Blackfin arch: fix bug - MPU crashes under stress
Bug Description:
a customer reported under IRQ stress, running applications may
wrongly trigger an ICPLB miss and be killed. after playing a
bit more, here's a test case that may be triggering the same bug.
Fixing:
After modifying page protections, only modify the active CPLBs if the
protection change was made for the active mm.
Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
diff --git a/include/asm-blackfin/mmu_context.h b/include/asm-blackfin/mmu_context.h
index f55ec3c..8529552 100644
--- a/include/asm-blackfin/mmu_context.h
+++ b/include/asm-blackfin/mmu_context.h
@@ -173,8 +173,10 @@
static inline void update_protections(struct mm_struct *mm)
{
- flush_switched_cplbs();
- set_mask_dcplbs(mm->context.page_rwx_mask);
+ if (mm->context.page_rwx_mask == current_rwx_mask) {
+ flush_switched_cplbs();
+ set_mask_dcplbs(mm->context.page_rwx_mask);
+ }
}
#endif
