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linux/lib/memcpy_kunit.c
Nick Desaulniers bce5a1e8a3 x86/mem: Move memmove to out of line assembler 
When building ARCH=i386 with CONFIG_LTO_CLANG_FULL=y, it's possible
(depending on additional configs which I have not been able to isolate)
to observe a failure during register allocation:

  error: inline assembly requires more registers than available

when memmove is inlined into tcp_v4_fill_cb() or tcp_v6_fill_cb().

memmove is quite large and probably shouldn't be inlined due to size
alone. A noinline function attribute would be the simplest fix, but
there's a few things that stand out with the current definition:

In addition to having complex constraints that can't always be resolved,
the clobber list seems to be missing %bx. By using numbered operands
rather than symbolic operands, the constraints are quite obnoxious to
refactor.

Having a large function be 99% inline asm is a code smell that this
function should simply be written in stand-alone out-of-line assembler.

Moving this to out of line assembler guarantees that the
compiler cannot inline calls to memmove.

This has been done previously for 64b:
commit 9599ec0471 ("x86-64, mem: Convert memmove() to assembly file
and fix return value bug")

That gives the opportunity for other cleanups like fixing the
inconsistent use of tabs vs spaces and instruction suffixes, and the
label 3 appearing twice.  Symbolic operands, local labels, and
additional comments would provide this code with a fresh coat of paint.

Finally, add a test that tickles the `rep movsl` implementation to test
it for correctness, since it has implicit operands.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Suggested-by: David Laight <David.Laight@aculab.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/all/20221018172155.287409-1-ndesaulniers%40google.com
2022-11-01 15:44:07 -07:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Test cases for memcpy(), memmove(), and memset().
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <kunit/test.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/overflow.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
struct some_bytes {
union {
u8 data[32];
struct {
u32 one;
u16 two;
u8 three;
/* 1 byte hole */
u32 four[4];
};
};
};
#define check(instance, v) do { \
BUILD_BUG_ON(sizeof(instance.data) != 32); \
for (size_t i = 0; i < sizeof(instance.data); i++) { \
KUNIT_ASSERT_EQ_MSG(test, instance.data[i], v, \
"line %d: '%s' not initialized to 0x%02x @ %d (saw 0x%02x)\n", \
__LINE__, #instance, v, i, instance.data[i]); \
} \
} while (0)
#define compare(name, one, two) do { \
BUILD_BUG_ON(sizeof(one) != sizeof(two)); \
for (size_t i = 0; i < sizeof(one); i++) { \
KUNIT_EXPECT_EQ_MSG(test, one.data[i], two.data[i], \
"line %d: %s.data[%d] (0x%02x) != %s.data[%d] (0x%02x)\n", \
__LINE__, #one, i, one.data[i], #two, i, two.data[i]); \
} \
kunit_info(test, "ok: " TEST_OP "() " name "\n"); \
} while (0)
static void memcpy_test(struct kunit *test)
{
#define TEST_OP "memcpy"
struct some_bytes control = {
.data = { 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
},
};
struct some_bytes zero = { };
struct some_bytes middle = {
.data = { 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
},
};
struct some_bytes three = {
.data = { 0x00, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x00, 0x00, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
},
};
struct some_bytes dest = { };
int count;
u8 *ptr;
/* Verify static initializers. */
check(control, 0x20);
check(zero, 0);
compare("static initializers", dest, zero);
/* Verify assignment. */
dest = control;
compare("direct assignment", dest, control);
/* Verify complete overwrite. */
memcpy(dest.data, zero.data, sizeof(dest.data));
compare("complete overwrite", dest, zero);
/* Verify middle overwrite. */
dest = control;
memcpy(dest.data + 12, zero.data, 7);
compare("middle overwrite", dest, middle);
/* Verify argument side-effects aren't repeated. */
dest = control;
ptr = dest.data;
count = 1;
memcpy(ptr++, zero.data, count++);
ptr += 8;
memcpy(ptr++, zero.data, count++);
compare("argument side-effects", dest, three);
#undef TEST_OP
}
static unsigned char larger_array [2048];
static void memmove_test(struct kunit *test)
{
#define TEST_OP "memmove"
struct some_bytes control = {
.data = { 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes zero = { };
struct some_bytes middle = {
.data = { 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes five = {
.data = { 0x00, 0x00, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x00, 0x00, 0x00, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes overlap = {
.data = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes overlap_expected = {
.data = { 0x00, 0x01, 0x00, 0x01, 0x02, 0x03, 0x04, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
},
};
struct some_bytes dest = { };
int count;
u8 *ptr;
/* Verify static initializers. */
check(control, 0x99);
check(zero, 0);
compare("static initializers", zero, dest);
/* Verify assignment. */
dest = control;
compare("direct assignment", dest, control);
/* Verify complete overwrite. */
memmove(dest.data, zero.data, sizeof(dest.data));
compare("complete overwrite", dest, zero);
/* Verify middle overwrite. */
dest = control;
memmove(dest.data + 12, zero.data, 7);
compare("middle overwrite", dest, middle);
/* Verify argument side-effects aren't repeated. */
dest = control;
ptr = dest.data;
count = 2;
memmove(ptr++, zero.data, count++);
ptr += 9;
memmove(ptr++, zero.data, count++);
compare("argument side-effects", dest, five);
/* Verify overlapping overwrite is correct. */
ptr = &overlap.data[2];
memmove(ptr, overlap.data, 5);
compare("overlapping write", overlap, overlap_expected);
/* Verify larger overlapping moves. */
larger_array[256] = 0xAAu;
/*
* Test a backwards overlapping memmove first. 256 and 1024 are
* important for i386 to use rep movsl.
*/
memmove(larger_array, larger_array + 256, 1024);
KUNIT_ASSERT_EQ(test, larger_array[0], 0xAAu);
KUNIT_ASSERT_EQ(test, larger_array[256], 0x00);
KUNIT_ASSERT_NULL(test,
memchr(larger_array + 1, 0xaa, ARRAY_SIZE(larger_array) - 1));
/* Test a forwards overlapping memmove. */
larger_array[0] = 0xBBu;
memmove(larger_array + 256, larger_array, 1024);
KUNIT_ASSERT_EQ(test, larger_array[0], 0xBBu);
KUNIT_ASSERT_EQ(test, larger_array[256], 0xBBu);
KUNIT_ASSERT_NULL(test, memchr(larger_array + 1, 0xBBu, 256 - 1));
KUNIT_ASSERT_NULL(test,
memchr(larger_array + 257, 0xBBu, ARRAY_SIZE(larger_array) - 257));
#undef TEST_OP
}
static void memset_test(struct kunit *test)
{
#define TEST_OP "memset"
struct some_bytes control = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
},
};
struct some_bytes complete = {
.data = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
},
};
struct some_bytes middle = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x31, 0x31, 0x31, 0x31,
0x31, 0x31, 0x31, 0x31, 0x31, 0x31, 0x31, 0x31,
0x31, 0x31, 0x31, 0x31, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
},
};
struct some_bytes three = {
.data = { 0x60, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x61, 0x61, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
},
};
struct some_bytes after = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x72,
0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
},
};
struct some_bytes startat = {
.data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
},
};
struct some_bytes dest = { };
int count, value;
u8 *ptr;
/* Verify static initializers. */
check(control, 0x30);
check(dest, 0);
/* Verify assignment. */
dest = control;
compare("direct assignment", dest, control);
/* Verify complete overwrite. */
memset(dest.data, 0xff, sizeof(dest.data));
compare("complete overwrite", dest, complete);
/* Verify middle overwrite. */
dest = control;
memset(dest.data + 4, 0x31, 16);
compare("middle overwrite", dest, middle);
/* Verify argument side-effects aren't repeated. */
dest = control;
ptr = dest.data;
value = 0x60;
count = 1;
memset(ptr++, value++, count++);
ptr += 8;
memset(ptr++, value++, count++);
compare("argument side-effects", dest, three);
/* Verify memset_after() */
dest = control;
memset_after(&dest, 0x72, three);
compare("memset_after()", dest, after);
/* Verify memset_startat() */
dest = control;
memset_startat(&dest, 0x79, four);
compare("memset_startat()", dest, startat);
#undef TEST_OP
}
static void strtomem_test(struct kunit *test)
{
static const char input[sizeof(unsigned long)] = "hi";
static const char truncate[] = "this is too long";
struct {
unsigned long canary1;
unsigned char output[sizeof(unsigned long)] __nonstring;
unsigned long canary2;
} wrap;
memset(&wrap, 0xFF, sizeof(wrap));
KUNIT_EXPECT_EQ_MSG(test, wrap.canary1, ULONG_MAX,
"bad initial canary value");
KUNIT_EXPECT_EQ_MSG(test, wrap.canary2, ULONG_MAX,
"bad initial canary value");
/* Check unpadded copy leaves surroundings untouched. */
strtomem(wrap.output, input);
KUNIT_EXPECT_EQ(test, wrap.canary1, ULONG_MAX);
KUNIT_EXPECT_EQ(test, wrap.output[0], input[0]);
KUNIT_EXPECT_EQ(test, wrap.output[1], input[1]);
for (size_t i = 2; i < sizeof(wrap.output); i++)
KUNIT_EXPECT_EQ(test, wrap.output[i], 0xFF);
KUNIT_EXPECT_EQ(test, wrap.canary2, ULONG_MAX);
/* Check truncated copy leaves surroundings untouched. */
memset(&wrap, 0xFF, sizeof(wrap));
strtomem(wrap.output, truncate);
KUNIT_EXPECT_EQ(test, wrap.canary1, ULONG_MAX);
for (size_t i = 0; i < sizeof(wrap.output); i++)
KUNIT_EXPECT_EQ(test, wrap.output[i], truncate[i]);
KUNIT_EXPECT_EQ(test, wrap.canary2, ULONG_MAX);
/* Check padded copy leaves only string padded. */
memset(&wrap, 0xFF, sizeof(wrap));
strtomem_pad(wrap.output, input, 0xAA);
KUNIT_EXPECT_EQ(test, wrap.canary1, ULONG_MAX);
KUNIT_EXPECT_EQ(test, wrap.output[0], input[0]);
KUNIT_EXPECT_EQ(test, wrap.output[1], input[1]);
for (size_t i = 2; i < sizeof(wrap.output); i++)
KUNIT_EXPECT_EQ(test, wrap.output[i], 0xAA);
KUNIT_EXPECT_EQ(test, wrap.canary2, ULONG_MAX);
/* Check truncated padded copy has no padding. */
memset(&wrap, 0xFF, sizeof(wrap));
strtomem(wrap.output, truncate);
KUNIT_EXPECT_EQ(test, wrap.canary1, ULONG_MAX);
for (size_t i = 0; i < sizeof(wrap.output); i++)
KUNIT_EXPECT_EQ(test, wrap.output[i], truncate[i]);
KUNIT_EXPECT_EQ(test, wrap.canary2, ULONG_MAX);
}
static struct kunit_case memcpy_test_cases[] = {
KUNIT_CASE(memset_test),
KUNIT_CASE(memcpy_test),
KUNIT_CASE(memmove_test),
KUNIT_CASE(strtomem_test),
{}
};
static struct kunit_suite memcpy_test_suite = {
.name = "memcpy",
.test_cases = memcpy_test_cases,
};
kunit_test_suite(memcpy_test_suite);
MODULE_LICENSE("GPL");
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