[PATCH v1 08/15] powerpc/mm: don't use pte_alloc_kernel() until slab is available on PPC32

[Christophe Leroy]

In the same way as PPC64, implement early allocation functions and
avoid calling pte_alloc_kernel() before slab is available.

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
 arch/powerpc/mm/pgtable_32.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 6e56a6240bfa..a1c3062f0665 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -43,11 +43,8 @@ EXPORT_SYMBOL(ioremap_bot);  /* aka VMALLOC_END */
 
 extern char etext[], _stext[], _sinittext[], _einittext[];
 
-__ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
+pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 {
-       if (!slab_is_available())
-               return memblock_alloc(PTE_FRAG_SIZE, PTE_FRAG_SIZE);
-
        return (pte_t *)pte_fragment_alloc(mm, 1);
 }
 
@@ -205,7 +202,29 @@ void iounmap(volatile void __iomem *addr)
 }
 EXPORT_SYMBOL(iounmap);
 
-int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
+static void __init *early_alloc_pgtable(unsigned long size)
+{
+       void *ptr = memblock_alloc(size, size);
+
+       if (!ptr)
+               panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
+                     __func__, size, size);
+
+       return ptr;
+}
+
+static pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
+{
+       if (pmd_none(*pmdp)) {
+               pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
+
+               pmd_populate_kernel(&init_mm, pmdp, ptep);
+       }
+       return pte_offset_kernel(pmdp, va);
+}
+
+
+int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
 {
        pmd_t *pd;
        pte_t *pg;
@@ -214,7 +233,10 @@ 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 (likely(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