diff options
| -rw-r--r-- | tools/lib/bpf/bpf_helpers.h | 19 |
1 files changed, 6 insertions, 13 deletions
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index 867b734839dd..7349b16b8e2f 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -131,7 +131,7 @@ /* * Helper function to perform a tail call with a constant/immediate map slot. */ -#if (!defined(__clang__) || __clang_major__ >= 8) && defined(__bpf__) +#if __clang_major__ >= 8 && defined(__bpf__) static __always_inline void bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) { @@ -139,8 +139,8 @@ bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) __bpf_unreachable(); /* - * Provide a hard guarantee that the compiler won't optimize setting r2 - * (map pointer) and r3 (constant map index) from _different paths_ ending + * Provide a hard guarantee that LLVM won't optimize setting r2 (map + * pointer) and r3 (constant map index) from _different paths_ ending * up at the _same_ call insn as otherwise we won't be able to use the * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key @@ -148,19 +148,12 @@ bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) * * Note on clobber list: we need to stay in-line with BPF calling * convention, so even if we don't end up using r0, r4, r5, we need - * to mark them as clobber so that the compiler doesn't end up using - * them before / after the call. + * to mark them as clobber so that LLVM doesn't end up using them + * before / after the call. */ - asm volatile( -#ifdef __clang__ - "r1 = %[ctx]\n\t" + asm volatile("r1 = %[ctx]\n\t" "r2 = %[map]\n\t" "r3 = %[slot]\n\t" -#else - "mov %%r1,%[ctx]\n\t" - "mov %%r2,%[map]\n\t" - "mov %%r3,%[slot]\n\t" -#endif "call 12" :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) : "r0", "r1", "r2", "r3", "r4", "r5"); |