From: "Alexis Lothoré (eBPF Foundation)" <alexis.lothore@bootlin•com>
To: Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <daniel@iogearbox•net>,
Andrii Nakryiko <andrii@kernel•org>,
Martin KaFai Lau <martin.lau@linux•dev>,
Eduard Zingerman <eddyz87@gmail•com>,
Kumar Kartikeya Dwivedi <memxor@gmail•com>,
Song Liu <song@kernel•org>,
Yonghong Song <yonghong.song@linux•dev>,
Jiri Olsa <jolsa@kernel•org>,
John Fastabend <john.fastabend@gmail•com>,
Thomas Gleixner <tglx@kernel•org>,
Ingo Molnar <mingo@redhat•com>, Borislav Petkov <bp@alien8•de>,
Dave Hansen <dave.hansen@linux•intel.com>,
x86@kernel•org, "H. Peter Anvin" <hpa@zytor•com>,
Shuah Khan <shuah@kernel•org>,
Maxime Coquelin <mcoquelin.stm32@gmail•com>,
Alexandre Torgue <alexandre.torgue@foss•st.com>,
Ihor Solodrai <ihor.solodrai@linux•dev>
Cc: ebpf@linuxfoundation•org,
"Bastien Curutchet" <bastien.curutchet@bootlin•com>,
"Thomas Petazzoni" <thomas.petazzoni@bootlin•com>,
bpf@vger•kernel.org, linux-kernel@vger•kernel.org,
linux-kselftest@vger•kernel.org,
linux-stm32@st-md-mailman•stormreply.com,
linux-arm-kernel@lists•infradead.org,
"Alexis Lothoré (eBPF Foundation)" <alexis.lothore@bootlin•com>
Subject: [PATCH bpf-next v2 4/8] bpf, x86: refactor BPF_ST management in do_jit
Date: Thu, 04 Jun 2026 22:22:02 +0200 [thread overview]
Message-ID: <20260604-kasan-v2-4-c066e627fda8@bootlin.com> (raw)
In-Reply-To: <20260604-kasan-v2-0-c066e627fda8@bootlin.com>
In order to prepare for KASAN checks insertion before every
memory-related load or store, group all BPF_ST instructions that indeed
access memory in a single block of fall-through cases to allow
instrumenting those in one call, rather than having to instrument all
cases individually.
Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin•com>
---
arch/x86/net/bpf_jit_comp.c | 53 ++++++++++++++++++++++++++-------------------
1 file changed, 31 insertions(+), 22 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 0981791014eb..943a0f315cf2 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2300,41 +2300,50 @@ static int do_jit(struct bpf_verifier_env *env, struct bpf_prog *bpf_prog, int *
EMIT_LFENCE();
break;
- /* ST: *(u8*)(dst_reg + off) = imm */
case BPF_ST | BPF_MEM | BPF_B:
- if (is_ereg(dst_reg))
- EMIT2(0x41, 0xC6);
- else
- EMIT1(0xC6);
- goto st;
case BPF_ST | BPF_MEM | BPF_H:
- if (is_ereg(dst_reg))
- EMIT3(0x66, 0x41, 0xC7);
- else
- EMIT2(0x66, 0xC7);
- goto st;
case BPF_ST | BPF_MEM | BPF_W:
- if (is_ereg(dst_reg))
- EMIT2(0x41, 0xC7);
- else
- EMIT1(0xC7);
- goto st;
case BPF_ST | BPF_MEM | BPF_DW:
- if (dst_reg == BPF_REG_PARAMS && insn->off == -8) {
- /* Arg 6: store immediate in r9 register */
- emit_mov_imm64(&prog, X86_REG_R9, imm32 >> 31, (u32)imm32);
+ switch (BPF_SIZE(insn->code)) {
+ case BPF_B:
+ if (is_ereg(dst_reg))
+ EMIT2(0x41, 0xC6);
+ else
+ EMIT1(0xC6);
+ break;
+ case BPF_H:
+ if (is_ereg(dst_reg))
+ EMIT3(0x66, 0x41, 0xC7);
+ else
+ EMIT2(0x66, 0xC7);
+ break;
+ case BPF_W:
+ if (is_ereg(dst_reg))
+ EMIT2(0x41, 0xC7);
+ else
+ EMIT1(0xC7);
+ break;
+ case BPF_DW:
+ if (dst_reg == BPF_REG_PARAMS &&
+ insn->off == -8) {
+ /* Arg 6: store immediate in r9 register */
+ emit_mov_imm64(&prog, X86_REG_R9,
+ imm32 >> 31, (u32)imm32);
+ break;
+ }
+ EMIT2(add_1mod(0x48, dst_reg), 0xC7);
break;
}
- EMIT2(add_1mod(0x48, dst_reg), 0xC7);
-st: insn_off = insn->off;
+ insn_off = insn->off;
if (dst_reg == BPF_REG_PARAMS) {
/*
* Args 7+: reverse BPF negative offsets to
* x86 positive rsp offsets.
* BPF off=-16 → [rsp+0], off=-24 → [rsp+8], ...
*/
- insn_off = outgoing_arg_base - outgoing_rsp - insn_off - 16;
+ insn_off = outgoing_arg_base - outgoing_rsp -
+ insn_off - 16;
dst_reg = BPF_REG_FP;
}
if (is_imm8(insn_off))
--
2.54.0
next prev parent reply other threads:[~2026-06-04 20:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-04 20:21 [PATCH bpf-next v2 0/8] bpf: add support for KASAN checks in JITed programs Alexis Lothoré (eBPF Foundation)
2026-06-04 20:21 ` [PATCH bpf-next v2 1/8] bpf: mark instructions accessing program stack Alexis Lothoré (eBPF Foundation)
2026-06-04 21:13 ` bot+bpf-ci
2026-06-04 20:22 ` [PATCH bpf-next v2 2/8] bpf: add BPF_JIT_KASAN for KASAN instrumentation of JITed programs Alexis Lothoré (eBPF Foundation)
2026-06-04 21:13 ` bot+bpf-ci
2026-06-04 20:22 ` [PATCH bpf-next v2 3/8] bpf, x86: add helper to emit kasan checks in x86 " Alexis Lothoré (eBPF Foundation)
2026-06-04 20:22 ` Alexis Lothoré (eBPF Foundation) [this message]
2026-06-04 21:13 ` [PATCH bpf-next v2 4/8] bpf, x86: refactor BPF_ST management in do_jit bot+bpf-ci
2026-06-04 20:22 ` [PATCH bpf-next v2 5/8] bpf, x86: emit KASAN checks into x86 JITed programs Alexis Lothoré (eBPF Foundation)
2026-06-04 20:22 ` [PATCH bpf-next v2 6/8] bpf, x86: enable KASAN for JITed programs on x86 Alexis Lothoré (eBPF Foundation)
2026-06-04 20:22 ` [PATCH bpf-next v2 7/8] selftests/bpf: add helper to check whether eBPF KASAN is active Alexis Lothoré (eBPF Foundation)
2026-06-04 20:22 ` [PATCH bpf-next v2 8/8] selftests/bpf: add tests to validate KASAN on JIT programs Alexis Lothoré (eBPF Foundation)
2026-06-04 21:45 ` bot+bpf-ci
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=20260604-kasan-v2-4-c066e627fda8@bootlin.com \
--to=alexis.lothore@bootlin$(echo .)com \
--cc=alexandre.torgue@foss$(echo .)st.com \
--cc=andrii@kernel$(echo .)org \
--cc=ast@kernel$(echo .)org \
--cc=bastien.curutchet@bootlin$(echo .)com \
--cc=bp@alien8$(echo .)de \
--cc=bpf@vger$(echo .)kernel.org \
--cc=daniel@iogearbox$(echo .)net \
--cc=dave.hansen@linux$(echo .)intel.com \
--cc=ebpf@linuxfoundation$(echo .)org \
--cc=eddyz87@gmail$(echo .)com \
--cc=hpa@zytor$(echo .)com \
--cc=ihor.solodrai@linux$(echo .)dev \
--cc=john.fastabend@gmail$(echo .)com \
--cc=jolsa@kernel$(echo .)org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linux-kselftest@vger$(echo .)kernel.org \
--cc=linux-stm32@st-md-mailman$(echo .)stormreply.com \
--cc=martin.lau@linux$(echo .)dev \
--cc=mcoquelin.stm32@gmail$(echo .)com \
--cc=memxor@gmail$(echo .)com \
--cc=mingo@redhat$(echo .)com \
--cc=shuah@kernel$(echo .)org \
--cc=song@kernel$(echo .)org \
--cc=tglx@kernel$(echo .)org \
--cc=thomas.petazzoni@bootlin$(echo .)com \
--cc=x86@kernel$(echo .)org \
--cc=yonghong.song@linux$(echo .)dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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