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| author | Carsten Otte <cotte@de.ibm.com> | 2011-10-30 15:17:02 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2011-10-30 15:16:45 +0100 |
| commit | 499069e1a421e2a85e76846c3237f00f1a5cb435 (patch) | |
| tree | 01cf74636909b06b5a986f97a90bf0af5040212d | |
| parent | cc772456ac9b460693492b3a3d89e8c81eda5874 (diff) | |
| download | op-kernel-dev-499069e1a421e2a85e76846c3237f00f1a5cb435.zip op-kernel-dev-499069e1a421e2a85e76846c3237f00f1a5cb435.tar.gz | |
[S390] take mmap_sem when walking guest page table
gmap_fault needs to walk the guest page table. However, parts of
that may change if some other thread does munmap. In that case
gmap_unmap_notifier will also unmap the corresponding parts from
the guest page table. We need to take mmap_sem in order to serialize
these operations.
do_exception now calls __gmap_fault with mmap_sem held which does
not get exported to modules. The exported function, which is called
from KVM, now takes mmap_sem.
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/pgtable.h | 1 | ||||
| -rw-r--r-- | arch/s390/mm/fault.c | 2 | ||||
| -rw-r--r-- | arch/s390/mm/pgtable.c | 15 |
3 files changed, 16 insertions, 2 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index c0cb794..bc5f520 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -696,6 +696,7 @@ void gmap_disable(struct gmap *gmap); int gmap_map_segment(struct gmap *gmap, unsigned long from, unsigned long to, unsigned long length); int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len); +unsigned long __gmap_fault(unsigned long address, struct gmap *); unsigned long gmap_fault(unsigned long address, struct gmap *); /* diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index de3af0c..1766def 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -307,7 +307,7 @@ static inline int do_exception(struct pt_regs *regs, int access, #ifdef CONFIG_PGSTE if (test_tsk_thread_flag(current, TIF_SIE) && S390_lowcore.gmap) { - address = gmap_fault(address, + address = __gmap_fault(address, (struct gmap *) S390_lowcore.gmap); if (address == -EFAULT) { fault = VM_FAULT_BADMAP; diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 96e85ac..441d344 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -393,7 +393,10 @@ out_unmap: } EXPORT_SYMBOL_GPL(gmap_map_segment); -unsigned long gmap_fault(unsigned long address, struct gmap *gmap) +/* + * this function is assumed to be called with mmap_sem held + */ +unsigned long __gmap_fault(unsigned long address, struct gmap *gmap) { unsigned long *table, vmaddr, segment; struct mm_struct *mm; @@ -461,7 +464,17 @@ unsigned long gmap_fault(unsigned long address, struct gmap *gmap) return vmaddr | (address & ~PMD_MASK); } return -EFAULT; +} + +unsigned long gmap_fault(unsigned long address, struct gmap *gmap) +{ + unsigned long rc; + + down_read(&gmap->mm->mmap_sem); + rc = __gmap_fault(address, gmap); + up_read(&gmap->mm->mmap_sem); + return rc; } EXPORT_SYMBOL_GPL(gmap_fault); |
