From e368b64f8b0c8066115ad1da71f83f20f7bb43af Mon Sep 17 00:00:00 2001 From: Björn Töpel Date: Mon, 16 Dec 2019 10:13:41 +0100 Subject: riscv, bpf: Optimize calls Instead of using emit_imm() and emit_jalr() which can expand to six instructions, start using jal or auipc+jalr. Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20191216091343.23260-8-bjorn.topel@gmail.com --- arch/riscv/net/bpf_jit_comp.c | 101 ++++++++++++++++++++++++++---------------- 1 file changed, 64 insertions(+), 37 deletions(-) diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c index 46cff093f526..8d7e3343a08c 100644 --- a/arch/riscv/net/bpf_jit_comp.c +++ b/arch/riscv/net/bpf_jit_comp.c @@ -811,11 +811,12 @@ static void emit_sext_32_rd(u8 *rd, struct rv_jit_context *ctx) *rd = RV_REG_T2; } -static void emit_jump_and_link(u8 rd, int rvoff, struct rv_jit_context *ctx) +static void emit_jump_and_link(u8 rd, s64 rvoff, bool force_jalr, + struct rv_jit_context *ctx) { s64 upper, lower; - if (is_21b_int(rvoff)) { + if (rvoff && is_21b_int(rvoff) && !force_jalr) { emit(rv_jal(rd, rvoff >> 1), ctx); return; } @@ -832,6 +833,28 @@ static bool is_signed_bpf_cond(u8 cond) cond == BPF_JSGE || cond == BPF_JSLE; } +static int emit_call(bool fixed, u64 addr, struct rv_jit_context *ctx) +{ + s64 off = 0; + u64 ip; + u8 rd; + + if (addr && ctx->insns) { + ip = (u64)(long)(ctx->insns + ctx->ninsns); + off = addr - ip; + if (!is_32b_int(off)) { + pr_err("bpf-jit: target call addr %pK is out of range\n", + (void *)addr); + return -ERANGE; + } + } + + emit_jump_and_link(RV_REG_RA, off, !fixed, ctx); + rd = bpf_to_rv_reg(BPF_REG_0, ctx); + emit(rv_addi(rd, RV_REG_A0, 0), ctx); + return 0; +} + static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, bool extra_pass) { @@ -1107,7 +1130,7 @@ out_be: /* JUMP off */ case BPF_JMP | BPF_JA: rvoff = rv_offset(i, off, ctx); - emit_jump_and_link(RV_REG_ZERO, rvoff, ctx); + emit_jump_and_link(RV_REG_ZERO, rvoff, false, ctx); break; /* IF (dst COND src) JUMP off */ @@ -1209,7 +1232,7 @@ out_be: case BPF_JMP | BPF_CALL: { bool fixed; - int i, ret; + int ret; u64 addr; mark_call(ctx); @@ -1217,20 +1240,9 @@ out_be: &fixed); if (ret < 0) return ret; - if (fixed) { - emit_imm(RV_REG_T1, addr, ctx); - } else { - i = ctx->ninsns; - emit_imm(RV_REG_T1, addr, ctx); - for (i = ctx->ninsns - i; i < 8; i++) { - /* nop */ - emit(rv_addi(RV_REG_ZERO, RV_REG_ZERO, 0), - ctx); - } - } - emit(rv_jalr(RV_REG_RA, RV_REG_T1, 0), ctx); - rd = bpf_to_rv_reg(BPF_REG_0, ctx); - emit(rv_addi(rd, RV_REG_A0, 0), ctx); + ret = emit_call(fixed, addr, ctx); + if (ret) + return ret; break; } /* tail call */ @@ -1245,7 +1257,7 @@ out_be: break; rvoff = epilogue_offset(ctx); - emit_jump_and_link(RV_REG_ZERO, rvoff, ctx); + emit_jump_and_link(RV_REG_ZERO, rvoff, false, ctx); break; /* dst = imm64 */ @@ -1508,7 +1520,7 @@ static void build_epilogue(struct rv_jit_context *ctx) __build_epilogue(false, ctx); } -static int build_body(struct rv_jit_context *ctx, bool extra_pass) +static int build_body(struct rv_jit_context *ctx, bool extra_pass, int *offset) { const struct bpf_prog *prog = ctx->prog; int i; @@ -1520,12 +1532,12 @@ static int build_body(struct rv_jit_context *ctx, bool extra_pass) ret = emit_insn(insn, ctx, extra_pass); if (ret > 0) { i++; - if (ctx->insns == NULL) - ctx->offset[i] = ctx->ninsns; + if (offset) + offset[i] = ctx->ninsns; continue; } - if (ctx->insns == NULL) - ctx->offset[i] = ctx->ninsns; + if (offset) + offset[i] = ctx->ninsns; if (ret) return ret; } @@ -1553,8 +1565,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) struct bpf_prog *tmp, *orig_prog = prog; int pass = 0, prev_ninsns = 0, i; struct rv_jit_data *jit_data; + unsigned int image_size = 0; struct rv_jit_context *ctx; - unsigned int image_size; if (!prog->jit_requested) return orig_prog; @@ -1599,36 +1611,51 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) for (i = 0; i < 16; i++) { pass++; ctx->ninsns = 0; - if (build_body(ctx, extra_pass)) { + if (build_body(ctx, extra_pass, ctx->offset)) { prog = orig_prog; goto out_offset; } build_prologue(ctx); ctx->epilogue_offset = ctx->ninsns; build_epilogue(ctx); - if (ctx->ninsns == prev_ninsns) - break; + + if (ctx->ninsns == prev_ninsns) { + if (jit_data->header) + break; + + image_size = sizeof(u32) * ctx->ninsns; + jit_data->header = + bpf_jit_binary_alloc(image_size, + &jit_data->image, + sizeof(u32), + bpf_fill_ill_insns); + if (!jit_data->header) { + prog = orig_prog; + goto out_offset; + } + + ctx->insns = (u32 *)jit_data->image; + /* Now, when the image is allocated, the image + * can potentially shrink more (auipc/jalr -> + * jal). + */ + } prev_ninsns = ctx->ninsns; } - /* Allocate image, now that we know the size. */ - image_size = sizeof(u32) * ctx->ninsns; - jit_data->header = bpf_jit_binary_alloc(image_size, &jit_data->image, - sizeof(u32), - bpf_fill_ill_insns); - if (!jit_data->header) { + if (i == 16) { + pr_err("bpf-jit: image did not converge in <%d passes!\n", i); + bpf_jit_binary_free(jit_data->header); prog = orig_prog; goto out_offset; } - /* Second, real pass, that acutally emits the image. */ - ctx->insns = (u32 *)jit_data->image; skip_init_ctx: pass++; ctx->ninsns = 0; build_prologue(ctx); - if (build_body(ctx, extra_pass)) { + if (build_body(ctx, extra_pass, NULL)) { bpf_jit_binary_free(jit_data->header); prog = orig_prog; goto out_offset; -- cgit v1.2.3