ARM: net: bpf: avoid reloading 'index' (aaffd2f5) · Commits · 戴 / test

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>

arch/arm/net/bpf_jit_32.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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);

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