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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: davem@davemloft.net
Cc: daniel@iogearbox.net, andrii@kernel.org, netdev@vger.kernel.org,
	bpf@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH v2 bpf-next 10/16] bpf: Add bpf_btf_find_by_name_kind() helper.
Date: Thu, 22 Apr 2021 17:26:40 -0700	[thread overview]
Message-ID: <20210423002646.35043-11-alexei.starovoitov@gmail.com> (raw)
In-Reply-To: <20210423002646.35043-1-alexei.starovoitov@gmail.com>

From: Alexei Starovoitov <ast@kernel.org>

Add new helper:

long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, int flags)
	Description
		Find given name with given type in BTF pointed to by btf_fd.
		If btf_fd is zero look for the name in vmlinux BTF and in module's BTFs.
	Return
		Returns btf_id and btf_obj_fd in lower and upper 32 bits.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 include/linux/bpf.h            |  1 +
 include/uapi/linux/bpf.h       |  8 ++++
 kernel/bpf/btf.c               | 68 ++++++++++++++++++++++++++++++++++
 kernel/bpf/syscall.c           |  2 +
 tools/include/uapi/linux/bpf.h |  8 ++++
 5 files changed, 87 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0f841bd0cb85..4cf361eb6a80 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1972,6 +1972,7 @@ extern const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto;
 extern const struct bpf_func_proto bpf_task_storage_get_proto;
 extern const struct bpf_func_proto bpf_task_storage_delete_proto;
 extern const struct bpf_func_proto bpf_for_each_map_elem_proto;
+extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;
 
 const struct bpf_func_proto *bpf_tracing_func_proto(
 	enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index de58a714ed36..253f5f031f08 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4748,6 +4748,13 @@ union bpf_attr {
  * 		Execute bpf syscall with given arguments.
  * 	Return
  * 		A syscall result.
+ *
+ * long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, int flags)
+ * 	Description
+ * 		Find given name with given type in BTF pointed to by btf_fd.
+ * 		If btf_fd is zero look for the name in vmlinux BTF and in module's BTFs.
+ * 	Return
+ * 		Returns btf_id and btf_obj_fd in lower and upper 32 bits.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -4917,6 +4924,7 @@ union bpf_attr {
 	FN(for_each_map_elem),		\
 	FN(snprintf),			\
 	FN(sys_bpf),			\
+	FN(btf_find_by_name_kind),	\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index fbf6c06a9d62..446c64171464 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6085,3 +6085,71 @@ struct module *btf_try_get_module(const struct btf *btf)
 
 	return res;
 }
+
+BPF_CALL_4(bpf_btf_find_by_name_kind, int, btf_fd, char *, name, u32, kind, int, flags)
+{
+	char kname[KSYM_NAME_LEN];
+	struct btf *btf;
+	long ret;
+
+	if (flags)
+		return -EINVAL;
+
+	ret = strncpy_from_kernel_nofault(kname, name, sizeof(kname));
+	if (ret < 0)
+		return ret;
+	if (btf_fd)
+		btf = btf_get_by_fd(btf_fd);
+	else
+		btf = bpf_get_btf_vmlinux();
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
+
+	ret = btf_find_by_name_kind(btf, kname, kind);
+	/* ret is never zero, since btf_find_by_name_kind returns
+	 * positive btf_id or negative error.
+	 */
+	if (btf_fd)
+		btf_put(btf);
+	else if (ret < 0) {
+		struct btf *mod_btf;
+		int id;
+
+		/* If name is not found in vmlinux's BTF then search in module's BTFs */
+		spin_lock_bh(&btf_idr_lock);
+		idr_for_each_entry(&btf_idr, mod_btf, id) {
+			if (!btf_is_module(mod_btf))
+				continue;
+			/* linear search could be slow hence unlock/lock
+			 * the IDR to avoiding holding it for too long
+			 */
+			btf_get(mod_btf);
+			spin_unlock_bh(&btf_idr_lock);
+			ret = btf_find_by_name_kind(mod_btf, kname, kind);
+			if (ret > 0) {
+				int btf_obj_fd;
+
+				btf_obj_fd = __btf_new_fd(mod_btf);
+				if (btf_obj_fd < 0) {
+					btf_put(mod_btf);
+					return btf_obj_fd;
+				}
+				return ret | (((u64)btf_obj_fd) << 32);
+			}
+			spin_lock_bh(&btf_idr_lock);
+			btf_put(mod_btf);
+		}
+		spin_unlock_bh(&btf_idr_lock);
+	}
+	return ret;
+}
+
+const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
+	.func		= bpf_btf_find_by_name_kind,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_ANYTHING,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_ANYTHING,
+};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index a81496c5d09f..638c7acad925 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4574,6 +4574,8 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	switch (func_id) {
 	case BPF_FUNC_sys_bpf:
 		return &bpf_sys_bpf_proto;
+	case BPF_FUNC_btf_find_by_name_kind:
+		return &bpf_btf_find_by_name_kind_proto;
 	default:
 		return tracing_prog_func_proto(func_id, prog);
 	}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 6c8e178d8ffa..5841adb44de6 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4748,6 +4748,13 @@ union bpf_attr {
  * 		Execute bpf syscall with given arguments.
  * 	Return
  * 		A syscall result.
+ *
+ * long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, int flags)
+ * 	Description
+ * 		Find given name with given type in BTF pointed to by btf_fd.
+ * 		If btf_fd is zero look for the name in vmlinux BTF and in module's BTFs.
+ * 	Return
+ * 		Returns btf_id and btf_obj_fd in lower and upper 32 bits.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -4917,6 +4924,7 @@ union bpf_attr {
 	FN(for_each_map_elem),		\
 	FN(snprintf),			\
 	FN(sys_bpf),			\
+	FN(btf_find_by_name_kind),	\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
-- 
2.30.2


  parent reply	other threads:[~2021-04-23  0:27 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23  0:26 [PATCH v2 bpf-next 00/16] bpf: syscall program, FD array, loader program, light skeleton Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 01/16] bpf: Introduce bpf_sys_bpf() helper and program type Alexei Starovoitov
2021-04-23 18:15   ` Yonghong Song
2021-04-23 18:28     ` Alexei Starovoitov
2021-04-23 19:32       ` Yonghong Song
2021-04-26 16:51   ` Andrii Nakryiko
2021-04-27 18:45   ` John Fastabend
2021-04-23  0:26 ` [PATCH v2 bpf-next 02/16] bpf: Introduce bpfptr_t user/kernel pointer Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 03/16] bpf: Prepare bpf syscall to be used from kernel and user space Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 04/16] libbpf: Support for syscall program type Alexei Starovoitov
2021-04-26 22:24   ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 05/16] selftests/bpf: Test " Alexei Starovoitov
2021-04-26 17:02   ` Andrii Nakryiko
2021-04-27  2:43     ` Alexei Starovoitov
2021-04-27 16:28       ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 06/16] bpf: Make btf_load command to be bpfptr_t compatible Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 07/16] selftests/bpf: Test for btf_load command Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 08/16] bpf: Introduce fd_idx Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 09/16] libbpf: Support for fd_idx Alexei Starovoitov
2021-04-26 17:14   ` Andrii Nakryiko
2021-04-27  2:53     ` Alexei Starovoitov
2021-04-27 16:36       ` Andrii Nakryiko
2021-04-28  1:32         ` Alexei Starovoitov
2021-04-28 18:40           ` Andrii Nakryiko
2021-04-23  0:26 ` Alexei Starovoitov [this message]
2021-04-26 22:46   ` [PATCH v2 bpf-next 10/16] bpf: Add bpf_btf_find_by_name_kind() helper Andrii Nakryiko
2021-04-27  3:37     ` Alexei Starovoitov
2021-04-27 17:45       ` Andrii Nakryiko
2021-04-28  1:55         ` Alexei Starovoitov
2021-04-28 18:44           ` Andrii Nakryiko
2021-04-27 21:00   ` John Fastabend
2021-04-27 21:05     ` John Fastabend
2021-04-28  2:10     ` Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 11/16] bpf: Add bpf_sys_close() helper Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 12/16] libbpf: Change the order of data and text relocations Alexei Starovoitov
2021-04-26 17:29   ` Andrii Nakryiko
2021-04-27  3:00     ` Alexei Starovoitov
2021-04-27 16:47       ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 13/16] libbpf: Add bpf_object pointer to kernel_supports() Alexei Starovoitov
2021-04-26 17:30   ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 14/16] libbpf: Generate loader program out of BPF ELF file Alexei Starovoitov
2021-04-26 22:22   ` Andrii Nakryiko
2021-04-27  3:25     ` Alexei Starovoitov
2021-04-27 17:34       ` Andrii Nakryiko
2021-04-28  1:42         ` Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 15/16] bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command Alexei Starovoitov
2021-04-26 22:35   ` Andrii Nakryiko
2021-04-27  3:28     ` Alexei Starovoitov
2021-04-27 17:38       ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 16/16] selftests/bpf: Convert few tests to light skeleton Alexei Starovoitov
2021-04-23 21:36 ` [PATCH v2 bpf-next 00/16] bpf: syscall program, FD array, loader program, " Yonghong Song
2021-04-23 23:16   ` Alexei Starovoitov

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