Merge tag 'mm-nonmm-stable-2022-08-06-2' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc updates from Andrew Morton:
 "Updates to various subsystems which I help look after. lib, ocfs2,
  fatfs, autofs, squashfs, procfs, etc. A relatively small amount of
  material this time"

* tag 'mm-nonmm-stable-2022-08-06-2' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (72 commits)
  scripts/gdb: ensure the absolute path is generated on initial source
  MAINTAINERS: kunit: add David Gow as a maintainer of KUnit
  mailmap: add linux.dev alias for Brendan Higgins
  mailmap: update Kirill's email
  profile: setup_profiling_timer() is moslty not implemented
  ocfs2: fix a typo in a comment
  ocfs2: use the bitmap API to simplify code
  ocfs2: remove some useless functions
  lib/mpi: fix typo 'the the' in comment
  proc: add some (hopefully) insightful comments
  bdi: remove enum wb_congested_state
  kernel/hung_task: fix address space of proc_dohung_task_timeout_secs
  lib/lzo/lzo1x_compress.c: replace ternary operator with min() and min_t()
  squashfs: support reading fragments in readahead call
  squashfs: implement readahead
  squashfs: always build "file direct" version of page actor
  Revert "squashfs: provide backing_dev_info in order to disable read-ahead"
  fs/ocfs2: Fix spelling typo in comment
  ia64: old_rr4 added under CONFIG_HUGETLB_PAGE
  proc: fix test for "vsyscall=xonly" boot option
  ...

1 files changed, 68 insertions, 7 deletions

diff --git a/tools/testing/selftests/proc/proc-pid-vm.c b/tools/testing/selftests/proc/proc-pid-vm.c
index 28604c9f805c..e5962f4794f5 100644
--- a/tools/testing/selftests/proc/proc-pid-vm.c
+++ b/tools/testing/selftests/proc/proc-pid-vm.c
@@ -211,10 +211,19 @@ static int make_exe(const uint8_t *payload, size_t len)
 }
 #endif
 
-static bool g_vsyscall = false;
+/*
+ * 0: vsyscall VMA doesn't exist	vsyscall=none
+ * 1: vsyscall VMA is r-xp		vsyscall=emulate
+ * 2: vsyscall VMA is --xp		vsyscall=xonly
+ */
+static int g_vsyscall;
+static const char *str_vsyscall;
 
-static const char str_vsyscall[] =
+static const char str_vsyscall_0[] = "";
+static const char str_vsyscall_1[] =
 "ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]\n";
+static const char str_vsyscall_2[] =
+"ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]\n";
 
 #ifdef __x86_64__
 static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
@@ -223,7 +232,7 @@ static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
 }
 
 /*
- * vsyscall page can't be unmapped, probe it with memory load.
+ * vsyscall page can't be unmapped, probe it directly.
  */
 static void vsyscall(void)
 {
@@ -246,13 +255,52 @@ static void vsyscall(void)
 		act.sa_sigaction = sigaction_SIGSEGV;
 		(void)sigaction(SIGSEGV, &act, NULL);
 
+		/* gettimeofday(NULL, NULL); */
+		asm volatile (
+			"call %P0"
+			:
+			: "i" (0xffffffffff600000), "D" (NULL), "S" (NULL)
+			: "rax", "rcx", "r11"
+		);
+		exit(0);
+	}
+	waitpid(pid, &wstatus, 0);
+	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0) {
+		/* vsyscall page exists and is executable. */
+	} else {
+		/* vsyscall page doesn't exist. */
+		g_vsyscall = 0;
+		return;
+	}
+
+	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);
+
+		/* Hide "segfault at ffffffffff600000" messages. */
+		struct sigaction act;
+		memset(&act, 0, sizeof(struct sigaction));
+		act.sa_flags = SA_SIGINFO;
+		act.sa_sigaction = sigaction_SIGSEGV;
+		(void)sigaction(SIGSEGV, &act, NULL);
+
 		*(volatile int *)0xffffffffff600000UL;
 		exit(0);
 	}
 	waitpid(pid, &wstatus, 0);
 	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0) {
-		g_vsyscall = true;
+		/* vsyscall page is readable and executable. */
+		g_vsyscall = 1;
+		return;
 	}
+
+	/* vsyscall page is executable but unreadable. */
+	g_vsyscall = 2;
 }
 
 int main(void)
@@ -261,6 +309,19 @@ int main(void)
 	int exec_fd;
 
 	vsyscall();
+	switch (g_vsyscall) {
+	case 0:
+		str_vsyscall = str_vsyscall_0;
+		break;
+	case 1:
+		str_vsyscall = str_vsyscall_1;
+		break;
+	case 2:
+		str_vsyscall = str_vsyscall_2;
+		break;
+	default:
+		abort();
+	}
 
 	atexit(ate);
 
@@ -314,7 +375,7 @@ int main(void)
 
 	/* Test /proc/$PID/maps */
 	{
-		const size_t len = strlen(buf0) + (g_vsyscall ? strlen(str_vsyscall) : 0);
+		const size_t len = strlen(buf0) + strlen(str_vsyscall);
 		char buf[256];
 		ssize_t rv;
 		int fd;
@@ -327,7 +388,7 @@ int main(void)
 		rv = read(fd, buf, sizeof(buf));
 		assert(rv == len);
 		assert(memcmp(buf, buf0, strlen(buf0)) == 0);
-		if (g_vsyscall) {
+		if (g_vsyscall > 0) {
 			assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0);
 		}
 	}
@@ -374,7 +435,7 @@ int main(void)
 			assert(memmem(buf, rv, S[i], strlen(S[i])));
 		}
 
-		if (g_vsyscall) {
+		if (g_vsyscall > 0) {
 			assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall)));
 		}
 	}