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.1575916... 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)