x86: update populate_extra_pte() and add populate_extra_pmd()

Impact: minor change to populate_extra_pte() and addition of pmd flavor

Update populate_extra_pte() to return pointer to the pte_t for the
specified address and add populate_extra_pmd() which only populates
till the pmd and returns pointer to the pmd entry for the address.

For 64bit, pud/pmd/pte fill functions are separated out from
set_pte_vaddr[_pud]() and used for set_pte_vaddr[_pud]() and
populate_extra_{pte|pmd}().

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 45 insertions, 30 deletions

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 7f91e2cdc4c..7d4e76da336 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -168,34 +168,51 @@ static __ref void *spp_getpage(void)
 	return ptr;
 }
 
-void
-set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte)
+static pud_t * __init fill_pud(pgd_t *pgd, unsigned long vaddr)
 {
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *pte;
+	if (pgd_none(*pgd)) {
+		pud_t *pud = (pud_t *)spp_getpage();
+		pgd_populate(&init_mm, pgd, pud);
+		if (pud != pud_offset(pgd, 0))
+			printk(KERN_ERR "PAGETABLE BUG #00! %p <-> %p\n",
+			       pud, pud_offset(pgd, 0));
+	}
+	return pud_offset(pgd, vaddr);
+}
 
-	pud = pud_page + pud_index(vaddr);
+static pmd_t * __init fill_pmd(pud_t *pud, unsigned long vaddr)
+{
 	if (pud_none(*pud)) {
-		pmd = (pmd_t *) spp_getpage();
+		pmd_t *pmd = (pmd_t *) spp_getpage();
 		pud_populate(&init_mm, pud, pmd);
-		if (pmd != pmd_offset(pud, 0)) {
+		if (pmd != pmd_offset(pud, 0))
 			printk(KERN_ERR "PAGETABLE BUG #01! %p <-> %p\n",
-				pmd, pmd_offset(pud, 0));
-			return;
-		}
+			       pmd, pmd_offset(pud, 0));
 	}
-	pmd = pmd_offset(pud, vaddr);
+	return pmd_offset(pud, vaddr);
+}
+
+static pte_t * __init fill_pte(pmd_t *pmd, unsigned long vaddr)
+{
 	if (pmd_none(*pmd)) {
-		pte = (pte_t *) spp_getpage();
+		pte_t *pte = (pte_t *) spp_getpage();
 		pmd_populate_kernel(&init_mm, pmd, pte);
-		if (pte != pte_offset_kernel(pmd, 0)) {
+		if (pte != pte_offset_kernel(pmd, 0))
 			printk(KERN_ERR "PAGETABLE BUG #02!\n");
-			return;
-		}
 	}
+	return pte_offset_kernel(pmd, vaddr);
+}
+
+void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte)
+{
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	pud = pud_page + pud_index(vaddr);
+	pmd = fill_pmd(pud, vaddr);
+	pte = fill_pte(pmd, vaddr);
 
-	pte = pte_offset_kernel(pmd, vaddr);
 	set_pte(pte, new_pte);
 
 	/*
@@ -205,8 +222,7 @@ set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte)
 	__flush_tlb_one(vaddr);
 }
 
-void
-set_pte_vaddr(unsigned long vaddr, pte_t pteval)
+void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
 {
 	pgd_t *pgd;
 	pud_t *pud_page;
@@ -223,23 +239,22 @@ set_pte_vaddr(unsigned long vaddr, pte_t pteval)
 	set_pte_vaddr_pud(pud_page, vaddr, pteval);
 }
 
-void __init populate_extra_pte(unsigned long vaddr)
+pmd_t * __init populate_extra_pmd(unsigned long vaddr)
 {
 	pgd_t *pgd;
 	pud_t *pud;
 
 	pgd = pgd_offset_k(vaddr);
-	if (pgd_none(*pgd)) {
-		pud = (pud_t *)spp_getpage();
-		pgd_populate(&init_mm, pgd, pud);
-		if (pud != pud_offset(pgd, 0)) {
-			printk(KERN_ERR "PAGETABLE BUG #00! %p <-> %p\n",
-			       pud, pud_offset(pgd, 0));
-			return;
-		}
-	}
+	pud = fill_pud(pgd, vaddr);
+	return fill_pmd(pud, vaddr);
+}
+
+pte_t * __init populate_extra_pte(unsigned long vaddr)
+{
+	pmd_t *pmd;
 
-	set_pte_vaddr_pud((pud_t *)pgd_page_vaddr(*pgd), vaddr, __pte(0));
+	pmd = populate_extra_pmd(vaddr);
+	return fill_pte(pmd, vaddr);
 }
 
 /*