Messages in this thread | | | Date | Wed, 10 Apr 2024 09:45:41 +0530 | Subject | Re: [PATCH 1/4] selftests/arm: Add mm test | From | Dev Jain <> |
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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(); >> +}
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