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authorRussell King <rmk+kernel@armlinux.org.uk>2018-07-11 10:32:22 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2018-07-12 20:45:23 +0200
commitaaffd2f5c3d58f154ca7b3d104a2ee6b6e40bc6b (patch)
treea4607bc0ea818a20af3453d6b8aba221dc686efd /arch/arm/net
parent2b6958ef1151452cb2160fde75a5c5382b512c34 (diff)
downloadlinux-aaffd2f5c3d58f154ca7b3d104a2ee6b6e40bc6b.tar.bz2
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>
Diffstat (limited to 'arch/arm/net')
-rw-r--r--arch/arm/net/bpf_jit_32.c5
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);