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Date: Mon, 23 Jun 2014 10:38:56 +0100
From: Markos Chandras <markos.chandras@...tec.com>
To: <linux-mips@...ux-mips.org>
CC: Markos Chandras <markos.chandras@...tec.com>,
"David S. Miller" <davem@...emloft.net>,
Daniel Borkmann <dborkman@...hat.com>,
"Alexei Starovoitov" <ast@...mgrid.com>, <netdev@...r.kernel.org>
Subject: [PATCH 13/17] MIPS: bpf: Drop update_on_xread and always initialize the X register
Previously, update_on_xread() only set the reset flag if SEEN_X hasn't
been set already. However, SEEN_X is used to indicate that X is used
as destination or source register so there are some cases where X
is only used as source register and we really need to make sure that it
has been initialized in time. As a result of which, drop this function and
always set X to zero if it's used in any of the opcodes.
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Daniel Borkmann <dborkman@...hat.com>
Cc: Alexei Starovoitov <ast@...mgrid.com>
Cc: netdev@...r.kernel.org
Signed-off-by: Markos Chandras <markos.chandras@...tec.com>
---
arch/mips/net/bpf_jit.c | 22 +---------------------
1 file changed, 1 insertion(+), 21 deletions(-)
diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
index 00c4c83972bb..1bcd599d9971 100644
--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -119,8 +119,6 @@
/* Arguments used by JIT */
#define ARGS_USED_BY_JIT 2 /* only applicable to 64-bit */
-#define FLAG_NEED_X_RESET (1 << 0)
-
#define SBIT(x) (1 << (x)) /* Signed version of BIT() */
/**
@@ -549,14 +547,6 @@ static inline u16 align_sp(unsigned int num)
return num;
}
-static inline void update_on_xread(struct jit_ctx *ctx)
-{
- if (!(ctx->flags & SEEN_X))
- ctx->flags |= FLAG_NEED_X_RESET;
-
- ctx->flags |= SEEN_X;
-}
-
static bool is_load_to_a(u16 inst)
{
switch (inst) {
@@ -701,7 +691,7 @@ static void build_prologue(struct jit_ctx *ctx)
if (ctx->flags & SEEN_SKB)
emit_reg_move(r_skb, MIPS_R_A0, ctx);
- if (ctx->flags & FLAG_NEED_X_RESET)
+ if (ctx->flags & SEEN_X)
emit_jit_reg_move(r_X, r_zero, ctx);
/* Do not leak kernel data to userspace */
@@ -876,7 +866,6 @@ load_common:
/* A <- P[X + k:1] */
load_order = 0;
load_ind:
- update_on_xread(ctx);
ctx->flags |= SEEN_OFF | SEEN_X;
emit_addiu(r_off, r_X, k, ctx);
goto load_common;
@@ -972,7 +961,6 @@ load_ind:
break;
case BPF_ALU | BPF_MUL | BPF_X:
/* A *= X */
- update_on_xread(ctx);
ctx->flags |= SEEN_A | SEEN_X;
emit_mul(r_A, r_A, r_X, ctx);
break;
@@ -1002,7 +990,6 @@ load_ind:
break;
case BPF_ALU | BPF_DIV | BPF_X:
/* A /= X */
- update_on_xread(ctx);
ctx->flags |= SEEN_X | SEEN_A;
/* Check if r_X is zero */
emit_bcond(MIPS_COND_EQ, r_X, r_zero,
@@ -1012,7 +999,6 @@ load_ind:
break;
case BPF_ALU | BPF_MOD | BPF_X:
/* A %= X */
- update_on_xread(ctx);
ctx->flags |= SEEN_X | SEEN_A;
/* Check if r_X is zero */
emit_bcond(MIPS_COND_EQ, r_X, r_zero,
@@ -1027,7 +1013,6 @@ load_ind:
break;
case BPF_ALU | BPF_OR | BPF_X:
/* A |= X */
- update_on_xread(ctx);
ctx->flags |= SEEN_A;
emit_ori(r_A, r_A, r_X, ctx);
break;
@@ -1039,7 +1024,6 @@ load_ind:
case BPF_ANC | SKF_AD_ALU_XOR_X:
case BPF_ALU | BPF_XOR | BPF_X:
/* A ^= X */
- update_on_xread(ctx);
ctx->flags |= SEEN_A;
emit_xor(r_A, r_A, r_X, ctx);
break;
@@ -1050,7 +1034,6 @@ load_ind:
break;
case BPF_ALU | BPF_AND | BPF_X:
/* A &= X */
- update_on_xread(ctx);
ctx->flags |= SEEN_A | SEEN_X;
emit_and(r_A, r_A, r_X, ctx);
break;
@@ -1062,7 +1045,6 @@ load_ind:
case BPF_ALU | BPF_LSH | BPF_X:
/* A <<= X */
ctx->flags |= SEEN_A | SEEN_X;
- update_on_xread(ctx);
emit_sllv(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_RSH | BPF_K:
@@ -1072,7 +1054,6 @@ load_ind:
break;
case BPF_ALU | BPF_RSH | BPF_X:
ctx->flags |= SEEN_A | SEEN_X;
- update_on_xread(ctx);
emit_srlv(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_NEG:
@@ -1243,7 +1224,6 @@ jmp_cmp:
case BPF_MISC | BPF_TXA:
/* A = X */
ctx->flags |= SEEN_A | SEEN_X;
- update_on_xread(ctx);
emit_jit_reg_move(r_A, r_X, ctx);
break;
/* AUX */
--
2.0.0
--
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