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

From: [email-masked] (Lorenzo Pieralisi)
Date: Wed, 11 Nov 2015 11:40:39 +0000

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.

Thanks a lot,
Lorenzo

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 <[email-masked]>
> ---
>  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);
>  }
>  
>  
> -- 
> 2.1.4
>