linux-kernel - Re: [PATCH v2] compiler: remove __ADDRESSABLE_ASM{

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Message-ID: <d66254fc-79a3-45cf-8195-ea0b49bb28a0@suse.com>
Date: Fri, 14 Mar 2025 08:56:45 +0100
From: Jan Beulich <jbeulich@...e.com>
To: Juergen Gross <jgross@...e.com>,
 Stefano Stabellini <sstabellini@...nel.org>
Cc: lkml <linux-kernel@...r.kernel.org>, Peter Zijlstra
 <peterz@...radead.org>, Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
 Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH v2] compiler: remove __ADDRESSABLE_ASM{_STR,}() again

On 17.02.2025 21:29, Josh Poimboeuf wrote:
> On Mon, Feb 17, 2025 at 05:40:09PM +0100, Jan Beulich wrote:
>> __ADDRESSABLE_ASM_STR() is where the necessary stringification happens.
>> As long as "sym" doesn't contain any odd characters, no quoting is
>> required for its use with .quad / .long. In fact the quotation gets in
>> the way with gas 2.25; it's only from 2.26 onwards that quoted symbols
>> are half-way properly supported.
>>
>> However, assembly being different from C anyway, drop
>> __ADDRESSABLE_ASM_STR() and its helper macro altogether. A simple
>> .global directive will suffice to get the symbol "declared", i.e. into
>> the symbol table. While there also stop open-coding STATIC_CALL_TRAMP()
>> and STATIC_CALL_KEY().
>>
>> Fixes: 0ef8047b737d ("x86/static-call: provide a way to do very early static-call updates")
>> Signed-off-by: Jan Beulich <jbeulich@...e.com>
>> Cc: stable@...r.kernel.org
>> ---
>> v2: Drop constructs instead of fixing them. Use STATIC_CALL_KEY().
>> ---
>> Whether the "ADDRESSABLE" in __ADDRESSABLE_xen_hypercall is still
>> meaningful to keep I'm uncertain about. The situation, as said, is quite
>> different in assembly, compared to C's requirements.
> 
> The .global still makes it "addressable", so IMO it's named
> appropriately.
> 
> Thanks!
> 
> Acked-by: Josh Poimboeuf <jpoimboe@...nel.org>

Since this is addressing a (mild) regression, I wonder if this could still
make 6.14?

Jan