mm: pgtable: add shortcuts for accessing kernel PMD and PTE

The powerpc 32-bit implementation of pgtable has nice shortcuts for
accessing kernel PMD and PTE for a given virtual address.  Make these
helpers available for all architectures.

[rppt@linux.ibm.com: microblaze: fix page table traversal in setup_rt_frame()]
  Link: http://lkml.kernel.org/r/20200518191511.GD1118872@kernel.org
[akpm@linux-foundation.org: s/pmd_ptr_k/pmd_off_k/ in various powerpc places]

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200514170327.31389-9-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 6 insertions, 30 deletions

diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c
index 6ff6e2a9f9b3..d1fc9a7b7d78 100644
--- a/arch/sparc/mm/highmem.c
+++ b/arch/sparc/mm/highmem.c
@@ -36,18 +36,10 @@ static pte_t *kmap_pte;
 
 void __init kmap_init(void)
 {
-	unsigned long address;
-	p4d_t *p4d;
-	pud_t *pud;
-	pmd_t *dir;
-
-	address = __fix_to_virt(FIX_KMAP_BEGIN);
-	p4d = p4d_offset(pgd_offset_k(address), address);
-	pud = pud_offset(p4d, address);
-	dir = pmd_offset(pud, address);
+	unsigned long address = __fix_to_virt(FIX_KMAP_BEGIN);
 
         /* cache the first kmap pte */
-        kmap_pte = pte_offset_kernel(dir, address);
+        kmap_pte = virt_to_kpte(address);
 }
 
 void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 141614f19084..02e6e5e0f106 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -503,11 +503,7 @@ void __kprobes flush_icache_range(unsigned long start, unsigned long end)
 			if (kaddr >= PAGE_OFFSET)
 				paddr = kaddr & mask;
 			else {
-				pgd_t *pgdp = pgd_offset_k(kaddr);
-				p4d_t *p4dp = p4d_offset(pgdp, kaddr);
-				pud_t *pudp = pud_offset(p4dp, kaddr);
-				pmd_t *pmdp = pmd_offset(pudp, kaddr);
-				pte_t *ptep = pte_offset_kernel(pmdp, kaddr);
+				pte_t *ptep = virt_to_kpte(kaddr);
 
 				paddr = pte_val(*ptep) & mask;
 			}
diff --git a/arch/sparc/mm/io-unit.c b/arch/sparc/mm/io-unit.c
index 4aeed580b4d4..bfcc04bfce54 100644
--- a/arch/sparc/mm/io-unit.c
+++ b/arch/sparc/mm/io-unit.c
@@ -240,21 +240,15 @@ static void *iounit_alloc(struct device *dev, size_t len,
 	while(addr < end) {
 		page = va;
 		{
-			pgd_t *pgdp;
-			p4d_t *p4dp;
-			pud_t *pudp;
 			pmd_t *pmdp;
 			pte_t *ptep;
 			long i;
 
-			pgdp = pgd_offset(&init_mm, addr);
-			p4dp = p4d_offset(pgdp, addr);
-			pudp = pud_offset(p4dp, addr);
-			pmdp = pmd_offset(pudp, addr);
+			pmdp = pmd_off_k(addr);
 			ptep = pte_offset_map(pmdp, addr);
 
 			set_pte(ptep, mk_pte(virt_to_page(page), dvma_prot));
-			
+
 			i = ((addr - IOUNIT_DMA_BASE) >> PAGE_SHIFT);
 
 			iopte = iounit->page_table + i;
diff --git a/arch/sparc/mm/iommu.c b/arch/sparc/mm/iommu.c
index fa9e298fd985..35b002eb312e 100644
--- a/arch/sparc/mm/iommu.c
+++ b/arch/sparc/mm/iommu.c
@@ -348,9 +348,6 @@ static void *sbus_iommu_alloc(struct device *dev, size_t len,
 	while(addr < end) {
 		page = va;
 		{
-			pgd_t *pgdp;
-			p4d_t *p4dp;
-			pud_t *pudp;
 			pmd_t *pmdp;
 			pte_t *ptep;
 
@@ -361,10 +358,7 @@ static void *sbus_iommu_alloc(struct device *dev, size_t len,
 			else
 				__flush_page_to_ram(page);
 
-			pgdp = pgd_offset(&init_mm, addr);
-			p4dp = p4d_offset(pgdp, addr);
-			pudp = pud_offset(p4dp, addr);
-			pmdp = pmd_offset(pudp, addr);
+			pmdp = pmd_off_k(addr);
 			ptep = pte_offset_map(pmdp, addr);
 
 			set_pte(ptep, mk_pte(virt_to_page(page), dvma_prot));