linux-kernel - Re: [PATCH 1/1] perf symbols: Handle '1' symbols in /proc/kallsyms

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Message-ID: <aQltxZIVd6w5VNtI@google.com>
Date: Mon, 3 Nov 2025 19:06:45 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Benno Lossin <lossin@...nel.org>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Danilo Krummrich <dakr@...nel.org>, Gary Guo <gary@...yguo.net>,
	Trevor Gross <tmgross@...ch.edu>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Ian Rogers <irogers@...gle.com>,
	James Clark <james.clark@...aro.org>, Jiri Olsa <jolsa@...nel.org>,
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 1/1] perf symbols: Handle '1' symbols in /proc/kallsyms

Hi Arnaldo,

On Mon, Nov 03, 2025 at 03:03:23PM -0300, Arnaldo Carvalho de Melo wrote:
> Just FYI, I'm carrying this on the perf tools tree.
> 
> I started seeing this in recent Fedora 42 kernels:
> 
>   root@x1:~# uname -a
>   Linux x1 6.17.4-200.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Sun Oct 19 18:47:49 UTC 2025 x86_64 GNU/Linux
>   root@x1:~#
> 
>   root@x1:~# perf test 1
>     1: vmlinux symtab matches kallsyms     : FAILED!
>   root@x1:~#
> 
> Related to:
> 
>   root@x1:~# grep ' 1 ' /proc/kallsyms
>   ffffffffb098bc00 1 __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
>   ffffffffb098bc10 1 _RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
>   root@x1:~#
> 
> That is found in:
> 
>   root@x1:~# pahole --running_kernel_vmlinux
>   /usr/lib/debug/lib/modules/6.17.4-200.fc42.x86_64/vmlinux
>   root@x1:~#
> 
>   root@x1:~# readelf -sW /usr/lib/debug/lib/modules/6.17.4-200.fc42.x86_64/vmlinux | grep __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
>   150649: ffffffff81f8bc00    16 FUNC    LOCAL  DEFAULT    1 __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
>   root@x1:~#
> 
> But was being filtered out when reading /proc/kallsyms, as the '1'
> symbol type was not being handled, do it, there are just two of them at
> this point.

Do you know what the type '1' means?  It seems they are from Rust.

Thanks,
Namhyung

> 
> Cc: Alex Gaynor <alex.gaynor@...il.com>
> Cc: Alice Ryhl <aliceryhl@...gle.com>
> Cc: Andreas Hindborg <a.hindborg@...nel.org>
> Cc: Benno Lossin <lossin@...nel.org>
> Cc: Björn Roy Baron <bjorn3_gh@...tonmail.com>
> Cc: Boqun Feng <boqun.feng@...il.com>
> Cc: Danilo Krummrich <dakr@...nel.org>
> Cc: Gary Guo <gary@...yguo.net>
> Cc: Miguel Ojeda <ojeda@...nel.org>
> Cc: Trevor Gross <tmgross@...ch.edu>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> ---
>  tools/perf/util/symbol.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index cc26b7bf302b29d6..948d3e8ad782bc2a 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -112,9 +112,13 @@ static bool symbol_type__filter(char __symbol_type)
>  	// 'N' first seen in:
>  	// ffffffff9b35d130 N __pfx__RNCINvNtNtNtCsbDUBuN8AbD4_4core4iter8adapters3map12map_try_foldjNtCs6vVzKs5jPr6_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
>  	// a seemingly Rust mangled name
> +	// Ditto for '1':
> +	// root@x1:~# grep ' 1 ' /proc/kallsyms
> +	// ffffffffb098bc00 1 __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
> +	// ffffffffb098bc10 1 _RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
>  	char symbol_type = toupper(__symbol_type);
>  	return symbol_type == 'T' || symbol_type == 'W' || symbol_type == 'D' || symbol_type == 'B' ||
> -	       __symbol_type == 'u' || __symbol_type == 'l' || __symbol_type == 'N';
> +	       __symbol_type == 'u' || __symbol_type == 'l' || __symbol_type == 'N' || __symbol_type == '1';
>  }
>  
>  static int prefix_underscores_count(const char *str)
> -- 
> 2.51.1
>