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 <shua...@osg.samsung.com>
Cc: linux-kselft...@vger.kernel.org
Suggested-by: Andy Lutomirski <l...@kernel.org>
Signed-off-by: Dmitry Safonov <dsafo...@virtuozzo.com>
Acked-by: Andy Lutomirski <l...@kernel.org>
---
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/test_mremap_vdso.c | 99 ++++++++++++++++++++++++++
2 files changed, 100 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 c73425de3cfe..a691cdeb1fef 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -5,7 +5,7 @@ include ../lib.mk
.PHONY: all all_32 all_64 warn_32bit_failure clean
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt
ptrace_syscall \
- check_initial_reg_state sigreturn ldt_gdt iopl
+ check_initial_reg_state sigreturn ldt_gdt iopl
test_mremap_vdso
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso
unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
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..831e2e0107d9
--- /dev/null
+++ b/tools/testing/selftests/x86/test_mremap_vdso.c
@@ -0,0 +1,99 @@
+/*
+ * 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>
+
+#define PAGE_SIZE 4096
+
+static int try_to_remap(void *vdso_addr, unsigned long size)
+{
+ void *dest_addr, *new_addr;
+
+ dest_addr = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+ if (dest_addr == MAP_FAILED) {
+ printf("[WARN]\tmmap failed (%d): %m\n", errno);
+ return 0;
+ }
+
+ printf("[NOTE]\tMoving vDSO: [%p, %#lx] -> [%p, %#lx]\n",
+ vdso_addr, (unsigned long)vdso_addr + size,
+ dest_addr, (unsigned long)dest_addr + size);
+ fflush(stdout);
+
+ new_addr = mremap(vdso_addr, size, size,
+ MREMAP_FIXED|MREMAP_MAYMOVE, dest_addr);
+ if ((unsigned long)new_addr == (unsigned long)-1) {
+ munmap(dest_addr, size);
+ if (errno == EINVAL) {
+ printf("[NOTE]\tvDSO partial move failed, will try with
bigger size\n");
+ return -1; /* retry with larger */
+ }
+ printf("[FAIL]\tmremap failed (%d): %m\n", errno);
+ return 1;
+ }
+
+ return 0;
+
+}
+
+int main(int argc, char **argv, char **envp)
+{
+ unsigned long auxval;
+ const char *ok_string = "[OK]\n";
+ int ret = -1;
+ unsigned long vdso_size = PAGE_SIZE;
+
+ auxval = getauxval(AT_SYSINFO_EHDR);
+ printf("\tAT_SYSINFO_EHDR is %#lx\n", auxval);
+ if (!auxval || auxval == -ENOENT) {
+ printf("[WARN]\tgetauxval failed\n");
+ return 0;
+ }
+
+ /* simpler than parsing ELF header */
+ while (ret < 0) {
+ ret = try_to_remap((void *)auxval, vdso_size);
+ vdso_size += PAGE_SIZE;
+ }
+
+ if (!ret)
+#if defined(__i386__)
+ 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" (!!ret));
+#else
+ asm volatile ("syscall" : :
+ "a" (__NR_write), "D" (STDOUT_FILENO),
+ "S" (ok_string), "d" (strlen(ok_string)));
+
+ asm volatile ("syscall" : : "a" (__NR_exit), "D" (!!ret));
+#endif
+
+ return 0;
+}
--
2.8.0
