xref: /linux/tools/testing/selftests/mm/vm_util.c (revision bd4d67e76f699688d15e6194f1505b8bdfee0dd7)

// SPDX-License-Identifier: GPL-2.0
#include <string.h>
#include <fcntl.h>
#include "../kselftest.h"
#include "vm_util.h"

#define PMD_SIZE_FILE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size"
#define SMAP_FILE_PATH "/proc/self/smaps"
#define MAX_LINE_LENGTH 500

unsigned int __page_size;
unsigned int __page_shift;

uint64_t pagemap_get_entry(int fd, char *start)
{
	const unsigned long pfn = (unsigned long)start / getpagesize();
	uint64_t entry;
	int ret;

	ret = pread(fd, &entry, sizeof(entry), pfn * sizeof(entry));
	if (ret != sizeof(entry))
		ksft_exit_fail_msg("reading pagemap failed\n");
	return entry;
}

bool pagemap_is_softdirty(int fd, char *start)
{
	uint64_t entry = pagemap_get_entry(fd, start);

	// Check if dirty bit (55th bit) is set
	return entry & 0x0080000000000000ull;
}

bool pagemap_is_swapped(int fd, char *start)
{
	uint64_t entry = pagemap_get_entry(fd, start);

	return entry & 0x4000000000000000ull;
}

bool pagemap_is_populated(int fd, char *start)
{
	uint64_t entry = pagemap_get_entry(fd, start);

	/* Present or swapped. */
	return entry & 0xc000000000000000ull;
}

unsigned long pagemap_get_pfn(int fd, char *start)
{
	uint64_t entry = pagemap_get_entry(fd, start);

	/* If present (63th bit), PFN is at bit 0 -- 54. */
	if (entry & 0x8000000000000000ull)
		return entry & 0x007fffffffffffffull;
	return -1ul;
}

void clear_softdirty(void)
{
	int ret;
	const char *ctrl = "4";
	int fd = open("/proc/self/clear_refs", O_WRONLY);

	if (fd < 0)
		ksft_exit_fail_msg("opening clear_refs failed\n");
	ret = write(fd, ctrl, strlen(ctrl));
	close(fd);
	if (ret != strlen(ctrl))
		ksft_exit_fail_msg("writing clear_refs failed\n");
}

bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
{
	while (fgets(buf, len, fp)) {
		if (!strncmp(buf, pattern, strlen(pattern)))
			return true;
	}
	return false;
}

uint64_t read_pmd_pagesize(void)
{
	int fd;
	char buf[20];
	ssize_t num_read;

	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
	if (fd == -1)
		return 0;

	num_read = read(fd, buf, 19);
	if (num_read < 1) {
		close(fd);
		return 0;
	}
	buf[num_read] = '\0';
	close(fd);

	return strtoul(buf, NULL, 10);
}

bool __check_huge(void *addr, char *pattern, int nr_hpages,
		  uint64_t hpage_size)
{
	uint64_t thp = -1;
	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)
		ksft_exit_fail_msg("%s: Pattern is too long\n", __func__);

	fp = fopen(SMAP_FILE_PATH, "r");
	if (!fp)
		ksft_exit_fail_msg("%s: Failed to open file %s\n", __func__, SMAP_FILE_PATH);

	if (!check_for_pattern(fp, addr_pattern, buffer, sizeof(buffer)))
		goto err_out;

	/*
	 * Fetch the pattern in the same block and check the number of
	 * hugepages.
	 */
	if (!check_for_pattern(fp, pattern, buffer, sizeof(buffer)))
		goto err_out;

	snprintf(addr_pattern, MAX_LINE_LENGTH, "%s%%9ld kB", pattern);

	if (sscanf(buffer, addr_pattern, &thp) != 1)
		ksft_exit_fail_msg("Reading smap error\n");

err_out:
	fclose(fp);
	return thp == (nr_hpages * (hpage_size >> 10));
}

bool check_huge_anon(void *addr, int nr_hpages, uint64_t hpage_size)
{
	return __check_huge(addr, "AnonHugePages: ", nr_hpages, hpage_size);
}

bool check_huge_file(void *addr, int nr_hpages, uint64_t hpage_size)
{
	return __check_huge(addr, "FilePmdMapped:", nr_hpages, hpage_size);
}

bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size)
{
	return __check_huge(addr, "ShmemPmdMapped:", nr_hpages, hpage_size);
}

int64_t allocate_transhuge(void *ptr, int pagemap_fd)
{
	uint64_t ent[2];

	/* drop pmd */
	if (mmap(ptr, HPAGE_SIZE, PROT_READ | PROT_WRITE,
		 MAP_FIXED | MAP_ANONYMOUS |
		 MAP_NORESERVE | MAP_PRIVATE, -1, 0) != ptr)
		errx(2, "mmap transhuge");

	if (madvise(ptr, HPAGE_SIZE, MADV_HUGEPAGE))
		err(2, "MADV_HUGEPAGE");

	/* allocate transparent huge page */
	*(volatile void **)ptr = ptr;

	if (pread(pagemap_fd, ent, sizeof(ent),
		  (uintptr_t)ptr >> (pshift() - 3)) != sizeof(ent))
		err(2, "read pagemap");

	if (PAGEMAP_PRESENT(ent[0]) && PAGEMAP_PRESENT(ent[1]) &&
	    PAGEMAP_PFN(ent[0]) + 1 == PAGEMAP_PFN(ent[1]) &&
	    !(PAGEMAP_PFN(ent[0]) & ((1 << (HPAGE_SHIFT - pshift())) - 1)))
		return PAGEMAP_PFN(ent[0]);

	return -1;
}

unsigned long default_huge_page_size(void)
{
	unsigned long hps = 0;
	char *line = NULL;
	size_t linelen = 0;
	FILE *f = fopen("/proc/meminfo", "r");

	if (!f)
		return 0;
	while (getline(&line, &linelen, f) > 0) {
		if (sscanf(line, "Hugepagesize:       %lu kB", &hps) == 1) {
			hps <<= 10;
			break;
		}
	}

	free(line);
	fclose(f);
	return hps;
}