On Mon, 16 Dec 2019 01:13:39 PST (-0800), Bjorn Topel wrote:
Remove one addi, and instead use the offset part of jalr.
Signed-off-by: Björn Töpel <bjorn.topel@xxxxxxxxx>
---
arch/riscv/net/bpf_jit_comp.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
index 2fc0f24ad30f..8aa19c846881 100644
--- a/arch/riscv/net/bpf_jit_comp.c
+++ b/arch/riscv/net/bpf_jit_comp.c
@@ -552,7 +552,7 @@ static int epilogue_offset(struct rv_jit_context *ctx)
return (to - from) << 2;
}
-static void __build_epilogue(u8 reg, struct rv_jit_context *ctx)
+static void __build_epilogue(bool is_tail_call, struct rv_jit_context *ctx)
{
int stack_adjust = ctx->stack_size, store_offset = stack_adjust - 8;
@@ -589,9 +589,11 @@ static void __build_epilogue(u8 reg, struct rv_jit_context *ctx)
emit(rv_addi(RV_REG_SP, RV_REG_SP, stack_adjust), ctx);
/* Set return value. */
- if (reg == RV_REG_RA)
+ if (!is_tail_call)
emit(rv_addi(RV_REG_A0, RV_REG_A5, 0), ctx);
- emit(rv_jalr(RV_REG_ZERO, reg, 0), ctx);
+ emit(rv_jalr(RV_REG_ZERO, is_tail_call ? RV_REG_T3 : RV_REG_RA,
+ is_tail_call ? 4 : 0), /* skip TCC init */
+ ctx);
}
/* return -1 or inverted cond */
@@ -751,9 +753,8 @@ static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx)
if (is_12b_check(off, insn))
return -1;
emit(rv_ld(RV_REG_T3, off, RV_REG_T2), ctx);
- emit(rv_addi(RV_REG_T3, RV_REG_T3, 4), ctx);
emit(rv_addi(RV_REG_TCC, RV_REG_T1, 0), ctx);
- __build_epilogue(RV_REG_T3, ctx);
+ __build_epilogue(true, ctx);
return 0;
}
@@ -1504,7 +1505,7 @@ static void build_prologue(struct rv_jit_context *ctx)
static void build_epilogue(struct rv_jit_context *ctx)
{
- __build_epilogue(RV_REG_RA, ctx);
+ __build_epilogue(false, ctx);
}
static int build_body(struct rv_jit_context *ctx, bool extra_pass)
Reviewed-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
Acked-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
