From: Alexei Starovoitov <ast@kernel.org>
To: <davem@davemloft.net>
Cc: <daniel@iogearbox.net>, <netdev@vger.kernel.org>,
<bpf@vger.kernel.org>, <kernel-team@fb.com>
Subject: [PATCH v3 bpf-next 1/6] libbpf: Sanitize global functions
Date: Thu, 9 Jan 2020 22:41:19 -0800 [thread overview]
Message-ID: <20200110064124.1760511-2-ast@kernel.org> (raw)
In-Reply-To: <20200110064124.1760511-1-ast@kernel.org>
In case the kernel doesn't support BTF_FUNC_GLOBAL sanitize BTF produced by the
compiler for global functions.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
---
tools/include/uapi/linux/btf.h | 6 ++++++
tools/lib/bpf/libbpf.c | 35 +++++++++++++++++++++++++++++++++-
2 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/tools/include/uapi/linux/btf.h b/tools/include/uapi/linux/btf.h
index 1a2898c482ee..5a667107ad2c 100644
--- a/tools/include/uapi/linux/btf.h
+++ b/tools/include/uapi/linux/btf.h
@@ -146,6 +146,12 @@ enum {
BTF_VAR_GLOBAL_EXTERN = 2,
};
+enum btf_func_linkage {
+ BTF_FUNC_STATIC = 0,
+ BTF_FUNC_GLOBAL = 1,
+ BTF_FUNC_EXTERN = 2,
+};
+
/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
* additional information related to the variable such as its linkage.
*/
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ee2620b2aa55..3afd780b0f06 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -173,6 +173,8 @@ struct bpf_capabilities {
__u32 btf_datasec:1;
/* BPF_F_MMAPABLE is supported for arrays */
__u32 array_mmap:1;
+ /* BTF_FUNC_GLOBAL is supported */
+ __u32 btf_func_global:1;
};
enum reloc_type {
@@ -2209,13 +2211,14 @@ static bool section_have_execinstr(struct bpf_object *obj, int idx)
static void bpf_object__sanitize_btf(struct bpf_object *obj)
{
+ bool has_func_global = obj->caps.btf_func_global;
bool has_datasec = obj->caps.btf_datasec;
bool has_func = obj->caps.btf_func;
struct btf *btf = obj->btf;
struct btf_type *t;
int i, j, vlen;
- if (!obj->btf || (has_func && has_datasec))
+ if (!obj->btf || (has_func && has_datasec && has_func_global))
return;
for (i = 1; i <= btf__get_nr_types(btf); i++) {
@@ -2263,6 +2266,9 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj)
} else if (!has_func && btf_is_func(t)) {
/* replace FUNC with TYPEDEF */
t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
+ } else if (!has_func_global && btf_is_func(t)) {
+ /* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
+ t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
}
}
}
@@ -3205,6 +3211,32 @@ static int bpf_object__probe_btf_func(struct bpf_object *obj)
return 0;
}
+static int bpf_object__probe_btf_func_global(struct bpf_object *obj)
+{
+ static const char strs[] = "\0int\0x\0a";
+ /* static void x(int a) {} */
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* FUNC_PROTO */ /* [2] */
+ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+ BTF_PARAM_ENC(7, 1),
+ /* FUNC x BTF_FUNC_GLOBAL */ /* [3] */
+ BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
+ };
+ int btf_fd;
+
+ btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs));
+ if (btf_fd >= 0) {
+ obj->caps.btf_func_global = 1;
+ close(btf_fd);
+ return 1;
+ }
+
+ return 0;
+}
+
static int bpf_object__probe_btf_datasec(struct bpf_object *obj)
{
static const char strs[] = "\0x\0.data";
@@ -3260,6 +3292,7 @@ bpf_object__probe_caps(struct bpf_object *obj)
bpf_object__probe_name,
bpf_object__probe_global_data,
bpf_object__probe_btf_func,
+ bpf_object__probe_btf_func_global,
bpf_object__probe_btf_datasec,
bpf_object__probe_array_mmap,
};
--
2.23.0
next prev parent reply other threads:[~2020-01-10 6:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 6:41 [PATCH v3 bpf-next 0/6] bpf: Introduce global functions Alexei Starovoitov
2020-01-10 6:41 ` Alexei Starovoitov [this message]
2020-01-10 6:41 ` [PATCH v3 bpf-next 2/6] bpf: Introduce function-by-function verification Alexei Starovoitov
2020-01-10 6:41 ` [PATCH v3 bpf-next 3/6] selftests/bpf: Add fexit-to-skb test for global funcs Alexei Starovoitov
2020-01-10 6:41 ` [PATCH v3 bpf-next 4/6] selftests/bpf: Add a test for a large global function Alexei Starovoitov
2020-01-10 6:41 ` [PATCH v3 bpf-next 5/6] selftests/bpf: Modify a test to check global functions Alexei Starovoitov
2020-01-10 6:41 ` [PATCH v3 bpf-next 6/6] selftests/bpf: Add unit tests for " Alexei Starovoitov
2020-01-10 16:29 ` [PATCH v3 bpf-next 0/6] bpf: Introduce " Daniel Borkmann
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