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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-07-23 22:11:42 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-08-29 13:20:11 +0200 |
| commit | 0944fe3f4a323f436180d39402cae7f9c46ead17 (patch) | |
| tree | 7b2ada69ff7e3c1fae20ec0b1dffe5e0d0ec2cc6 /arch/s390/mm/vmem.c | |
| parent | fbd70035fb2b03deb346052084794bc1d0e25aa2 (diff) | |
| download | linux-0944fe3f4a323f436180d39402cae7f9c46ead17.tar.gz | |
s390/mm: implement software referenced bits
The last remaining use for the storage key of the s390 architecture is reference counting. The alternative is to make page table entries invalid while they are old. On access the fault handler marks the pte/pmd as young which makes the pte/pmd valid if the access rights allow read access. The pte/pmd invalidations required for software managed reference bits cost a bit of performance, on the other hand the RRBE/RRBM instructions to read and reset the referenced bits are quite expensive as well. Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm/vmem.c')
| -rw-r--r-- | arch/s390/mm/vmem.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c index e1299d40818d..bcfb70b60be6 100644 --- a/arch/s390/mm/vmem.c +++ b/arch/s390/mm/vmem.c @@ -118,6 +118,7 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro) !(address & ~PMD_MASK) && (address + PMD_SIZE <= end)) { pmd_val(*pm_dir) = __pa(address) | _SEGMENT_ENTRY | _SEGMENT_ENTRY_LARGE | + _SEGMENT_ENTRY_YOUNG | (ro ? _SEGMENT_ENTRY_PROTECT : 0); address += PMD_SIZE; continue; |