zdtm/vdso: Add test for restoring task without vdso blob

Check that task without vvar & vdso blobs is restored without them.
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

test/zdtm/static/Makefile

@@ -54,6 +54,7 @@ TST_NOFILE	:=				\
 		pthread02			\
 		vdso00				\
 		vdso01				\
+		vdso02				\
 		utsname				\
 		pstree				\
 		sockets01			\

test/zdtm/static/vdso02.c

+#include <signal.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc	= "Restoring task with unmapped vDSO blob. Poor man's test for C/R on vdso64_enabled=0 booted kernel.\n";
+const char *test_author	= "Dmitry Safonov <dsafonov@virtuozzo.com>";
+
+#define BUILD_BUG_ON(condition)	((void)sizeof(char[1 - 2*!!(condition)]))
+#define VDSO_BAD_ADDR		(-1ul)
+#define VVAR_BAD_ADDR		(-1ul)
+#define BUF_SZ			1024
+
+struct vm_area {
+	unsigned long start;
+	unsigned long end;
+};
+
+static int parse_vm_area(char *buf, struct vm_area *vma)
+{
+	if (sscanf(buf, "%lx-%lx", &vma->start, &vma->end) == 2)
+		return 0;
+
+	pr_perror("Can't find VMA bounds");
+	return -1;
+}
+
+static int find_blobs(pid_t pid, struct vm_area *vdso, struct vm_area *vvar)
+{
+	char buf[BUF_SZ];
+	int ret = -1;
+	FILE *maps;
+
+	vdso->start	= VDSO_BAD_ADDR;
+	vdso->end	= VDSO_BAD_ADDR;
+	vvar->start	= VVAR_BAD_ADDR;
+	vvar->end	= VVAR_BAD_ADDR;
+
+	if (snprintf(buf, BUF_SZ, "/proc/%d/maps", pid) < 0) {
+		pr_perror("snprintf() failure for path");
+		return -1;
+	}
+
+	maps = fopen(buf, "r");
+	if (!maps) {
+		pr_perror("Can't open maps for %d", pid);
+		return -1;
+	}
+
+	while (fgets(buf, sizeof(buf), maps)) {
+		if (strstr(buf, "[vdso]") && parse_vm_area(buf, vdso))
+			goto err;
+
+		if (strstr(buf, "[vvar]") && parse_vm_area(buf, vvar))
+			goto err;
+	}
+
+	if (vdso->start != VDSO_BAD_ADDR)
+		test_msg("[vdso] %lx-%lx\n", vdso->start, vdso->end);
+	if (vvar->start != VVAR_BAD_ADDR)
+		test_msg("[vvar] %lx-%lx\n", vvar->start, vvar->end);
+	ret = 0;
+err:
+	fclose(maps);
+	return ret;
+}
+
+#ifdef __i386__
+/*
+ * On i386 syscalls for speed are optimized trough vdso,
+ * call raw int80 as vdso is unmapped.
+ */
+#define __NR32_munmap	91
+#define __NR32_kill	37
+#define __NR32_exit	1
+struct syscall_args32 {
+	uint32_t nr, arg0, arg1;
+};
+
+static inline void do_full_int80(struct syscall_args32 *args)
+{
+	asm volatile (
+			"int $0x80\n\t"
+		      : "+a" (args->nr),
+			"+b" (args->arg0), "+c" (args->arg1));
+}
+
+int sys_munmap(void *addr, size_t len)
+{
+	struct syscall_args32 s = {0};
+
+	s.nr    = __NR32_munmap;
+	s.arg0  = (uint32_t)(uintptr_t)addr;
+	s.arg1  = (uint32_t)len;
+
+	do_full_int80(&s);
+
+	return (int)s.nr;
+}
+
+int sys_kill(pid_t pid, int sig)
+{
+	struct syscall_args32 s = {0};
+
+	s.nr    = __NR32_kill;
+	s.arg0  = (uint32_t)pid;
+	s.arg1  = (uint32_t)sig;
+
+	do_full_int80(&s);
+
+	return (int)s.nr;
+}
+
+void sys_exit(int status)
+{
+	struct syscall_args32 s = {0};
+
+	s.nr    = __NR32_exit;
+	s.arg0  = (uint32_t)status;
+
+	do_full_int80(&s);
+}
+
+#else /* !__i386__ */
+
+int sys_munmap(void *addr, size_t len)
+{
+	return syscall(SYS_munmap, addr, len);
+}
+
+int sys_kill(pid_t pid, int sig)
+{
+	return syscall(SYS_kill, pid, sig);
+}
+
+void sys_exit(int status)
+{
+	syscall(SYS_exit, status);
+}
+
+#endif
+
+static int unmap_blobs(void)
+{
+	struct vm_area vdso, vvar;
+	int ret;
+
+	if (find_blobs(getpid(), &vdso, &vvar))
+		return -1;
+
+	if (vdso.start != VDSO_BAD_ADDR) {
+		ret = sys_munmap((void*)vdso.start, vdso.end - vdso.start);
+		if (ret)
+			return ret;
+	}
+	if (vvar.start != VVAR_BAD_ADDR) {
+		ret = sys_munmap((void*)vvar.start, vvar.end - vvar.start);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	struct vm_area vdso, vvar;
+	pid_t child;
+	int status, ret = -1;
+
+	test_init(argc, argv);
+
+	child = fork();
+	if (child < 0) {
+		pr_perror("fork() failed");
+		exit(1);
+	}
+
+	if (child == 0) {
+		child = getpid();
+		if (unmap_blobs() < 0)
+			syscall(SYS_exit, 1);
+		sys_kill(child, SIGSTOP);
+		sys_exit(2);
+	}
+
+	waitpid(child, &status, WUNTRACED);
+	if (WIFEXITED(status)) {
+		int ret = WEXITSTATUS(status);
+
+		pr_err("Child unexpectedly exited with %d\n", ret);
+		goto out_kill;
+	} else if (WIFSIGNALED(status)) {
+		int sig = WTERMSIG(status);
+
+		pr_err("Child unexpectedly signaled with %d: %s\n",
+				sig, strsignal(sig));
+		goto out_kill;
+	} else if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) {
+		pr_err("Child is unstoppable or was stopped by other means\n");
+		goto out_kill;
+	}
+
+	if (find_blobs(child, &vdso, &vvar))
+		goto out_kill;
+	if (vdso.start != VDSO_BAD_ADDR || vvar.start != VVAR_BAD_ADDR) {
+		pr_err("Found vvar or vdso blob(s) in child, which should have unmapped them\n");
+		goto out_kill;
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	if (find_blobs(child, &vdso, &vvar))
+		goto out_kill;
+	if (vdso.start != VDSO_BAD_ADDR || vvar.start != VVAR_BAD_ADDR) {
+		pr_err("Child without vdso got it after C/R\n");
+		fail();
+		goto out_kill;
+	}
+
+	pass();
+
+	ret = 0;
+out_kill:
+	kill(child, SIGKILL);
+	return ret;
+}