tools/testing/selftests/proc/proc-pid-vm.c: test with vsyscall in mind

: selftests: proc: proc-pid-vm
: ========================================
: proc-pid-vm: proc-pid-vm.c:277: main: Assertion `rv == strlen(buf0)' failed.
: Aborted

Because the vsyscall mapping is enabled.  Read from vsyscall page to tell
if vsyscall is being used.

Link: http://lkml.kernel.org/r/20190307183204.GA11405@avx2
Link: http://lkml.kernel.org/r/20190219094722.GB28258@shao2-debian
Fixes: 34aab6bec23e7e9 ("proc: test /proc/*/maps, smaps, smaps_rollup, statm")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: kernel test robot <rong.a.chen@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 46 insertions, 3 deletions

diff --git a/tools/testing/selftests/proc/proc-pid-vm.c b/tools/testing/selftests/proc/proc-pid-vm.c
index bbe8150d18aa..7202bbac976e 100644
--- a/tools/testing/selftests/proc/proc-pid-vm.c
+++ b/tools/testing/selftests/proc/proc-pid-vm.c
@@ -29,6 +29,7 @@
 #include <errno.h>
 #include <sched.h>
 #include <signal.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
@@ -36,11 +37,14 @@
 #include <sys/mount.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <sys/syscall.h>
 #include <sys/uio.h>
 #include <linux/kdev_t.h>
+#include <sys/time.h>
+#include <sys/resource.h>
 
 static inline long sys_execveat(int dirfd, const char *pathname, char **argv, char **envp, int flags)
 {
@@ -205,12 +209,44 @@ static int make_exe(const uint8_t *payload, size_t len)
 }
 #endif
 
+static bool g_vsyscall = false;
+
+static const char str_vsyscall[] =
+"ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]\n";
+
 #ifdef __x86_64__
+/*
+ * vsyscall page can't be unmapped, probe it with memory load.
+ */
+static void vsyscall(void)
+{
+        pid_t pid;
+        int wstatus;
+
+        pid = fork();
+        if (pid < 0) {
+                fprintf(stderr, "fork, errno %d\n", errno);
+                exit(1);
+        }
+        if (pid == 0) {
+                struct rlimit rlim = {0, 0};
+                (void)setrlimit(RLIMIT_CORE, &rlim);
+                *(volatile int *)0xffffffffff600000UL;
+                exit(0);
+        }
+        wait(&wstatus);
+        if (WIFEXITED(wstatus)) {
+                g_vsyscall = true;
+        }
+}
+
 int main(void)
 {
         int pipefd[2];
         int exec_fd;
 
+        vsyscall();
+
         atexit(ate);
 
         make_private_tmp();
@@ -261,9 +297,9 @@ int main(void)
         snprintf(buf0 + MAPS_OFFSET, sizeof(buf0) - MAPS_OFFSET,
                  "/tmp/#%llu (deleted)\n", (unsigned long long)st.st_ino);
 
-
         /* Test /proc/$PID/maps */
         {
+                const size_t len = strlen(buf0) + (g_vsyscall ? strlen(str_vsyscall) : 0);
                 char buf[256];
                 ssize_t rv;
                 int fd;
@@ -274,13 +310,16 @@ int main(void)
                         return 1;
                 }
                 rv = read(fd, buf, sizeof(buf));
-                assert(rv == strlen(buf0));
+                assert(rv == len);
                 assert(memcmp(buf, buf0, strlen(buf0)) == 0);
+                if (g_vsyscall) {
+                        assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0);
+                }
         }
 
         /* Test /proc/$PID/smaps */
         {
-                char buf[1024];
+                char buf[4096];
                 ssize_t rv;
                 int fd;
 
@@ -319,6 +358,10 @@ int main(void)
                 for (i = 0; i < sizeof(S)/sizeof(S[0]); i++) {
                         assert(memmem(buf, rv, S[i], strlen(S[i])));
                 }
+
+                if (g_vsyscall) {
+                        assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall)));
+                }
         }
 
         /* Test /proc/$PID/smaps_rollup */