314 lines
9.7 KiB
C
314 lines
9.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
/*
|
|
* Tests for mremap w/ MREMAP_DONTUNMAP.
|
|
*
|
|
* Copyright 2020, Brian Geffon <bgeffon@google.com>
|
|
*/
|
|
#define _GNU_SOURCE
|
|
#include <sys/mman.h>
|
|
#include <errno.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
|
|
#include "../kselftest.h"
|
|
|
|
#ifndef MREMAP_DONTUNMAP
|
|
#define MREMAP_DONTUNMAP 4
|
|
#endif
|
|
|
|
unsigned long page_size;
|
|
char *page_buffer;
|
|
|
|
static void dump_maps(void)
|
|
{
|
|
char cmd[32];
|
|
|
|
snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid());
|
|
system(cmd);
|
|
}
|
|
|
|
#define BUG_ON(condition, description) \
|
|
do { \
|
|
if (condition) { \
|
|
fprintf(stderr, "[FAIL]\t%s():%d\t%s:%s\n", __func__, \
|
|
__LINE__, (description), strerror(errno)); \
|
|
dump_maps(); \
|
|
exit(1); \
|
|
} \
|
|
} while (0)
|
|
|
|
// Try a simple operation for to "test" for kernel support this prevents
|
|
// reporting tests as failed when it's run on an older kernel.
|
|
static int kernel_support_for_mremap_dontunmap()
|
|
{
|
|
int ret = 0;
|
|
unsigned long num_pages = 1;
|
|
void *source_mapping = mmap(NULL, num_pages * page_size, PROT_NONE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(source_mapping == MAP_FAILED, "mmap");
|
|
|
|
// This simple remap should only fail if MREMAP_DONTUNMAP isn't
|
|
// supported.
|
|
void *dest_mapping =
|
|
mremap(source_mapping, num_pages * page_size, num_pages * page_size,
|
|
MREMAP_DONTUNMAP | MREMAP_MAYMOVE, 0);
|
|
if (dest_mapping == MAP_FAILED) {
|
|
ret = errno;
|
|
} else {
|
|
BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
|
|
"unable to unmap destination mapping");
|
|
}
|
|
|
|
BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
|
|
"unable to unmap source mapping");
|
|
return ret;
|
|
}
|
|
|
|
// This helper will just validate that an entire mapping contains the expected
|
|
// byte.
|
|
static int check_region_contains_byte(void *addr, unsigned long size, char byte)
|
|
{
|
|
BUG_ON(size & (page_size - 1),
|
|
"check_region_contains_byte expects page multiples");
|
|
BUG_ON((unsigned long)addr & (page_size - 1),
|
|
"check_region_contains_byte expects page alignment");
|
|
|
|
memset(page_buffer, byte, page_size);
|
|
|
|
unsigned long num_pages = size / page_size;
|
|
unsigned long i;
|
|
|
|
// Compare each page checking that it contains our expected byte.
|
|
for (i = 0; i < num_pages; ++i) {
|
|
int ret =
|
|
memcmp(addr + (i * page_size), page_buffer, page_size);
|
|
if (ret) {
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
// this test validates that MREMAP_DONTUNMAP moves the pagetables while leaving
|
|
// the source mapping mapped.
|
|
static void mremap_dontunmap_simple()
|
|
{
|
|
unsigned long num_pages = 5;
|
|
|
|
void *source_mapping =
|
|
mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(source_mapping == MAP_FAILED, "mmap");
|
|
|
|
memset(source_mapping, 'a', num_pages * page_size);
|
|
|
|
// Try to just move the whole mapping anywhere (not fixed).
|
|
void *dest_mapping =
|
|
mremap(source_mapping, num_pages * page_size, num_pages * page_size,
|
|
MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
|
|
BUG_ON(dest_mapping == MAP_FAILED, "mremap");
|
|
|
|
// Validate that the pages have been moved, we know they were moved if
|
|
// the dest_mapping contains a's.
|
|
BUG_ON(check_region_contains_byte
|
|
(dest_mapping, num_pages * page_size, 'a') != 0,
|
|
"pages did not migrate");
|
|
BUG_ON(check_region_contains_byte
|
|
(source_mapping, num_pages * page_size, 0) != 0,
|
|
"source should have no ptes");
|
|
|
|
BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
|
|
"unable to unmap destination mapping");
|
|
BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
|
|
"unable to unmap source mapping");
|
|
}
|
|
|
|
// This test validates MREMAP_DONTUNMAP will move page tables to a specific
|
|
// destination using MREMAP_FIXED, also while validating that the source
|
|
// remains intact.
|
|
static void mremap_dontunmap_simple_fixed()
|
|
{
|
|
unsigned long num_pages = 5;
|
|
|
|
// Since we want to guarantee that we can remap to a point, we will
|
|
// create a mapping up front.
|
|
void *dest_mapping =
|
|
mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(dest_mapping == MAP_FAILED, "mmap");
|
|
memset(dest_mapping, 'X', num_pages * page_size);
|
|
|
|
void *source_mapping =
|
|
mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(source_mapping == MAP_FAILED, "mmap");
|
|
memset(source_mapping, 'a', num_pages * page_size);
|
|
|
|
void *remapped_mapping =
|
|
mremap(source_mapping, num_pages * page_size, num_pages * page_size,
|
|
MREMAP_FIXED | MREMAP_DONTUNMAP | MREMAP_MAYMOVE,
|
|
dest_mapping);
|
|
BUG_ON(remapped_mapping == MAP_FAILED, "mremap");
|
|
BUG_ON(remapped_mapping != dest_mapping,
|
|
"mremap should have placed the remapped mapping at dest_mapping");
|
|
|
|
// The dest mapping will have been unmap by mremap so we expect the Xs
|
|
// to be gone and replaced with a's.
|
|
BUG_ON(check_region_contains_byte
|
|
(dest_mapping, num_pages * page_size, 'a') != 0,
|
|
"pages did not migrate");
|
|
|
|
// And the source mapping will have had its ptes dropped.
|
|
BUG_ON(check_region_contains_byte
|
|
(source_mapping, num_pages * page_size, 0) != 0,
|
|
"source should have no ptes");
|
|
|
|
BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
|
|
"unable to unmap destination mapping");
|
|
BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
|
|
"unable to unmap source mapping");
|
|
}
|
|
|
|
// This test validates that we can MREMAP_DONTUNMAP for a portion of an
|
|
// existing mapping.
|
|
static void mremap_dontunmap_partial_mapping()
|
|
{
|
|
/*
|
|
* source mapping:
|
|
* --------------
|
|
* | aaaaaaaaaa |
|
|
* --------------
|
|
* to become:
|
|
* --------------
|
|
* | aaaaa00000 |
|
|
* --------------
|
|
* With the destination mapping containing 5 pages of As.
|
|
* ---------
|
|
* | aaaaa |
|
|
* ---------
|
|
*/
|
|
unsigned long num_pages = 10;
|
|
void *source_mapping =
|
|
mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(source_mapping == MAP_FAILED, "mmap");
|
|
memset(source_mapping, 'a', num_pages * page_size);
|
|
|
|
// We will grab the last 5 pages of the source and move them.
|
|
void *dest_mapping =
|
|
mremap(source_mapping + (5 * page_size), 5 * page_size,
|
|
5 * page_size,
|
|
MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
|
|
BUG_ON(dest_mapping == MAP_FAILED, "mremap");
|
|
|
|
// We expect the first 5 pages of the source to contain a's and the
|
|
// final 5 pages to contain zeros.
|
|
BUG_ON(check_region_contains_byte(source_mapping, 5 * page_size, 'a') !=
|
|
0, "first 5 pages of source should have original pages");
|
|
BUG_ON(check_region_contains_byte
|
|
(source_mapping + (5 * page_size), 5 * page_size, 0) != 0,
|
|
"final 5 pages of source should have no ptes");
|
|
|
|
// Finally we expect the destination to have 5 pages worth of a's.
|
|
BUG_ON(check_region_contains_byte(dest_mapping, 5 * page_size, 'a') !=
|
|
0, "dest mapping should contain ptes from the source");
|
|
|
|
BUG_ON(munmap(dest_mapping, 5 * page_size) == -1,
|
|
"unable to unmap destination mapping");
|
|
BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
|
|
"unable to unmap source mapping");
|
|
}
|
|
|
|
// This test validates that we can remap over only a portion of a mapping.
|
|
static void mremap_dontunmap_partial_mapping_overwrite(void)
|
|
{
|
|
/*
|
|
* source mapping:
|
|
* ---------
|
|
* |aaaaa|
|
|
* ---------
|
|
* dest mapping initially:
|
|
* -----------
|
|
* |XXXXXXXXXX|
|
|
* ------------
|
|
* Source to become:
|
|
* ---------
|
|
* |00000|
|
|
* ---------
|
|
* With the destination mapping containing 5 pages of As.
|
|
* ------------
|
|
* |aaaaaXXXXX|
|
|
* ------------
|
|
*/
|
|
void *source_mapping =
|
|
mmap(NULL, 5 * page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(source_mapping == MAP_FAILED, "mmap");
|
|
memset(source_mapping, 'a', 5 * page_size);
|
|
|
|
void *dest_mapping =
|
|
mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(dest_mapping == MAP_FAILED, "mmap");
|
|
memset(dest_mapping, 'X', 10 * page_size);
|
|
|
|
// We will grab the last 5 pages of the source and move them.
|
|
void *remapped_mapping =
|
|
mremap(source_mapping, 5 * page_size,
|
|
5 * page_size,
|
|
MREMAP_DONTUNMAP | MREMAP_MAYMOVE | MREMAP_FIXED, dest_mapping);
|
|
BUG_ON(dest_mapping == MAP_FAILED, "mremap");
|
|
BUG_ON(dest_mapping != remapped_mapping, "expected to remap to dest_mapping");
|
|
|
|
BUG_ON(check_region_contains_byte(source_mapping, 5 * page_size, 0) !=
|
|
0, "first 5 pages of source should have no ptes");
|
|
|
|
// Finally we expect the destination to have 5 pages worth of a's.
|
|
BUG_ON(check_region_contains_byte(dest_mapping, 5 * page_size, 'a') != 0,
|
|
"dest mapping should contain ptes from the source");
|
|
|
|
// Finally the last 5 pages shouldn't have been touched.
|
|
BUG_ON(check_region_contains_byte(dest_mapping + (5 * page_size),
|
|
5 * page_size, 'X') != 0,
|
|
"dest mapping should have retained the last 5 pages");
|
|
|
|
BUG_ON(munmap(dest_mapping, 10 * page_size) == -1,
|
|
"unable to unmap destination mapping");
|
|
BUG_ON(munmap(source_mapping, 5 * page_size) == -1,
|
|
"unable to unmap source mapping");
|
|
}
|
|
|
|
int main(void)
|
|
{
|
|
page_size = sysconf(_SC_PAGE_SIZE);
|
|
|
|
// test for kernel support for MREMAP_DONTUNMAP skipping the test if
|
|
// not.
|
|
if (kernel_support_for_mremap_dontunmap() != 0) {
|
|
printf("No kernel support for MREMAP_DONTUNMAP\n");
|
|
return KSFT_SKIP;
|
|
}
|
|
|
|
// Keep a page sized buffer around for when we need it.
|
|
page_buffer =
|
|
mmap(NULL, page_size, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
BUG_ON(page_buffer == MAP_FAILED, "unable to mmap a page.");
|
|
|
|
mremap_dontunmap_simple();
|
|
mremap_dontunmap_simple_fixed();
|
|
mremap_dontunmap_partial_mapping();
|
|
mremap_dontunmap_partial_mapping_overwrite();
|
|
|
|
BUG_ON(munmap(page_buffer, page_size) == -1,
|
|
"unable to unmap page buffer");
|
|
|
|
printf("OK\n");
|
|
return 0;
|
|
}
|