linux-kernel - Re: [PATCH] kallsyms: remove unused arch_get

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Message-Id: <a3d01d39-3d45-4fdc-8f73-b6c33bcae24b@app.fastmail.com>
Date:   Wed, 24 May 2023 08:25:13 +0200
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Luis Chamberlain" <mcgrof@...nel.org>,
        "Arnd Bergmann" <arnd@...nel.org>,
        "Andy Lutomirski" <luto@...nel.org>, "Borislav Petkov" <bp@...e.de>
Cc:     linux-modules@...r.kernel.org,
        "Zhen Lei" <thunder.leizhen@...wei.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Kees Cook" <keescook@...omium.org>, linux-kernel@...r.kernel.org,
        "Andrew Morton" <akpm@...ux-foundation.org>
Subject: Re: [PATCH] kallsyms: remove unused arch_get_kallsym() helper

On Wed, May 24, 2023, at 07:07, Luis Chamberlain wrote:
> On Wed, May 17, 2023 at 03:18:07PM +0200, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@...db.de>
>> 
>> The arch_get_kallsym() function was introduced so that x86 could override
>> it, but that override was removed in bf904d2762ee ("x86/pti/64: Remove
>> the SYSCALL64 entry trampoline"), so now this does nothing except causing
>> a warning about a missing prototype:
>> 
>> kernel/kallsyms.c:662:12: error: no previous prototype for 'arch_get_kallsym' [-Werror=missing-prototypes]
>>   662 | int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
>> 
>> Restore the old behavior before d83212d5dd67 ("kallsyms, x86: Export
>> addresses of PTI entry trampolines") to simplify the code and avoid
>> the warning.
>> 
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>
> Shouldn't this go through x86 as this sort of fixesss commit
> bf904d2762ee ("x86/pti/64: Remove the SYSCALL64 entry trampoline")?

That works for me as well, as long as someone picks it up. It's
not really x86 any more though since that commit is five years
old and removed the last reference from the x86 code.

I sent it to you since you are the one that merged most of
the kallsyms patches through the module tree, but I guess
you are not actually maintaining that file (not blaming you,
I'd also try to stay away from kallsyms).

I can resend it to Andrew for the -mm tree.

     Arnd