3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zi Shen Lim <zlim.lnx@xxxxxxxxx> commit 51c9fbb1b146f3336a93d398c439b6fbfe5ab489 upstream. Earlier implementation assumed last instruction is BPF_EXIT. Since this is no longer a restriction in eBPF, we remove this limitation. Per Alexei Starovoitov [1]: > classic BPF has a restriction that last insn is always BPF_RET. > eBPF doesn't have BPF_RET instruction and this restriction. > It has BPF_EXIT insn which can appear anywhere in the program > one or more times and it doesn't have to be last insn. [1] https://lkml.org/lkml/2014/11/27/2 Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Acked-by: Alexei Starovoitov <ast@xxxxxxxxxxxx> Signed-off-by: Zi Shen Lim <zlim.lnx@xxxxxxxxx> Signed-off-by: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/net/bpf_jit_comp.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -60,7 +60,7 @@ struct jit_ctx { const struct bpf_prog *prog; int idx; int tmp_used; - int body_offset; + int epilogue_offset; int *offset; u32 *image; }; @@ -130,8 +130,8 @@ static void jit_fill_hole(void *area, un static inline int epilogue_offset(const struct jit_ctx *ctx) { - int to = ctx->offset[ctx->prog->len - 1]; - int from = ctx->idx - ctx->body_offset; + int to = ctx->epilogue_offset; + int from = ctx->idx; return to - from; } @@ -463,6 +463,8 @@ emit_cond_jmp: } /* function return */ case BPF_JMP | BPF_EXIT: + /* Optimization: when last instruction is EXIT, + simply fallthrough to epilogue. */ if (i == ctx->prog->len - 1) break; jmp_offset = epilogue_offset(ctx); @@ -685,11 +687,13 @@ void bpf_int_jit_compile(struct bpf_prog /* 1. Initial fake pass to compute ctx->idx. */ - /* Fake pass to fill in ctx->offset. */ + /* Fake pass to fill in ctx->offset and ctx->tmp_used. */ if (build_body(&ctx)) goto out; build_prologue(&ctx); + + ctx.epilogue_offset = ctx.idx; build_epilogue(&ctx); /* Now we know the actual image size. */ @@ -706,7 +710,6 @@ void bpf_int_jit_compile(struct bpf_prog build_prologue(&ctx); - ctx.body_offset = ctx.idx; if (build_body(&ctx)) { bpf_jit_binary_free(header); goto out; -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html