On 4/7/24 02:53, Muhammad Usama Anjum wrote:
On 4/5/24 1:44 PM, Dev Jain wrote:
This patch tests the 4GB VA restriction for 32-bit processes; it is required to test the compat layer, whether the kernel knows that it is running a 32-bit process or not. Chunks are allocated until the VA gets exhausted; mmap must fail beyond 4GB. This is asserted against the VA mappings found in /proc/self/maps.
Signed-off-by: Dev Jain dev.jain@arm.com
tools/testing/selftests/arm/mm/compat_va.c | 94 ++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 tools/testing/selftests/arm/mm/compat_va.c
diff --git a/tools/testing/selftests/arm/mm/compat_va.c b/tools/testing/selftests/arm/mm/compat_va.c new file mode 100644 index 000000000000..3a78f240bc87 --- /dev/null +++ b/tools/testing/selftests/arm/mm/compat_va.c @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0 +/*
- Copyright (C) 2024 ARM Limited
- Author : Dev Jain dev.jain@arm.com
- Tests 4GB VA restriction for 32 bit process
- */
+#define _GNU_SOURCE +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/mman.h>
+#include <linux/sizes.h> +#include <kselftest.h>
+#define MAP_CHUNK_SIZE SZ_1M +#define NR_CHUNKS_4G (SZ_1G / MAP_CHUNK_SIZE) * 4 /* prevent overflow */
+static int validate_address_hint(void) +{
- char *ptr;
- ptr = mmap((void *) (1UL << 29), MAP_CHUNK_SIZE, PROT_READ |
PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);- if (ptr == MAP_FAILED)
return 0;- return 1;
Usually we return negative value instead of positive one which indicates error situation.
+}
+int main(int argc, char *argv[]) +{
- char *ptr[NR_CHUNKS_4G + 3];
- char line[1000];
- const char *file_name;
- int chunks;
- FILE *file;
- int i;
- ksft_print_header();
- ksft_set_plan(1);
There are multiple test cases. Instead of saying there is only 1 test. There should be multiple ksft_test_result{_pass,_fail} statements for each sub-tests.
My initial idea was to treat this as a single logical test, as I
am asserting the restriction on the number of chunks against
the VMAs. I guess your approach is cleaner; thanks.
- /* try allocation beyond 4 GB */
- for (i = 0; i < NR_CHUNKS_4G + 3; ++i) {
ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE,MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);if (ptr[i] == MAP_FAILED) {if (validate_address_hint())ksft_exit_fail_msg("VA exhaustion failed\n");break;}- }
- chunks = i;
- if (chunks >= NR_CHUNKS_4G) {
ksft_test_result_fail("mmapped chunks beyond 4GB\n");ksft_finished();- }
- /* parse /proc/self/maps, confirm 32 bit VA mappings */
- file_name = "/proc/self/maps";
- file = fopen(file_name, "r");
- if (file == NULL)
ksft_exit_fail_msg("/proc/self/maps cannot be opened\n");- while (fgets(line, sizeof(line), file)) {
const char *whitespace_loc, *hyphen_loc;hyphen_loc = strchr(line, '-');whitespace_loc = strchr(line, ' ');if (!(hyphen_loc && whitespace_loc)) {ksft_test_result_skip("Unexpected format");ksft_finished();I'm unable to follow as there are too many return statements. If you divide the test into multiple sub-tests, you can skip/pass/fail each sub-test easily.
}if ((hyphen_loc - line > 8) ||(whitespace_loc - hyphen_loc) > 9) {ksft_test_result_fail("Memory map more than 32 bits\n");ksft_finished();}- }
- for (int i = 0; i < chunks; ++i)
munmap(ptr[i], MAP_CHUNK_SIZE);- ksft_test_result_pass("Test\n");
- ksft_finished();
+}