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// SPDX-License-Identifier: GPL-2.0
/*
* Test cases for SL[AOU]B/page initialization at alloc/free time.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#define GARBAGE_INT (0x09A7BA9E)
#define GARBAGE_BYTE (0x9E)
#define REPORT_FAILURES_IN_FN() \
do { \
if (failures) \
pr_info("%s failed %d out of %d times\n", \
__func__, failures, num_tests); \
else \
pr_info("all %d tests in %s passed\n", \
num_tests, __func__); \
} while (0)
/* Calculate the number of uninitialized bytes in the buffer. */
static int __init count_nonzero_bytes(void *ptr, size_t size)
{
int i, ret = 0;
unsigned char *p = (unsigned char *)ptr;
for (i = 0; i < size; i++)
if (p[i])
ret++;
return ret;
}
/* Fill a buffer with garbage, skipping |skip| first bytes. */
static void __init fill_with_garbage_skip(void *ptr, int size, size_t skip)
{
unsigned int *p = (unsigned int *)((char *)ptr + skip);
int i = 0;
WARN_ON(skip > size);
size -= skip;
while (size >= sizeof(*p)) {
p[i] = GARBAGE_INT;
i++;
size -= sizeof(*p);
}
if (size)
memset(&p[i], GARBAGE_BYTE, size);
}
static void __init fill_with_garbage(void *ptr, size_t size)
{
fill_with_garbage_skip(ptr, size, 0);
}
static int __init do_alloc_pages_order(int order, int *total_failures)
{
struct page *page;
void *buf;
size_t size = PAGE_SIZE << order;
page = alloc_pages(GFP_KERNEL, order);
buf = page_address(page);
fill_with_garbage(buf, size);
__free_pages(page, order);
page = alloc_pages(GFP_KERNEL, order);
buf = page_address(page);
if (count_nonzero_bytes(buf, size))
(*total_failures)++;
fill_with_garbage(buf, size);
__free_pages(page, order);
return 1;
}
/* Test the page allocator by calling alloc_pages with different orders. */
static int __init test_pages(int *total_failures)
{
int failures = 0, num_tests = 0;
int i;
for (i = 0; i < 10; i++)
num_tests += do_alloc_pages_order(i, &failures);
REPORT_FAILURES_IN_FN();
*total_failures += failures;
return num_tests;
}
/* Test kmalloc() with given parameters. */
static int __init do_kmalloc_size(size_t size, int *total_failures)
{
void *buf;
buf = kmalloc(size, GFP_KERNEL);
fill_with_garbage(buf, size);
kfree(buf);
buf = kmalloc(size, GFP_KERNEL);
if (count_nonzero_bytes(buf, size))
(*total_failures)++;
fill_with_garbage(buf, size);
kfree(buf);
return 1;
}
/* Test vmalloc() with given parameters. */
static int __init do_vmalloc_size(size_t size, int *total_failures)
{
void *buf;
buf = vmalloc(size);
fill_with_garbage(buf, size);
vfree(buf);
buf = vmalloc(size);
if (count_nonzero_bytes(buf, size))
(*total_failures)++;
fill_with_garbage(buf, size);
vfree(buf);
return 1;
}
/* Test kmalloc()/vmalloc() by allocating objects of different sizes. */
static int __init test_kvmalloc(int *total_failures)
{
int failures = 0, num_tests = 0;
int i, size;
for (i = 0; i < 20; i++) {
size = 1 << i;
num_tests += do_kmalloc_size(size, &failures);
num_tests += do_vmalloc_size(size, &failures);
}
REPORT_FAILURES_IN_FN();
*total_failures += failures;
return num_tests;
}
#define CTOR_BYTES (sizeof(unsigned int))
#define CTOR_PATTERN (0x41414141)
/* Initialize the first 4 bytes of the object. */
static void test_ctor(void *obj)
{
*(unsigned int *)obj = CTOR_PATTERN;
}
/*
* Check the invariants for the buffer allocated from a slab cache.
* If the cache has a test constructor, the first 4 bytes of the object must
* always remain equal to CTOR_PATTERN.
* If the cache isn't an RCU-typesafe one, or if the allocation is done with
* __GFP_ZERO, then the object contents must be zeroed after allocation.
* If the cache is an RCU-typesafe one, the object contents must never be
* zeroed after the first use. This is checked by memcmp() in
* do_kmem_cache_size().
*/
static bool __init check_buf(void *buf, int size, bool want_ctor,
bool want_rcu, bool want_zero)
{
int bytes;
bool fail = false;
bytes = count_nonzero_bytes(buf, size);
WARN_ON(want_ctor && want_zero);
if (want_zero)
return bytes;
if (want_ctor) {
if (*(unsigned int *)buf != CTOR_PATTERN)
fail = 1;
} else {
if (bytes)
fail = !want_rcu;
}
return fail;
}
#define BULK_SIZE 100
static void *bulk_array[BULK_SIZE];
/*
* Test kmem_cache with given parameters:
* want_ctor - use a constructor;
* want_rcu - use SLAB_TYPESAFE_BY_RCU;
* want_zero - use __GFP_ZERO.
*/
static int __init do_kmem_cache_size(size_t size, bool want_ctor,
bool want_rcu, bool want_zero,
int *total_failures)
{
struct kmem_cache *c;
int iter;
bool fail = false;
gfp_t alloc_mask = GFP_KERNEL | (want_zero ? __GFP_ZERO : 0);
void *buf, *buf_copy;
c = kmem_cache_create("test_cache", size, 1,
want_rcu ? SLAB_TYPESAFE_BY_RCU : 0,
want_ctor ? test_ctor : NULL);
for (iter = 0; iter < 10; iter++) {
/* Do a test of bulk allocations */
if (!want_rcu && !want_ctor) {
int ret;
ret = kmem_cache_alloc_bulk(c, alloc_mask, BULK_SIZE, bulk_array);
if (!ret) {
fail = true;
} else {
int i;
for (i = 0; i < ret; i++)
fail |= check_buf(bulk_array[i], size, want_ctor, want_rcu, want_zero);
kmem_cache_free_bulk(c, ret, bulk_array);
}
}
buf = kmem_cache_alloc(c, alloc_mask);
/* Check that buf is zeroed, if it must be. */
fail |= check_buf(buf, size, want_ctor, want_rcu, want_zero);
fill_with_garbage_skip(buf, size, want_ctor ? CTOR_BYTES : 0);
if (!want_rcu) {
kmem_cache_free(c, buf);
continue;
}
/*
* If this is an RCU cache, use a critical section to ensure we
* can touch objects after they're freed.
*/
rcu_read_lock();
/*
* Copy the buffer to check that it's not wiped on
* free().
*/
buf_copy = kmalloc(size, GFP_ATOMIC);
if (buf_copy)
memcpy(buf_copy, buf, size);
kmem_cache_free(c, buf);
/*
* Check that |buf| is intact after kmem_cache_free().
* |want_zero| is false, because we wrote garbage to
* the buffer already.
*/
fail |= check_buf(buf, size, want_ctor, want_rcu,
false);
if (buf_copy) {
fail |= (bool)memcmp(buf, buf_copy, size);
kfree(buf_copy);
}
rcu_read_unlock();
}
kmem_cache_destroy(c);
*total_failures += fail;
return 1;
}
/*
* Check that the data written to an RCU-allocated object survives
* reallocation.
*/
static int __init do_kmem_cache_rcu_persistent(int size, int *total_failures)
{
struct kmem_cache *c;
void *buf, *buf_contents, *saved_ptr;
void **used_objects;
int i, iter, maxiter = 1024;
bool fail = false;
c = kmem_cache_create("test_cache", size, size, SLAB_TYPESAFE_BY_RCU,
NULL);
buf = kmem_cache_alloc(c, GFP_KERNEL);
saved_ptr = buf;
fill_with_garbage(buf, size);
buf_contents = kmalloc(size, GFP_KERNEL);
if (!buf_contents)
goto out;
used_objects = kmalloc_array(maxiter, sizeof(void *), GFP_KERNEL);
if (!used_objects) {
kfree(buf_contents);
goto out;
}
memcpy(buf_contents, buf, size);
kmem_cache_free(c, buf);
/*
* Run for a fixed number of iterations. If we never hit saved_ptr,
* assume the test passes.
*/
for (iter = 0; iter < maxiter; iter++) {
buf = kmem_cache_alloc(c, GFP_KERNEL);
used_objects[iter] = buf;
if (buf == saved_ptr) {
fail = memcmp(buf_contents, buf, size);
for (i = 0; i <= iter; i++)
kmem_cache_free(c, used_objects[i]);
goto free_out;
}
}
free_out:
kmem_cache_destroy(c);
kfree(buf_contents);
kfree(used_objects);
out:
*total_failures += fail;
return 1;
}
static int __init do_kmem_cache_size_bulk(int size, int *total_failures)
{
struct kmem_cache *c;
int i, iter, maxiter = 1024;
int num, bytes;
bool fail = false;
void *objects[10];
c = kmem_cache_create("test_cache", size, size, 0, NULL);
for (iter = 0; (iter < maxiter) && !fail; iter++) {
num = kmem_cache_alloc_bulk(c, GFP_KERNEL, ARRAY_SIZE(objects),
objects);
for (i = 0; i < num; i++) {
bytes = count_nonzero_bytes(objects[i], size);
if (bytes)
fail = true;
fill_with_garbage(objects[i], size);
}
if (num)
kmem_cache_free_bulk(c, num, objects);
}
*total_failures += fail;
return 1;
}
/*
* Test kmem_cache allocation by creating caches of different sizes, with and
* without constructors, with and without SLAB_TYPESAFE_BY_RCU.
*/
static int __init test_kmemcache(int *total_failures)
{
int failures = 0, num_tests = 0;
int i, flags, size;
bool ctor, rcu, zero;
for (i = 0; i < 10; i++) {
size = 8 << i;
for (flags = 0; flags < 8; flags++) {
ctor = flags & 1;
rcu = flags & 2;
zero = flags & 4;
if (ctor & zero)
continue;
num_tests += do_kmem_cache_size(size, ctor, rcu, zero,
&failures);
}
num_tests += do_kmem_cache_size_bulk(size, &failures);
}
REPORT_FAILURES_IN_FN();
*total_failures += failures;
return num_tests;
}
/* Test the behavior of SLAB_TYPESAFE_BY_RCU caches of different sizes. */
static int __init test_rcu_persistent(int *total_failures)
{
int failures = 0, num_tests = 0;
int i, size;
for (i = 0; i < 10; i++) {
size = 8 << i;
num_tests += do_kmem_cache_rcu_persistent(size, &failures);
}
REPORT_FAILURES_IN_FN();
*total_failures += failures;
return num_tests;
}
/*
* Run the tests. Each test function returns the number of executed tests and
* updates |failures| with the number of failed tests.
*/
static int __init test_meminit_init(void)
{
int failures = 0, num_tests = 0;
num_tests += test_pages(&failures);
num_tests += test_kvmalloc(&failures);
num_tests += test_kmemcache(&failures);
num_tests += test_rcu_persistent(&failures);
if (failures == 0)
pr_info("all %d tests passed!\n", num_tests);
else
pr_info("failures: %d out of %d\n", failures, num_tests);
return failures ? -EINVAL : 0;
}
module_init(test_meminit_init);
MODULE_LICENSE("GPL");