From ec1f77f6557b46639fa47c6980ef9d38995c1e05 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 23 Aug 2024 01:06:42 -0700 Subject: [PATCH 1/3] selftests/bpf: test_loader.c:get_current_arch() should not return 0 At the moment, when test_loader.c:get_current_arch() can't determine the arch, it returns 0. The arch check in run_subtest() looks as follows: if ((get_current_arch() & spec->arch_mask) == 0) { test__skip(); return; } Which means that all test_loader based tests would be skipped if arch could not be determined. get_current_arch() recognizes x86_64, arm64 and riscv64. Which means that CI skips test_loader tests for s390. Fix this by making sure that get_current_arch() always returns non-zero value. In combination with default spec->arch_mask == -1 this should cover all possibilities. Fixes: f406026fefa7 ("selftests/bpf: by default use arch mask allowing all archs") Fixes: 7d743e4c759c ("selftests/bpf: __jited test tag to check disassembly after jit") Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240823080644.263943-2-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/test_loader.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c index 2ca9b73e5a6b..4223cffc090e 100644 --- a/tools/testing/selftests/bpf/test_loader.c +++ b/tools/testing/selftests/bpf/test_loader.c @@ -336,9 +336,10 @@ static const char *skip_dynamic_pfx(const char *s, const char *pfx) } enum arch { - ARCH_X86_64 = 0x1, - ARCH_ARM64 = 0x2, - ARCH_RISCV64 = 0x4, + ARCH_UNKNOWN = 0x1, + ARCH_X86_64 = 0x2, + ARCH_ARM64 = 0x4, + ARCH_RISCV64 = 0x8, }; static int get_current_arch(void) @@ -350,7 +351,7 @@ static int get_current_arch(void) #elif defined(__riscv) && __riscv_xlen == 64 return ARCH_RISCV64; #endif - return 0; + return ARCH_UNKNOWN; } /* Uses btf_decl_tag attributes to describe the expected test From c52a1e6eb74ffe4f217e9b53ed75440a45b08c4c Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 23 Aug 2024 01:06:43 -0700 Subject: [PATCH 2/3] selftests/bpf: match both retq/rethunk in verifier_tailcall_jit Depending on kernel parameters, x86 jit generates either retq or jump to rethunk for 'exit' instruction. The difference could be seen when kernel is booted with and without mitigations=off parameter. Relax the verifier_tailcall_jit test case to match both variants. Fixes: e5bdd6a8be78 ("selftests/bpf: validate jit behaviour for tail calls") Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240823080644.263943-3-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/progs/verifier_tailcall_jit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/verifier_tailcall_jit.c b/tools/testing/selftests/bpf/progs/verifier_tailcall_jit.c index 06d327cf1e1f..8d60c634a114 100644 --- a/tools/testing/selftests/bpf/progs/verifier_tailcall_jit.c +++ b/tools/testing/selftests/bpf/progs/verifier_tailcall_jit.c @@ -59,7 +59,7 @@ __jited(" movq -0x10(%rbp), %rax") __jited(" callq 0x{{.*}}") /* call to sub() */ __jited(" xorl %eax, %eax") __jited(" leave") -__jited(" retq") +__jited(" {{(retq|jmp 0x)}}") /* return or jump to rethunk */ __jited("...") /* subprogram entry for sub(), regular function prologue */ __jited(" endbr64") @@ -89,7 +89,7 @@ __jited(" popq %rax") __jited(" popq %rax") __jited(" jmp {{.*}}") /* jump to tail call tgt */ __jited("L0: leave") -__jited(" retq") +__jited(" {{(retq|jmp 0x)}}") /* return or jump to rethunk */ SEC("tc") __naked int main(void) { From 21a56fc503faae7589167fcd2771ab6dce36ab39 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 23 Aug 2024 01:06:44 -0700 Subject: [PATCH 3/3] selftests/bpf: #define LOCAL_LABEL_LEN for jit_disasm_helpers.c Extract local label length as a #define directive and elaborate why 'i % MAX_LOCAL_LABELS' expression is needed for local labels array initialization. Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240823080644.263943-4-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov --- .../testing/selftests/bpf/jit_disasm_helpers.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/bpf/jit_disasm_helpers.c b/tools/testing/selftests/bpf/jit_disasm_helpers.c index 1b0f1fd267c0..febd6b12e372 100644 --- a/tools/testing/selftests/bpf/jit_disasm_helpers.c +++ b/tools/testing/selftests/bpf/jit_disasm_helpers.c @@ -16,6 +16,11 @@ */ #define MAX_LOCAL_LABELS 32 +/* Local labels are encoded as 'L42', this requires 4 bytes of storage: + * 3 characters + zero byte + */ +#define LOCAL_LABEL_LEN 4 + static bool llvm_initialized; struct local_labels { @@ -23,7 +28,7 @@ struct local_labels { __u32 prog_len; __u32 cnt; __u32 pcs[MAX_LOCAL_LABELS]; - char names[MAX_LOCAL_LABELS][4]; + char names[MAX_LOCAL_LABELS][LOCAL_LABEL_LEN]; }; static const char *lookup_symbol(void *data, uint64_t ref_value, uint64_t *ref_type, @@ -118,8 +123,14 @@ static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len) } qsort(labels.pcs, labels.cnt, sizeof(*labels.pcs), cmp_u32); for (i = 0; i < labels.cnt; ++i) - /* use (i % 100) to avoid format truncation warning */ - snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % 100); + /* gcc is unable to infer upper bound for labels.cnt and assumes + * it to be U32_MAX. U32_MAX takes 10 decimal digits. + * snprintf below prints into labels.names[*], + * which has space only for two digits and a letter. + * To avoid truncation warning use (i % MAX_LOCAL_LABELS), + * which informs gcc about printed value upper bound. + */ + snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % MAX_LOCAL_LABELS); /* now print with labels */ labels.print_phase = true;