From mboxrd@z Thu Jan  1 00:00:00 1970
From: rjw@rjwysocki.net (Rafael J. Wysocki)
Date: Thu, 12 Nov 2015 01:48:32 +0100
Subject: [PATCH v2 10/11] PM / Hibernate: clean cached pages on
 architectures that require it
In-Reply-To: <20151111114039.GA8375@red-moon>
References: <1445966960-31724-1-git-send-email-james.morse@arm.com>
 <1445966960-31724-11-git-send-email-james.morse@arm.com>
 <20151111114039.GA8375@red-moon>
Message-ID: <2039611.PJaFlk1sMi@vostro.rjw.lan>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wednesday, November 11, 2015 11:40:39 AM Lorenzo Pieralisi wrote:
> Hi Pavel, Rafael,
> 
> Do you have any feedback on this patch ?
> 
> It is fundamental to this series and affects Hibernate core code so if you
> have any feedback that would be much appreciated.

I'm really not familiar with the flush_icache_range() interface.

What exactly does it do?

Rafael


> On Tue, Oct 27, 2015 at 05:29:19PM +0000, James Morse wrote:
> > Some architectures require code written to memory as if it were data to be
> > 'cleaned' from any data caches so that the processor can fetch them as new
> > instructions.
> > 
> > During resume from hibernate, the snapshot code copies some pages directly,
> > meaning these architectures do not get a chance to perform their cache
> > maintenance. Add a call to flush_icache_range(), which is provided by
> > architectures that require it, to perform the maintenance.
> > 
> > This mirrors the kernel's behaviour when loading kernel modules and when
> > mapping executable pages to user space.
> > 
> > Signed-off-by: James Morse <james.morse@arm.com>
> > ---
> >  kernel/power/snapshot.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> > index 5235dd4e1e2f..139fc449ad75 100644
> > --- a/kernel/power/snapshot.c
> > +++ b/kernel/power/snapshot.c
> > @@ -31,6 +31,7 @@
> >  #include <linux/ktime.h>
> >  
> >  #include <asm/uaccess.h>
> > +#include <asm/cacheflush.h>
> >  #include <asm/mmu_context.h>
> >  #include <asm/pgtable.h>
> >  #include <asm/tlbflush.h>
> > @@ -1196,9 +1197,12 @@ static unsigned int count_data_pages(void)
> >  static inline void do_copy_page(long *dst, long *src)
> >  {
> >  	int n;
> > +	unsigned long __maybe_unused start = (unsigned long)dst;
> >  
> >  	for (n = PAGE_SIZE / sizeof(long); n; n--)
> >  		*dst++ = *src++;
> > +
> > +	flush_icache_range(start, start+PAGE_SIZE);
> >  }
> >  
> >  
> --
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.