diff options
| author | Zi Shen Lim <zlim.lnx@gmail.com> | 2016-01-14 10:33:22 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-01-18 03:15:26 +0300 |
| commit | 42ff712bc0c3d7cd60d29b319aecd2d2c8cc75d4 (patch) | |
| tree | 41722ff39391f428b5ee48ce461b32329be4fda4 /arch/arm64 | |
| parent | c94ae4f7c5ec6b6fddde1c08809d5e32a963d7f3 (diff) | |
| download | linux-42ff712bc0c3d7cd60d29b319aecd2d2c8cc75d4.tar.xz | |
arm64: bpf: add extra pass to handle faulty codegen
Code generation functions in arch/arm64/kernel/insn.c previously
BUG_ON invalid parameters. Following change of that behavior, now we
need to handle the error case where AARCH64_BREAK_FAULT is returned.
Instead of error-handling on every emit() in JIT, we add a new
validation pass at the end of JIT compilation. There's no point in
running JITed code at run-time only to trap due to AARCH64_BREAK_FAULT.
Instead, we drop this failed JIT compilation and allow the system to
gracefully fallback on the BPF interpreter.
Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/net/bpf_jit_comp.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 7658612d915c..a34420a5df9a 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1,7 +1,7 @@ /* * BPF JIT compiler for ARM64 * - * Copyright (C) 2014-2015 Zi Shen Lim <zlim.lnx@gmail.com> + * Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@gmail.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -737,6 +737,20 @@ static int build_body(struct jit_ctx *ctx) return 0; } +static int validate_code(struct jit_ctx *ctx) +{ + int i; + + for (i = 0; i < ctx->idx; i++) { + u32 a64_insn = le32_to_cpu(ctx->image[i]); + + if (a64_insn == AARCH64_BREAK_FAULT) + return -1; + } + + return 0; +} + static inline void bpf_flush_icache(void *start, void *end) { flush_icache_range((unsigned long)start, (unsigned long)end); @@ -799,6 +813,12 @@ void bpf_int_jit_compile(struct bpf_prog *prog) build_epilogue(&ctx); + /* 3. Extra pass to validate JITed code. */ + if (validate_code(&ctx)) { + bpf_jit_binary_free(header); + goto out; + } + /* And we're done. */ if (bpf_jit_enable > 1) bpf_jit_dump(prog->len, image_size, 2, ctx.image); |