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authorDavid S. Miller <davem@davemloft.net>2019-04-12 03:00:05 +0300
committerDavid S. Miller <davem@davemloft.net>2019-04-12 03:00:05 +0300
commitbb23581b9b38703257acabd520aa5ebf1db008af (patch)
tree9d9f7b7ccad9697dfd2eab3b1fda37056b0e47f6 /Documentation
parent78f07adac86186b5ef0318b7faec377b6d31ea9f (diff)
parent947e8b595b82d3551750641445d0a97b8f29b536 (diff)
downloadlinux-bb23581b9b38703257acabd520aa5ebf1db008af.tar.xz
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says: ==================== pull-request: bpf-next 2019-04-12 The following pull-request contains BPF updates for your *net-next* tree. The main changes are: 1) Improve BPF verifier scalability for large programs through two optimizations: i) remove verifier states that are not useful in pruning, ii) stop walking parentage chain once first LIVE_READ is seen. Combined gives approx 20x speedup. Increase limits for accepting large programs under root, and add various stress tests, from Alexei. 2) Implement global data support in BPF. This enables static global variables for .data, .rodata and .bss sections to be properly handled which allows for more natural program development. This also opens up the possibility to optimize program workflow by compiling ELFs only once and later only rewriting section data before reload, from Daniel and with test cases and libbpf refactoring from Joe. 3) Add config option to generate BTF type info for vmlinux as part of the kernel build process. DWARF debug info is converted via pahole to BTF. Latter relies on libbpf and makes use of BTF deduplication algorithm which results in 100x savings compared to DWARF data. Resulting .BTF section is typically about 2MB in size, from Andrii. 4) Add BPF verifier support for stack access with variable offset from helpers and add various test cases along with it, from Andrey. 5) Extend bpf_skb_adjust_room() growth BPF helper to mark inner MAC header so that L2 encapsulation can be used for tc tunnels, from Alan. 6) Add support for input __sk_buff context in BPF_PROG_TEST_RUN so that users can define a subset of allowed __sk_buff fields that get fed into the test program, from Stanislav. 7) Add bpf fs multi-dimensional array tests for BTF test suite and fix up various UBSAN warnings in bpftool, from Yonghong. 8) Generate a pkg-config file for libbpf, from Luca. 9) Dump program's BTF id in bpftool, from Prashant. 10) libbpf fix to use smaller BPF log buffer size for AF_XDP's XDP program, from Magnus. 11) kallsyms related fixes for the case when symbols are not present in BPF selftests and samples, from Daniel ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/bpf/btf.rst57
1 files changed, 57 insertions, 0 deletions
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 7313d354f20e..29396e6943b0 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
*****************