This introduces three tests:

1) Sanity check soft dirty basic semantics: allocate area, clean, dirty, check if the SD bit flipped.

2) Check VMA reuse: validate the VM_SOFTDIRTY usage

3) Check soft-dirty on huge pages

This was motivated by Will Deacon's fix commit 912efa17e512 ("mm: proc: Invalidate TLB after clearing soft-dirty page state"). I was tracking the same issue that he fixed, and this test would have caught it.

Cc: Will Deacon will@kernel.org Signed-off-by: Gabriel Krisman Bertazi krisman@collabora.com --- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/soft-dirty/.gitignore | 1 + tools/testing/selftests/soft-dirty/Makefile | 9 + .../testing/selftests/soft-dirty/soft-dirty.c | 254 ++++++++++++++++++ 4 files changed, 265 insertions(+) create mode 100644 tools/testing/selftests/soft-dirty/.gitignore create mode 100644 tools/testing/selftests/soft-dirty/Makefile create mode 100644 tools/testing/selftests/soft-dirty/soft-dirty.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index bc3299a20338..c8dcd7defd33 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -55,6 +55,7 @@ TARGETS += seccomp TARGETS += sgx TARGETS += sigaltstack TARGETS += size +TARGETS += soft-dirty TARGETS += sparc64 TARGETS += splice TARGETS += static_keys diff --git a/tools/testing/selftests/soft-dirty/.gitignore b/tools/testing/selftests/soft-dirty/.gitignore new file mode 100644 index 000000000000..cfb0cfda9bdf --- /dev/null +++ b/tools/testing/selftests/soft-dirty/.gitignore @@ -0,0 +1 @@ +soft-dirty diff --git a/tools/testing/selftests/soft-dirty/Makefile b/tools/testing/selftests/soft-dirty/Makefile new file mode 100644 index 000000000000..d76ad8e0f10d --- /dev/null +++ b/tools/testing/selftests/soft-dirty/Makefile @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: GPL-2.0 +top_srcdir = ../../../.. +INSTALL_HDR_PATH = $(top_srcdir)/usr +LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/ + +CFLAGS += -Wall -I$(LINUX_HDR_PATH) -O0 -g3 + +TEST_GEN_PROGS := soft-dirty +include ../lib.mk diff --git a/tools/testing/selftests/soft-dirty/soft-dirty.c b/tools/testing/selftests/soft-dirty/soft-dirty.c new file mode 100644 index 000000000000..47af76f9df50 --- /dev/null +++ b/tools/testing/selftests/soft-dirty/soft-dirty.c @@ -0,0 +1,254 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <stdint.h> +#include <unistd.h> +#include <stdio.h> +#include <unistd.h> +#include <syscall.h> +#include <errno.h> +#include <stdlib.h> +#include <sys/mman.h> +#include <err.h> +#include <string.h> +#include <stdbool.h> +#include <malloc.h> + +#define PAGEMAP_PATH "/proc/self/pagemap" +#define CLEAR_REFS_PATH "/proc/self/clear_refs" +#define SMAP_PATH "/proc/self/smaps" +#define MAX_LINE_LENGTH 512 + +#define TEST_ITERATIONS 10000 + +#define PMD_SIZE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size" + +int clear_refs; +int pagemap; + +int pagesize; +int mmap_size; /* Size of test region */ + +static void clear_all_refs(void) +{ + if (write(clear_refs, "4\n", 2) != 2) + printf("%s: failed to clear references\n", __func__); +} + +static void touch_page(char *map, int n) +{ + map[(page_size * n) + 1]++; +} + +static int check_page(char *map, uint64_t n, int clear) +{ + uint64_t off; + uint64_t buf = 0; + + off = (n + ((uint64_t)map >> 12)) << 3; + + if (lseek(pagemap, off, SEEK_SET) == (off_t) -1) + errx(EXIT_FAILURE, "pagemap llseek failed"); + + if (read(pagemap, &buf, 8) != 8) + errx(EXIT_FAILURE, "pagemap read failed"); + + if (clear) + clear_all_refs(); + + return ((buf >> 55) & 1); +} + +static void test_simple(void) +{ + int i; + char *map; + + printf("- Test %s:\n", __func__); + + map = aligned_alloc(page_size, mmap_size); + if (!map) + errx(EXIT_FAILURE, "mmap"); + + clear_all_refs(); + + for (i = 0 ; i < TEST_ITERATIONS; i++) { + if (check_page(map, 2, 1) == 1) { + errx(EXIT_FAILURE, "dirty bit was 1, but should be 0 (i=%d)", i); + break; + } + + touch_page(map, 2); + + if (check_page(map, 2, 1) == 0) { + errx(EXIT_FAILURE, "dirty bit was 0, but should be 1 (i=%d)", i); + break; + } + + } + free(map); + + printf("success\n"); +} + +static void test_vma_reuse(void) +{ + char *map, *map2; + + printf("- Test %s:\n", __func__); + + map = (char *) 0x900000000000; + map = mmap(map, mmap_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); + if (map == MAP_FAILED) + errx(EXIT_FAILURE, "mmap"); + + clear_all_refs(); + touch_page(map, 2); + + munmap(map, mmap_size); + map2 = mmap(map, mmap_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); + if (map2 == MAP_FAILED) + errx(EXIT_FAILURE, "mmap2"); + + if (map != map2) + errx(EXIT_FAILURE, "map != map2"); + + if (check_page(map, 2, 1) == 0) + errx(-1, "map/unmap lost dirty"); + + munmap(map2, mmap_size); + + printf("success\n"); +} + +/* + * read_pmd_pagesize(), check_for_pattern() and check_huge() adapted + * from 'tools/testing/selftest/vm/split_huge_page_test.c' + */ +static uint64_t read_pmd_pagesize(void) +{ + int fd; + char buf[20]; + ssize_t num_read; + + fd = open(PMD_SIZE_PATH, O_RDONLY); + if (fd == -1) + errx(EXIT_FAILURE, "Open hpage_pmd_size failed"); + + num_read = read(fd, buf, 19); + if (num_read < 1) { + close(fd); + errx(EXIT_FAILURE, "Read hpage_pmd_size failed"); + } + buf[num_read] = '\0'; + close(fd); + + return strtoul(buf, NULL, 10); +} + +static bool check_for_pattern(FILE *fp, const char *pattern, char *buf) +{ + while (fgets(buf, MAX_LINE_LENGTH, fp) != NULL) { + if (!strncmp(buf, pattern, strlen(pattern))) + return true; + } + return false; +} + +static uint64_t check_huge(void *addr) +{ + uint64_t thp = 0; + int ret; + FILE *fp; + char buffer[MAX_LINE_LENGTH]; + char addr_pattern[MAX_LINE_LENGTH]; + + ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-", + (unsigned long) addr); + if (ret >= MAX_LINE_LENGTH) + errx(EXIT_FAILURE, "%s: Pattern is too long\n", __func__); + + fp = fopen(SMAP_PATH, "r"); + if (!fp) + errx(EXIT_FAILURE, "%s: Failed to open file %s\n", __func__, SMAP_PATH); + + if (!check_for_pattern(fp, addr_pattern, buffer)) + goto err_out; + + /* + * Fetch the AnonHugePages: in the same block and check the number of + * hugepages. + */ + if (!check_for_pattern(fp, "AnonHugePages:", buffer)) + goto err_out; + + if (sscanf(buffer, "AnonHugePages:%10ld kB", &thp) != 1) + errx(EXIT_FAILURE, "Reading smap error\n"); + +err_out: + fclose(fp); + + return thp; +} + +static void test_hugepage(void) +{ + char *map; + int i, ret; + size_t hpage_len = read_pmd_pagesize(); + + printf("- Test %s:\n", __func__); + + map = memalign(hpage_len, hpage_len); + if (!map) + errx(EXIT_FAILURE, "memalign"); + + ret = madvise(map, hpage_len, MADV_HUGEPAGE); + if (ret) + errx(EXIT_FAILURE, "madvise %d", ret); + + for (i = 0; i < hpage_len; i++) + map[i] = (char)i; + + if (!check_huge(map)) + errx(EXIT_FAILURE, "failed to allocate THP"); + + clear_all_refs(); + for (i = 0 ; i < TEST_ITERATIONS ; i++) { + if (check_page(map, 2, 1) == 1) { + errx(EXIT_FAILURE, "dirty bit was 1, but should be 0 (i=%d)", i); + break; + } + + touch_page(map, 2); + + if (check_page(map, 2, 1) == 0) { + errx(EXIT_FAILURE, "dirty bit was 0, but should be 1 (i=%d)", i); + break; + } + } + munmap(map, mmap_size); + + printf("success\n"); +} + +int main(int argc, char **argv) +{ + pagemap = open(PAGEMAP_PATH, O_RDONLY, 0); + if (pagemap < 0) + errx(EXIT_FAILURE, "Failed to open %s", PAGEMAP_PATH); + + clear_refs = open(CLEAR_REFS_PATH, O_WRONLY, 0); + if (clear_refs < 0) + errx(EXIT_FAILURE, "Failed to open %s", CLEAR_REFS_PATH); + + pagesize = getpagesize(); + mmap_size = 10 * pagesize(); + + test_simple(); + test_vma_reuse(); + test_hugepage(); + + return 0; +}