From: Russell King <rmk+kernel@armlinux.org.uk>
To: netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH net-next v2 12/14] ARM: net: bpf: avoid reloading 'array'
Date: Wed, 11 Jul 2018 10:32:28 +0100 [thread overview]
Message-ID: <E1fdBU4-0001Jh-2m@rmk-PC.armlinux.org.uk> (raw)
In-Reply-To: <20180711093033.GP17271@n2100.armlinux.org.uk>
Rearranging the order of the initial tail call code a little allows is
to avoid reloading the 'array' pointer.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
arch/arm/net/bpf_jit_32.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 0a8b3d0903c4..f0cad9692952 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -1064,16 +1064,16 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
BUILD_BUG_ON(offsetof(struct bpf_array, map.max_entries) >
ARM_INST_LDST__IMM12);
off = offsetof(struct bpf_array, map.max_entries);
- /* array->map.max_entries */
- r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx);
- emit(ARM_LDR_I(tmp[1], r_array, off), ctx);
+ r_array = arm_bpf_get_reg32(r2[1], tmp2[0], ctx);
/* index is 32-bit for arrays */
r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx);
+ /* array->map.max_entries */
+ emit(ARM_LDR_I(tmp[1], r_array, off), ctx);
/* index >= array->map.max_entries */
emit(ARM_CMP_R(r_index, tmp[1]), ctx);
_emit(ARM_COND_CS, ARM_B(jmp_offset), ctx);
- /* tmp2[1] = index */
+ /* tmp2[0] = array, tmp2[1] = index */
/* if (tail_call_cnt > MAX_TAIL_CALL_CNT)
* goto out;
@@ -1095,7 +1095,6 @@ 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[0], ctx);
emit(ARM_ADD_I(tmp[1], r_array, off), ctx);
emit(ARM_LDR_R_SI(tmp[1], tmp[1], r_index, SRTYPE_ASL, 2), ctx);
emit(ARM_CMP_I(tmp[1], 0), ctx);
--
2.7.4
next prev parent reply other threads:[~2018-07-11 9:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 9:30 [PATCH 00/14] ARM BPF jit compiler improvements Russell King - ARM Linux
2018-07-11 9:31 ` [PATCH net-next v2 01/14] ARM: net: bpf: enumerate the JIT scratch stack layout Russell King
2018-07-11 9:31 ` [PATCH net-next v2 02/14] ARM: net: bpf: provide load/store ops with negative immediates Russell King
2018-07-11 9:31 ` [PATCH net-next v2 03/14] ARM: net: bpf: use negative numbers for stacked registers Russell King
2018-07-11 9:31 ` [PATCH net-next v2 04/14] ARM: net: bpf: remove is_on_stack() and sstk/dstk Russell King
2018-07-11 9:31 ` [PATCH net-next v2 05/14] ARM: net: bpf: provide accessor functions for BPF registers Russell King
2018-07-11 9:31 ` [PATCH net-next v2 06/14] ARM: net: bpf: 64-bit " Russell King
2018-07-11 9:32 ` [PATCH net-next v2 07/14] ARM: net: bpf: access eBPF scratch space using ARM FP register Russell King
2018-07-11 9:32 ` [PATCH net-next v2 08/14] ARM: net: bpf: imm12 constant conversion Russell King
2018-07-11 9:32 ` [PATCH net-next v2 09/14] ARM: net: bpf: use immediate forms of instructions where possible Russell King
2018-07-11 9:32 ` [PATCH net-next v2 10/14] ARM: net: bpf: use ldr instructions with shifted rm register Russell King
2018-07-11 9:32 ` [PATCH net-next v2 11/14] ARM: net: bpf: avoid reloading 'index' Russell King
2018-07-11 9:32 ` Russell King [this message]
2018-07-11 9:32 ` [PATCH net-next v2 13/14] ARM: net: bpf: always use odd/even register pair Russell King
2018-07-11 9:32 ` [PATCH net-next v2 14/14] ARM: net: bpf: use double-word load/stores where available Russell King
2018-07-12 19:02 ` [PATCH 00/14] ARM BPF jit compiler improvements Daniel Borkmann
2018-07-12 21:02 ` Russell King - ARM Linux
2018-07-12 21:12 ` Daniel Borkmann
2018-07-12 21:35 ` Russell King - ARM Linux
2018-07-13 13:24 ` Daniel Borkmann
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