Rather than moving constants to a register and then using them in a
subsequent instruction, use them directly in the desired instruction
cutting out the "middle" register. This removes two instructions from
the tail call code path.
Signed-off-by: Russell King <rmk+ker...@armlinux.org.uk>
---
arch/arm/net/bpf_jit_32.c | 21 ++++++++++++---------
arch/arm/net/bpf_jit_32.h | 1 +
2 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 2cc66aa44dfe..645653e1931e 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -304,7 +304,7 @@ static u32 arm_bpf_ldst_imm12(u32 op, u8 rt, u8 rn, s16
imm12)
op |= ARM_INST_LDST__U;
else
imm12 = -imm12;
- return op | (imm12 & 0xfff);
+ return op | (imm12 & ARM_INST_LDST__IMM12);
}
static u32 arm_bpf_ldst_imm8(u32 op, u8 rt, u8 rn, s16 imm8)
@@ -1054,17 +1054,19 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
const int idx0 = ctx->idx;
#define cur_offset (ctx->idx - idx0)
#define jmp_offset (out_offset - (cur_offset) - 2)
- u32 off, lo, hi;
+ u32 lo, hi;
s8 r_array, r_index;
+ int off;
/* if (index >= array->map.max_entries)
* goto out;
*/
+ 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 */
- emit_a32_mov_i(tmp[1], off, ctx);
r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx);
- emit(ARM_LDR_R(tmp[1], r_array, tmp[1]), ctx);
+ emit(ARM_LDR_I(tmp[1], r_array, off), ctx);
/* index is 32-bit for arrays */
r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx);
/* index >= array->map.max_entries */
@@ -1089,10 +1091,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
* if (prog == NULL)
* goto out;
*/
- off = offsetof(struct bpf_array, ptrs);
- emit_a32_mov_i(tmp[1], off, 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);
- emit(ARM_ADD_R(tmp[1], r_array, tmp[1]), ctx);
+ emit(ARM_ADD_I(tmp[1], r_array, off), ctx);
r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx);
emit(ARM_MOV_SI(tmp[0], r_index, SRTYPE_ASL, 2), ctx);
emit(ARM_LDR_R(tmp[1], tmp[1], tmp[0]), ctx);
@@ -1100,9 +1102,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
_emit(ARM_COND_EQ, ARM_B(jmp_offset), ctx);
/* goto *(prog->bpf_func + prologue_size); */
+ BUILD_BUG_ON(offsetof(struct bpf_prog, bpf_func) >
+ ARM_INST_LDST__IMM12);
off = offsetof(struct bpf_prog, bpf_func);
- emit_a32_mov_i(tmp2[1], off, ctx);
- emit(ARM_LDR_R(tmp[1], tmp[1], tmp2[1]), ctx);
+ emit(ARM_LDR_I(tmp[1], tmp[1], off), ctx);
emit(ARM_ADD_I(tmp[1], tmp[1], ctx->prologue_bytes), ctx);
emit_bx_r(tmp[1], ctx);
diff --git a/arch/arm/net/bpf_jit_32.h b/arch/arm/net/bpf_jit_32.h
index c55bc39d3e22..dee8a76fb0bc 100644
--- a/arch/arm/net/bpf_jit_32.h
+++ b/arch/arm/net/bpf_jit_32.h
@@ -78,6 +78,7 @@
#define ARM_INST_EOR_I 0x02200000
#define ARM_INST_LDST__U 0x00800000
+#define ARM_INST_LDST__IMM12 0x00000fff
#define ARM_INST_LDRB_I 0x05500000
#define ARM_INST_LDRB_R 0x07d00000
#define ARM_INST_LDRH_I 0x015000b0
--
2.7.4
