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-rw-r--r--arch/s390/lib/uaccess.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
index c4f8039a35e8..0267405ab7c6 100644
--- a/arch/s390/lib/uaccess.c
+++ b/arch/s390/lib/uaccess.c
@@ -64,10 +64,13 @@ mm_segment_t enable_sacf_uaccess(void)
{
mm_segment_t old_fs;
unsigned long asce, cr;
+ unsigned long flags;
old_fs = current->thread.mm_segment;
if (old_fs & 1)
return old_fs;
+ /* protect against a concurrent page table upgrade */
+ local_irq_save(flags);
current->thread.mm_segment |= 1;
asce = S390_lowcore.kernel_asce;
if (likely(old_fs == USER_DS)) {
@@ -83,6 +86,7 @@ mm_segment_t enable_sacf_uaccess(void)
__ctl_load(asce, 7, 7);
set_cpu_flag(CIF_ASCE_SECONDARY);
}
+ local_irq_restore(flags);
return old_fs;
}
EXPORT_SYMBOL(enable_sacf_uaccess);