From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
[ Upstream commit 16391bfc862342f285195013b73c1394fab28b97 ]
This tests that when a process with a mapping above 512TB forks we
correctly separate the parent and child address spaces. This exercises
the bug in the context id handling fixed in the previous commit.
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/testing/selftests/powerpc/mm/.gitignore | 3 +-
tools/testing/selftests/powerpc/mm/Makefile | 4 +-
.../powerpc/mm/large_vm_fork_separation.c | 87 +++++++++++++++++++
3 files changed, 92 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/powerpc/mm/large_vm_fork_separation.c
diff --git a/tools/testing/selftests/powerpc/mm/.gitignore b/tools/testing/selftests/powerpc/mm/.gitignore
index ba919308fe30..d503b8764a8e 100644
--- a/tools/testing/selftests/powerpc/mm/.gitignore
+++ b/tools/testing/selftests/powerpc/mm/.gitignore
@@ -3,4 +3,5 @@ subpage_prot
tempfile
prot_sao
segv_errors
-wild_bctr
\ No newline at end of file
+wild_bctr
+large_vm_fork_separation
\ No newline at end of file
diff --git a/tools/testing/selftests/powerpc/mm/Makefile b/tools/testing/selftests/powerpc/mm/Makefile
index 43d68420e363..f1fbc15800c4 100644
--- a/tools/testing/selftests/powerpc/mm/Makefile
+++ b/tools/testing/selftests/powerpc/mm/Makefile
@@ -2,7 +2,8 @@
noarg:
$(MAKE) -C ../
-TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot prot_sao segv_errors wild_bctr
+TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot prot_sao segv_errors wild_bctr \
+ large_vm_fork_separation
TEST_GEN_FILES := tempfile
top_srcdir = ../../../../..
@@ -13,6 +14,7 @@ $(TEST_GEN_PROGS): ../harness.c
$(OUTPUT)/prot_sao: ../utils.c
$(OUTPUT)/wild_bctr: CFLAGS += -m64
+$(OUTPUT)/large_vm_fork_separation: CFLAGS += -m64
$(OUTPUT)/tempfile:
dd if=/dev/zero of=$@ bs=64k count=1
diff --git a/tools/testing/selftests/powerpc/mm/large_vm_fork_separation.c b/tools/testing/selftests/powerpc/mm/large_vm_fork_separation.c
new file mode 100644
index 000000000000..2363a7f3ab0d
--- /dev/null
+++ b/tools/testing/selftests/powerpc/mm/large_vm_fork_separation.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright 2019, Michael Ellerman, IBM Corp.
+//
+// Test that allocating memory beyond the memory limit and then forking is
+// handled correctly, ie. the child is able to access the mappings beyond the
+// memory limit and the child's writes are not visible to the parent.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+
+#ifndef MAP_FIXED_NOREPLACE
+#define MAP_FIXED_NOREPLACE MAP_FIXED // "Should be safe" above 512TB
+#endif
+
+
+static int test(void)
+{
+ int p2c[2], c2p[2], rc, status, c, *p;
+ unsigned long page_size;
+ pid_t pid;
+
+ page_size = sysconf(_SC_PAGESIZE);
+ SKIP_IF(page_size != 65536);
+
+ // Create a mapping at 512TB to allocate an extended_id
+ p = mmap((void *)(512ul << 40), page_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE, -1, 0);
+ if (p == MAP_FAILED) {
+ perror("mmap");
+ printf("Error: couldn't mmap(), confirm kernel has 4TB support?\n");
+ return 1;
+ }
+
+ printf("parent writing %p = 1\n", p);
+ *p = 1;
+
+ FAIL_IF(pipe(p2c) == -1 || pipe(c2p) == -1);
+
+ pid = fork();
+ if (pid == 0) {
+ FAIL_IF(read(p2c[0], &c, 1) != 1);
+
+ pid = getpid();
+ printf("child writing %p = %d\n", p, pid);
+ *p = pid;
+
+ FAIL_IF(write(c2p[1], &c, 1) != 1);
+ FAIL_IF(read(p2c[0], &c, 1) != 1);
+ exit(0);
+ }
+
+ c = 0;
+ FAIL_IF(write(p2c[1], &c, 1) != 1);
+ FAIL_IF(read(c2p[0], &c, 1) != 1);
+
+ // Prevent compiler optimisation
+ barrier();
+
+ rc = 0;
+ printf("parent reading %p = %d\n", p, *p);
+ if (*p != 1) {
+ printf("Error: BUG! parent saw child's write! *p = %d\n", *p);
+ rc = 1;
+ }
+
+ FAIL_IF(write(p2c[1], &c, 1) != 1);
+ FAIL_IF(waitpid(pid, &status, 0) == -1);
+ FAIL_IF(!WIFEXITED(status) || WEXITSTATUS(status));
+
+ if (rc == 0)
+ printf("success: test completed OK\n");
+
+ return rc;
+}
+
+int main(void)
+{
+ return test_harness(test, "large_vm_fork_separation");
+}
--
2.20.1
