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

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Date:   Wed, 24 May 2023 00:24:20 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Arnd Bergmann <arnd@...nel.org>, Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...e.de>, 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 08:25:13AM +0200, Arnd Bergmann wrote:
> 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.

Fair enough.

> 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.

OK, I just took the patch in, it's on the train, better get on before
it gets lost.

  Luis