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Date: Thu, 4 Jun 2015 11:56:11 +0100
From: Markos Chandras <markos.chandras@...tec.com>
To: <linux-mips@...ux-mips.org>
CC: Markos Chandras <markos.chandras@...tec.com>,
<netdev@...r.kernel.org>, "David S. Miller" <davem@...emloft.net>,
Alexei Starovoitov <ast@...mgrid.com>,
Daniel Borkmann <dborkman@...hat.com>,
"Hannes Frederic Sowa" <hannes@...essinduktion.org>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH 1/6] MIPS: net: BPF: Free up some callee-saved registers
Move the two scratch registers from s0 and s1 to t4 and t5 in order
to free up some callee-saved registers. We will use these callee-saved
registers to store some permanent data on them in a subsequent patch.
Cc: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Alexei Starovoitov <ast@...mgrid.com>
Cc: Daniel Borkmann <dborkman@...hat.com>
Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Markos Chandras <markos.chandras@...tec.com>
---
arch/mips/net/bpf_jit.c | 35 +++++++++++++++--------------------
arch/mips/net/bpf_jit.h | 2 ++
2 files changed, 17 insertions(+), 20 deletions(-)
diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 5d6139390bf8..850b08ee3fab 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -29,9 +29,6 @@
/* ABI
*
- * s0 1st scratch register
- * s1 2nd scratch register
- * s2 offset register
* s3 BPF register A
* s4 BPF register X
* s5 *skb
@@ -88,13 +85,13 @@
* any of the $s0-$s6 registers will only be preserved if
* they are going to actually be used.
*/
-#define r_s0 MIPS_R_S0 /* scratch reg 1 */
-#define r_s1 MIPS_R_S1 /* scratch reg 2 */
#define r_off MIPS_R_S2
#define r_A MIPS_R_S3
#define r_X MIPS_R_S4
#define r_skb MIPS_R_S5
#define r_M MIPS_R_S6
+#define r_s0 MIPS_R_T4 /* scratch reg 1 */
+#define r_s1 MIPS_R_T5 /* scratch reg 2 */
#define r_tmp_imm MIPS_R_T6 /* No need to preserve this */
#define r_tmp MIPS_R_T7 /* No need to preserve this */
#define r_zero MIPS_R_ZERO
@@ -108,8 +105,6 @@
#define SEEN_SREG_SFT (BPF_MEMWORDS + 1)
#define SEEN_SREG_BASE (1 << SEEN_SREG_SFT)
#define SEEN_SREG(x) (SEEN_SREG_BASE << (x))
-#define SEEN_S0 SEEN_SREG(0)
-#define SEEN_S1 SEEN_SREG(1)
#define SEEN_OFF SEEN_SREG(2)
#define SEEN_A SEEN_SREG(3)
#define SEEN_X SEEN_SREG(4)
@@ -817,7 +812,7 @@ load_common:
b_imm(prog->len, ctx), ctx);
emit_reg_move(r_ret, r_zero, ctx);
- ctx->flags |= SEEN_CALL | SEEN_OFF | SEEN_S0 |
+ ctx->flags |= SEEN_CALL | SEEN_OFF |
SEEN_SKB | SEEN_A;
emit_load_func(r_s0, (ptr)load_func[load_order],
@@ -883,7 +878,7 @@ load_ind:
return -ENOTSUPP;
/* X <- 4 * (P[k:1] & 0xf) */
- ctx->flags |= SEEN_X | SEEN_CALL | SEEN_S0 | SEEN_SKB;
+ ctx->flags |= SEEN_X | SEEN_CALL | SEEN_SKB;
/* Load offset to a1 */
emit_load_func(r_s0, (ptr)jit_get_skb_b, ctx);
/*
@@ -947,7 +942,7 @@ load_ind:
case BPF_ALU | BPF_MUL | BPF_K:
/* A *= K */
/* Load K to scratch register before MUL */
- ctx->flags |= SEEN_A | SEEN_S0;
+ ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
emit_mul(r_A, r_A, r_s0, ctx);
break;
@@ -965,7 +960,7 @@ load_ind:
emit_srl(r_A, r_A, k, ctx);
break;
}
- ctx->flags |= SEEN_A | SEEN_S0;
+ ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
emit_div(r_A, r_s0, ctx);
break;
@@ -975,7 +970,7 @@ load_ind:
ctx->flags |= SEEN_A;
emit_jit_reg_move(r_A, r_zero, ctx);
} else {
- ctx->flags |= SEEN_A | SEEN_S0;
+ ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
emit_mod(r_A, r_s0, ctx);
}
@@ -1089,10 +1084,10 @@ jmp_cmp:
if ((condt & MIPS_COND_GE) ||
(condt & MIPS_COND_GT)) {
if (condt & MIPS_COND_K) { /* K */
- ctx->flags |= SEEN_S0 | SEEN_A;
+ ctx->flags |= SEEN_A;
emit_sltiu(r_s0, r_A, k, ctx);
} else { /* X */
- ctx->flags |= SEEN_S0 | SEEN_A |
+ ctx->flags |= SEEN_A |
SEEN_X;
emit_sltu(r_s0, r_A, r_X, ctx);
}
@@ -1104,7 +1099,7 @@ jmp_cmp:
/* A > (K|X) ? scratch = 0 */
if (condt & MIPS_COND_GT) {
/* Checking for equality */
- ctx->flags |= SEEN_S0 | SEEN_A | SEEN_X;
+ ctx->flags |= SEEN_A | SEEN_X;
if (condt & MIPS_COND_K)
emit_load_imm(r_s0, k, ctx);
else
@@ -1127,7 +1122,7 @@ jmp_cmp:
} else {
/* A == K|X */
if (condt & MIPS_COND_K) { /* K */
- ctx->flags |= SEEN_S0 | SEEN_A;
+ ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
/* jump true */
b_off = b_imm(i + inst->jt + 1, ctx);
@@ -1157,7 +1152,7 @@ jmp_cmp:
}
break;
case BPF_JMP | BPF_JSET | BPF_K:
- ctx->flags |= SEEN_S0 | SEEN_S1 | SEEN_A;
+ ctx->flags |= SEEN_A;
/* pc += (A & K) ? pc -> jt : pc -> jf */
emit_load_imm(r_s1, k, ctx);
emit_and(r_s0, r_A, r_s1, ctx);
@@ -1171,7 +1166,7 @@ jmp_cmp:
emit_nop(ctx);
break;
case BPF_JMP | BPF_JSET | BPF_X:
- ctx->flags |= SEEN_S0 | SEEN_X | SEEN_A;
+ ctx->flags |= SEEN_X | SEEN_A;
/* pc += (A & X) ? pc -> jt : pc -> jf */
emit_and(r_s0, r_A, r_X, ctx);
/* jump true */
@@ -1255,7 +1250,7 @@ jmp_cmp:
break;
case BPF_ANC | SKF_AD_IFINDEX:
/* A = skb->dev->ifindex */
- ctx->flags |= SEEN_SKB | SEEN_A | SEEN_S0;
+ ctx->flags |= SEEN_SKB | SEEN_A;
off = offsetof(struct sk_buff, dev);
/* Load *dev pointer */
emit_load_ptr(r_s0, r_skb, off, ctx);
@@ -1282,7 +1277,7 @@ jmp_cmp:
break;
case BPF_ANC | SKF_AD_VLAN_TAG:
case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
- ctx->flags |= SEEN_SKB | SEEN_S0 | SEEN_A;
+ ctx->flags |= SEEN_SKB | SEEN_A;
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
vlan_tci) != 2);
off = offsetof(struct sk_buff, vlan_tci);
diff --git a/arch/mips/net/bpf_jit.h b/arch/mips/net/bpf_jit.h
index 3a5751b4335a..f9b5a4d3dbf4 100644
--- a/arch/mips/net/bpf_jit.h
+++ b/arch/mips/net/bpf_jit.h
@@ -18,6 +18,8 @@
#define MIPS_R_V1 3
#define MIPS_R_A0 4
#define MIPS_R_A1 5
+#define MIPS_R_T4 12
+#define MIPS_R_T5 13
#define MIPS_R_T6 14
#define MIPS_R_T7 15
#define MIPS_R_S0 16
--
2.4.2
--
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