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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /tools/testing/selftests/vDSO/vdso_standalone_test_x86.c | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/testing/selftests/vDSO/vdso_standalone_test_x86.c')
-rw-r--r-- | tools/testing/selftests/vDSO/vdso_standalone_test_x86.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c new file mode 100644 index 000000000..8a44ff973 --- /dev/null +++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c @@ -0,0 +1,126 @@ +// 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 + * + * 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. + */ + +#include <sys/syscall.h> +#include <sys/time.h> +#include <unistd.h> +#include <stdint.h> + +#include "parse_vdso.h" + +/* We need a 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; +} + +/* ...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--; + } +} + +__attribute__((externally_visible)) 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_auxv((void *)stack); + + /* Find gettimeofday. */ + typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); + gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday"); + + if (!gtod) + linux_exit(1); + + struct timeval tv; + long ret = gtod(&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); + } else { + linux_exit(ret); + } + + linux_exit(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" + "jmp c_main" +#else + "push %esp\n\t" + "call c_main\n\t" + "int $3" +#endif + ); |