[PATCH bpf v3 2/2] selftests/bpf: Check per-CPU address resolution per register
Vineet Gupta <[email protected]>
| Newsgroups | org.kernel.vger.bpf,org.kernel.vger.stable |
|---|---|
| Message-ID | <[email protected]> |
An ld_imm64 of a per-CPU map value is followed by a mov_percpu_addr that reuses the same register, so which register the address lands in decides how the JIT encodes the add. Getting the REX prefix wrong there is invisible to a functional test unless the address happens to land in an extended register, which is why this went unnoticed. Load a .percpu variable into every register in one program and match the JITed add against the register each one must resolve into. Signed-off-by: Vineet Gupta <[email protected]> --- .../selftests/bpf/prog_tests/verifier.c | 2 + .../bpf/progs/verifier_percpu_addr.c | 72 +++++++++++++++++++ 2 files changed, 74 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/verifier_percpu_addr.c diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c index 8113fea7ba86..64ac49ad67e6 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -79,6 +79,7 @@ #include "verifier_netfilter_retcode.skel.h" #include "verifier_bpf_fastcall.skel.h" #include "verifier_or_jmp32_k.skel.h" +#include "verifier_percpu_addr.skel.h" #include "verifier_precision.skel.h" #include "verifier_prevent_map_lookup.skel.h" #include "verifier_private_stack.skel.h" @@ -240,6 +241,7 @@ void test_verifier_netfilter_ctx(void) { RUN(verifier_netfilter_ctx); } void test_verifier_netfilter_retcode(void) { RUN(verifier_netfilter_retcode); } void test_verifier_bpf_fastcall(void) { RUN(verifier_bpf_fastcall); } void test_verifier_or_jmp32_k(void) { RUN(verifier_or_jmp32_k); } +void test_verifier_percpu_addr(void) { RUN(verifier_percpu_addr); } void test_verifier_precision(void) { RUN(verifier_precision); } void test_verifier_prevent_map_lookup(void) { RUN(verifier_prevent_map_lookup); } void test_verifier_private_stack(void) { RUN(verifier_private_stack); } diff --git a/tools/testing/selftests/bpf/progs/verifier_percpu_addr.c b/tools/testing/selftests/bpf/progs/verifier_percpu_addr.c new file mode 100644 index 000000000000..967f4e6e3a49 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_percpu_addr.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <vmlinux.h> +#include <bpf/bpf_helpers.h> +#include "bpf_misc.h" + +#if defined(__TARGET_ARCH_x86) + +int percpu_data SEC(".percpu"); + +/* + * An ld_imm64 of a per-CPU map value is followed by a mov_percpu_addr that + * reuses the same register, so check that the add resolves into the register + * the address was loaded into, for every register. + */ +SEC("raw_tp") +__description("per-CPU address resolution") +__success +__arch_x86_64 +__jited(" movabsq $0x{{.*}}, %rax") +__jited(" addq %gs:{{.*}}, %rax") +__jited(" movabsq $0x{{.*}}, %rdi") +__jited(" addq %gs:{{.*}}, %rdi") +__jited(" movabsq $0x{{.*}}, %rsi") +__jited(" addq %gs:{{.*}}, %rsi") +__jited(" movabsq $0x{{.*}}, %rdx") +__jited(" addq %gs:{{.*}}, %rdx") +__jited(" movabsq $0x{{.*}}, %rcx") +__jited(" addq %gs:{{.*}}, %rcx") +__jited(" movabsq $0x{{.*}}, %r8") +__jited(" addq %gs:{{.*}}, %r8") +__jited(" movabsq $0x{{.*}}, %rbx") +__jited(" addq %gs:{{.*}}, %rbx") +__jited(" movabsq $0x{{.*}}, %r13") +__jited(" addq %gs:{{.*}}, %r13") +__jited(" movabsq $0x{{.*}}, %r14") +__jited(" addq %gs:{{.*}}, %r14") +__jited(" movabsq $0x{{.*}}, %r15") +__jited(" addq %gs:{{.*}}, %r15") +__naked void percpu_addr(void) +{ + asm volatile (" \ + r0 = %[percpu_data] ll; \ + r1 = %[percpu_data] ll; \ + r2 = %[percpu_data] ll; \ + r3 = %[percpu_data] ll; \ + r4 = %[percpu_data] ll; \ + r5 = %[percpu_data] ll; \ + r6 = %[percpu_data] ll; \ + r7 = %[percpu_data] ll; \ + r8 = %[percpu_data] ll; \ + r9 = %[percpu_data] ll; \ + r0 = 0; \ + exit; \ +" : + : __imm_addr(percpu_data) + : __clobber_all); +} + +#else + +SEC("raw_tp") +__description("percpu addr dummy") +__success +int dummy_test(void) +{ + return 0; +} + +#endif + +char _license[] SEC("license") = "GPL"; -- 2.53.0-Meta