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682158ab |
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14-Feb-2024 |
Yonghong Song <yonghong.song@linux.dev> |
bpf: Fix test verif_scale_strobemeta_subprogs failure due to llvm19 With latest llvm19, I hit the following selftest failures with $ ./test_progs -j libbpf: prog 'on_event': BPF program load failed: Permission denied libbpf: prog 'on_event': -- BEGIN PROG LOAD LOG -- combined stack size of 4 calls is 544. Too large verification time 1344153 usec stack depth 24+440+0+32 processed 51008 insns (limit 1000000) max_states_per_insn 19 total_states 1467 peak_states 303 mark_read 146 -- END PROG LOAD LOG -- libbpf: prog 'on_event': failed to load: -13 libbpf: failed to load object 'strobemeta_subprogs.bpf.o' scale_test:FAIL:expect_success unexpected error: -13 (errno 13) #498 verif_scale_strobemeta_subprogs:FAIL The verifier complains too big of the combined stack size (544 bytes) which exceeds the maximum stack limit 512. This is a regression from llvm19 ([1]). In the above error log, the original stack depth is 24+440+0+32. To satisfy interpreter's need, in verifier the stack depth is adjusted to 32+448+32+32=544 which exceeds 512, hence the error. The same adjusted stack size is also used for jit case. But the jitted codes could use smaller stack size. $ egrep -r stack_depth | grep round_up arm64/net/bpf_jit_comp.c: ctx->stack_size = round_up(prog->aux->stack_depth, 16); loongarch/net/bpf_jit.c: bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16); powerpc/net/bpf_jit_comp.c: cgctx.stack_size = round_up(fp->aux->stack_depth, 16); riscv/net/bpf_jit_comp32.c: round_up(ctx->prog->aux->stack_depth, STACK_ALIGN); riscv/net/bpf_jit_comp64.c: bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16); s390/net/bpf_jit_comp.c: u32 stack_depth = round_up(fp->aux->stack_depth, 8); sparc/net/bpf_jit_comp_64.c: stack_needed += round_up(stack_depth, 16); x86/net/bpf_jit_comp.c: EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8)); x86/net/bpf_jit_comp.c: int tcc_off = -4 - round_up(stack_depth, 8); x86/net/bpf_jit_comp.c: round_up(stack_depth, 8)); x86/net/bpf_jit_comp.c: int tcc_off = -4 - round_up(stack_depth, 8); x86/net/bpf_jit_comp.c: EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8)); In the above, STACK_ALIGN in riscv/net/bpf_jit_comp32.c is defined as 16. So stack is aligned in either 8 or 16, x86/s390 having 8-byte stack alignment and the rest having 16-byte alignment. This patch calculates total stack depth based on 16-byte alignment if jit is requested. For the above failing case, the new stack size will be 32+448+0+32=512 and no verification failure. llvm19 regression will be discussed separately in llvm upstream. The verifier change caused three test failures as these tests compared messages with stack size. More specifically, - test_global_funcs/global_func1: fail with interpreter mode and success with jit mode. Adjusted stack sizes so both jit and interpreter modes will fail. - async_stack_depth/{pseudo_call_check, async_call_root_check}: since jit and interpreter will calculate different stack sizes, the failure msg is adjusted to omit those specific stack size numbers. [1] https://lore.kernel.org/bpf/32bde0f0-1881-46c9-931a-673be566c61d@linux.dev/ Suggested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20240214232951.4113094-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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f1f5553d |
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25-Apr-2023 |
Yonghong Song <yhs@fb.com> |
selftests/bpf: Fix selftest test_global_funcs/global_func1 failure with latest clang The selftest test_global_funcs/global_func1 failed with the latest clang17. The reason is due to upstream ArgumentPromotionPass ([1]), which may manipulate static function parameters and cause inlining although the funciton is marked as noinline. The original code: static __attribute__ ((noinline)) int f0(int var, struct __sk_buff *skb) { return skb->len; } __attribute__ ((noinline)) int f1(struct __sk_buff *skb) { ... return f0(0, skb) + skb->len; } ... SEC("tc") __failure __msg("combined stack size of 4 calls is 544") int global_func1(struct __sk_buff *skb) { return f0(1, skb) + f1(skb) + f2(2, skb) + f3(3, skb, 4); } After ArgumentPromotionPass, the code is translated to static __attribute__ ((noinline)) int f0(int var, int skb_len) { return skb_len; } __attribute__ ((noinline)) int f1(struct __sk_buff *skb) { ... return f0(0, skb->len) + skb->len; } ... SEC("tc") __failure __msg("combined stack size of 4 calls is 544") int global_func1(struct __sk_buff *skb) { return f0(1, skb->len) + f1(skb) + f2(2, skb) + f3(3, skb, 4); } And later llvm InstCombine phase recognized that f0() simplify returns the value of the second argument and removed f0() completely and the final code looks like: __attribute__ ((noinline)) int f1(struct __sk_buff *skb) { ... return skb->len + skb->len; } ... SEC("tc") __failure __msg("combined stack size of 4 calls is 544") int global_func1(struct __sk_buff *skb) { return skb->len + f1(skb) + f2(2, skb) + f3(3, skb, 4); } If f0() is not inlined, the verification will fail with stack size 544 for a particular callchain. With f0() inlined, the maximum stack size is 512 which is in the limit. Let us add a `asm volatile ("")` in f0() to prevent ArgumentPromotionPass from hoisting the code to its caller, and this fixed the test failure. [1] https://reviews.llvm.org/D148269 Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20230425174744.1758515-1-yhs@fb.com
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c8ed6685 |
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08-Mar-2023 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: fix lots of silly mistakes pointed out by compiler Once we enable -Wall for BPF sources, compiler will complain about lots of unused variables, variables that are set but never read, etc. Fix all these issues first before enabling -Wall in Makefile. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230309054015.4068562-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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c22bdd28 |
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28-Sep-2021 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: Switch SEC("classifier*") usage to a strict SEC("tc") Convert all SEC("classifier*") uses to a new and strict SEC("tc") section name. In reference_tracking selftests switch from ambiguous searching by program title (section name) to non-ambiguous searching by name in some selftests, getting closer to completely removing bpf_object__find_program_by_title(). Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210928161946.2512801-4-andrii@kernel.org
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3e689141 |
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20-Jan-2020 |
Toke Høiland-Jørgensen <toke@redhat.com> |
selftests: Use consistent include paths for libbpf Fix all selftests to include libbpf header files with the bpf/ prefix, to be consistent with external users of the library. Also ensure that all includes of exported libbpf header files (those that are exported on 'make install' of the library) use bracketed includes instead of quoted. To not break the build, keep the old include path until everything has been changed to the new one; a subsequent patch will remove that. Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/157952560568.1683545.9649335788846513446.stgit@toke.dk
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