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From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	mark.rutland@arm.com, dvyukov@google.com, seanjc@google.com,
	pbonzini@redhat.com, mbenes@suse.cz
Subject: Re: [RFC][PATCH 11/22] x86,xen: Remove .fixup usage
Date: Fri, 5 Nov 2021 08:56:46 +0100	[thread overview]
Message-ID: <20211105075646.GH174703@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20211104223151.k553ng4cx6nbke4z@treble>

On Thu, Nov 04, 2021 at 03:31:51PM -0700, Josh Poimboeuf wrote:
> On Thu, Nov 04, 2021 at 05:47:40PM +0100, Peter Zijlstra wrote:
> > Employ the fancy new EX_TYPE_IMM_REG to create EX_TYPE_NEG_REG to
> > store '-1' into the designated register and use this to remove some
> > Xen .fixup usage.
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > ---
> >  arch/x86/include/asm/extable_fixup_types.h |    1 +
> >  arch/x86/include/asm/xen/page.h            |   12 ++----------
> >  2 files changed, 3 insertions(+), 10 deletions(-)
> > 
> > --- a/arch/x86/include/asm/extable_fixup_types.h
> > +++ b/arch/x86/include/asm/extable_fixup_types.h
> > @@ -35,5 +35,6 @@
> >  
> >  #define	EX_TYPE_IMM_REG			17 /* reg := (long)imm */
> >  #define	EX_TYPE_EFAULT_REG		(EX_TYPE_IMM_REG | EX_TYPE_IMM(-EFAULT))
> > +#define	EX_TYPE_NEG_REG			(EX_TYPE_IMM_REG | EX_TYPE_IMM(-1))
> >  
> >  #endif
> > --- a/arch/x86/include/asm/xen/page.h
> > +++ b/arch/x86/include/asm/xen/page.h
> > @@ -96,11 +96,7 @@ static inline int xen_safe_write_ulong(u
> >  
> >  	asm volatile("1: mov %[val], %[ptr]\n"
> >  		     "2:\n"
> > -		     ".section .fixup, \"ax\"\n"
> > -		     "3: sub $1, %[ret]\n"
> > -		     "   jmp 2b\n"
> > -		     ".previous\n"
> > -		     _ASM_EXTABLE(1b, 3b)
> > +		     _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_NEG_REG, %[ret])
> >  		     : [ret] "+r" (ret), [ptr] "=m" (*addr)
> >  		     : [val] "r" (val));
> >  
> > @@ -115,11 +111,7 @@ static inline int xen_safe_read_ulong(co
> >  
> >  	asm volatile("1: mov %[ptr], %[rval]\n"
> >  		     "2:\n"
> > -		     ".section .fixup, \"ax\"\n"
> > -		     "3: sub $1, %[ret]\n"
> > -		     "   jmp 2b\n"
> > -		     ".previous\n"
> > -		     _ASM_EXTABLE(1b, 3b)
> > +		     _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_NEG_REG, %[ret])
> >  		     : [ret] "+r" (ret), [rval] "+r" (rval)
> >  		     : [ptr] "m" (*addr));
> >  	*val = rval;
> 
> -EFAULT is also negative, and presumably more appropriate than -1.

Possibly, means I'll have to go audit all it's users. I'll put it on the
todo list.

  reply	other threads:[~2021-11-05  7:57 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-04 16:47 [RFC][PATCH 00/22] x86: Remove anonymous out-of-line fixups Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 01/22] bitfield.h: Fix "type of reg too small for mask" test Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 02/22] x86,mmx_32: Remove .fixup usage Peter Zijlstra
2021-11-04 18:00   ` Borislav Petkov
2021-11-05 11:20     ` David Laight
2021-11-04 20:22   ` Josh Poimboeuf
2021-11-05  8:05     ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 03/22] x86,copy_user_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 04/22] x86,copy_mc_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 05/22] x86,entry_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 06/22] x86,entry_32: " Peter Zijlstra
2021-11-04 20:39   ` Josh Poimboeuf
2021-11-05  7:43     ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 07/22] x86,extable: Extend extable functionality Peter Zijlstra
2021-11-04 21:49   ` Josh Poimboeuf
2021-11-05  7:54     ` Peter Zijlstra
2021-11-05 10:16       ` Mark Rutland
2021-11-05 17:32   ` Sean Christopherson
2021-11-05 18:45     ` Peter Zijlstra
2021-11-05 19:17       ` Sean Christopherson
2021-11-05 19:32         ` Peter Zijlstra
2021-11-05 19:47           ` Sean Christopherson
2021-11-05 20:15             ` Peter Zijlstra
2021-11-05 20:26               ` Peter Zijlstra
2021-11-05 22:30                 ` Sean Christopherson
2021-11-04 16:47 ` [RFC][PATCH 08/22] x86,msr: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 09/22] x86,futex: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 10/22] x86,uaccess: " Peter Zijlstra
2021-11-04 22:28   ` Josh Poimboeuf
2021-11-04 16:47 ` [RFC][PATCH 11/22] x86,xen: " Peter Zijlstra
2021-11-04 22:31   ` Josh Poimboeuf
2021-11-05  7:56     ` Peter Zijlstra [this message]
2021-11-04 16:47 ` [RFC][PATCH 12/22] x86,fpu: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 13/22] x86,segment: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 14/22] x86,ftrace: " Peter Zijlstra
2021-11-04 22:35   ` Josh Poimboeuf
2021-11-05  7:57     ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 15/22] x86,vmx: " Peter Zijlstra
2021-11-04 18:50   ` Paolo Bonzini
2021-11-05 18:17   ` Sean Christopherson
2021-11-05 18:52     ` Peter Zijlstra
2021-11-05 20:58     ` Peter Zijlstra
2021-11-05 22:29       ` Sean Christopherson
2021-11-06  7:05     ` Paolo Bonzini
2021-11-06  8:36       ` Peter Zijlstra
2021-11-07 19:13         ` Paolo Bonzini
2021-11-06  8:28     ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 16/22] x86,checksum_32: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 17/22] x86,sgx: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 18/22] x86,kvm: " Peter Zijlstra
2021-11-04 18:50   ` Paolo Bonzini
2021-11-05  7:58     ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 19/22] x86,usercopy_32: Simplify Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 20/22] x86,usercopy: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 21/22] x86,word-at-a-time: " Peter Zijlstra
2021-11-04 23:33   ` Josh Poimboeuf
2021-11-05  8:04     ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 22/22] x86: Remove .fixup section Peter Zijlstra
2021-11-04 23:00   ` Josh Poimboeuf

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