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Message-Id: <3efc170e0e166e15f0150c9fdb37d52488b9c0a4.1402598632.git.luto@amacapital.net>
Date: Thu, 12 Jun 2014 11:47:42 -0700
From: Andy Lutomirski <luto@...capital.net>
To: <hpa@...or.com>, Kui Zhang <kuizhang@...il.com>
Cc: x86@...nel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Andy Lutomirski <luto@...capital.net>
Subject: [PATCH 1/3] doc,vdso: Rename vdso_test.c to vdso_standalone_test_x86.c
This thing is hopelessly x86_64-specific: it's an example of how to
access the vDSO without any runtime support at all.
Signed-off-by: Andy Lutomirski <luto@...capital.net>
---
Documentation/vDSO/vdso_standalone_test_x86.c | 111 ++++++++++++++++++++++++++
Documentation/vDSO/vdso_test.c | 111 --------------------------
2 files changed, 111 insertions(+), 111 deletions(-)
create mode 100644 Documentation/vDSO/vdso_standalone_test_x86.c
delete mode 100644 Documentation/vDSO/vdso_test.c
diff --git a/Documentation/vDSO/vdso_standalone_test_x86.c b/Documentation/vDSO/vdso_standalone_test_x86.c
new file mode 100644
index 0000000..1523f5d
--- /dev/null
+++ b/Documentation/vDSO/vdso_standalone_test_x86.c
@@ -0,0 +1,111 @@
+/*
+ * vdso_test.c: Sample code to test parse_vdso.c on x86_64
+ * Copyright (c) 2011 Andy Lutomirski
+ * Subject to the GNU General Public License, version 2
+ *
+ * You can amuse yourself by compiling with:
+ * gcc -std=gnu99 -nostdlib
+ * -Os -fno-asynchronous-unwind-tables -flto
+ * vdso_standalone_test_x86.c parse_vdso.c
+ * to generate a small binary with no dependencies at all.
+ */
+
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <stdint.h>
+
+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... */
+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_64-specific. */
+static inline long linux_write(int fd, const void *data, size_t len)
+{
+
+ long ret;
+ asm volatile ("syscall" : "=a" (ret) : "a" (__NR_write),
+ "D" (fd), "S" (data), "d" (len) :
+ "cc", "memory", "rcx",
+ "r8", "r9", "r10", "r11" );
+ return ret;
+}
+
+static inline void linux_exit(int code)
+{
+ asm volatile ("syscall" : : "a" (__NR_exit), "D" (code));
+}
+
+void to_base10(char *lastdig, uint64_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"
+ "mov %rsp,%rdi\n\t"
+ "jmp c_main"
+ );
diff --git a/Documentation/vDSO/vdso_test.c b/Documentation/vDSO/vdso_test.c
deleted file mode 100644
index fff6334..0000000
--- a/Documentation/vDSO/vdso_test.c
+++ /dev/null
@@ -1,111 +0,0 @@
-/*
- * vdso_test.c: Sample code to test parse_vdso.c on x86_64
- * Copyright (c) 2011 Andy Lutomirski
- * Subject to the GNU General Public License, version 2
- *
- * You can amuse yourself by compiling with:
- * gcc -std=gnu99 -nostdlib
- * -Os -fno-asynchronous-unwind-tables -flto
- * vdso_test.c parse_vdso.c -o vdso_test
- * to generate a small binary with no dependencies at all.
- */
-
-#include <sys/syscall.h>
-#include <sys/time.h>
-#include <unistd.h>
-#include <stdint.h>
-
-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... */
-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_64-specific. */
-static inline long linux_write(int fd, const void *data, size_t len)
-{
-
- long ret;
- asm volatile ("syscall" : "=a" (ret) : "a" (__NR_write),
- "D" (fd), "S" (data), "d" (len) :
- "cc", "memory", "rcx",
- "r8", "r9", "r10", "r11" );
- return ret;
-}
-
-static inline void linux_exit(int code)
-{
- asm volatile ("syscall" : : "a" (__NR_exit), "D" (code));
-}
-
-void to_base10(char *lastdig, uint64_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"
- "mov %rsp,%rdi\n\t"
- "jmp c_main"
- );
--
1.9.3
--
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