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| author | Russell King <rmk+kernel@armlinux.org.uk> | 2018-07-11 11:32:22 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-07-12 20:45:23 +0200 |
| commit | aaffd2f5c3d58f154ca7b3d104a2ee6b6e40bc6b (patch) | |
| tree | a4607bc0ea818a20af3453d6b8aba221dc686efd | |
| parent | ARM: net: bpf: use ldr instructions with shifted rm register (diff) | |
| download | linux-aaffd2f5c3d58f154ca7b3d104a2ee6b6e40bc6b.tar.xz linux-aaffd2f5c3d58f154ca7b3d104a2ee6b6e40bc6b.zip | |
ARM: net: bpf: avoid reloading 'index'
Avoid reloading 'index' after we have validated it - it remains in
tmp2[1] up to the point that we begin the code to index the pointer
array, so with a little rearrangement of the registers, we can use
the already loaded value.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
| -rw-r--r-- | arch/arm/net/bpf_jit_32.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index e22dc828420c..0a8b3d0903c4 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -1073,6 +1073,8 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) emit(ARM_CMP_R(r_index, tmp[1]), ctx); _emit(ARM_COND_CS, ARM_B(jmp_offset), ctx); + /* tmp2[1] = index */ + /* if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; * tail_call_cnt++; @@ -1093,9 +1095,8 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) */ BUILD_BUG_ON(imm8m(offsetof(struct bpf_array, ptrs)) < 0); off = imm8m(offsetof(struct bpf_array, ptrs)); - r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx); + r_array = arm_bpf_get_reg32(r2[1], tmp2[0], ctx); emit(ARM_ADD_I(tmp[1], r_array, off), ctx); - r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx); emit(ARM_LDR_R_SI(tmp[1], tmp[1], r_index, SRTYPE_ASL, 2), ctx); emit(ARM_CMP_I(tmp[1], 0), ctx); _emit(ARM_COND_EQ, ARM_B(jmp_offset), ctx); |