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Commit 0b4e273f authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
Browse files

uml: customize tlb.h 



Customize the hooks in tlb.h to optimize TLB flushing some more.

Add start and end fields to tlb_gather_mmu, which are used to limit
the address space range scanned when a region is unmapped.

The interfaces which just free page tables, without actually changing
mappings, don't need to cause a TLB flush.

Signed-off-by: default avatarJeff Dike <jdike@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 909e90d3

arch/um/kernel/tlb.c

+18 −7
Original line number Diff line number Diff line
@@ -193,18 +193,18 @@ static inline int update_pte_range(pmd_t *pmd, unsigned long addr, 
		if (!pte_young(*pte)) {

			r = 0;

			w = 0;

		} else if (!pte_dirty(*pte)) {

		} else if (!pte_dirty(*pte))

			w = 0;

		}



		prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |

			(x ? UM_PROT_EXEC : 0));

		if (hvc->force || pte_newpage(*pte)) {

			if (pte_present(*pte))

				ret = add_mmap(addr, pte_val(*pte) & PAGE_MASK,

					       PAGE_SIZE, prot, hvc);

			else ret = add_munmap(addr, PAGE_SIZE, hvc);

		}

		else if (pte_newprot(*pte))

			else

				ret = add_munmap(addr, PAGE_SIZE, hvc);

		} else if (pte_newprot(*pte))

			ret = add_mprotect(addr, PAGE_SIZE, prot, hvc);

		*pte = pte_mkuptodate(*pte);

	} while (pte++, addr += PAGE_SIZE, ((addr < end) && !ret));
@@ -500,7 +500,8 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start, 
	else fix_range(vma->vm_mm, start, end, 0);

}



void flush_tlb_mm(struct mm_struct *mm)

void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,

			unsigned long end)

{

	/*

	 * Don't bother flushing if this address space is about to be
@@ -509,7 +510,17 @@ void flush_tlb_mm(struct mm_struct *mm) 
	if (atomic_read(&mm->mm_users) == 0)

		return;



	fix_range(mm, 0, TASK_SIZE, 0);

	fix_range(mm, start, end, 0);

}



void flush_tlb_mm(struct mm_struct *mm)

{

	struct vm_area_struct *vma = mm->mmap;



	while (vma != NULL) {

		fix_range(mm, vma->vm_start, vma->vm_end, 0);

		vma = vma->vm_next;

	}

}



void force_flush_all(void)

include/asm-um/tlb.h

+121 −1
Original line number Diff line number Diff line 
#ifndef __UM_TLB_H

#define __UM_TLB_H



#include <asm/arch/tlb.h>

#include <linux/swap.h>

#include <asm/percpu.h>

#include <asm/pgalloc.h>

#include <asm/tlbflush.h>



#define tlb_start_vma(tlb, vma) do { } while (0)

#define tlb_end_vma(tlb, vma) do { } while (0)

#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)



/* struct mmu_gather is an opaque type used by the mm code for passing around

 * any data needed by arch specific code for tlb_remove_page.

 */

struct mmu_gather {

	struct mm_struct	*mm;

	unsigned int		need_flush; /* Really unmapped some ptes? */

	unsigned long		start;

	unsigned long		end;

	unsigned int		fullmm; /* non-zero means full mm flush */

};



/* Users of the generic TLB shootdown code must declare this storage space. */

DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);



static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,

					  unsigned long address)

{

	if (tlb->start > address)

		tlb->start = address;

	if (tlb->end < address + PAGE_SIZE)

		tlb->end = address + PAGE_SIZE;

}



static inline void init_tlb_gather(struct mmu_gather *tlb)

{

	tlb->need_flush = 0;



	tlb->start = TASK_SIZE;

	tlb->end = 0;



	if (tlb->fullmm) {

		tlb->start = 0;

		tlb->end = TASK_SIZE;

	}

}



/* tlb_gather_mmu

 *	Return a pointer to an initialized struct mmu_gather.

 */

static inline struct mmu_gather *

tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)

{

	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);



	tlb->mm = mm;

	tlb->fullmm = full_mm_flush;



	init_tlb_gather(tlb);



	return tlb;

}



extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,

			       unsigned long end);



static inline void

tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)

{

	if (!tlb->need_flush)

		return;



	flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end);

	init_tlb_gather(tlb);

}



/* tlb_finish_mmu

 *	Called at the end of the shootdown operation to free up any resources

 *	that were required.

 */

static inline void

tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)

{

	tlb_flush_mmu(tlb, start, end);



	/* keep the page table cache within bounds */

	check_pgt_cache();



	put_cpu_var(mmu_gathers);

}



/* tlb_remove_page

 *	Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)),

 *	while handling the additional races in SMP caused by other CPUs

 *	caching valid mappings in their TLBs.

 */

static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)

{

	tlb->need_flush = 1;

	free_page_and_swap_cache(page);

	return;

}



/**

 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.

 *

 * Record the fact that pte's were really umapped in ->need_flush, so we can

 * later optimise away the tlb invalidate.   This helps when userspace is

 * unmapping already-unmapped pages, which happens quite a lot.

 */

#define tlb_remove_tlb_entry(tlb, ptep, address)		\

	do {							\

		tlb->need_flush = 1;				\

		__tlb_remove_tlb_entry(tlb, ptep, address);	\

	} while (0)



#define pte_free_tlb(tlb, ptep) __pte_free_tlb(tlb, ptep)



#define pud_free_tlb(tlb, pudp) __pud_free_tlb(tlb, pudp)



#define pmd_free_tlb(tlb, pmdp) __pmd_free_tlb(tlb, pmdp)



#define tlb_migrate_finish(mm) do {} while (0)



#endif