From ce6234b5298902aaec831a67d5f8d9bd2ef5a488 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 2 May 2007 19:27:15 +0200 Subject: [PATCH] [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: Jeremy Fitzhardinge Signed-off-by: Andi Kleen Cc: Zachary Amsden --- arch/i386/kernel/paravirt.c | 5 +++++ arch/i386/mm/highmem.c | 9 +++++++-- include/asm-i386/highmem.h | 6 ++++++ include/asm-i386/paravirt.h | 15 +++++++++++++++ include/asm-i386/pgtable.h | 4 ++-- include/linux/highmem.h | 6 ++++++ mm/highmem.c | 9 +++++++++ 7 files changed, 50 insertions(+), 4 deletions(-) diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c index 13f41b5c887a..596f382c641c 100644 --- a/arch/i386/kernel/paravirt.c +++ b/arch/i386/kernel/paravirt.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include @@ -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, diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c index ac70d09df7ee..a1a21abf742e 100644 --- a/arch/i386/mm/highmem.c +++ b/arch/i386/mm/highmem.c @@ -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; diff --git a/include/asm-i386/highmem.h b/include/asm-i386/highmem.h index e9a34ebc25d5..13cdcd66fff2 100644 --- a/include/asm-i386/highmem.h +++ b/include/asm-i386/highmem.h @@ -24,6 +24,7 @@ #include #include #include +#include /* 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__ */ diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h index 10f44af76b49..5048b41428fa 100644 --- a/include/asm-i386/paravirt.h +++ b/include/asm-i386/paravirt.h @@ -16,7 +16,9 @@ #ifndef __ASSEMBLY__ #include #include +#include +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) { diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h index 6599f2aa91b7..befc697821e5 100644 --- a/include/asm-i386/pgtable.h +++ b/include/asm-i386/pgtable.h @@ -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 diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 645d440807c2..bca8e2dfa355 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -27,6 +27,8 @@ static inline void flush_kernel_dcache_page(struct page *page) unsigned int nr_free_highpages(void); extern unsigned long totalhigh_pages; +void kmap_flush_unused(void); + #else /* CONFIG_HIGHMEM */ static inline unsigned int nr_free_highpages(void) { return 0; } @@ -44,9 +46,13 @@ static inline void *kmap(struct page *page) #define kmap_atomic(page, idx) \ ({ pagefault_disable(); page_address(page); }) +#define kmap_atomic_prot(page, idx, prot) kmap_atomic(page, idx) + #define kunmap_atomic(addr, idx) do { pagefault_enable(); } while (0) #define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx)) #define kmap_atomic_to_page(ptr) virt_to_page(ptr) + +#define kmap_flush_unused() do {} while(0) #endif #endif /* CONFIG_HIGHMEM */ diff --git a/mm/highmem.c b/mm/highmem.c index 51e1c1995fec..be8f8d36a8b9 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -99,6 +99,15 @@ static void flush_all_zero_pkmaps(void) flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); } +/* Flush all unused kmap mappings in order to remove stray + mappings. */ +void kmap_flush_unused(void) +{ + spin_lock(&kmap_lock); + flush_all_zero_pkmaps(); + spin_unlock(&kmap_lock); +} + static inline unsigned long map_new_virtual(struct page *page) { unsigned long vaddr;