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authorZi Shen Lim <zlim.lnx@gmail.com>2016-01-13 23:33:22 -0800
committerDavid S. Miller <davem@davemloft.net>2016-01-17 19:15:26 -0500
commit42ff712bc0c3d7cd60d29b319aecd2d2c8cc75d4 (patch)
tree41722ff39391f428b5ee48ce461b32329be4fda4 /arch/arm64/net/bpf_jit_comp.c
parentarm64: insn: remove BUG_ON from codegen (diff)
downloadlinux-dev-42ff712bc0c3d7cd60d29b319aecd2d2c8cc75d4.tar.xz
linux-dev-42ff712bc0c3d7cd60d29b319aecd2d2c8cc75d4.zip
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 '')
-rw-r--r--arch/arm64/net/bpf_jit_comp.c22
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);