linux-kernel - Re: [PATCH] ftrace: make ftrace

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Message-ID: <20250415074633.3cf7546d@gandalf.local.home>
Date: Tue, 15 Apr 2025 07:46:33 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Jin Guo <menglong8.dong@...il.com>
Cc: mhiramat@...nel.org, mark.rutland@....com,
 mathieu.desnoyers@...icios.com, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, Jin Guo <guoj17@...natelecom.cn>
Subject: Re: [PATCH] ftrace: make ftrace_location() more accurate

On Tue, 15 Apr 2025 19:27:50 +0800
Jin Guo <menglong8.dong@...il.com> wrote:

> The function ftrace_location is used to lookup the ftrace location with an
> ip. However, the result that it returns can be wrong in some case.
> 
> Let's image that we have the following kallsyms:
> 
>   ffffffff812c35f0 T sys_ni_syscall
>   ffffffff812c38b0 W __pfx___x64_sys_io_pgetevents_time32
>   ffffffff812c38c0 W __x64_sys_io_pgetevents_time32

Have you tried the latest kernel? because on x86, weak functions that are
not used should no longer be in the ftrace table. That is, you should never
see __ftrace_invalid_addres_* anymore.

See https://lore.kernel.org/all/20250218195918.255228630@goodmis.org/

That was just added this merge window, which would make your patch obsolete.

-- Steve