Re: [PATCH 2/6] genalloc: selftest

From: Kees Cook
Date: Mon Feb 12 2018 - 18:51:12 EST

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On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa <igor.stoppa@xxxxxxxxxx> wrote:
> Introduce a set of macros for writing concise test cases for genalloc.
>
> The test cases are meant to provide regression testing, when working on
> new functionality for genalloc.
>
> Primarily they are meant to confirm that the various allocation strategy
> will continue to work as expected.
>
> The execution of the self testing is controlled through a Kconfig option.
>
> Signed-off-by: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
> ---
> include/linux/genalloc-selftest.h | 26 +++
> init/main.c | 2 +
> lib/Kconfig | 15 ++
> lib/Makefile | 1 +
> lib/genalloc-selftest.c | 400 ++++++++++++++++++++++++++++++++++++++

Nit: make this test_genalloc.c instead.

> 5 files changed, 444 insertions(+)
> create mode 100644 include/linux/genalloc-selftest.h
> create mode 100644 lib/genalloc-selftest.c
>
> diff --git a/include/linux/genalloc-selftest.h b/include/linux/genalloc-selftest.h
> new file mode 100644
> index 000000000000..e0ac8f963abc
> --- /dev/null
> +++ b/include/linux/genalloc-selftest.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * genalloc-selftest.h
> + *
> + * (C) Copyright 2017 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
> + */
> +
> +
> +#ifndef __LINUX_GENALLOC_SELFTEST_H
> +#define __LINUX_GENALLOC_SELFTEST_H
> +
> +
> +#ifdef CONFIG_GENERIC_ALLOCATOR_SELFTEST
> +
> +#include <linux/genalloc.h>
> +
> +void genalloc_selftest(void);
> +
> +#else
> +
> +static inline void genalloc_selftest(void){};
> +
> +#endif
> +
> +#endif
> diff --git a/init/main.c b/init/main.c
> index a8100b954839..fb844aa3eb8c 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -89,6 +89,7 @@
> #include <linux/io.h>
> #include <linux/cache.h>
> #include <linux/rodata_test.h>
> +#include <linux/genalloc-selftest.h>
>
> #include <asm/io.h>
> #include <asm/bugs.h>
> @@ -660,6 +661,7 @@ asmlinkage __visible void __init start_kernel(void)
> */
> mem_encrypt_init();
>
> + genalloc_selftest();

I wonder if it's possible to make this module-loadable instead? That
way it could be built and tested separately. Regardless, I love
gaining more internal selftests, this is great. :)

> #ifdef CONFIG_BLK_DEV_INITRD
> if (initrd_start && !initrd_below_start_ok &&
> page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
> diff --git a/lib/Kconfig b/lib/Kconfig
> index e96089499371..0d526c004e81 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -287,6 +287,21 @@ config DECOMPRESS_LZ4
> config GENERIC_ALLOCATOR
> bool
>
> +config GENERIC_ALLOCATOR_SELFTEST

Like the other lib/test_*.c targets, I'd call this TEST_GENERIC_ALLOCATOR.

> + bool "genalloc tester"
> + default n
> + select GENERIC_ALLOCATOR
> + help
> + Enable automated testing of the generic allocator.
> + The testing is primarily for the tracking of allocated space.
> +
> +config GENERIC_ALLOCATOR_SELFTEST_VERBOSE
> + bool "make the genalloc tester more verbose"
> + default n
> + select GENERIC_ALLOCATOR_SELFTEST
> + help
> + More information will be displayed during the self-testing.
> +
> #
> # reed solomon support is select'ed if needed
> #
> diff --git a/lib/Makefile b/lib/Makefile
> index a90d4fcd748f..fadb30abde08 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -108,6 +108,7 @@ obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
> obj-$(CONFIG_CRC8) += crc8.o
> obj-$(CONFIG_XXHASH) += xxhash.o
> obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
> +obj-$(CONFIG_GENERIC_ALLOCATOR_SELFTEST) += genalloc-selftest.o
>
> obj-$(CONFIG_842_COMPRESS) += 842/
> obj-$(CONFIG_842_DECOMPRESS) += 842/
> diff --git a/lib/genalloc-selftest.c b/lib/genalloc-selftest.c
> new file mode 100644
> index 000000000000..e86be22c5512
> --- /dev/null
> +++ b/lib/genalloc-selftest.c
> @@ -0,0 +1,400 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * genalloc-selftest.c
> + *
> + * (C) Copyright 2017 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/printk.h>
> +#include <linux/init.h>
> +#include <linux/vmalloc.h>
> +#include <linux/string.h>
> +#include <linux/debugfs.h>
> +#include <linux/atomic.h>
> +#include <linux/genalloc.h>
> +
> +#include <linux/genalloc-selftest.h>
> +/*
> + * Keep the bitmap small, while including case of cross-ulong mapping.
> + * For simplicity, the test cases use only 1 chunk of memory.
> + */
> +#define BITMAP_SIZE_C 16
> +#define ALLOC_ORDER 0
> +
> +#define ULONG_SIZE (sizeof(unsigned long))
> +#define BITMAP_SIZE_UL (BITMAP_SIZE_C / ULONG_SIZE)
> +#define MIN_ALLOC_SIZE (1 << ALLOC_ORDER)
> +#define ENTRIES (BITMAP_SIZE_C * 8)
> +#define CHUNK_SIZE (MIN_ALLOC_SIZE * ENTRIES)
> +
> +#ifndef CONFIG_GENERIC_ALLOCATOR_SELFTEST_VERBOSE
> +
> +static inline void print_first_chunk_bitmap(struct gen_pool *pool) {}
> +
> +#else
> +
> +static void print_first_chunk_bitmap(struct gen_pool *pool)
> +{
> + struct gen_pool_chunk *chunk;
> + char bitmap[BITMAP_SIZE_C * 2 + 1];
> + unsigned long i;
> + char *bm = bitmap;
> + char *entry;
> +
> + if (unlikely(pool == NULL || pool->chunks.next == NULL))
> + return;
> +
> + chunk = container_of(pool->chunks.next, struct gen_pool_chunk,
> + next_chunk);
> + entry = (void *)chunk->entries;
> + for (i = 1; i <= BITMAP_SIZE_C; i++)
> + bm += snprintf(bm, 3, "%02hhx", entry[BITMAP_SIZE_C - i]);
> + *bm = '\0';
> + pr_notice("chunk: %p bitmap: 0x%s\n", chunk, bitmap);
> +
> +}
> +
> +#endif
> +
> +enum test_commands {
> + CMD_ALLOCATOR,
> + CMD_ALLOCATE,
> + CMD_FLUSH,
> + CMD_FREE,
> + CMD_NUMBER,
> + CMD_END = CMD_NUMBER,
> +};
> +
> +struct null_struct {
> + void *null;
> +};
> +
> +struct test_allocator {
> + genpool_algo_t algo;
> + union {
> + struct genpool_data_align align;
> + struct genpool_data_fixed offset;
> + struct null_struct null;
> + } data;
> +};
> +
> +struct test_action {
> + unsigned int location;
> + char pattern[BITMAP_SIZE_C];
> + unsigned int size;
> +};
> +
> +
> +struct test_command {
> + enum test_commands command;
> + union {
> + struct test_allocator allocator;
> + struct test_action action;
> + };
> +};
> +
> +
> +/*
> + * To pass an array literal as parameter to a macro, it must go through
> + * this one, first.
> + */
> +#define ARR(...) __VA_ARGS__
> +
> +#define SET_DATA(parameter, value) \
> + .parameter = { \
> + .parameter = value, \
> + } \
> +
> +#define SET_ALLOCATOR(alloc, parameter, value) \
> +{ \
> + .command = CMD_ALLOCATOR, \
> + .allocator = { \
> + .algo = (alloc), \
> + .data = { \
> + SET_DATA(parameter, value), \
> + }, \
> + } \
> +}
> +
> +#define ACTION_MEM(act, mem_size, mem_loc, match) \
> +{ \
> + .command = act, \
> + .action = { \
> + .size = (mem_size), \
> + .location = (mem_loc), \
> + .pattern = match, \
> + }, \
> +}
> +
> +#define ALLOCATE_MEM(mem_size, mem_loc, match) \
> + ACTION_MEM(CMD_ALLOCATE, mem_size, mem_loc, ARR(match))
> +
> +#define FREE_MEM(mem_size, mem_loc, match) \
> + ACTION_MEM(CMD_FREE, mem_size, mem_loc, ARR(match))
> +
> +#define FLUSH_MEM() \
> +{ \
> + .command = CMD_FLUSH, \
> +}
> +
> +#define END() \
> +{ \
> + .command = CMD_END, \
> +}
> +
> +static inline int compare_bitmaps(const struct gen_pool *pool,
> + const char *reference)
> +{
> + struct gen_pool_chunk *chunk;
> + char *bitmap;
> + unsigned int i;
> +
> + chunk = container_of(pool->chunks.next, struct gen_pool_chunk,
> + next_chunk);
> + bitmap = (char *)chunk->entries;
> +
> + for (i = 0; i < BITMAP_SIZE_C; i++)
> + if (bitmap[i] != reference[i])
> + return -1;
> + return 0;
> +}
> +
> +static void callback_set_allocator(struct gen_pool *pool,
> + const struct test_command *cmd,
> + unsigned long *locations)
> +{
> + gen_pool_set_algo(pool, cmd->allocator.algo,
> + (void *)&cmd->allocator.data);
> +}
> +
> +static void callback_allocate(struct gen_pool *pool,
> + const struct test_command *cmd,
> + unsigned long *locations)
> +{
> + const struct test_action *action = &cmd->action;
> +
> + locations[action->location] = gen_pool_alloc(pool, action->size);
> + BUG_ON(!locations[action->location]);
> + print_first_chunk_bitmap(pool);
> + BUG_ON(compare_bitmaps(pool, action->pattern));

There's been a lot recently on BUG vs WARN. It does seem crazy to not
BUG for an allocator selftest, but if we can avoid it, we should.

Also, I wonder if it might make sense to split this series up a little
more, as in:

1/n: add genalloc selftest
2/n: update bitmaps
3/n: add/change bitmap tests to selftest

Maybe I'm over-thinking it, but the great thing about this self test
is that it's checking much more than just the bitmap changes you're
making, and that can be used to "prove" that genalloc continues to
work after the changes (i.e. the selftest passes before the changes,
and after, rather than just after).

> +}
> +
> +static void callback_flush(struct gen_pool *pool,
> + const struct test_command *cmd,
> + unsigned long *locations)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < ENTRIES; i++)
> + if (locations[i]) {
> + gen_pool_free(pool, locations[i], 0);
> + locations[i] = 0;
> + }
> +}
> +
> +static void callback_free(struct gen_pool *pool,
> + const struct test_command *cmd,
> + unsigned long *locations)
> +{
> + const struct test_action *action = &cmd->action;
> +
> + gen_pool_free(pool, locations[action->location], 0);
> + locations[action->location] = 0;
> + print_first_chunk_bitmap(pool);
> + BUG_ON(compare_bitmaps(pool, action->pattern));
> +}
> +
> +static void (* const callbacks[CMD_NUMBER])(struct gen_pool *,
> + const struct test_command *,
> + unsigned long *) = {
> + [CMD_ALLOCATOR] = callback_set_allocator,
> + [CMD_ALLOCATE] = callback_allocate,
> + [CMD_FREE] = callback_free,
> + [CMD_FLUSH] = callback_flush,
> +};
> +
> +static const struct test_command test_first_fit[] = {
> + SET_ALLOCATOR(gen_pool_first_fit, null, NULL),
> + ALLOCATE_MEM(3, 0, ARR({0x2b})),
> + ALLOCATE_MEM(2, 1, ARR({0xeb, 0x02})),
> + ALLOCATE_MEM(5, 2, ARR({0xeb, 0xae, 0x0a})),
> + FREE_MEM(2, 1, ARR({0x2b, 0xac, 0x0a})),
> + ALLOCATE_MEM(1, 1, ARR({0xeb, 0xac, 0x0a})),
> + FREE_MEM(0, 2, ARR({0xeb})),
> + FREE_MEM(0, 0, ARR({0xc0})),
> + FREE_MEM(0, 1, ARR({0x00})),
> + END(),
> +};
> +
> +/*
> + * To make the test work for both 32bit and 64bit ulong sizes,
> + * allocate (8 / 2 * 4 - 1) = 15 bytes bytes, then 16, then 2.
> + * The first allocation prepares for the crossing of the 32bit ulong
> + * threshold. The following crosses the 32bit threshold and prepares for
> + * crossing the 64bit thresholds. The last is large enough (2 bytes) to
> + * cross the 64bit threshold.
> + * Then free the allocations in the order: 2nd, 1st, 3rd.
> + */
> +static const struct test_command test_ulong_span[] = {
> + SET_ALLOCATOR(gen_pool_first_fit, null, NULL),
> + ALLOCATE_MEM(15, 0, ARR({0xab, 0xaa, 0xaa, 0x2a})),
> + ALLOCATE_MEM(16, 1, ARR({0xab, 0xaa, 0xaa, 0xea,
> + 0xaa, 0xaa, 0xaa, 0x2a})),
> + ALLOCATE_MEM(2, 2, ARR({0xab, 0xaa, 0xaa, 0xea,
> + 0xaa, 0xaa, 0xaa, 0xea,
> + 0x02})),
> + FREE_MEM(0, 1, ARR({0xab, 0xaa, 0xaa, 0x2a,
> + 0x00, 0x00, 0x00, 0xc0,
> + 0x02})),
> + FREE_MEM(0, 0, ARR({0x00, 0x00, 0x00, 0x00,
> + 0x00, 0x00, 0x00, 0xc0,
> + 0x02})),
> + FREE_MEM(0, 2, ARR({0x00})),
> + END(),
> +};
> +
> +/*
> + * Create progressively smaller allocations A B C D E.
> + * then free B and D.
> + * Then create new allocation that would fit in both of the gaps left by
> + * B and D. Verify that it uses the gap from B.
> + */
> +static const struct test_command test_first_fit_gaps[] = {
> + SET_ALLOCATOR(gen_pool_first_fit, null, NULL),
> + ALLOCATE_MEM(10, 0, ARR({0xab, 0xaa, 0x0a})),
> + ALLOCATE_MEM(8, 1, ARR({0xab, 0xaa, 0xba, 0xaa,
> + 0x0a})),
> + ALLOCATE_MEM(6, 2, ARR({0xab, 0xaa, 0xba, 0xaa,
> + 0xba, 0xaa})),
> + ALLOCATE_MEM(4, 3, ARR({0xab, 0xaa, 0xba, 0xaa,
> + 0xba, 0xaa, 0xab})),
> + ALLOCATE_MEM(2, 4, ARR({0xab, 0xaa, 0xba, 0xaa,
> + 0xba, 0xaa, 0xab, 0x0b})),
> + FREE_MEM(0, 1, ARR({0xab, 0xaa, 0x0a, 0x00,
> + 0xb0, 0xaa, 0xab, 0x0b})),
> + FREE_MEM(0, 3, ARR({0xab, 0xaa, 0x0a, 0x00,
> + 0xb0, 0xaa, 0x00, 0x0b})),
> + ALLOCATE_MEM(3, 3, ARR({0xab, 0xaa, 0xba, 0x02,
> + 0xb0, 0xaa, 0x00, 0x0b})),
> + FLUSH_MEM(),
> + END(),
> +};
> +
> +/* Test first fit align */
> +static const struct test_command test_first_fit_align[] = {
> + SET_ALLOCATOR(gen_pool_first_fit_align, align, 4),
> + ALLOCATE_MEM(5, 0, ARR({0xab, 0x02})),
> + ALLOCATE_MEM(3, 1, ARR({0xab, 0x02, 0x2b})),
> + ALLOCATE_MEM(2, 2, ARR({0xab, 0x02, 0x2b, 0x0b})),
> + ALLOCATE_MEM(1, 3, ARR({0xab, 0x02, 0x2b, 0x0b, 0x03})),
> + FREE_MEM(0, 0, ARR({0x00, 0x00, 0x2b, 0x0b, 0x03})),
> + FREE_MEM(0, 2, ARR({0x00, 0x00, 0x2b, 0x00, 0x03})),
> + ALLOCATE_MEM(2, 0, ARR({0x0b, 0x00, 0x2b, 0x00, 0x03})),
> + FLUSH_MEM(),
> + END(),
> +};
> +
> +
> +/* Test fixed alloc */
> +static const struct test_command test_fixed_data[] = {
> + SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 1),
> + ALLOCATE_MEM(5, 0, ARR({0xac, 0x0a})),
> + SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 8),
> + ALLOCATE_MEM(3, 1, ARR({0xac, 0x0a, 0x2b})),
> + SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 6),
> + ALLOCATE_MEM(2, 2, ARR({0xac, 0xba, 0x2b})),
> + SET_ALLOCATOR(gen_pool_fixed_alloc, offset, 30),
> + ALLOCATE_MEM(40, 3, ARR({0xac, 0xba, 0x2b, 0x00,
> + 0x00, 0x00, 0x00, 0xb0,
> + 0xaa, 0xaa, 0xaa, 0xaa,
> + 0xaa, 0xaa, 0xaa, 0xaa})),
> + FLUSH_MEM(),
> + END(),
> +};
> +
> +
> +/* Test first fit order align */
> +static const struct test_command test_first_fit_order_align[] = {
> + SET_ALLOCATOR(gen_pool_first_fit_order_align, null, NULL),
> + ALLOCATE_MEM(5, 0, ARR({0xab, 0x02})),
> + ALLOCATE_MEM(3, 1, ARR({0xab, 0x02, 0x2b})),
> + ALLOCATE_MEM(2, 2, ARR({0xab, 0xb2, 0x2b})),
> + ALLOCATE_MEM(1, 3, ARR({0xab, 0xbe, 0x2b})),
> + ALLOCATE_MEM(1, 4, ARR({0xab, 0xbe, 0xeb})),
> + ALLOCATE_MEM(2, 5, ARR({0xab, 0xbe, 0xeb, 0x0b})),
> + FLUSH_MEM(),
> + END(),
> +};
> +
> +
> +/* 007 Test best fit */
> +static const struct test_command test_best_fit[] = {
> + SET_ALLOCATOR(gen_pool_best_fit, null, NULL),
> + ALLOCATE_MEM(5, 0, ARR({0xab, 0x02})),
> + ALLOCATE_MEM(3, 1, ARR({0xab, 0xae})),
> + ALLOCATE_MEM(3, 2, ARR({0xab, 0xae, 0x2b})),
> + ALLOCATE_MEM(1, 3, ARR({0xab, 0xae, 0xeb})),
> + FREE_MEM(0, 0, ARR({0x00, 0xac, 0xeb})),
> + FREE_MEM(0, 2, ARR({0x00, 0xac, 0xc0})),
> + ALLOCATE_MEM(2, 0, ARR({0x00, 0xac, 0xcb})),
> + FLUSH_MEM(),
> + END(),
> +};
> +
> +
> +enum test_cases_indexes {
> + TEST_CASE_FIRST_FIT,
> + TEST_CASE_ULONG_SPAN,
> + TEST_CASE_FIRST_FIT_GAPS,
> + TEST_CASE_FIRST_FIT_ALIGN,
> + TEST_CASE_FIXED_DATA,
> + TEST_CASE_FIRST_FIT_ORDER_ALIGN,
> + TEST_CASE_BEST_FIT,
> + TEST_CASES_NUM,
> +};
> +
> +static const struct test_command *test_cases[TEST_CASES_NUM] = {
> + [TEST_CASE_FIRST_FIT] = test_first_fit,
> + [TEST_CASE_ULONG_SPAN] = test_ulong_span,
> + [TEST_CASE_FIRST_FIT_GAPS] = test_first_fit_gaps,
> + [TEST_CASE_FIRST_FIT_ALIGN] = test_first_fit_align,
> + [TEST_CASE_FIXED_DATA] = test_fixed_data,
> + [TEST_CASE_FIRST_FIT_ORDER_ALIGN] = test_first_fit_order_align,
> + [TEST_CASE_BEST_FIT] = test_best_fit,
> +};
> +
> +
> +void genalloc_selftest(void)
> +{
> + static struct gen_pool *pool;
> + unsigned long locations[ENTRIES];
> + char chunk[CHUNK_SIZE];
> + int retval;
> + unsigned int i;
> + const struct test_command *cmd;
> +
> + pool = gen_pool_create(ALLOC_ORDER, -1);
> + if (unlikely(!pool)) {
> + pr_err("genalloc-selftest: no memory for pool.");
> + return;
> + }
> +
> + retval = gen_pool_add_virt(pool, (unsigned long)chunk, 0,
> + CHUNK_SIZE, -1);
> + if (unlikely(retval)) {
> + pr_err("genalloc-selftest: could not register chunk.");
> + goto destroy_pool;
> + }
> +
> + memset(locations, 0, ENTRIES * sizeof(unsigned long));
> + for (i = 0; i < TEST_CASES_NUM; i++)
> + for (cmd = test_cases[i]; cmd->command < CMD_END; cmd++)
> + callbacks[cmd->command](pool, cmd, locations);
> + pr_notice("genalloc-selftest: executed successfully %d tests",
> + TEST_CASES_NUM);
> +
> +destroy_pool:
> + gen_pool_destroy(pool);
> +}
> --
> 2.14.1
>

-Kees

--
Kees Cook
Pixel Security

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