Subject: [PATCH v2 10/11] PM / Hibernate: clean cached pages on architectures that require it

From: [email-masked] (Pavel Machek)
Date: Mon, 16 Nov 2015 13:36:15 +0100

On Mon 2015-11-16 12:27:07, James Morse wrote:
> On 14/11/15 20:26, Pavel Machek wrote:
> > On Tue 2015-10-27 17:29:19, 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 <[email-masked]>
> > 
> > Looks reasonable.
> > 
> > Acked-by: Pavel Machek <[email-masked]>
> 
> Thanks!
> 
> > 
> >> ---
> >>  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
> >> @@ -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;
> > 
> > Why the "maybe unused"?
> 
> To avoid a build warning on x86_64, and any other architectures that don't
> use the arguments in their flush_icache_range() implementation.

That's wrong fix, I believe.

flush_icache_range() should use their arguments. We should not have
all the callers caring about this.

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html