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

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Message-ID: <Z1n_wGj0CGjh_gLP@krava>
Date: Wed, 11 Dec 2024 22:10:24 +0100
From: Jiri Olsa <olsajiri@...il.com>
To: Laura Nao <laura.nao@...labora.com>
Cc: olsajiri@...il.com, alan.maguire@...cle.com, 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

On Tue, Dec 10, 2024 at 02:55:01PM +0100, Laura Nao wrote:
> Hi Jiri,
> 
> Thanks for the feedback!
> 
> On 12/6/24 13:35, Jiri Olsa wrote:
> > On Fri, Nov 15, 2024 at 06:17:12PM +0100, Laura Nao wrote:
> >> 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?
> > 
> > yes, that seems wrong.. but I can't reproduce with your config
> > together with pahole 1.24 .. could you try with latest one?
> 
> I just tested next-20241210 with the latest pahole version (1.28 from
> the master branch[1]), and the issue does not occur with this version
> (I can see only one instance of rcu_data in the BTF data, as expected).
> 
> I can confirm that the same kernel revision still exhibits the issue
> with pahole 1.24.
> 
> If helpful, I can also test versions between 1.24 and 1.28 to identify
> which ones work.

I managed to reproduce finally with gcc-12, but had to use pahole 1.25,
1.24 failed with unknown attribute

	[95096] VAR 'rcu_data' type_id=94868, linkage=static
	[95098] VAR 'rcu_data' type_id=4, linkage=static
	type_id=95096 offset=177088 size=1152 (VAR 'rcu_data')
	type_id=95098 offset=177088 size=1152 (VAR 'rcu_data')

will try to check what's going on

jirka