blob: 0e74635c8c3d97fca497e73ac1e41a17f1677a0e [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* A test of splitting PMD THPs and PTE-mapped THPs from a specified virtual
* address range in a process via <debugfs>/split_huge_pages interface.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <inttypes.h>
#include <string.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <malloc.h>
#include <stdbool.h>
#include "vm_util.h"
uint64_t pagesize;
unsigned int pageshift;
uint64_t pmd_pagesize;
#define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
#define INPUT_MAX 80
#define PID_FMT "%d,0x%lx,0x%lx"
#define PATH_FMT "%s,0x%lx,0x%lx"
#define PFN_MASK ((1UL<<55)-1)
#define KPF_THP (1UL<<22)
int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
{
uint64_t paddr;
uint64_t page_flags;
if (pagemap_file) {
pread(pagemap_file, &paddr, sizeof(paddr),
((long)vaddr >> pageshift) * sizeof(paddr));
if (kpageflags_file) {
pread(kpageflags_file, &page_flags, sizeof(page_flags),
(paddr & PFN_MASK) * sizeof(page_flags));
return !!(page_flags & KPF_THP);
}
}
return 0;
}
static int write_file(const char *path, const char *buf, size_t buflen)
{
int fd;
ssize_t numwritten;
fd = open(path, O_WRONLY);
if (fd == -1)
return 0;
numwritten = write(fd, buf, buflen - 1);
close(fd);
if (numwritten < 1)
return 0;
return (unsigned int) numwritten;
}
static void write_debugfs(const char *fmt, ...)
{
char input[INPUT_MAX];
int ret;
va_list argp;
va_start(argp, fmt);
ret = vsnprintf(input, INPUT_MAX, fmt, argp);
va_end(argp);
if (ret >= INPUT_MAX) {
printf("%s: Debugfs input is too long\n", __func__);
exit(EXIT_FAILURE);
}
if (!write_file(SPLIT_DEBUGFS, input, ret + 1)) {
perror(SPLIT_DEBUGFS);
exit(EXIT_FAILURE);
}
}
void split_pmd_thp(void)
{
char *one_page;
size_t len = 4 * pmd_pagesize;
size_t i;
one_page = memalign(pmd_pagesize, len);
if (!one_page) {
printf("Fail to allocate memory\n");
exit(EXIT_FAILURE);
}
madvise(one_page, len, MADV_HUGEPAGE);
for (i = 0; i < len; i++)
one_page[i] = (char)i;
if (!check_huge_anon(one_page, 4, pmd_pagesize)) {
printf("No THP is allocated\n");
exit(EXIT_FAILURE);
}
/* split all THPs */
write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
(uint64_t)one_page + len);
for (i = 0; i < len; i++)
if (one_page[i] != (char)i) {
printf("%ld byte corrupted\n", i);
exit(EXIT_FAILURE);
}
if (!check_huge_anon(one_page, 0, pmd_pagesize)) {
printf("Still AnonHugePages not split\n");
exit(EXIT_FAILURE);
}
printf("Split huge pages successful\n");
free(one_page);
}
void split_pte_mapped_thp(void)
{
char *one_page, *pte_mapped, *pte_mapped2;
size_t len = 4 * pmd_pagesize;
uint64_t thp_size;
size_t i;
const char *pagemap_template = "/proc/%d/pagemap";
const char *kpageflags_proc = "/proc/kpageflags";
char pagemap_proc[255];
int pagemap_fd;
int kpageflags_fd;
if (snprintf(pagemap_proc, 255, pagemap_template, getpid()) < 0) {
perror("get pagemap proc error");
exit(EXIT_FAILURE);
}
pagemap_fd = open(pagemap_proc, O_RDONLY);
if (pagemap_fd == -1) {
perror("read pagemap:");
exit(EXIT_FAILURE);
}
kpageflags_fd = open(kpageflags_proc, O_RDONLY);
if (kpageflags_fd == -1) {
perror("read kpageflags:");
exit(EXIT_FAILURE);
}
one_page = mmap((void *)(1UL << 30), len, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
madvise(one_page, len, MADV_HUGEPAGE);
for (i = 0; i < len; i++)
one_page[i] = (char)i;
if (!check_huge_anon(one_page, 4, pmd_pagesize)) {
printf("No THP is allocated\n");
exit(EXIT_FAILURE);
}
/* remap the first pagesize of first THP */
pte_mapped = mremap(one_page, pagesize, pagesize, MREMAP_MAYMOVE);
/* remap the Nth pagesize of Nth THP */
for (i = 1; i < 4; i++) {
pte_mapped2 = mremap(one_page + pmd_pagesize * i + pagesize * i,
pagesize, pagesize,
MREMAP_MAYMOVE|MREMAP_FIXED,
pte_mapped + pagesize * i);
if (pte_mapped2 == (char *)-1) {
perror("mremap failed");
exit(EXIT_FAILURE);
}
}
/* smap does not show THPs after mremap, use kpageflags instead */
thp_size = 0;
for (i = 0; i < pagesize * 4; i++)
if (i % pagesize == 0 &&
is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
thp_size++;
if (thp_size != 4) {
printf("Some THPs are missing during mremap\n");
exit(EXIT_FAILURE);
}
/* split all remapped THPs */
write_debugfs(PID_FMT, getpid(), (uint64_t)pte_mapped,
(uint64_t)pte_mapped + pagesize * 4);
/* smap does not show THPs after mremap, use kpageflags instead */
thp_size = 0;
for (i = 0; i < pagesize * 4; i++) {
if (pte_mapped[i] != (char)i) {
printf("%ld byte corrupted\n", i);
exit(EXIT_FAILURE);
}
if (i % pagesize == 0 &&
is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
thp_size++;
}
if (thp_size) {
printf("Still %ld THPs not split\n", thp_size);
exit(EXIT_FAILURE);
}
printf("Split PTE-mapped huge pages successful\n");
munmap(one_page, len);
close(pagemap_fd);
close(kpageflags_fd);
}
void split_file_backed_thp(void)
{
int status;
int fd;
ssize_t num_written;
char tmpfs_template[] = "/tmp/thp_split_XXXXXX";
const char *tmpfs_loc = mkdtemp(tmpfs_template);
char testfile[INPUT_MAX];
uint64_t pgoff_start = 0, pgoff_end = 1024;
printf("Please enable pr_debug in split_huge_pages_in_file() if you need more info.\n");
status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=always,size=4m");
if (status) {
printf("Unable to create a tmpfs for testing\n");
exit(EXIT_FAILURE);
}
status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc);
if (status >= INPUT_MAX) {
printf("Fail to create file-backed THP split testing file\n");
goto cleanup;
}
fd = open(testfile, O_CREAT|O_WRONLY);
if (fd == -1) {
perror("Cannot open testing file\n");
goto cleanup;
}
/* write something to the file, so a file-backed THP can be allocated */
num_written = write(fd, tmpfs_loc, strlen(tmpfs_loc) + 1);
close(fd);
if (num_written < 1) {
printf("Fail to write data to testing file\n");
goto cleanup;
}
/* split the file-backed THP */
write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end);
status = unlink(testfile);
if (status)
perror("Cannot remove testing file\n");
cleanup:
status = umount(tmpfs_loc);
if (status) {
printf("Unable to umount %s\n", tmpfs_loc);
exit(EXIT_FAILURE);
}
status = rmdir(tmpfs_loc);
if (status) {
perror("cannot remove tmp dir");
exit(EXIT_FAILURE);
}
printf("file-backed THP split test done, please check dmesg for more information\n");
}
int main(int argc, char **argv)
{
if (geteuid() != 0) {
printf("Please run the benchmark as root\n");
exit(EXIT_FAILURE);
}
pagesize = getpagesize();
pageshift = ffs(pagesize) - 1;
pmd_pagesize = read_pmd_pagesize();
if (!pmd_pagesize) {
printf("Reading PMD pagesize failed\n");
exit(EXIT_FAILURE);
}
split_pmd_thp();
split_pte_mapped_thp();
split_file_backed_thp();
return 0;
}