libbpf: Sanitize global functions (2d3eb67f) · Commits · 戴 / test

tools/include/uapi/linux/btf.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -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.
		*/

tools/lib/bpf/libbpf.c

+34 −1

Original line number	Diff line number	Diff line
		@@ -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,
		};

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