
- ".global _start\n"
- ".type _start,@function\n"
- "_start:\n\t"
-#ifdef __x86_64__
- "mov %rsp,%rdi\n\t"
- "and $-16,%rsp\n\t"
- "sub $8,%rsp\n\t"
- "jmp c_main"
-#else
- "push %esp\n\t"
- "call c_main\n\t"
- "int $3"
-#endif
- );
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