Bug 218320 - HID-BPF fails to initialise, EINVAL
Summary: HID-BPF fails to initialise, EINVAL
Status: NEW
Alias: None
Product: Linux
Classification: Unclassified
Component: Kernel (show other bugs)
Hardware: All Linux
: P3 normal
Assignee: Virtual assignee for kernel bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2023-12-25 23:29 UTC by Chris Rankin
Modified: 2023-12-28 00:10 UTC (History)
0 users

See Also:
Kernel Version: 6.6.8
Subsystem: hid-bpf
Regression: No
Bisected commit-id:

Attachments
Kernel config for 6.6.8 (176.78 KB, text/plain)
2023-12-25 23:29 UTC, Chris Rankin 		Details
Add an attachment (proposed patch, testcase, etc.)

Description Chris Rankin 2023-12-25 23:29:22 UTC 
Created attachment 305655 [details]
Kernel config for 6.6.8

Trying to configure a 6.6.8 kernel to use HID-BPF, but it fails to initialise:

[    3.210054] hid_bpf: error while preloading HID BPF dispatcher: -22

The issue appears to relate to entrypoints_bpf__load(), specifically the "run" stage of bpf_load_and_run().

This is almost certainly a configuration issue, and so I have attached my kernel config. I suspect that hid-bpf has a missing extra dependency beyond CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS=y.
Comment 1 Chris Rankin 2023-12-28 00:10:25 UTC 
FWIW I have discovered that my kernel was missing CONFIG_DEBUG_INFO_BTF, and I also hadn't installed the pahole tool on my build machine. Perhaps the Kconfig rules need updating?
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