| From f522c2c36e486d2225b323abfc278aad7c51812a Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| 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 |
| |
| From: Paul Chaignon <paul.chaignon@orange.com> |
| |
| [ Upstream commit 96bc4432f5ade1045521f3b247f516b1478166bd ] |
| |
| 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 <khezri.mahshid@gmail.com> |
| Signed-off-by: Paul Chaignon <paul.chaignon@orange.com> |
| Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> |
| Acked-by: Björn Töpel <bjorn.topel@gmail.com> |
| Acked-by: Martin KaFai Lau <kafai@fb.com> |
| Link: https://lore.kernel.org/bpf/966fe384383bf23a0ee1efe8d7291c78a3fb832b.1575916815.git.paul.chaignon@gmail.com |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/riscv/net/bpf_jit_comp.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| 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) |
| -- |
| 2.20.1 |
| |