powerpc/mm: Add new hash_page_mm()

This adds a new function hash_page_mm() based on the existing hash_page().
This version allows any struct mm to be passed in, rather than assuming
current. This is useful for servicing co-processor faults which are not in the
context of the current running process.

We need to be careful here as the current hash_page() assumes current in a few
places.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 17 insertions, 7 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index fe5609d7a9d7..d5339a3b9945 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -904,7 +904,7 @@ void demote_segment_4k(struct mm_struct *mm, unsigned long addr)
                 return;
         slice_set_range_psize(mm, addr, 1, MMU_PAGE_4K);
         copro_flush_all_slbs(mm);
-        if (get_paca_psize(addr) != MMU_PAGE_4K) {
+        if ((get_paca_psize(addr) != MMU_PAGE_4K) && (current->mm == mm)) {
                 get_paca()->context = mm->context;
                 slb_flush_and_rebolt();
         }
@@ -989,12 +989,11 @@ static void check_paca_psize(unsigned long ea, struct mm_struct *mm,
  * -1 - critical hash insertion error
  * -2 - access not permitted by subpage protection mechanism
  */
-int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
+int hash_page_mm(struct mm_struct *mm, unsigned long ea, unsigned long access, unsigned long trap)
 {
         enum ctx_state prev_state = exception_enter();
         pgd_t *pgdir;
         unsigned long vsid;
-        struct mm_struct *mm;
         pte_t *ptep;
         unsigned hugeshift;
         const struct cpumask *tmp;
@@ -1008,7 +1007,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
         switch (REGION_ID(ea)) {
         case USER_REGION_ID:
                 user_region = 1;
-                mm = current->mm;
                 if (! mm) {
                         DBG_LOW(" user region with no mm !\n");
                         rc = 1;
@@ -1019,7 +1017,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
                 vsid = get_vsid(mm->context.id, ea, ssize);
                 break;
         case VMALLOC_REGION_ID:
-                mm = &init_mm;
                 vsid = get_kernel_vsid(ea, mmu_kernel_ssize);
                 if (ea < VMALLOC_END)
                         psize = mmu_vmalloc_psize;
@@ -1104,7 +1101,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
                         WARN_ON(1);
                 }
 #endif
-                check_paca_psize(ea, mm, psize, user_region);
+                if (current->mm == mm)
+                        check_paca_psize(ea, mm, psize, user_region);
 
                 goto bail;
         }
@@ -1145,7 +1143,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
                 }
         }
 
-        check_paca_psize(ea, mm, psize, user_region);
+        if (current->mm == mm)
+                check_paca_psize(ea, mm, psize, user_region);
 #endif /* CONFIG_PPC_64K_PAGES */
 
 #ifdef CONFIG_PPC_HAS_HASH_64K
@@ -1180,6 +1179,17 @@ bail:
         exception_exit(prev_state);
         return rc;
 }
+EXPORT_SYMBOL_GPL(hash_page_mm);
+
+int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
+{
+        struct mm_struct *mm = current->mm;
+
+        if (REGION_ID(ea) == VMALLOC_REGION_ID)
+                mm = &init_mm;
+
+        return hash_page_mm(mm, ea, access, trap);
+}
 EXPORT_SYMBOL_GPL(hash_page);
 
 void hash_preload(struct mm_struct *mm, unsigned long ea,