From: Paul Chaignon <paul.chaignon@orange.com>
To: "Paul Burton" <paulburton@kernel.org>,
"Björn Töpel" <bjorn.topel@gmail.com>
Cc: Mahshid Khezri <khezri.mahshid@gmail.com>,
paul.chaignon@gmail.com, bpf@vger.kernel.org,
netdev@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH bpf 1/2] bpf, riscv: limit to 33 tail calls
Date: Mon, 9 Dec 2019 19:52:07 +0100 [thread overview]
Message-ID: <966fe384383bf23a0ee1efe8d7291c78a3fb832b.1575916815.git.paul.chaignon@gmail.com> (raw)
In-Reply-To: <cover.1575916815.git.paul.chaignon@gmail.com>
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>
---
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)
--
2.17.1
next prev parent reply other threads:[~2019-12-09 18:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 18:51 [PATCH bpf 0/2] Limit tail calls to 33 in all JIT compilers Paul Chaignon
2019-12-09 18:52 ` Paul Chaignon [this message]
2019-12-09 19:57 ` [PATCH bpf 1/2] bpf, riscv: limit to 33 tail calls Björn Töpel
2019-12-10 6:31 ` Björn Töpel
2019-12-10 9:36 ` Paul Chaignon
2019-12-09 18:52 ` [PATCH bpf 2/2] bpf, mips: " Paul Chaignon
2019-12-10 23:23 ` Paul Burton
2019-12-12 16:19 ` Daniel Borkmann
2019-12-18 9:32 ` Alexander Lobakin
2019-12-18 9:58 ` Paul Chaignon
2019-12-18 10:02 ` Alexander Lobakin
2019-12-10 18:19 ` [PATCH bpf 0/2] Limit tail calls to 33 in all JIT compilers Martin Lau
2019-12-11 13:00 ` Daniel Borkmann
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