From: Yonghong Song <yhs@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>, <bpf@ietf.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Fangrui Song <maskray@google.com>, <kernel-team@fb.com>
Subject: [PATCH bpf-next v3 03/17] bpf: Handle sign-extenstin ctx member accesses
Date: Wed, 19 Jul 2023 17:01:19 -0700 [thread overview]
Message-ID: <20230720000119.103561-1-yhs@fb.com> (raw)
In-Reply-To: <20230720000103.99949-1-yhs@fb.com>
Currently, if user accesses a ctx member with signed types,
the compiler will generate an unsigned load followed by
necessary left and right shifts.
With the introduction of sign-extension load, compiler may
just emit a ldsx insn instead. Let us do a final movsx sign
extension to the final unsigned ctx load result to
satisfy original sign extension requirement.
Signed-off-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/verifier.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index fc82b5e77cbe..b9be8706bf48 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -17716,6 +17716,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
for (i = 0; i < insn_cnt; i++, insn++) {
bpf_convert_ctx_access_t convert_ctx_access;
+ u8 mode;
if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
@@ -17797,6 +17798,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
size = BPF_LDST_BYTES(insn);
+ mode = BPF_MODE(insn->code);
/* If the read access is a narrower load of the field,
* convert to a 4/8-byte load, to minimum program type specific
@@ -17856,6 +17858,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
(1ULL << size * 8) - 1);
}
}
+ if (mode == BPF_MEMSX)
+ insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X,
+ insn->dst_reg, insn->dst_reg,
+ size * 8, 0);
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
--
2.34.1
next prev parent reply other threads:[~2023-07-20 0:01 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-20 0:01 [PATCH bpf-next v3 00/17] bpf: Support new insns from cpu v4 Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 01/17] bpf: Support new sign-extension load insns Yonghong Song
2023-07-20 20:33 ` Eduard Zingerman
2023-07-24 4:03 ` [Bpf] " Yonghong Song
2023-07-24 4:03 ` Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 02/17] bpf: Support new sign-extension mov insns Yonghong Song
2023-07-20 0:01 ` Yonghong Song [this message]
2023-07-20 0:01 ` [PATCH bpf-next v3 04/17] bpf: Support new unconditional bswap instruction Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 05/17] bpf: Support new signed div/mod instructions Yonghong Song
2023-07-20 0:01 ` [Bpf] " Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 06/17] bpf: Fix jit blinding with new sdiv/smov insns Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 07/17] bpf: Support new 32bit offset jmp instruction Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 08/17] bpf: Add kernel/bpftool asm support for new instructions Yonghong Song
2023-07-21 14:36 ` Quentin Monnet
2023-07-21 14:36 ` [Bpf] " Quentin Monnet
2023-07-20 0:01 ` [PATCH bpf-next v3 09/17] selftests/bpf: Fix a test_verifier failure Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 10/17] selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 11/17] selftests/bpf: Add unit tests for new sign-extension load insns Yonghong Song
2023-07-20 6:31 ` [Bpf] " Yonghong Song
2023-07-20 6:31 ` Yonghong Song
2023-07-20 6:36 ` [Bpf] " Yonghong Song
2023-07-20 6:36 ` Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 12/17] selftests/bpf: Add unit tests for new sign-extension mov insns Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 13/17] selftests/bpf: Add unit tests for new bswap insns Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 14/17] selftests/bpf: Add unit tests for new sdiv/smod insns Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 15/17] selftests/bpf: Add unit tests for new gotol insn Yonghong Song
2023-07-20 0:02 ` [Bpf] " Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 16/17] selftests/bpf: Test ldsx with more complex cases Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 17/17] docs/bpf: Add documentation for new instructions Yonghong Song
2023-07-20 20:35 ` [PATCH bpf-next v3 00/17] bpf: Support new insns from cpu v4 Eduard Zingerman
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