Merge tag 'pm-turbostat-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git...

[karo-tx-linux.git] / arch / powerpc / mm / fault.c

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 62a50d6d1053c9f1e3854ecb9de877e0f02cbb3b..8dc7586589727d1697683849ac7a0aa518ca93a1 100644 (file)
--- 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,