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asm-generic: introduce __ARCH_USE_5LEVEL_HACK 

We are going to introduce <asm-generic/pgtable-nop4d.h> to provide
abstraction for properly (in opposite to 5level-fixup.h hack) folded
p4d level. The new header will be included from pgtable-nopud.h.

If an architecture uses <asm-generic/nop*d.h>, we cannot use
5level-fixup.h directly to quickly convert the architecture to 5-level
paging as it would conflict with pgtable-nop4d.h.

With this patch an architecture can define __ARCH_USE_5LEVEL_HACK before
inclusion <asm-genenric/nop*d.h> to use 5level-fixup.h.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2017-03-09 17:24:04 +03:00 committed by Linus Torvalds
parent 505a60e225
commit 30ec842660
2 changed files with 67 additions and 0 deletions
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62
include/asm-generic/pgtable-nop4d-hack.h Normal file
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@ -0,0 +1,62 @@
#ifndef _PGTABLE_NOP4D_HACK_H
#define _PGTABLE_NOP4D_HACK_H
#ifndef __ASSEMBLY__
#include <asm-generic/5level-fixup.h>
#define __PAGETABLE_PUD_FOLDED
/*
* Having the pud type consist of a pgd gets the size right, and allows
* us to conceptually access the pgd entry that this pud is folded into
* without casting.
*/
typedef struct { pgd_t pgd; } pud_t;
#define PUD_SHIFT PGDIR_SHIFT
#define PTRS_PER_PUD 1
#define PUD_SIZE (1UL << PUD_SHIFT)
#define PUD_MASK (~(PUD_SIZE-1))
/*
* The "pgd_xxx()" functions here are trivial for a folded two-level
* setup: the pud is never bad, and a pud always exists (as it's folded
* into the pgd entry)
*/
static inline int pgd_none(pgd_t pgd) { return 0; }
static inline int pgd_bad(pgd_t pgd) { return 0; }
static inline int pgd_present(pgd_t pgd) { return 1; }
static inline void pgd_clear(pgd_t *pgd) { }
#define pud_ERROR(pud) (pgd_ERROR((pud).pgd))
#define pgd_populate(mm, pgd, pud) do { } while (0)
/*
* (puds are folded into pgds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
*/
#define set_pgd(pgdptr, pgdval) set_pud((pud_t *)(pgdptr), (pud_t) { pgdval })
static inline pud_t *pud_offset(pgd_t *pgd, unsigned long address)
{
return (pud_t *)pgd;
}
#define pud_val(x) (pgd_val((x).pgd))
#define __pud(x) ((pud_t) { __pgd(x) })
#define pgd_page(pgd) (pud_page((pud_t){ pgd }))
#define pgd_page_vaddr(pgd) (pud_page_vaddr((pud_t){ pgd }))
/*
* allocating and freeing a pud is trivial: the 1-entry pud is
* inside the pgd, so has no extra memory associated with it.
*/
#define pud_alloc_one(mm, address) NULL
#define pud_free(mm, x) do { } while (0)
#define __pud_free_tlb(tlb, x, a) do { } while (0)
#undef pud_addr_end
#define pud_addr_end(addr, end) (end)
#endif /* __ASSEMBLY__ */
#endif /* _PGTABLE_NOP4D_HACK_H */

5
include/asm-generic/pgtable-nopud.h
View File

@ -3,6 +3,10 @@
#ifndef __ASSEMBLY__
#ifdef __ARCH_USE_5LEVEL_HACK
#include <asm-generic/pgtable-nop4d-hack.h>
#else
#define __PAGETABLE_PUD_FOLDED
/*
@ -58,4 +62,5 @@ static inline pud_t * pud_offset(pgd_t * pgd, unsigned long address)
#define pud_addr_end(addr, end) (end)
#endif /* __ASSEMBLY__ */
#endif /* !__ARCH_USE_5LEVEL_HACK */
#endif /* _PGTABLE_NOPUD_H */