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 2/2] bpf, mips: limit to 33 tail calls
Date: Mon, 9 Dec 2019 19:52:52 +0100 [thread overview]
Message-ID: <b8eb2caac1c25453c539248e56ca22f74b5316af.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 MIPS' JIT compiler to allow
33 tail calls.
Fixes: b6bd53f9c4e8 ("MIPS: Add missing file for eBPF JIT.")
Reported-by: Mahshid Khezri <khezri.mahshid@gmail.com>
Signed-off-by: Paul Chaignon <paul.chaignon@orange.com>
---
arch/mips/net/ebpf_jit.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
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)
--
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 ` [PATCH bpf 1/2] bpf, riscv: limit to 33 tail calls Paul Chaignon
2019-12-09 19:57 ` Björn Töpel
2019-12-10 6:31 ` Björn Töpel
2019-12-10 9:36 ` Paul Chaignon
2019-12-09 18:52 ` Paul Chaignon [this message]
2019-12-10 23:23 ` [PATCH bpf 2/2] bpf, mips: " 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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=b8eb2caac1c25453c539248e56ca22f74b5316af.1575916815.git.paul.chaignon@gmail.com \
--to=paul.chaignon@orange.com \
--cc=andriin@fb.com \
--cc=ast@kernel.org \
--cc=bjorn.topel@gmail.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kafai@fb.com \
--cc=khezri.mahshid@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=paul.chaignon@gmail.com \
--cc=paulburton@kernel.org \
--cc=songliubraving@fb.com \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).