On 8/3/20 7:15 PM, Daniel Borkmann wrote:
On 8/3/20 12:29 AM, Alexei Starovoitov wrote:
From: Alexei Starovoitov <ast@xxxxxxxxxx>
Add kernel module with user mode driver that populates bpffs with
BPF iterators.
$ mount bpffs /my/bpffs/ -t bpf
$ ls -la /my/bpffs/
total 4
drwxrwxrwt 2 root root 0 Jul 2 00:27 .
drwxr-xr-x 19 root root 4096 Jul 2 00:09 ..
-rw------- 1 root root 0 Jul 2 00:27 maps.debug
-rw------- 1 root root 0 Jul 2 00:27 progs.debug
The user mode driver will load BPF Type Formats, create BPF maps, populate BPF
maps, load two BPF programs, attach them to BPF iterators, and finally send two
bpf_link IDs back to the kernel.
The kernel will pin two bpf_links into newly mounted bpffs instance under
names "progs.debug" and "maps.debug". These two files become human readable.
$ cat /my/bpffs/progs.debug
id name attached
11 dump_bpf_map bpf_iter_bpf_map
12 dump_bpf_prog bpf_iter_bpf_prog
27 test_pkt_access
32 test_main test_pkt_access test_pkt_access
33 test_subprog1 test_pkt_access_subprog1 test_pkt_access
34 test_subprog2 test_pkt_access_subprog2 test_pkt_access
35 test_subprog3 test_pkt_access_subprog3 test_pkt_access
36 new_get_skb_len get_skb_len test_pkt_access
37 new_get_skb_ifindex get_skb_ifindex test_pkt_access
38 new_get_constant get_constant test_pkt_access
The BPF program dump_bpf_prog() in iterators.bpf.c is printing this data about
all BPF programs currently loaded in the system. This information is unstable
and will change from kernel to kernel as ".debug" suffix conveys.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
[...]
diff --git a/kernel/bpf/preload/Kconfig b/kernel/bpf/preload/Kconfig
new file mode 100644
index 000000000000..b8ba5a9398ed
--- /dev/null
+++ b/kernel/bpf/preload/Kconfig
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig BPF_PRELOAD
+ bool "Preload BPF file system with kernel specific program and map iterators"
+ depends on BPF
+ help
+ This builds kernel module with several embedded BPF programs that are
+ pinned into BPF FS mount point as human readable files that are
+ useful in debugging and introspection of BPF programs and maps.
+
+if BPF_PRELOAD
+config BPF_PRELOAD_UMD
+ tristate "bpf_preload kernel module with user mode driver"
+ depends on CC_CAN_LINK
+ depends on m || CC_CAN_LINK_STATIC
+ default m
+ help
+ This builds bpf_preload kernel module with embedded user mode driver.
+endif
[...]
When I applied this set locally to run build & selftests I noticed that the above
kconfig will appear in the top-level menuconfig. This is how it looks in menuconfig:
│ ┌────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ │
│ │ General setup ---> │ │
│ │ [*] 64-bit kernel │ │
│ │ Processor type and features ---> │ │
│ │ Power management and ACPI options ---> │ │
│ │ Bus options (PCI etc.) ---> │ │
│ │ Binary Emulations ---> │ │
│ │ Firmware Drivers ---> │ │
│ │ [*] Virtualization ---> │ │
│ │ General architecture-dependent options ---> │ │
│ │ [*] Enable loadable module support ---> │ │
│ │ -*- Enable the block layer ---> │ │
│ │ IO Schedulers ---> │ │
│ │ [ ] Preload BPF file system with kernel specific program and map iterators ---- │ │
│ │ Executable file formats ---> │ │
│ │ Memory Management options ---> │ │
│ │ [*] Networking support ---> │ │
│ │ Device Drivers ---> │ │
│ │ File systems ---> │ │
│ │ Security options ---> │ │
[...]
I assume the original intention was to have it under 'general setup' on a similar level for
the JIT settings, or is this intentional to have it at this high level next to 'networking
support' and others?
Hm, my config has:
CONFIG_BPF_PRELOAD=y
CONFIG_BPF_PRELOAD_UMD=y
I'm getting the following 3 warnings and build error below:
root@tank:~/bpf-next# make -j8 > /dev/null
arch/x86/hyperv/hv_apic.c: In function ‘hv_send_ipi_mask_allbutself’:
arch/x86/hyperv/hv_apic.c:236:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]
}
^
make[3]: *** No rule to make target 'kernel/bpf/preload/./../../tools/lib/bpf/bpf.c', needed by 'kernel/bpf/preload/./../../tools/lib/bpf/bpf.o'. Stop.
make[3]: *** Waiting for unfinished jobs....
kernel/bpf/preload/iterators/iterators.c: In function ‘main’:
kernel/bpf/preload/iterators/iterators.c:50:2: warning: ignoring return value of ‘dup’, declared with attribute warn_unused_result [-Wunused-result]
dup(debug_fd);
^~~~~~~~~~~~~
kernel/bpf/preload/iterators/iterators.c:53:2: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result]
read(from_kernel, &magic, sizeof(magic));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/bpf/preload/iterators/iterators.c:85:2: warning: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Wunused-result]
read(from_kernel, &magic, sizeof(magic));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
make[2]: *** [kernel/bpf/preload] Error 2
make[1]: *** [kernel/bpf] Error 2
make: *** [kernel] Error 2
make: *** Waiting for unfinished jobs....
[...]
Have you seen the target error before, what am I missing?
Thanks,
Daniel
