From ff3afe5da9985b465427a4a7ab14d27598de0d44 Mon Sep 17 00:00:00 2001 From: Peilin Ye Date: Tue, 4 Mar 2025 01:06:46 +0000 Subject: selftests/bpf: Add selftests for load-acquire and store-release instructions Add several ./test_progs tests: - arena_atomics/load_acquire - arena_atomics/store_release - verifier_load_acquire/* - verifier_store_release/* - verifier_precision/bpf_load_acquire - verifier_precision/bpf_store_release The last two tests are added to check if backtrack_insn() handles the new instructions correctly. Additionally, the last test also makes sure that the verifier "remembers" the value (in src_reg) we store-release into e.g. a stack slot. For example, if we take a look at the test program: #0: r1 = 8; /* store_release((u64 *)(r10 - 8), r1); */ #1: .8byte %[store_release]; #2: r1 = *(u64 *)(r10 - 8); #3: r2 = r10; #4: r2 += r1; #5: r0 = 0; #6: exit; At #1, if the verifier doesn't remember that we wrote 8 to the stack, then later at #4 we would be adding an unbounded scalar value to the stack pointer, which would cause the program to be rejected: VERIFIER LOG: ============= ... math between fp pointer and register with unbounded min value is not allowed For easier CI integration, instead of using built-ins like __atomic_{load,store}_n() which depend on the new __BPF_FEATURE_LOAD_ACQ_STORE_REL pre-defined macro, manually craft load-acquire/store-release instructions using __imm_insn(), as suggested by Eduard. All new tests depend on: (1) Clang major version >= 18, and (2) ENABLE_ATOMICS_TESTS is defined (currently implies -mcpu=v3 or v4), and (3) JIT supports load-acquire/store-release (currently arm64 and x86-64) In .../progs/arena_atomics.c: /* 8-byte-aligned */ __u8 __arena_global load_acquire8_value = 0x12; /* 1-byte hole */ __u16 __arena_global load_acquire16_value = 0x1234; That 1-byte hole in the .addr_space.1 ELF section caused clang-17 to crash: fatal error: error in backend: unable to write nop sequence of 1 bytes To work around such llvm-17 CI job failures, conditionally define __arena_global variables as 64-bit if __clang_major__ < 18, to make sure .addr_space.1 has no holes. Ideally we should avoid compiling this file using clang-17 at all (arena tests depend on __BPF_FEATURE_ADDR_SPACE_CAST, and are skipped for llvm-17 anyway), but that is a separate topic. Acked-by: Eduard Zingerman Signed-off-by: Peilin Ye Link: https://lore.kernel.org/r/1b46c6feaf0f1b6984d9ec80e500cc7383e9da1a.1741049567.git.yepeilin@google.com Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/prog_tests/arena_atomics.c | 66 +++++++++++++++++++++- tools/testing/selftests/bpf/prog_tests/verifier.c | 4 ++ 2 files changed, 69 insertions(+), 1 deletion(-) (limited to 'tools/testing/selftests/bpf/prog_tests') diff --git a/tools/testing/selftests/bpf/prog_tests/arena_atomics.c b/tools/testing/selftests/bpf/prog_tests/arena_atomics.c index 26e7c06c6cb4..d98577a6babc 100644 --- a/tools/testing/selftests/bpf/prog_tests/arena_atomics.c +++ b/tools/testing/selftests/bpf/prog_tests/arena_atomics.c @@ -162,6 +162,66 @@ static void test_uaf(struct arena_atomics *skel) ASSERT_EQ(skel->arena->uaf_recovery_fails, 0, "uaf_recovery_fails"); } +static void test_load_acquire(struct arena_atomics *skel) +{ + LIBBPF_OPTS(bpf_test_run_opts, topts); + int err, prog_fd; + + if (skel->data->skip_lacq_srel_tests) { + printf("%s:SKIP: ENABLE_ATOMICS_TESTS not defined, Clang doesn't support addr_space_cast, and/or JIT doesn't support load-acquire\n", + __func__); + test__skip(); + return; + } + + /* No need to attach it, just run it directly */ + prog_fd = bpf_program__fd(skel->progs.load_acquire); + err = bpf_prog_test_run_opts(prog_fd, &topts); + if (!ASSERT_OK(err, "test_run_opts err")) + return; + if (!ASSERT_OK(topts.retval, "test_run_opts retval")) + return; + + ASSERT_EQ(skel->arena->load_acquire8_result, 0x12, + "load_acquire8_result"); + ASSERT_EQ(skel->arena->load_acquire16_result, 0x1234, + "load_acquire16_result"); + ASSERT_EQ(skel->arena->load_acquire32_result, 0x12345678, + "load_acquire32_result"); + ASSERT_EQ(skel->arena->load_acquire64_result, 0x1234567890abcdef, + "load_acquire64_result"); +} + +static void test_store_release(struct arena_atomics *skel) +{ + LIBBPF_OPTS(bpf_test_run_opts, topts); + int err, prog_fd; + + if (skel->data->skip_lacq_srel_tests) { + printf("%s:SKIP: ENABLE_ATOMICS_TESTS not defined, Clang doesn't support addr_space_cast, and/or JIT doesn't support store-release\n", + __func__); + test__skip(); + return; + } + + /* No need to attach it, just run it directly */ + prog_fd = bpf_program__fd(skel->progs.store_release); + err = bpf_prog_test_run_opts(prog_fd, &topts); + if (!ASSERT_OK(err, "test_run_opts err")) + return; + if (!ASSERT_OK(topts.retval, "test_run_opts retval")) + return; + + ASSERT_EQ(skel->arena->store_release8_result, 0x12, + "store_release8_result"); + ASSERT_EQ(skel->arena->store_release16_result, 0x1234, + "store_release16_result"); + ASSERT_EQ(skel->arena->store_release32_result, 0x12345678, + "store_release32_result"); + ASSERT_EQ(skel->arena->store_release64_result, 0x1234567890abcdef, + "store_release64_result"); +} + void test_arena_atomics(void) { struct arena_atomics *skel; @@ -171,7 +231,7 @@ void test_arena_atomics(void) if (!ASSERT_OK_PTR(skel, "arena atomics skeleton open")) return; - if (skel->data->skip_tests) { + if (skel->data->skip_all_tests) { printf("%s:SKIP:no ENABLE_ATOMICS_TESTS or no addr_space_cast support in clang", __func__); test__skip(); @@ -198,6 +258,10 @@ void test_arena_atomics(void) test_xchg(skel); if (test__start_subtest("uaf")) test_uaf(skel); + if (test__start_subtest("load_acquire")) + test_load_acquire(skel); + if (test__start_subtest("store_release")) + test_store_release(skel); cleanup: arena_atomics__destroy(skel); diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c index 8a0e1ff8a2dc..cfe47b529e01 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -45,6 +45,7 @@ #include "verifier_ldsx.skel.h" #include "verifier_leak_ptr.skel.h" #include "verifier_linked_scalars.skel.h" +#include "verifier_load_acquire.skel.h" #include "verifier_loops1.skel.h" #include "verifier_lwt.skel.h" #include "verifier_map_in_map.skel.h" @@ -80,6 +81,7 @@ #include "verifier_spill_fill.skel.h" #include "verifier_spin_lock.skel.h" #include "verifier_stack_ptr.skel.h" +#include "verifier_store_release.skel.h" #include "verifier_subprog_precision.skel.h" #include "verifier_subreg.skel.h" #include "verifier_tailcall_jit.skel.h" @@ -173,6 +175,7 @@ void test_verifier_int_ptr(void) { RUN(verifier_int_ptr); } void test_verifier_iterating_callbacks(void) { RUN(verifier_iterating_callbacks); } void test_verifier_jeq_infer_not_null(void) { RUN(verifier_jeq_infer_not_null); } void test_verifier_jit_convergence(void) { RUN(verifier_jit_convergence); } +void test_verifier_load_acquire(void) { RUN(verifier_load_acquire); } void test_verifier_ld_ind(void) { RUN(verifier_ld_ind); } void test_verifier_ldsx(void) { RUN(verifier_ldsx); } void test_verifier_leak_ptr(void) { RUN(verifier_leak_ptr); } @@ -211,6 +214,7 @@ void test_verifier_sockmap_mutate(void) { RUN(verifier_sockmap_mutate); } void test_verifier_spill_fill(void) { RUN(verifier_spill_fill); } void test_verifier_spin_lock(void) { RUN(verifier_spin_lock); } void test_verifier_stack_ptr(void) { RUN(verifier_stack_ptr); } +void test_verifier_store_release(void) { RUN(verifier_store_release); } void test_verifier_subprog_precision(void) { RUN(verifier_subprog_precision); } void test_verifier_subreg(void) { RUN(verifier_subreg); } void test_verifier_tailcall_jit(void) { RUN(verifier_tailcall_jit); } -- cgit v1.2.3