linux-kernel - Re: [REGRESSION] module BTF validation failure (Error -22) on next

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Message-Id: <20241115171712.427535-1-laura.nao@collabora.com>
Date: Fri, 15 Nov 2024 18:17:12 +0100
From: Laura Nao <laura.nao@...labora.com>
To: laura.nao@...labora.com,
	alan.maguire@...cle.com
Cc: bpf@...r.kernel.org,
	chrome-platform@...ts.linux.dev,
	kernel@...labora.com,
	linux-kernel@...r.kernel.org,
	regressions@...ts.linux.dev
Subject: Re: [REGRESSION] module BTF validation failure (Error -22) on next

On 11/13/24 10:37, Laura Nao wrote:
> 
> Currently, KernelCI only retains the bzImage, not the vmlinux binary. The
> bzImage can be downloaded from the same link mentioned above by selecting
> 'kernel' from the dropdown menu (modules can also be downloaded the same
> way). I’ll try to replicate the build on my end and share the vmlinux
> with DWARF data stripped for convenience.
> 

I managed to reproduce the issue locally and I've uploaded the vmlinux[1]
(stripped of DWARF data) and vmlinux.raw[2] files, as well as one of the 
modules[3] and its btf data[4] extracted with:

bpftool -B vmlinux btf dump file cros_kbd_led_backlight.ko > cros_kbd_led_backlight.ko.raw

Looking again at the logs[5], I've noticed the following is reported:

[    0.415885] BPF: 	 type_id=115803 offset=177920 size=1152
[    0.416029] BPF:  
[    0.416083] BPF: Invalid offset
[    0.416165] BPF: 

There are two different definitions of rcu_data in '.data..percpu', one
is a struct and the other is an integer:

type_id=115801 offset=177920 size=1152 (VAR 'rcu_data')
type_id=115803 offset=177920 size=1152 (VAR 'rcu_data')

[115801] VAR 'rcu_data' type_id=115572, linkage=static
[115803] VAR 'rcu_data' type_id=1, linkage=static

[115572] STRUCT 'rcu_data' size=1152 vlen=69
[1] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none)

I assume that's not expected, correct?

I'll dig a bit deeper and report back if I can find anything else.

[1] https://people.collabora.com/~laura.nao/dbg-btf-mismatch-next-20241113/vmlinux
[2] https://people.collabora.com/~laura.nao/dbg-btf-mismatch-next-20241113/vmlinux.raw
[3] https://people.collabora.com/~laura.nao/dbg-btf-mismatch-next-20241113/cros_kbd_led_backlight.ko
[4] https://people.collabora.com/~laura.nao/dbg-btf-mismatch-next-20241113/cros_kbd_led_backlight.ko.raw
[5] https://pastebin.com/raw/FvvrPhAY

Best,

Laura