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linux/include/asm-x86/pgtable-3level.h
Jeremy Fitzhardinge edd6bcd820 x86: pud_clear: only reload cr3 if necessary
Rather than unconditionally reloading cr3, only do so if the pud we're
updating is within the active pgd.

This eliminates TLB flushes most of the time.  The
performance-critical uses of pud_clear are during execve and exit, but
in those cases cr3 is referring to some other pagetable.  The only
other use of pud_clear is during a large (1Gbyte+) munmap, and those
are sufficiently rare that a couple of cr3 reloads won't hurt.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-02-04 16:48:02 +01:00

173 lines
4.6 KiB
C

#ifndef _I386_PGTABLE_3LEVEL_H
#define _I386_PGTABLE_3LEVEL_H
/*
* Intel Physical Address Extension (PAE) Mode - three-level page
* tables on PPro+ CPUs.
*
* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
*/
#define pte_ERROR(e) \
printk("%s:%d: bad pte %p(%08lx%08lx).\n", __FILE__, __LINE__, &(e), (e).pte_high, (e).pte_low)
#define pmd_ERROR(e) \
printk("%s:%d: bad pmd %p(%016Lx).\n", __FILE__, __LINE__, &(e), pmd_val(e))
#define pgd_ERROR(e) \
printk("%s:%d: bad pgd %p(%016Lx).\n", __FILE__, __LINE__, &(e), pgd_val(e))
static inline int pud_none(pud_t pud)
{
return pud_val(pud) == 0;
}
static inline int pud_bad(pud_t pud)
{
return (pud_val(pud) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER)) != 0;
}
static inline int pud_present(pud_t pud)
{
return pud_val(pud) & _PAGE_PRESENT;
}
/* Rules for using set_pte: the pte being assigned *must* be
* either not present or in a state where the hardware will
* not attempt to update the pte. In places where this is
* not possible, use pte_get_and_clear to obtain the old pte
* value and then use set_pte to update it. -ben
*/
static inline void native_set_pte(pte_t *ptep, pte_t pte)
{
ptep->pte_high = pte.pte_high;
smp_wmb();
ptep->pte_low = pte.pte_low;
}
/*
* Since this is only called on user PTEs, and the page fault handler
* must handle the already racy situation of simultaneous page faults,
* we are justified in merely clearing the PTE present bit, followed
* by a set. The ordering here is important.
*/
static inline void native_set_pte_present(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
ptep->pte_low = 0;
smp_wmb();
ptep->pte_high = pte.pte_high;
smp_wmb();
ptep->pte_low = pte.pte_low;
}
static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
{
set_64bit((unsigned long long *)(ptep),native_pte_val(pte));
}
static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
{
set_64bit((unsigned long long *)(pmdp),native_pmd_val(pmd));
}
static inline void native_set_pud(pud_t *pudp, pud_t pud)
{
set_64bit((unsigned long long *)(pudp),native_pud_val(pud));
}
/*
* For PTEs and PDEs, we must clear the P-bit first when clearing a page table
* entry, so clear the bottom half first and enforce ordering with a compiler
* barrier.
*/
static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
ptep->pte_low = 0;
smp_wmb();
ptep->pte_high = 0;
}
static inline void native_pmd_clear(pmd_t *pmd)
{
u32 *tmp = (u32 *)pmd;
*tmp = 0;
smp_wmb();
*(tmp + 1) = 0;
}
static inline void pud_clear(pud_t *pudp)
{
unsigned long pgd;
set_pud(pudp, __pud(0));
/*
* Pentium-II erratum A13: in PAE mode we explicitly have to flush
* the TLB via cr3 if the top-level pgd is changed...
*
* Make sure the pud entry we're updating is within the
* current pgd to avoid unnecessary TLB flushes.
*/
pgd = read_cr3();
if (__pa(pudp) >= pgd && __pa(pudp) < (pgd + sizeof(pgd_t)*PTRS_PER_PGD))
write_cr3(pgd);
}
#define pud_page(pud) \
((struct page *) __va(pud_val(pud) & PAGE_MASK))
#define pud_page_vaddr(pud) \
((unsigned long) __va(pud_val(pud) & PAGE_MASK))
/* Find an entry in the second-level page table.. */
#define pmd_offset(pud, address) ((pmd_t *) pud_page(*(pud)) + \
pmd_index(address))
#ifdef CONFIG_SMP
static inline pte_t native_ptep_get_and_clear(pte_t *ptep)
{
pte_t res;
/* xchg acts as a barrier before the setting of the high bits */
res.pte_low = xchg(&ptep->pte_low, 0);
res.pte_high = ptep->pte_high;
ptep->pte_high = 0;
return res;
}
#else
#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
#endif
#define __HAVE_ARCH_PTE_SAME
static inline int pte_same(pte_t a, pte_t b)
{
return a.pte_low == b.pte_low && a.pte_high == b.pte_high;
}
#define pte_page(x) pfn_to_page(pte_pfn(x))
static inline int pte_none(pte_t pte)
{
return !pte.pte_low && !pte.pte_high;
}
static inline unsigned long pte_pfn(pte_t pte)
{
return (pte_val(pte) & ~_PAGE_NX) >> PAGE_SHIFT;
}
/*
* Bits 0, 6 and 7 are taken in the low part of the pte,
* put the 32 bits of offset into the high part.
*/
#define pte_to_pgoff(pte) ((pte).pte_high)
#define pgoff_to_pte(off) ((pte_t) { { .pte_low = _PAGE_FILE, .pte_high = (off) } })
#define PTE_FILE_MAX_BITS 32
/* Encode and de-code a swap entry */
#define __swp_type(x) (((x).val) & 0x1f)
#define __swp_offset(x) ((x).val >> 5)
#define __swp_entry(type, offset) ((swp_entry_t){(type) | (offset) << 5})
#define __pte_to_swp_entry(pte) ((swp_entry_t){ (pte).pte_high })
#define __swp_entry_to_pte(x) ((pte_t){ { .pte_high = (x).val } })
#endif /* _I386_PGTABLE_3LEVEL_H */