From 96bc4432f5ade1045521f3b247f516b1478166bd Mon Sep 17 00:00:00 2001 From: Paul Chaignon Date: Mon, 9 Dec 2019 19:52:07 +0100 Subject: bpf, riscv: Limit to 33 tail calls MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit All BPF JIT compilers except RISC-V's and MIPS' enforce a 33-tail calls limit at runtime. In addition, a test was recently added, in tailcalls2, to check this limit. This patch updates the tail call limit in RISC-V's JIT compiler to allow 33 tail calls. I tested it using the above selftest on an emulated RISCV64. Fixes: 2353ecc6f91f ("bpf, riscv: add BPF JIT for RV64G") Reported-by: Mahshid Khezri Signed-off-by: Paul Chaignon Signed-off-by: Daniel Borkmann Acked-by: Björn Töpel Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/966fe384383bf23a0ee1efe8d7291c78a3fb832b.1575916815.git.paul.chaignon@gmail.com --- arch/riscv/net/bpf_jit_comp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c index 5451ef3845f2..7fbf56aab661 100644 --- a/arch/riscv/net/bpf_jit_comp.c +++ b/arch/riscv/net/bpf_jit_comp.c @@ -631,14 +631,14 @@ static int emit_bpf_tail_call(int insn, struct rv_jit_context *ctx) return -1; emit(rv_bgeu(RV_REG_A2, RV_REG_T1, off >> 1), ctx); - /* if (--TCC < 0) + /* if (TCC-- < 0) * goto out; */ emit(rv_addi(RV_REG_T1, tcc, -1), ctx); off = (tc_ninsn - (ctx->ninsns - start_insn)) << 2; if (is_13b_check(off, insn)) return -1; - emit(rv_blt(RV_REG_T1, RV_REG_ZERO, off >> 1), ctx); + emit(rv_blt(tcc, RV_REG_ZERO, off >> 1), ctx); /* prog = array->ptrs[index]; * if (!prog) -- cgit From e49e6f6db04e915dccb494ae10fa14888fea6f89 Mon Sep 17 00:00:00 2001 From: Paul Chaignon Date: Mon, 9 Dec 2019 19:52:52 +0100 Subject: bpf, mips: Limit to 33 tail calls All BPF JIT compilers except RISC-V's and MIPS' enforce a 33-tail calls limit at runtime. In addition, a test was recently added, in tailcalls2, to check this limit. This patch updates the tail call limit in MIPS' JIT compiler to allow 33 tail calls. Fixes: b6bd53f9c4e8 ("MIPS: Add missing file for eBPF JIT.") Reported-by: Mahshid Khezri Signed-off-by: Paul Chaignon Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/b8eb2caac1c25453c539248e56ca22f74b5316af.1575916815.git.paul.chaignon@gmail.com --- arch/mips/net/ebpf_jit.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c index 46b76751f3a5..3ec69d9cbe88 100644 --- a/arch/mips/net/ebpf_jit.c +++ b/arch/mips/net/ebpf_jit.c @@ -604,6 +604,7 @@ static void emit_const_to_reg(struct jit_ctx *ctx, int dst, u64 value) static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx) { int off, b_off; + int tcc_reg; ctx->flags |= EBPF_SEEN_TC; /* @@ -616,14 +617,14 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx) b_off = b_imm(this_idx + 1, ctx); emit_instr(ctx, bne, MIPS_R_AT, MIPS_R_ZERO, b_off); /* - * if (--TCC < 0) + * if (TCC-- < 0) * goto out; */ /* Delay slot */ - emit_instr(ctx, daddiu, MIPS_R_T5, - (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4, -1); + tcc_reg = (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4; + emit_instr(ctx, daddiu, MIPS_R_T5, tcc_reg, -1); b_off = b_imm(this_idx + 1, ctx); - emit_instr(ctx, bltz, MIPS_R_T5, b_off); + emit_instr(ctx, bltz, tcc_reg, b_off); /* * prog = array->ptrs[index]; * if (prog == NULL) -- cgit