From: Yang Jihong <yangjihong1@huawei.com>
To: <ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
<martin.lau@linux.dev>, <song@kernel.org>, <yhs@fb.com>,
<john.fastabend@gmail.com>, <kpsingh@kernel.org>,
<sdf@google.com>, <haoluo@google.com>, <jolsa@kernel.org>,
<illusionist.neo@gmail.com>, <linux@armlinux.org.uk>,
<davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
<pabeni@redhat.com>, <mykolal@fb.com>, <shuah@kernel.org>,
<benjamin.tissoires@redhat.com>, <memxor@gmail.com>,
<asavkov@redhat.com>, <delyank@fb.com>, <bpf@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>
Cc: <yangjihong1@huawei.com>
Subject: [PATCH bpf v2 3/5] libbpf: Skip adjust mem size for load pointer in 32-bit arch in CO_RE
Date: Mon, 7 Nov 2022 17:20:30 +0800 [thread overview]
Message-ID: <20221107092032.178235-4-yangjihong1@huawei.com> (raw)
In-Reply-To: <20221107092032.178235-1-yangjihong1@huawei.com>
bpf_core_patch_insn modifies load's mem size from 8 bytes to 4 bytes.
As a result, the bpf check fails, we need to skip adjust mem size to fit
the verifier.
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
---
tools/lib/bpf/libbpf.c | 34 +++++++++++++++++++++++++++++-----
1 file changed, 29 insertions(+), 5 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 184ce1684dcd..e1c21b631a0b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5634,6 +5634,28 @@ static int bpf_core_resolve_relo(struct bpf_program *prog,
targ_res);
}
+static bool
+bpf_core_patch_insn_skip(const struct btf *local_btf, const struct bpf_insn *insn,
+ const struct bpf_core_relo_res *res)
+{
+ __u8 class;
+ const struct btf_type *orig_t;
+
+ class = BPF_CLASS(insn->code);
+ orig_t = btf_type_by_id(local_btf, res->orig_type_id);
+
+ /*
+ * verifier has to see a load of a pointer as a 8-byte load,
+ * CO_RE should not screws up access, bpf_core_patch_insn modifies
+ * load's mem size from 8 bytes to 4 bytes in 32-bit arch,
+ * so we skip adjust mem size.
+ */
+ if (class == BPF_LDX && btf_is_ptr(orig_t))
+ return true;
+
+ return false;
+}
+
static int
bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
{
@@ -5730,11 +5752,13 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
goto out;
}
- err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res);
- if (err) {
- pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %d\n",
- prog->name, i, insn_idx, err);
- goto out;
+ if (!bpf_core_patch_insn_skip(obj->btf, insn, &targ_res)) {
+ err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res);
+ if (err) {
+ pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %d\n",
+ prog->name, i, insn_idx, err);
+ goto out;
+ }
}
}
}
--
2.30.GIT
next prev parent reply other threads:[~2022-11-07 9:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-07 9:20 [PATCH bpf v2 0/5] bpf: Support kernel function call in 32-bit ARM Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 1/5] bpf: Adapt 32-bit return value kfunc for 32-bit ARM when zext extension Yang Jihong
2022-11-08 23:12 ` Martin KaFai Lau
2022-11-26 9:45 ` Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 2/5] bpf: Adjust sk size check for sk in bpf_skb_is_valid_access for CO_RE in 32-bit arch Yang Jihong
2022-11-07 9:20 ` Yang Jihong [this message]
2022-11-08 1:22 ` [PATCH bpf v2 3/5] libbpf: Skip adjust mem size for load pointer in 32-bit arch in CO_RE Andrii Nakryiko
2022-11-08 2:44 ` Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 4/5] bpf: Add kernel function call support in 32-bit ARM for EABI Yang Jihong
2022-11-07 12:33 ` Russell King (Oracle)
2022-11-08 0:52 ` Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 5/5] bpf:selftests: Add kfunc_call test for mixing 32-bit and 64-bit parameters Yang Jihong
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