[patch 74/86] alpha: use pgtable-nopud instead of 4level-fixup

Andrew Morton
2019-12-05T00:53:47Z

From: Mike Rapoport <rppt@linux.ibm.com>
Subject: alpha: use pgtable-nopud instead of 4level-fixup

Patch series "mm: remove __ARCH_HAS_4LEVEL_HACK", v13.

These patches convert several architectures to use page table folding and
remove __ARCH_HAS_4LEVEL_HACK along with
include/asm-generic/4level-fixup.h.

For the nommu configurations the folding is already implemented by the
generic code so the only change was to use the appropriate header file.

As for the rest, the changes are mostly about mechanical replacement of
pgd accessors with pud/pmd ones and the addition of higher levels to page
table traversals.

With Vineet's patches from "elide extraneous generated code for folded
p4d/pud/pmd" series [1] there is a small shrink of the kernel size of
about -0.01% for the defconfig builds.

This patch (of 13):

It is not likely alpha will have 5-level page tables.

Replace usage of include/asm-generic/4level-fixup.h and implied
__ARCH_HAS_4LEVEL_HACK with include/asm-generic/pgtable-nopud.h and adjust
page table manipulation macros and functions accordingly.

Link: http://lkml.kernel.org/r/1572938135-31886-2-git-send-email-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
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: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Peter Rosin <peda@axentia.se>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: Anatoly Pugachev <matorola@gmail.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

arch/alpha/include/asm/mmzone.h | 1 -
arch/alpha/include/asm/pgalloc.h | 4 ++--
arch/alpha/include/asm/pgtable.h | 24 ++++++++++++------------
arch/alpha/mm/init.c | 12 ++++++++----
4 files changed, 22 insertions(+), 19 deletions(-)

--- a/arch/alpha/include/asm/mmzone.h~alpha-use-pgtable-nopud-instead-of-4level-fixup
+++ a/arch/alpha/include/asm/mmzone.h
@@ -73,7 +73,6 @@ PLAT_NODE_DATA_LOCALNR(unsigned long p,
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)

#define pmd_page(pmd) (pfn_to_page(pmd_val(pmd) >> 32))
-#define pgd_page(pgd) (pfn_to_page(pgd_val(pgd) >> 32))
#define pte_pfn(pte) (pte_val(pte) >> 32)

#define mk_pte(page, pgprot) \
--- a/arch/alpha/include/asm/pgalloc.h~alpha-use-pgtable-nopud-instead-of-4level-fixup
+++ a/arch/alpha/include/asm/pgalloc.h
@@ -27,9 +27,9 @@ pmd_populate_kernel(struct mm_struct *mm
}

static inline void
-pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd)
+pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
{
- pgd_set(pgd, pmd);
+ pud_set(pud, pmd);
}

extern pgd_t *pgd_alloc(struct mm_struct *mm);
--- a/arch/alpha/include/asm/pgtable.h~alpha-use-pgtable-nopud-instead-of-4level-fixup
+++ a/arch/alpha/include/asm/pgtable.h
@@ -2,7 +2,7 @@
#ifndef _ALPHA_PGTABLE_H
#define _ALPHA_PGTABLE_H

-#include <asm-generic/4level-fixup.h>
+#include <asm-generic/pgtable-nopud.h>

/*
* This file contains the functions and defines necessary to modify and use
@@ -226,8 +226,8 @@ extern inline pte_t pte_modify(pte_t pte
extern inline void pmd_set(pmd_t * pmdp, pte_t * ptep)
{ pmd_val(*pmdp) = _PAGE_TABLE | ((((unsigned long) ptep) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }

-extern inline void pgd_set(pgd_t * pgdp, pmd_t * pmdp)
-{ pgd_val(*pgdp) = _PAGE_TABLE | ((((unsigned long) pmdp) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }
+extern inline void pud_set(pud_t * pudp, pmd_t * pmdp)
+{ pud_val(*pudp) = _PAGE_TABLE | ((((unsigned long) pmdp) - PAGE_OFFSET) << (32-PAGE_SHIFT)); }

extern inline unsigned long
@@ -238,11 +238,11 @@ pmd_page_vaddr(pmd_t pmd)

#ifndef CONFIG_DISCONTIGMEM
#define pmd_page(pmd) (mem_map + ((pmd_val(pmd) & _PFN_MASK) >> 32))
-#define pgd_page(pgd) (mem_map + ((pgd_val(pgd) & _PFN_MASK) >> 32))
+#define pud_page(pud) (mem_map + ((pud_val(pud) & _PFN_MASK) >> 32))
#endif

-extern inline unsigned long pgd_page_vaddr(pgd_t pgd)
-{ return PAGE_OFFSET + ((pgd_val(pgd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }
+extern inline unsigned long pud_page_vaddr(pud_t pgd)
+{ return PAGE_OFFSET + ((pud_val(pgd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }

extern inline int pte_none(pte_t pte) { return !pte_val(pte); }
extern inline int pte_present(pte_t pte) { return pte_val(pte) & _PAGE_VALID; }
@@ -256,10 +256,10 @@ extern inline int pmd_bad(pmd_t pmd) {
extern inline int pmd_present(pmd_t pmd) { return pmd_val(pmd) & _PAGE_VALID; }
extern inline void pmd_clear(pmd_t * pmdp) { pmd_val(*pmdp) = 0; }

-extern inline int pgd_none(pgd_t pgd) { return !pgd_val(pgd); }
-extern inline int pgd_bad(pgd_t pgd) { return (pgd_val(pgd) & ~_PFN_MASK) != _PAGE_TABLE; }
-extern inline int pgd_present(pgd_t pgd) { return pgd_val(pgd) & _PAGE_VALID; }
-extern inline void pgd_clear(pgd_t * pgdp) { pgd_val(*pgdp) = 0; }
+extern inline int pud_none(pud_t pud) { return !pud_val(pud); }
+extern inline int pud_bad(pud_t pud) { return (pud_val(pud) & ~_PFN_MASK) != _PAGE_TABLE; }
+extern inline int pud_present(pud_t pud) { return pud_val(pud) & _PAGE_VALID; }
+extern inline void pud_clear(pud_t * pudp) { pud_val(*pudp) = 0; }

/*
* The following only work if pte_present() is true.
@@ -301,9 +301,9 @@ extern inline pte_t pte_mkspecial(pte_t
*/

/* Find an entry in the second-level page table.. */
-extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
+extern inline pmd_t * pmd_offset(pud_t * dir, unsigned long address)
{
- pmd_t *ret = (pmd_t *) pgd_page_vaddr(*dir) + ((address >> PMD_SHIFT) & (PTRS_PER_PAGE - 1));
+ pmd_t *ret = (pmd_t *) pud_page_vaddr(*dir) + ((address >> PMD_SHIFT) & (PTRS_PER_PAGE - 1));
smp_read_barrier_depends(); /* see above */
return ret;
}
--- a/arch/alpha/mm/init.c~alpha-use-pgtable-nopud-instead-of-4level-fixup
+++ a/arch/alpha/mm/init.c
@@ -146,6 +146,8 @@ callback_init(void * kernel_end)
{
struct crb_struct * crb;
pgd_t *pgd;
+ p4d_t *p4d;
+ pud_t *pud;
pmd_t *pmd;
void *two_pages;

@@ -184,8 +186,10 @@ callback_init(void * kernel_end)
memset(two_pages, 0, 2*PAGE_SIZE);

pgd = pgd_offset_k(VMALLOC_START);
- pgd_set(pgd, (pmd_t *)two_pages);
- pmd = pmd_offset(pgd, VMALLOC_START);
+ p4d = p4d_offset(pgd, VMALLOC_START);
+ pud = pud_offset(p4d, VMALLOC_START);
+ pud_set(pud, (pmd_t *)two_pages);
+ pmd = pmd_offset(pud, VMALLOC_START);
pmd_set(pmd, (pte_t *)(two_pages + PAGE_SIZE));

if (alpha_using_srm) {
@@ -214,9 +218,9 @@ callback_init(void * kernel_end)
/* Newer consoles (especially on larger
systems) may require more pages of
PTEs. Grab additional pages as needed. */
- if (pmd != pmd_offset(pgd, vaddr)) {
+ if (pmd != pmd_offset(pud, vaddr)) {
memset(kernel_end, 0, PAGE_SIZE);
- pmd = pmd_offset(pgd, vaddr);
+ pmd = pmd_offset(pud, vaddr);
pmd_set(pmd, (pte_t *)kernel_end);
kernel_end += PAGE_SIZE;
}
_