diff options
| -rw-r--r-- | tools/testing/selftests/x86/test_vsyscall.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c index c41f24b517f4..65c141ebfbbd 100644 --- a/tools/testing/selftests/x86/test_vsyscall.c +++ b/tools/testing/selftests/x86/test_vsyscall.c @@ -462,6 +462,17 @@ static int test_vsys_x(void) return 0; } +/* + * Debuggers expect ptrace() to be able to peek at the vsyscall page. + * Use process_vm_readv() as a proxy for ptrace() to test this. We + * want it to work in the vsyscall=emulate case and to fail in the + * vsyscall=xonly case. + * + * It's worth noting that this ABI is a bit nutty. write(2) can't + * read from the vsyscall page on any kernel version or mode. The + * fact that ptrace() ever worked was a nice courtesy of old kernels, + * but the code to support it is fairly gross. + */ static int test_process_vm_readv(void) { #ifdef __x86_64__ @@ -477,8 +488,12 @@ static int test_process_vm_readv(void) remote.iov_len = 4096; ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0); if (ret != 4096) { - printf("[OK]\tprocess_vm_readv() failed (ret = %d, errno = %d)\n", ret, errno); - return 0; + /* + * We expect process_vm_readv() to work if and only if the + * vsyscall page is readable. + */ + printf("[%s]\tprocess_vm_readv() failed (ret = %d, errno = %d)\n", vsyscall_map_r ? "FAIL" : "OK", ret, errno); + return vsyscall_map_r ? 1 : 0; } if (vsyscall_map_r) { @@ -488,6 +503,9 @@ static int test_process_vm_readv(void) printf("[FAIL]\tIt worked but returned incorrect data\n"); return 1; } + } else { + printf("[FAIL]\tprocess_rm_readv() succeeded, but it should have failed in this configuration\n"); + return 1; } #endif |