Commit 98d666d0 authored by Brendan Jackman's avatar Brendan Jackman Committed by Alexei Starovoitov
Browse files

bpf: Add tests for new BPF atomic operations 

The prog_test that's added depends on Clang/LLVM features added by
Yonghong in commit 286daafd6512 (was https://reviews.llvm.org/D72184

).

Note the use of a define called ENABLE_ATOMICS_TESTS: this is used
to:

 - Avoid breaking the build for people on old versions of Clang
 - Avoid needing separate lists of test objects for no_alu32, where
   atomics are not supported even if Clang has the feature.

The atomics_test.o BPF object is built unconditionally both for
test_progs and test_progs-no_alu32. For test_progs, if Clang supports
atomics, ENABLE_ATOMICS_TESTS is defined, so it includes the proper
test code. Otherwise, progs and global vars are defined anyway, as
stubs; this means that the skeleton user code still builds.

The atomics_test.o userspace object is built once and used for both
test_progs and test_progs-no_alu32. A variable called skip_tests is
defined in the BPF object's data section, which tells the userspace
object whether to skip the atomics test.

Signed-off-by: default avatarBrendan Jackman <jackmanb@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-11-jackmanb@google.com
parent 981f94c3

tools/testing/selftests/bpf/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -414,10 +414,12 @@ TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \ 
		       $(wildcard progs/btf_dump_test_case_*.c)

TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE

TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)

TRUNNER_BPF_CFLAGS += -DENABLE_ATOMICS_TESTS

$(eval $(call DEFINE_TEST_RUNNER,test_progs))



# Define test_progs-no_alu32 test runner.

TRUNNER_BPF_BUILD_RULE := CLANG_NOALU32_BPF_BUILD_RULE

TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)

$(eval $(call DEFINE_TEST_RUNNER,test_progs,no_alu32))



# Define test_progs BPF-GCC-flavored test runner.

tools/testing/selftests/bpf/prog_tests/atomics.c

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+246 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <test_progs.h>



#include "atomics.skel.h"



static void test_add(struct atomics *skel)

{

	int err, prog_fd;

	__u32 duration = 0, retval;

	struct bpf_link *link;



	link = bpf_program__attach(skel->progs.add);

	if (CHECK(IS_ERR(link), "attach(add)", "err: %ld\n", PTR_ERR(link)))

		return;



	prog_fd = bpf_program__fd(skel->progs.add);

	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,

				NULL, NULL, &retval, &duration);

	if (CHECK(err || retval, "test_run add",

		  "err %d errno %d retval %d duration %d\n", err, errno, retval, duration))

		goto cleanup;



	ASSERT_EQ(skel->data->add64_value, 3, "add64_value");

	ASSERT_EQ(skel->bss->add64_result, 1, "add64_result");



	ASSERT_EQ(skel->data->add32_value, 3, "add32_value");

	ASSERT_EQ(skel->bss->add32_result, 1, "add32_result");



	ASSERT_EQ(skel->bss->add_stack_value_copy, 3, "add_stack_value");

	ASSERT_EQ(skel->bss->add_stack_result, 1, "add_stack_result");



	ASSERT_EQ(skel->data->add_noreturn_value, 3, "add_noreturn_value");



cleanup:

	bpf_link__destroy(link);

}



static void test_sub(struct atomics *skel)

{

	int err, prog_fd;

	__u32 duration = 0, retval;

	struct bpf_link *link;



	link = bpf_program__attach(skel->progs.sub);

	if (CHECK(IS_ERR(link), "attach(sub)", "err: %ld\n", PTR_ERR(link)))

		return;



	prog_fd = bpf_program__fd(skel->progs.sub);

	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,

				NULL, NULL, &retval, &duration);

	if (CHECK(err || retval, "test_run sub",

		  "err %d errno %d retval %d duration %d\n",

		  err, errno, retval, duration))

		goto cleanup;



	ASSERT_EQ(skel->data->sub64_value, -1, "sub64_value");

	ASSERT_EQ(skel->bss->sub64_result, 1, "sub64_result");



	ASSERT_EQ(skel->data->sub32_value, -1, "sub32_value");

	ASSERT_EQ(skel->bss->sub32_result, 1, "sub32_result");



	ASSERT_EQ(skel->bss->sub_stack_value_copy, -1, "sub_stack_value");

	ASSERT_EQ(skel->bss->sub_stack_result, 1, "sub_stack_result");



	ASSERT_EQ(skel->data->sub_noreturn_value, -1, "sub_noreturn_value");



cleanup:

	bpf_link__destroy(link);

}



static void test_and(struct atomics *skel)

{

	int err, prog_fd;

	__u32 duration = 0, retval;

	struct bpf_link *link;



	link = bpf_program__attach(skel->progs.and);

	if (CHECK(IS_ERR(link), "attach(and)", "err: %ld\n", PTR_ERR(link)))

		return;



	prog_fd = bpf_program__fd(skel->progs.and);

	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,

				NULL, NULL, &retval, &duration);

	if (CHECK(err || retval, "test_run and",

		  "err %d errno %d retval %d duration %d\n", err, errno, retval, duration))

		goto cleanup;



	ASSERT_EQ(skel->data->and64_value, 0x010ull << 32, "and64_value");

	ASSERT_EQ(skel->bss->and64_result, 0x110ull << 32, "and64_result");



	ASSERT_EQ(skel->data->and32_value, 0x010, "and32_value");

	ASSERT_EQ(skel->bss->and32_result, 0x110, "and32_result");



	ASSERT_EQ(skel->data->and_noreturn_value, 0x010ull << 32, "and_noreturn_value");

cleanup:

	bpf_link__destroy(link);

}



static void test_or(struct atomics *skel)

{

	int err, prog_fd;

	__u32 duration = 0, retval;

	struct bpf_link *link;



	link = bpf_program__attach(skel->progs.or);

	if (CHECK(IS_ERR(link), "attach(or)", "err: %ld\n", PTR_ERR(link)))

		return;



	prog_fd = bpf_program__fd(skel->progs.or);

	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,

				NULL, NULL, &retval, &duration);

	if (CHECK(err || retval, "test_run or",

		  "err %d errno %d retval %d duration %d\n",

		  err, errno, retval, duration))

		goto cleanup;



	ASSERT_EQ(skel->data->or64_value, 0x111ull << 32, "or64_value");

	ASSERT_EQ(skel->bss->or64_result, 0x110ull << 32, "or64_result");



	ASSERT_EQ(skel->data->or32_value, 0x111, "or32_value");

	ASSERT_EQ(skel->bss->or32_result, 0x110, "or32_result");



	ASSERT_EQ(skel->data->or_noreturn_value, 0x111ull << 32, "or_noreturn_value");

cleanup:

	bpf_link__destroy(link);

}



static void test_xor(struct atomics *skel)

{

	int err, prog_fd;

	__u32 duration = 0, retval;

	struct bpf_link *link;



	link = bpf_program__attach(skel->progs.xor);

	if (CHECK(IS_ERR(link), "attach(xor)", "err: %ld\n", PTR_ERR(link)))

		return;



	prog_fd = bpf_program__fd(skel->progs.xor);

	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,

				NULL, NULL, &retval, &duration);

	if (CHECK(err || retval, "test_run xor",

		  "err %d errno %d retval %d duration %d\n", err, errno, retval, duration))

		goto cleanup;



	ASSERT_EQ(skel->data->xor64_value, 0x101ull << 32, "xor64_value");

	ASSERT_EQ(skel->bss->xor64_result, 0x110ull << 32, "xor64_result");



	ASSERT_EQ(skel->data->xor32_value, 0x101, "xor32_value");

	ASSERT_EQ(skel->bss->xor32_result, 0x110, "xor32_result");



	ASSERT_EQ(skel->data->xor_noreturn_value, 0x101ull << 32, "xor_nxoreturn_value");

cleanup:

	bpf_link__destroy(link);

}



static void test_cmpxchg(struct atomics *skel)

{

	int err, prog_fd;

	__u32 duration = 0, retval;

	struct bpf_link *link;



	link = bpf_program__attach(skel->progs.cmpxchg);

	if (CHECK(IS_ERR(link), "attach(cmpxchg)", "err: %ld\n", PTR_ERR(link)))

		return;



	prog_fd = bpf_program__fd(skel->progs.cmpxchg);

	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,

				NULL, NULL, &retval, &duration);

	if (CHECK(err || retval, "test_run add",

		  "err %d errno %d retval %d duration %d\n", err, errno, retval, duration))

		goto cleanup;



	ASSERT_EQ(skel->data->cmpxchg64_value, 2, "cmpxchg64_value");

	ASSERT_EQ(skel->bss->cmpxchg64_result_fail, 1, "cmpxchg_result_fail");

	ASSERT_EQ(skel->bss->cmpxchg64_result_succeed, 1, "cmpxchg_result_succeed");



	ASSERT_EQ(skel->data->cmpxchg32_value, 2, "lcmpxchg32_value");

	ASSERT_EQ(skel->bss->cmpxchg32_result_fail, 1, "cmpxchg_result_fail");

	ASSERT_EQ(skel->bss->cmpxchg32_result_succeed, 1, "cmpxchg_result_succeed");



cleanup:

	bpf_link__destroy(link);

}



static void test_xchg(struct atomics *skel)

{

	int err, prog_fd;

	__u32 duration = 0, retval;

	struct bpf_link *link;



	link = bpf_program__attach(skel->progs.xchg);

	if (CHECK(IS_ERR(link), "attach(xchg)", "err: %ld\n", PTR_ERR(link)))

		return;



	prog_fd = bpf_program__fd(skel->progs.xchg);

	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,

				NULL, NULL, &retval, &duration);

	if (CHECK(err || retval, "test_run add",

		  "err %d errno %d retval %d duration %d\n", err, errno, retval, duration))

		goto cleanup;



	ASSERT_EQ(skel->data->xchg64_value, 2, "xchg64_value");

	ASSERT_EQ(skel->bss->xchg64_result, 1, "xchg64_result");



	ASSERT_EQ(skel->data->xchg32_value, 2, "xchg32_value");

	ASSERT_EQ(skel->bss->xchg32_result, 1, "xchg32_result");



cleanup:

	bpf_link__destroy(link);

}



void test_atomics(void)

{

	struct atomics *skel;

	__u32 duration = 0;



	skel = atomics__open_and_load();

	if (CHECK(!skel, "skel_load", "atomics skeleton failed\n"))

		return;



	if (skel->data->skip_tests) {

		printf("%s:SKIP:no ENABLE_ATOMICS_TESTS (missing Clang BPF atomics support)",

		       __func__);

		test__skip();

		goto cleanup;

	}



	if (test__start_subtest("add"))

		test_add(skel);

	if (test__start_subtest("sub"))

		test_sub(skel);

	if (test__start_subtest("and"))

		test_and(skel);

	if (test__start_subtest("or"))

		test_or(skel);

	if (test__start_subtest("xor"))

		test_xor(skel);

	if (test__start_subtest("cmpxchg"))

		test_cmpxchg(skel);

	if (test__start_subtest("xchg"))

		test_xchg(skel);



cleanup:

	atomics__destroy(skel);

}

tools/testing/selftests/bpf/progs/atomics.c

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+154 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include <stdbool.h>



#ifdef ENABLE_ATOMICS_TESTS

bool skip_tests __attribute((__section__(".data"))) = false;

#else

bool skip_tests = true;

#endif



__u64 add64_value = 1;

__u64 add64_result = 0;

__u32 add32_value = 1;

__u32 add32_result = 0;

__u64 add_stack_value_copy = 0;

__u64 add_stack_result = 0;

__u64 add_noreturn_value = 1;



SEC("fentry/bpf_fentry_test1")

int BPF_PROG(add, int a)

{

#ifdef ENABLE_ATOMICS_TESTS

	__u64 add_stack_value = 1;



	add64_result = __sync_fetch_and_add(&add64_value, 2);

	add32_result = __sync_fetch_and_add(&add32_value, 2);

	add_stack_result = __sync_fetch_and_add(&add_stack_value, 2);

	add_stack_value_copy = add_stack_value;

	__sync_fetch_and_add(&add_noreturn_value, 2);

#endif



	return 0;

}



__s64 sub64_value = 1;

__s64 sub64_result = 0;

__s32 sub32_value = 1;

__s32 sub32_result = 0;

__s64 sub_stack_value_copy = 0;

__s64 sub_stack_result = 0;

__s64 sub_noreturn_value = 1;



SEC("fentry/bpf_fentry_test1")

int BPF_PROG(sub, int a)

{

#ifdef ENABLE_ATOMICS_TESTS

	__u64 sub_stack_value = 1;



	sub64_result = __sync_fetch_and_sub(&sub64_value, 2);

	sub32_result = __sync_fetch_and_sub(&sub32_value, 2);

	sub_stack_result = __sync_fetch_and_sub(&sub_stack_value, 2);

	sub_stack_value_copy = sub_stack_value;

	__sync_fetch_and_sub(&sub_noreturn_value, 2);

#endif



	return 0;

}



__u64 and64_value = (0x110ull << 32);

__u64 and64_result = 0;

__u32 and32_value = 0x110;

__u32 and32_result = 0;

__u64 and_noreturn_value = (0x110ull << 32);



SEC("fentry/bpf_fentry_test1")

int BPF_PROG(and, int a)

{

#ifdef ENABLE_ATOMICS_TESTS



	and64_result = __sync_fetch_and_and(&and64_value, 0x011ull << 32);

	and32_result = __sync_fetch_and_and(&and32_value, 0x011);

	__sync_fetch_and_and(&and_noreturn_value, 0x011ull << 32);

#endif



	return 0;

}



__u64 or64_value = (0x110ull << 32);

__u64 or64_result = 0;

__u32 or32_value = 0x110;

__u32 or32_result = 0;

__u64 or_noreturn_value = (0x110ull << 32);



SEC("fentry/bpf_fentry_test1")

int BPF_PROG(or, int a)

{

#ifdef ENABLE_ATOMICS_TESTS

	or64_result = __sync_fetch_and_or(&or64_value, 0x011ull << 32);

	or32_result = __sync_fetch_and_or(&or32_value, 0x011);

	__sync_fetch_and_or(&or_noreturn_value, 0x011ull << 32);

#endif



	return 0;

}



__u64 xor64_value = (0x110ull << 32);

__u64 xor64_result = 0;

__u32 xor32_value = 0x110;

__u32 xor32_result = 0;

__u64 xor_noreturn_value = (0x110ull << 32);



SEC("fentry/bpf_fentry_test1")

int BPF_PROG(xor, int a)

{

#ifdef ENABLE_ATOMICS_TESTS

	xor64_result = __sync_fetch_and_xor(&xor64_value, 0x011ull << 32);

	xor32_result = __sync_fetch_and_xor(&xor32_value, 0x011);

	__sync_fetch_and_xor(&xor_noreturn_value, 0x011ull << 32);

#endif



	return 0;

}



__u64 cmpxchg64_value = 1;

__u64 cmpxchg64_result_fail = 0;

__u64 cmpxchg64_result_succeed = 0;

__u32 cmpxchg32_value = 1;

__u32 cmpxchg32_result_fail = 0;

__u32 cmpxchg32_result_succeed = 0;



SEC("fentry/bpf_fentry_test1")

int BPF_PROG(cmpxchg, int a)

{

#ifdef ENABLE_ATOMICS_TESTS

	cmpxchg64_result_fail = __sync_val_compare_and_swap(&cmpxchg64_value, 0, 3);

	cmpxchg64_result_succeed = __sync_val_compare_and_swap(&cmpxchg64_value, 1, 2);



	cmpxchg32_result_fail = __sync_val_compare_and_swap(&cmpxchg32_value, 0, 3);

	cmpxchg32_result_succeed = __sync_val_compare_and_swap(&cmpxchg32_value, 1, 2);

#endif



	return 0;

}



__u64 xchg64_value = 1;

__u64 xchg64_result = 0;

__u32 xchg32_value = 1;

__u32 xchg32_result = 0;



SEC("fentry/bpf_fentry_test1")

int BPF_PROG(xchg, int a)

{

#ifdef ENABLE_ATOMICS_TESTS

	__u64 val64 = 2;

	__u32 val32 = 2;



	xchg64_result = __sync_lock_test_and_set(&xchg64_value, val64);

	xchg32_result = __sync_lock_test_and_set(&xchg32_value, val32);

#endif



	return 0;

}

tools/testing/selftests/bpf/verifier/atomic_and.c

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Original line number Diff line number Diff line 
{

	"BPF_ATOMIC_AND without fetch",

	.insns = {

		/* val = 0x110; */

		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0x110),

		/* atomic_and(&val, 0x011); */

		BPF_MOV64_IMM(BPF_REG_1, 0x011),

		BPF_ATOMIC_OP(BPF_DW, BPF_AND, BPF_REG_10, BPF_REG_1, -8),

		/* if (val != 0x010) exit(2); */

		BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_10, -8),

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0x010, 2),

		BPF_MOV64_IMM(BPF_REG_0, 2),

		BPF_EXIT_INSN(),

		/* r1 should not be clobbered, no BPF_FETCH flag */

		BPF_MOV64_IMM(BPF_REG_0, 0),

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0x011, 1),

		BPF_MOV64_IMM(BPF_REG_0, 1),

		BPF_EXIT_INSN(),

	},

	.result = ACCEPT,

},

{

	"BPF_ATOMIC_AND with fetch",

	.insns = {

		BPF_MOV64_IMM(BPF_REG_0, 123),

		/* val = 0x110; */

		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0x110),

		/* old = atomic_fetch_and(&val, 0x011); */

		BPF_MOV64_IMM(BPF_REG_1, 0x011),

		BPF_ATOMIC_OP(BPF_DW, BPF_AND | BPF_FETCH, BPF_REG_10, BPF_REG_1, -8),

		/* if (old != 0x110) exit(3); */

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0x110, 2),

		BPF_MOV64_IMM(BPF_REG_0, 3),

		BPF_EXIT_INSN(),

		/* if (val != 0x010) exit(2); */

		BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_10, -8),

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0x010, 2),

		BPF_MOV64_IMM(BPF_REG_1, 2),

		BPF_EXIT_INSN(),

		/* Check R0 wasn't clobbered (for fear of x86 JIT bug) */

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 123, 2),

		BPF_MOV64_IMM(BPF_REG_0, 1),

		BPF_EXIT_INSN(),

		/* exit(0); */

		BPF_MOV64_IMM(BPF_REG_0, 0),

		BPF_EXIT_INSN(),

	},

	.result = ACCEPT,

},

{

	"BPF_ATOMIC_AND with fetch 32bit",

	.insns = {

		/* r0 = (s64) -1 */

		BPF_MOV64_IMM(BPF_REG_0, 0),

		BPF_ALU64_IMM(BPF_SUB, BPF_REG_0, 1),

		/* val = 0x110; */

		BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 0x110),

		/* old = atomic_fetch_and(&val, 0x011); */

		BPF_MOV32_IMM(BPF_REG_1, 0x011),

		BPF_ATOMIC_OP(BPF_W, BPF_AND | BPF_FETCH, BPF_REG_10, BPF_REG_1, -4),

		/* if (old != 0x110) exit(3); */

		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_1, 0x110, 2),

		BPF_MOV32_IMM(BPF_REG_0, 3),

		BPF_EXIT_INSN(),

		/* if (val != 0x010) exit(2); */

		BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -4),

		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_1, 0x010, 2),

		BPF_MOV32_IMM(BPF_REG_1, 2),

		BPF_EXIT_INSN(),

		/* Check R0 wasn't clobbered (for fear of x86 JIT bug)

		 * It should be -1 so add 1 to get exit code.

		 */

		BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 1),

		BPF_EXIT_INSN(),

	},

	.result = ACCEPT,

},

tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c

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+96 −0
Original line number Diff line number Diff line 
{

	"atomic compare-and-exchange smoketest - 64bit",

	.insns = {

		/* val = 3; */

		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 3),

		/* old = atomic_cmpxchg(&val, 2, 4); */

		BPF_MOV64_IMM(BPF_REG_1, 4),

		BPF_MOV64_IMM(BPF_REG_0, 2),

		BPF_ATOMIC_OP(BPF_DW, BPF_CMPXCHG, BPF_REG_10, BPF_REG_1, -8),

		/* if (old != 3) exit(2); */

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 3, 2),

		BPF_MOV64_IMM(BPF_REG_0, 2),

		BPF_EXIT_INSN(),

		/* if (val != 3) exit(3); */

		BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 3, 2),

		BPF_MOV64_IMM(BPF_REG_0, 3),

		BPF_EXIT_INSN(),

		/* old = atomic_cmpxchg(&val, 3, 4); */

		BPF_MOV64_IMM(BPF_REG_1, 4),

		BPF_MOV64_IMM(BPF_REG_0, 3),

		BPF_ATOMIC_OP(BPF_DW, BPF_CMPXCHG, BPF_REG_10, BPF_REG_1, -8),

		/* if (old != 3) exit(4); */

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 3, 2),

		BPF_MOV64_IMM(BPF_REG_0, 4),

		BPF_EXIT_INSN(),

		/* if (val != 4) exit(5); */

		BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),

		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 4, 2),

		BPF_MOV64_IMM(BPF_REG_0, 5),

		BPF_EXIT_INSN(),

		/* exit(0); */

		BPF_MOV64_IMM(BPF_REG_0, 0),

		BPF_EXIT_INSN(),

	},

	.result = ACCEPT,

},

{

	"atomic compare-and-exchange smoketest - 32bit",

	.insns = {

		/* val = 3; */

		BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 3),

		/* old = atomic_cmpxchg(&val, 2, 4); */

		BPF_MOV32_IMM(BPF_REG_1, 4),

		BPF_MOV32_IMM(BPF_REG_0, 2),

		BPF_ATOMIC_OP(BPF_W, BPF_CMPXCHG, BPF_REG_10, BPF_REG_1, -4),

		/* if (old != 3) exit(2); */

		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_0, 3, 2),

		BPF_MOV32_IMM(BPF_REG_0, 2),

		BPF_EXIT_INSN(),

		/* if (val != 3) exit(3); */

		BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_10, -4),

		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_0, 3, 2),

		BPF_MOV32_IMM(BPF_REG_0, 3),

		BPF_EXIT_INSN(),

		/* old = atomic_cmpxchg(&val, 3, 4); */

		BPF_MOV32_IMM(BPF_REG_1, 4),

		BPF_MOV32_IMM(BPF_REG_0, 3),

		BPF_ATOMIC_OP(BPF_W, BPF_CMPXCHG, BPF_REG_10, BPF_REG_1, -4),

		/* if (old != 3) exit(4); */

		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_0, 3, 2),

		BPF_MOV32_IMM(BPF_REG_0, 4),

		BPF_EXIT_INSN(),

		/* if (val != 4) exit(5); */

		BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_10, -4),

		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_0, 4, 2),

		BPF_MOV32_IMM(BPF_REG_0, 5),

		BPF_EXIT_INSN(),

		/* exit(0); */

		BPF_MOV32_IMM(BPF_REG_0, 0),

		BPF_EXIT_INSN(),

	},

	.result = ACCEPT,

},

{

	"Can't use cmpxchg on uninit src reg",

	.insns = {

		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 3),

		BPF_MOV64_IMM(BPF_REG_0, 3),

		BPF_ATOMIC_OP(BPF_DW, BPF_CMPXCHG, BPF_REG_10, BPF_REG_2, -8),

		BPF_EXIT_INSN(),

	},

	.result = REJECT,

	.errstr = "!read_ok",

},

{

	"Can't use cmpxchg on uninit memory",

	.insns = {

		BPF_MOV64_IMM(BPF_REG_0, 3),

		BPF_MOV64_IMM(BPF_REG_2, 4),

		BPF_ATOMIC_OP(BPF_DW, BPF_CMPXCHG, BPF_REG_10, BPF_REG_2, -8),

		BPF_EXIT_INSN(),

	},

	.result = REJECT,

	.errstr = "invalid read from stack",

},