powerpc: Replace find_linux_pte with find_linux_pte_or_hugepte

Replace find_linux_pte with find_linux_pte_or_hugepte and explicitly
document why we don't need to handle transparent hugepages at callsites.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 20 insertions, 5 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 2f470809876f..e8434ca6efd4 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1145,6 +1145,7 @@ EXPORT_SYMBOL_GPL(hash_page);
 void hash_preload(struct mm_struct *mm, unsigned long ea,
                   unsigned long access, unsigned long trap)
 {
+        int hugepage_shift;
         unsigned long vsid;
         pgd_t *pgdir;
         pte_t *ptep;
@@ -1166,10 +1167,15 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
         pgdir = mm->pgd;
         if (pgdir == NULL)
                 return;
-        ptep = find_linux_pte(pgdir, ea);
+        /*
+         * THP pages use update_mmu_cache_pmd. We don't do
+         * hash preload there. Hence can ignore THP here
+         */
+        ptep = find_linux_pte_or_hugepte(pgdir, ea, &hugepage_shift);
         if (!ptep)
                 return;
 
+        WARN_ON(hugepage_shift);
 #ifdef CONFIG_PPC_64K_PAGES
         /* If either _PAGE_4K_PFN or _PAGE_NO_CACHE is set (and we are on
          * a 64K kernel), then we don't preload, hash_page() will take
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 49282045ee96..8add58061003 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -105,6 +105,7 @@ int pgd_huge(pgd_t pgd)
 
 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 {
+        /* Only called for hugetlbfs pages, hence can ignore THP */
         return find_linux_pte_or_hugepte(mm->pgd, addr, NULL);
 }
 
@@ -673,11 +674,14 @@ follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
         struct page *page;
         unsigned shift;
         unsigned long mask;
-
+        /*
+         * Transparent hugepages are handled by generic code. We can skip them
+         * here.
+         */
         ptep = find_linux_pte_or_hugepte(mm->pgd, address, &shift);
 
         /* Verify it is a huge page else bail. */
-        if (!ptep || !shift)
+        if (!ptep || !shift || pmd_trans_huge(*(pmd_t *)ptep))
                 return ERR_PTR(-EINVAL);
 
         mask = (1UL << shift) - 1;
diff --git a/arch/powerpc/mm/tlb_hash64.c b/arch/powerpc/mm/tlb_hash64.c
index 48bf63ea6525..313c85c5aa90 100644
--- a/arch/powerpc/mm/tlb_hash64.c
+++ b/arch/powerpc/mm/tlb_hash64.c
@@ -189,6 +189,7 @@ void tlb_flush(struct mmu_gather *tlb)
 void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
                               unsigned long end)
 {
+        int hugepage_shift;
         unsigned long flags;
 
         start = _ALIGN_DOWN(start, PAGE_SIZE);
@@ -206,7 +207,8 @@ void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
         local_irq_save(flags);
         arch_enter_lazy_mmu_mode();
         for (; start < end; start += PAGE_SIZE) {
-                pte_t *ptep = find_linux_pte(mm->pgd, start);
+                pte_t *ptep = find_linux_pte_or_hugepte(mm->pgd, start,
+                                                        &hugepage_shift);
                 unsigned long pte;
 
                 if (ptep == NULL)
@@ -214,7 +216,10 @@ void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
                 pte = pte_val(*ptep);
                 if (!(pte & _PAGE_HASHPTE))
                         continue;
-                hpte_need_flush(mm, start, ptep, pte, 0);
+                if (unlikely(hugepage_shift && pmd_trans_huge(*(pmd_t *)pte)))
+                        hpte_do_hugepage_flush(mm, start, (pmd_t *)pte);
+                else
+                        hpte_need_flush(mm, start, ptep, pte, 0);
         }
         arch_leave_lazy_mmu_mode();
         local_irq_restore(flags);