On 04/21/2016 11:01 PM, Andy Lutomirski wrote:
On Mon, Apr 18, 2016 at 6:43 AM, Dmitry Safonov <dsafonov@xxxxxxxxxxxxx> wrote:
Should print on success:
[root@localhost ~]# ./test_mremap_vdso_32
AT_SYSINFO_EHDR is 0xf773f000
[NOTE] Moving vDSO: [f773f000, f7740000] -> [a000000, a001000]
[OK]
Or segfault if landing was bad (before patches):
[root@localhost ~]# ./test_mremap_vdso_32
AT_SYSINFO_EHDR is 0xf774f000
[NOTE] Moving vDSO: [f774f000, f7750000] -> [a000000, a001000]
Segmentation fault (core dumped)
Cc: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
Cc: linux-kselftest@xxxxxxxxxxxxxxx
Suggested-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx>
---
v5: initial version
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/test_mremap_vdso.c | 72 ++++++++++++++++++++++++++
2 files changed, 73 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/x86/test_mremap_vdso.c
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index b47ebd170690..c7162b511ab0 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -7,7 +7,7 @@ include ../lib.mk
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall \
check_initial_reg_state sigreturn ldt_gdt iopl
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
- test_FCMOV test_FCOMI test_FISTTP \
+ test_FCMOV test_FCOMI test_FISTTP test_mremap_vdso \
vdso_restorer
TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
new file mode 100644
index 000000000000..a470790e2118
--- /dev/null
+++ b/tools/testing/selftests/x86/test_mremap_vdso.c
@@ -0,0 +1,72 @@
+/*
+ * 32-bit test to check vdso mremap.
+ *
+ * Copyright (c) 2016 Dmitry Safonov
+ * Suggested-by: Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+/*
+ * Can be built statically:
+ * gcc -Os -Wall -static -m32 test_mremap_vdso.c
+ */
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <sys/mman.h>
+#include <sys/auxv.h>
+#include <sys/syscall.h>
+
+#if !defined(__i386__)
+int main(int argc, char **argv, char **envp)
+{
+ printf("[SKIP]\tNot a 32-bit x86 userspace\n");
+ return 0;
What's wrong with testing on 64-bit systems?
Ok, will drop this.
+}
+#else
+
+#define PAGE_SIZE 4096
+#define VDSO_SIZE PAGE_SIZE
The vdso is frequently bigger than a page.
Ok, will enlarge this. Are two pages big enough?
+
+int main(int argc, char **argv, char **envp)
+{
+ unsigned long vdso_addr, dest_addr;
+ void *new_addr;
+ const char *ok_string = "[OK]\n";
+
+ vdso_addr = getauxval(AT_SYSINFO_EHDR);
+ printf("\tAT_SYSINFO_EHDR is 0x%lx\n", vdso_addr);
+ if (!vdso_addr || vdso_addr == -ENOENT) {
+ printf("[FAIL]\tgetauxval failed\n");
+ return 1;
Let's make this [WARN] and return 0. The vdso is optional, and
getauxval is missing on many systems.
Ok
+ }
+
+ /* to low for stack, to high for lib/data/code mappings */
+ dest_addr = 0x0a000000;
This could be make reliable -- map a big enough area PROT_NONE and use
that address.
Oh, that's good, will do.
+ printf("[NOTE]\tMoving vDSO: [%lx, %lx] -> [%lx, %lx]\n",
+ vdso_addr, vdso_addr + VDSO_SIZE,
+ dest_addr, dest_addr + VDSO_SIZE);
fflush(stdout), please, for the benefit of test harnesses that use pipes.
Will add.
+ new_addr = mremap((void *)vdso_addr, VDSO_SIZE, VDSO_SIZE,
+ MREMAP_FIXED|MREMAP_MAYMOVE, dest_addr);
+ if ((unsigned long)new_addr == (unsigned long)-1) {
+ printf("[FAIL]\tmremap failed (%d): %m\n", errno);
+ return 1;
+ }
+
+ asm volatile ("int $0x80" : : "a" (__NR_write), "b" (STDOUT_FILENO),
+ "c" (ok_string), "d" (strlen(ok_string)));
+ asm volatile ("int $0x80" : : "a" (__NR_exit), "b" (0));
+
+ return 0;
+}
+#endif
--
2.8.0
--
Regards,
Dmitry Safonov
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