From: Daniel Borkmann <daniel@iogearbox.net>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, ast@kernel.org, joe@wand.net.nz,
yhs@fb.com, andrii.nakryiko@gmail.com, kafai@fb.com,
jannh@google.com, Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH bpf-next v6 06/16] bpf: add specification for BTF Var and DataSec kinds
Date: Tue, 9 Apr 2019 23:20:08 +0200 [thread overview]
Message-ID: <20190409212018.32423-7-daniel@iogearbox.net> (raw)
In-Reply-To: <20190409212018.32423-1-daniel@iogearbox.net>
This adds the BTF specification and UAPI bits for supporting BTF Var
and DataSec kinds. This is following LLVM upstream commit ac4082b77e07
("[BPF] Add BTF Var and DataSec Support") which has been merged recently.
Var itself is for describing a global variable and DataSec to describe
ELF sections e.g. data/bss/rodata sections that hold one or multiple
global variables.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
Documentation/bpf/btf.rst | 57 +++++++++++++++++++++++++++++++++++++++
include/uapi/linux/btf.h | 32 +++++++++++++++++++---
2 files changed, 85 insertions(+), 4 deletions(-)
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 9a60a5d60e38..60d87d7363ec 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -82,6 +82,8 @@ sequentially and type id is assigned to each recognized type starting from id
#define BTF_KIND_RESTRICT 11 /* Restrict */
#define BTF_KIND_FUNC 12 /* Function */
#define BTF_KIND_FUNC_PROTO 13 /* Function Proto */
+ #define BTF_KIND_VAR 14 /* Variable */
+ #define BTF_KIND_DATASEC 15 /* Section */
Note that the type section encodes debug info, not just pure types.
``BTF_KIND_FUNC`` is not a type, and it represents a defined subprogram.
@@ -393,6 +395,61 @@ refers to parameter type.
If the function has variable arguments, the last parameter is encoded with
``name_off = 0`` and ``type = 0``.
+2.2.14 BTF_KIND_VAR
+~~~~~~~~~~~~~~~~~~~
+
+``struct btf_type`` encoding requirement:
+ * ``name_off``: offset to a valid C identifier
+ * ``info.kind_flag``: 0
+ * ``info.kind``: BTF_KIND_VAR
+ * ``info.vlen``: 0
+ * ``type``: the type of the variable
+
+``btf_type`` is followed by a single ``struct btf_variable`` with the
+following data::
+
+ struct btf_var {
+ __u32 linkage;
+ };
+
+``struct btf_var`` encoding:
+ * ``linkage``: currently only static variable 0, or globally allocated
+ variable in ELF sections 1
+
+Not all type of global variables are supported by LLVM at this point.
+The following is currently available:
+
+ * static variables with or without section attributes
+ * global variables with section attributes
+
+The latter is for future extraction of map key/value type id's from a
+map definition.
+
+2.2.15 BTF_KIND_DATASEC
+~~~~~~~~~~~~~~~~~~~~~~~
+
+``struct btf_type`` encoding requirement:
+ * ``name_off``: offset to a valid name associated with a variable or
+ one of .data/.bss/.rodata
+ * ``info.kind_flag``: 0
+ * ``info.kind``: BTF_KIND_DATASEC
+ * ``info.vlen``: # of variables
+ * ``size``: total section size in bytes (0 at compilation time, patched
+ to actual size by BPF loaders such as libbpf)
+
+``btf_type`` is followed by ``info.vlen`` number of ``struct btf_var_secinfo``.::
+
+ struct btf_var_secinfo {
+ __u32 type;
+ __u32 offset;
+ __u32 size;
+ };
+
+``struct btf_var_secinfo`` encoding:
+ * ``type``: the type of the BTF_KIND_VAR variable
+ * ``offset``: the in-section offset of the variable
+ * ``size``: the size of the variable in bytes
+
3. BTF Kernel API
*****************
diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h
index 7b7475ef2f17..9310652ca4f9 100644
--- a/include/uapi/linux/btf.h
+++ b/include/uapi/linux/btf.h
@@ -39,11 +39,11 @@ struct btf_type {
* struct, union and fwd
*/
__u32 info;
- /* "size" is used by INT, ENUM, STRUCT and UNION.
+ /* "size" is used by INT, ENUM, STRUCT, UNION and DATASEC.
* "size" tells the size of the type it is describing.
*
* "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
- * FUNC and FUNC_PROTO.
+ * FUNC, FUNC_PROTO and VAR.
* "type" is a type_id referring to another type.
*/
union {
@@ -70,8 +70,10 @@ struct btf_type {
#define BTF_KIND_RESTRICT 11 /* Restrict */
#define BTF_KIND_FUNC 12 /* Function */
#define BTF_KIND_FUNC_PROTO 13 /* Function Proto */
-#define BTF_KIND_MAX 13
-#define NR_BTF_KINDS 14
+#define BTF_KIND_VAR 14 /* Variable */
+#define BTF_KIND_DATASEC 15 /* Section */
+#define BTF_KIND_MAX BTF_KIND_DATASEC
+#define NR_BTF_KINDS (BTF_KIND_MAX + 1)
/* For some specific BTF_KIND, "struct btf_type" is immediately
* followed by extra data.
@@ -138,4 +140,26 @@ struct btf_param {
__u32 type;
};
+enum {
+ BTF_VAR_STATIC = 0,
+ BTF_VAR_GLOBAL_ALLOCATED,
+};
+
+/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
+ * additional information related to the variable such as its linkage.
+ */
+struct btf_var {
+ __u32 linkage;
+};
+
+/* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
+ * to describe all BTF_KIND_VAR types it contains along with it's
+ * in-section offset as well as size.
+ */
+struct btf_var_secinfo {
+ __u32 type;
+ __u32 offset;
+ __u32 size;
+};
+
#endif /* _UAPI__LINUX_BTF_H__ */
--
2.17.1
next prev parent reply other threads:[~2019-04-09 21:20 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-09 21:20 [PATCH bpf-next v6 00/16] BPF support for global data Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 01/16] bpf: implement lookup-free direct value access for maps Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 02/16] bpf: do not retain flags that are not tied to map lifetime Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 03/16] bpf: add program side {rd, wr}only support for maps Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 04/16] bpf: add syscall side map freeze support Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 05/16] bpf: allow . char as part of the object name Daniel Borkmann
2019-04-09 21:20 ` Daniel Borkmann [this message]
2019-04-09 21:20 ` [PATCH bpf-next v6 07/16] bpf: kernel side support for BTF Var and DataSec Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 08/16] bpf: allow for key-less BTF in array map Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 09/16] bpf: sync {btf, bpf}.h uapi header from tools infrastructure Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 10/16] bpf, libbpf: refactor relocation handling Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 11/16] bpf, libbpf: support global data/bss/rodata sections Daniel Borkmann
2019-04-19 1:18 ` Andrii Nakryiko
2019-04-23 0:35 ` Daniel Borkmann
2019-04-23 4:06 ` Andrii Nakryiko
2019-04-23 8:31 ` Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 12/16] bpf, libbpf: add support for BTF Var and DataSec Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 13/16] bpf: bpftool support for dumping data/bss/rodata sections Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 14/16] bpf, selftest: test {rd, wr}only flags and direct value access Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 15/16] bpf, selftest: test global data/bss/rodata sections Daniel Borkmann
2019-04-09 21:20 ` [PATCH bpf-next v6 16/16] bpf, selftest: add test cases for BTF Var and DataSec Daniel Borkmann
-- strict thread matches above, loose matches on Subject: below --
2019-04-09 21:08 [PATCH bpf-next v6 00/16] BPF support for global data Daniel Borkmann
2019-04-09 21:09 ` [PATCH bpf-next v6 06/16] bpf: add specification for BTF Var and DataSec kinds Daniel Borkmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190409212018.32423-7-daniel@iogearbox.net \
--to=daniel@iogearbox.net \
--cc=andrii.nakryiko@gmail.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=jannh@google.com \
--cc=joe@wand.net.nz \
--cc=kafai@fb.com \
--cc=netdev@vger.kernel.org \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).