2012-10-25 13:08:31

by Peter Zijlstra

Subject: [PATCH 07/31] sched, numa, mm, s390/thp: Implement pmd_pgprot() for s390

From: Gerald Schaefer <[email protected]>

This patch adds an implementation of pmd_pgprot() for s390,
in preparation to future THP changes.

Reported-by: Stephen Rothwell <[email protected]>
Signed-off-by: Gerald Schaefer <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ralf Baechle <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/s390/include/asm/pgtable.h | 13 +++++++++++++
1 file changed, 13 insertions(+)

Index: tip/arch/s390/include/asm/pgtable.h
===================================================================
--- tip.orig/arch/s390/include/asm/pgtable.h
+++ tip/arch/s390/include/asm/pgtable.h
@@ -1240,6 +1240,19 @@ static inline void set_pmd_at(struct mm_
*pmdp = entry;
}

+static inline pgprot_t pmd_pgprot(pmd_t pmd)
+{
+ pgprot_t prot = PAGE_RW;
+
+ if (pmd_val(pmd) & _SEGMENT_ENTRY_RO) {
+ if (pmd_val(pmd) & _SEGMENT_ENTRY_INV)
+ prot = PAGE_NONE;
+ else
+ prot = PAGE_RO;
+ }
+ return prot;
+}
+
static inline unsigned long massage_pgprot_pmd(pgprot_t pgprot)
{
unsigned long pgprot_pmd = 0;

2012-11-01 10:49:51

by Mel Gorman

Subject: Re: [PATCH 07/31] sched, numa, mm, s390/thp: Implement pmd_pgprot() for s390

On Thu, Oct 25, 2012 at 02:16:24PM +0200, Peter Zijlstra wrote:
> From: Gerald Schaefer <[email protected]>
>
> This patch adds an implementation of pmd_pgprot() for s390,
> in preparation to future THP changes.
>

The additional pmd_pgprot implementations only are necessary if we want
to preserve the PROT_NONE protections across a split but that somewhat
forces that PROT_NONE be used as the protection bit across all
architectures. Is that possible? I think I would prefer that
prot-protection-across-splits just went away until it was proven
necessary and potentially recoded in terms of _PAGE_NUMA and friends
instead.

--
Mel Gorman
SUSE Labs