[PATCH v4 11/20] powerpc/mm: don't use pte_alloc_one_kernel() before slab is available

[Christophe Leroy]

In the same way as PPC64, let's handle pte allocation directly
in kernel_map_page() when slab is not available.

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
 arch/powerpc/mm/pgtable_32.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 5877f5aa8f5d..6c8a07624773 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -43,18 +43,9 @@ EXPORT_SYMBOL(ioremap_bot);  /* aka VMALLOC_END */
 
 extern char etext[], _stext[], _sinittext[], _einittext[];
 
-__ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
+pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 {
-       pte_t *pte;
-
-       if (slab_is_available()) {
-               pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
-       } else {
-               pte = __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
-               if (pte)
-                       clear_page(pte);
-       }
-       return pte;
+       return (pte_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 }
 
 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
@@ -222,7 +213,21 @@ void iounmap(volatile void __iomem *addr)
 }
 EXPORT_SYMBOL(iounmap);
 
-int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
+static __init pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
+{
+       if (!pmd_present(*pmdp)) {
+               pte_t *ptep = __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
+
+               if (!ptep)
+                       return NULL;
+
+               clear_page(ptep);
+               pmd_populate_kernel(&init_mm, pmdp, ptep);
+       }
+       return pte_offset_kernel(pmdp, va);
+}
+
+__ref int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
 {
        pmd_t *pd;
        pte_t *pg;
@@ -231,7 +236,10 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, 
pgprot_t prot)
        /* Use upper 10 bits of VA to index the first level map */
        pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
        /* Use middle 10 bits of VA to index the second-level map */
-       pg = pte_alloc_kernel(pd, va);
+       if (slab_is_available())
+               pg = pte_alloc_kernel(pd, va);
+       else
+               pg = early_pte_alloc_kernel(pd, va);
        if (pg != 0) {
                err = 0;
                /* The PTE should never be already set nor present in the
-- 
2.13.3