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authorAlexei Starovoitov <ast@kernel.org>2020-01-09 22:41:19 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2020-01-10 17:20:07 +0100
commit2d3eb67f64ec317bbfe340cfcc8325d40a6ff317 (patch)
tree5af845b22b56292a359da753e7dff4d53aa49aa6 /tools/lib/bpf/libbpf.c
parentMerge branch 'selftest-makefile-cleanup' (diff)
downloadlinux-dev-2d3eb67f64ec317bbfe340cfcc8325d40a6ff317.tar.xz
linux-dev-2d3eb67f64ec317bbfe340cfcc8325d40a6ff317.zip
libbpf: Sanitize global functions
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> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200110064124.1760511-2-ast@kernel.org
Diffstat (limited to '')
-rw-r--r--tools/lib/bpf/libbpf.c35
1 files changed, 34 insertions, 1 deletions
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,
};