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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2015-03-01 17:56:45 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2015-03-02 22:35:57 +0300
commit691d5264158e58004904f285417fefaf8650ffe6 (patch)
tree2a225e091af5d5ffb934ee4994db91ae0ad181aa /arch
parenta9ca8eb7afb4f1c90d8e43092e94c4e86785efbc (diff)
downloadlinux-691d5264158e58004904f285417fefaf8650ffe6.tar.xz
s390/mm: fix incorrect ASCE after crst_table_downgrade
The switch_mm function does nothing in case the prev and next mm are the same. It can happen that a crst_table_downgrade has changed the top-level pgd in the meantime on a different CPU. Always store the new ASCE to be picked up in entry.S. [heiko.carstens@de.ibm.com]: Bug was introduced with git commit 53e857f30867 ("s390/mm,tlb: race of lazy TLB flush vs. recreation of TLB entries") and causes random crashes due to broken page tables being used. Reported-by: Dominik Vogt <vogt@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/include/asm/mmu_context.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index f49b71954654..8fb3802f8fad 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -62,6 +62,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
{
int cpu = smp_processor_id();
+ S390_lowcore.user_asce = next->context.asce_bits | __pa(next->pgd);
if (prev == next)
return;
if (MACHINE_HAS_TLB_LC)
@@ -73,7 +74,6 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
atomic_dec(&prev->context.attach_count);
if (MACHINE_HAS_TLB_LC)
cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);
- S390_lowcore.user_asce = next->context.asce_bits | __pa(next->pgd);
}
#define finish_arch_post_lock_switch finish_arch_post_lock_switch