linux-kernel - Re: [PATCH] i386: do a global tlb flush in S4 resume

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Message-Id: <201003062254.46584.rjw@sisk.pl>
Date:	Sat, 6 Mar 2010 22:54:46 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Shaohua Li <shaohua.li@...el.com>, "H. Peter Anvin" <hpa@...or.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"colin.king@...onical.com" <colin.king@...onical.com>
Subject: Re: [PATCH] i386: do a global tlb flush in S4 resume

On Friday 05 March 2010, Rafael J. Wysocki wrote:
> On Friday 05 March 2010, Shaohua Li wrote:
> > On Fri, Mar 05, 2010 at 03:49:46AM +0800, Rafael J. Wysocki wrote:
> > > On Thursday 04 March 2010, Shaohua Li wrote:
> ...
> > > 
> > > In that case please also remove the turning GPE off down the road.
> > 
> >     i386: do a global tlb flush in S4 resume
> > 
> >     Colin reported a strange oops in S4 resume code path (see below). The test
> >     system has i5/i7 CPU. The kernel doesn't open PAE, so 4M page table is used.
> >     The oops always happen a virtual address 0xc03ff000, which is mapped to the
> >     last 4k of first 4M memory. Doing a global tlb flush fixes the issue.
> > 
> >     EIP: 0060:[<c0493a01>] EFLAGS: 00010086 CPU: 0
> >     EIP is at copy_loop+0xe/0x15
> >     EAX: 36aeb000 EBX: 00000000 ECX: 00000400 EDX: f55ad46c
> >     ESI: 0f800000 EDI: c03ff000 EBP: f67fbec4 ESP: f67fbea8
> >      DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
> >     ...
> >     ...
> >     CR2: 00000000c03ff000
> > 
> >     Tested-by: Colin Ian King <colin.king@...onical.com>
> >     Signed-off-by: Shaohua Li <shaohua.li@...el.com>
> > 
> > diff --git a/arch/x86/power/hibernate_asm_32.S b/arch/x86/power/hibernate_asm_32.S
> > index b641388..ad47dae 100644
> > --- a/arch/x86/power/hibernate_asm_32.S
> > +++ b/arch/x86/power/hibernate_asm_32.S
> > @@ -27,10 +27,17 @@ ENTRY(swsusp_arch_suspend)
> >  	ret
> >  
> >  ENTRY(restore_image)
> > +	movl	mmu_cr4_features, %ecx
> >  	movl	resume_pg_dir, %eax
> >  	subl	$__PAGE_OFFSET, %eax
> >  	movl	%eax, %cr3
> >  
> > +	jecxz	1f	# cr4 Pentium and higher, skip if zero
> > +	andl	$~(X86_CR4_PGE), %ecx
> > +	movl	%ecx, %cr4;  # turn off PGE
> > +	movl	%cr3, %eax;  # flush TLB
> > +	movl	%eax, %cr3
> > +1:
> >  	movl	restore_pblist, %edx
> >  	.p2align 4,,7
> >  
> > @@ -54,16 +61,8 @@ done:
> >  	movl	$swapper_pg_dir, %eax
> >  	subl	$__PAGE_OFFSET, %eax
> >  	movl	%eax, %cr3
> > -	/* Flush TLB, including "global" things (vmalloc) */
> >  	movl	mmu_cr4_features, %ecx
> >  	jecxz	1f	# cr4 Pentium and higher, skip if zero
> > -	movl	%ecx, %edx
> > -	andl	$~(X86_CR4_PGE), %edx
> > -	movl	%edx, %cr4;  # turn off PGE
> > -1:
> > -	movl	%cr3, %eax;  # flush TLB
> > -	movl	%eax, %cr3
> 
> Now that's too much removed.  We actually _want_ to do the TLB flush here,
> but not unset PGE, because it's been unset already.
> 
> So, the above two lines should not be removed.
> 
> Also, I'd remove the first jecxz and keep the second one.

Scratch that, the patch is fine, because we load cr3 right before that.
Sorry for the noise.

Acked-by: Rafael J. Wysocki <rjw@...k.pl>

Peter, are you going to take it or should I handle it?

Rafael
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