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Commit ce6234b5 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Andi Kleen
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[PATCH] i386: PARAVIRT: add kmap_atomic_pte for mapping highpte pages 



Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space.  These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.

Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.

This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings.  Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.

[ Zach - vmi.c will need some attention after this patch.  It wasn't
  immediately obvious to me what needs to be done. ]

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
parent a27fe809

arch/i386/kernel/paravirt.c

+5 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/efi.h>

#include <linux/bcd.h>

#include <linux/start_kernel.h>

#include <linux/highmem.h>



#include <asm/bug.h>

#include <asm/paravirt.h>
@@ -316,6 +317,10 @@ struct paravirt_ops paravirt_ops = { 


	.ptep_get_and_clear = native_ptep_get_and_clear,



#ifdef CONFIG_HIGHPTE

	.kmap_atomic_pte = kmap_atomic,

#endif



#ifdef CONFIG_X86_PAE

	.set_pte_atomic = native_set_pte_atomic,

	.set_pte_present = native_set_pte_present,

arch/i386/mm/highmem.c

+7 −2
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ void kunmap(struct page *page) 
 * However when holding an atomic kmap is is not legal to sleep, so atomic

 * kmaps are appropriate for short, tight code paths only.

 */

void *kmap_atomic(struct page *page, enum km_type type)

void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)

{

	enum fixed_addresses idx;

	unsigned long vaddr;
@@ -41,12 +41,17 @@ void *kmap_atomic(struct page *page, enum km_type type) 
		return page_address(page);



	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);

	set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));

	set_pte(kmap_pte-idx, mk_pte(page, prot));

	arch_flush_lazy_mmu_mode();



	return (void*) vaddr;

}



void *kmap_atomic(struct page *page, enum km_type type)

{

	return kmap_atomic_prot(page, type, kmap_prot);

}



void kunmap_atomic(void *kvaddr, enum km_type type)

{

	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;

include/asm-i386/highmem.h

+6 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <linux/threads.h>

#include <asm/kmap_types.h>

#include <asm/tlbflush.h>

#include <asm/paravirt.h>



/* declarations for highmem.c */

extern unsigned long highstart_pfn, highend_pfn;
@@ -67,11 +68,16 @@ extern void FASTCALL(kunmap_high(struct page *page)); 


void *kmap(struct page *page);

void kunmap(struct page *page);

void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot);

void *kmap_atomic(struct page *page, enum km_type type);

void kunmap_atomic(void *kvaddr, enum km_type type);

void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);

struct page *kmap_atomic_to_page(void *ptr);



#ifndef CONFIG_PARAVIRT

#define kmap_atomic_pte(page, type)	kmap_atomic(page, type)

#endif



#define flush_cache_kmaps()	do { } while (0)



#endif /* __KERNEL__ */

include/asm-i386/paravirt.h

+15 −0
Original line number Diff line number Diff line
@@ -16,7 +16,9 @@ 
#ifndef __ASSEMBLY__

#include <linux/types.h>

#include <linux/cpumask.h>

#include <asm/kmap_types.h>



struct page;

struct thread_struct;

struct Xgt_desc_struct;

struct tss_struct;
@@ -187,6 +189,10 @@ struct paravirt_ops 


 	pte_t (*ptep_get_and_clear)(pte_t *ptep);



#ifdef CONFIG_HIGHPTE

	void *(*kmap_atomic_pte)(struct page *page, enum km_type type);

#endif



#ifdef CONFIG_X86_PAE

	void (*set_pte_atomic)(pte_t *ptep, pte_t pteval);

 	void (*set_pte_present)(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte);
@@ -884,6 +890,15 @@ static inline void paravirt_release_pd(unsigned pfn) 
	PVOP_VCALL1(release_pd, pfn);

}



#ifdef CONFIG_HIGHPTE

static inline void *kmap_atomic_pte(struct page *page, enum km_type type)

{

	unsigned long ret;

	ret = PVOP_CALL2(unsigned long, kmap_atomic_pte, page, type);

	return (void *)ret;

}

#endif



static inline void pte_update(struct mm_struct *mm, unsigned long addr,

			      pte_t *ptep)

{

include/asm-i386/pgtable.h

+2 −2
Original line number Diff line number Diff line
@@ -476,9 +476,9 @@ extern pte_t *lookup_address(unsigned long address); 


#if defined(CONFIG_HIGHPTE)

#define pte_offset_map(dir, address) \

	((pte_t *)kmap_atomic(pmd_page(*(dir)),KM_PTE0) + pte_index(address))

	((pte_t *)kmap_atomic_pte(pmd_page(*(dir)),KM_PTE0) + pte_index(address))

#define pte_offset_map_nested(dir, address) \

	((pte_t *)kmap_atomic(pmd_page(*(dir)),KM_PTE1) + pte_index(address))

	((pte_t *)kmap_atomic_pte(pmd_page(*(dir)),KM_PTE1) + pte_index(address))

#define pte_unmap(pte) kunmap_atomic(pte, KM_PTE0)

#define pte_unmap_nested(pte) kunmap_atomic(pte, KM_PTE1)

#else