linux/Documentation/ABI/testing/sysfs-kernel-btf
Andrii Nakryiko 36e68442d1 bpf: Load and verify kernel module BTFs
Add kernel module listener that will load/validate and unload module BTF.
Module BTFs gets ID generated for them, which makes it possible to iterate
them with existing BTF iteration API. They are given their respective module's
names, which will get reported through GET_OBJ_INFO API. They are also marked
as in-kernel BTFs for tooling to distinguish them from user-provided BTFs.

Also, similarly to vmlinux BTF, kernel module BTFs are exposed through
sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space
tools to inspect module BTF contents and dump their types with existing tools:

[vmuser@archvm bpf]$ ls -la /sys/kernel/btf
total 0
drwxr-xr-x  2 root root       0 Nov  4 19:46 .
drwxr-xr-x 13 root root       0 Nov  4 19:46 ..

...

-r--r--r--  1 root root     888 Nov  4 19:46 irqbypass
-r--r--r--  1 root root  100225 Nov  4 19:46 kvm
-r--r--r--  1 root root   35401 Nov  4 19:46 kvm_intel
-r--r--r--  1 root root     120 Nov  4 19:46 pcspkr
-r--r--r--  1 root root     399 Nov  4 19:46 serio_raw
-r--r--r--  1 root root 4094095 Nov  4 19:46 vmlinux

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/bpf/20201110011932.3201430-5-andrii@kernel.org
2020-11-10 15:25:53 -08:00

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What: /sys/kernel/btf
Date: Aug 2019
KernelVersion: 5.5
Contact: bpf@vger.kernel.org
Description:
Contains BTF type information and related data for kernel and
kernel modules.
What: /sys/kernel/btf/vmlinux
Date: Aug 2019
KernelVersion: 5.5
Contact: bpf@vger.kernel.org
Description:
Read-only binary attribute exposing kernel's own BTF type
information with description of all internal kernel types. See
Documentation/bpf/btf.rst for detailed description of format
itself.
What: /sys/kernel/btf/<module-name>
Date: Nov 2020
KernelVersion: 5.11
Contact: bpf@vger.kernel.org
Description:
Read-only binary attribute exposing kernel module's BTF type
information as an add-on to the kernel's BTF (/sys/kernel/btf/vmlinux).