linux-kernel - Re: [PATCH v2 3/6] x86/uaccess: Rearrange putuser.S

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Message-ID: <20241018155513.zaufdhi7p5mrz2bp@treble>
Date: Fri, 18 Oct 2024 08:55:13 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: "Kirill A . Shutemov" <kirill@...temov.name>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	Waiman Long <longman@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	linuxppc-dev@...ts.ozlabs.org,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v2 3/6] x86/uaccess: Rearrange putuser.S

On Fri, Oct 18, 2024 at 11:51:06AM +0300, Kirill A . Shutemov wrote:
> On Thu, Oct 17, 2024 at 02:55:22PM -0700, Josh Poimboeuf wrote:
> >  SYM_FUNC_START(__put_user_2)
> >  	check_range size=2
> >  	ASM_STAC
> > -3:	movw %ax,(%_ASM_CX)
> > +2:	movw %ax,(%_ASM_CX)
> >  	xor %ecx,%ecx
> >  	ASM_CLAC
> >  	RET
> >  SYM_FUNC_END(__put_user_2)
> >  EXPORT_SYMBOL(__put_user_2)
> 
> This patch provides an opportunity to give these labels more meaningful
> names, so that future rearrangements do not require as much boilerplate.

Yeah, I can add a patch like Linus' patch to getuser.S which
encapsulates it all in a macro:

.macro UACCESS op src dst
1:	\op \src,\dst
	_ASM_EXTABLE_UA(1b, __get_user_handle_exception)
.endm

	.text
SYM_FUNC_START(__get_user_1)
	check_range size=1
	ASM_STAC
	UACCESS movzbl (%_ASM_AX),%edx
	xor %eax,%eax
	ASM_CLAC
	RET
SYM_FUNC_END(__get_user_1)
EXPORT_SYMBOL(__get_user_1)

-- 
Josh