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-rw-r--r--arch/powerpc/mm/fault.c43
1 files changed, 33 insertions, 10 deletions
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 62a50d6d1053..8dc758658972 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -407,15 +407,6 @@ good_area:
(cpu_has_feature(CPU_FTR_NOEXECUTE) ||
!(vma->vm_flags & (VM_READ | VM_WRITE))))
goto bad_area;
-
-#ifdef CONFIG_PPC_STD_MMU
- /*
- * protfault should only happen due to us
- * mapping a region readonly temporarily. PROT_NONE
- * is also covered by the VMA check above.
- */
- WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
-#endif /* CONFIG_PPC_STD_MMU */
/* a write */
} else if (is_write) {
if (!(vma->vm_flags & VM_WRITE))
@@ -425,8 +416,40 @@ good_area:
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto bad_area;
- WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
}
+#ifdef CONFIG_PPC_STD_MMU
+ /*
+ * For hash translation mode, we should never get a
+ * PROTFAULT. Any update to pte to reduce access will result in us
+ * removing the hash page table entry, thus resulting in a DSISR_NOHPTE
+ * fault instead of DSISR_PROTFAULT.
+ *
+ * A pte update to relax the access will not result in a hash page table
+ * entry invalidate and hence can result in DSISR_PROTFAULT.
+ * ptep_set_access_flags() doesn't do a hpte flush. This is why we have
+ * the special !is_write in the below conditional.
+ *
+ * For platforms that doesn't supports coherent icache and do support
+ * per page noexec bit, we do setup things such that we do the
+ * sync between D/I cache via fault. But that is handled via low level
+ * hash fault code (hash_page_do_lazy_icache()) and we should not reach
+ * here in such case.
+ *
+ * For wrong access that can result in PROTFAULT, the above vma->vm_flags
+ * check should handle those and hence we should fall to the bad_area
+ * handling correctly.
+ *
+ * For embedded with per page exec support that doesn't support coherent
+ * icache we do get PROTFAULT and we handle that D/I cache sync in
+ * set_pte_at while taking the noexec/prot fault. Hence this is WARN_ON
+ * is conditional for server MMU.
+ *
+ * For radix, we can get prot fault for autonuma case, because radix
+ * page table will have them marked noaccess for user.
+ */
+ if (!radix_enabled() && !is_write)
+ WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
+#endif /* CONFIG_PPC_STD_MMU */
/*
* If for any reason at all we couldn't handle the fault,