diff options
author | James Hogan <james.hogan@imgtec.com> | 2012-10-09 09:54:17 (GMT) |
---|---|---|
committer | James Hogan <james.hogan@imgtec.com> | 2013-03-02 20:09:20 (GMT) |
commit | bbc17704d5d3a8e4325dae74c2a2e77218c26057 (patch) | |
tree | fe13881c1f85fa781e3ac413216954dd946fafae /arch/metag/mm | |
parent | e624e95bd88f94fc70bbe612789bcac44c6f0923 (diff) | |
download | linux-bbc17704d5d3a8e4325dae74c2a2e77218c26057.tar.xz |
metag: Highmem support
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Diffstat (limited to 'arch/metag/mm')
-rw-r--r-- | arch/metag/mm/highmem.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/metag/mm/highmem.c b/arch/metag/mm/highmem.c new file mode 100644 index 0000000..d71f621 --- /dev/null +++ b/arch/metag/mm/highmem.c @@ -0,0 +1,133 @@ +#include <linux/export.h> +#include <linux/highmem.h> +#include <linux/sched.h> +#include <linux/smp.h> +#include <linux/interrupt.h> +#include <asm/fixmap.h> +#include <asm/tlbflush.h> + +static pte_t *kmap_pte; + +unsigned long highstart_pfn, highend_pfn; + +void *kmap(struct page *page) +{ + might_sleep(); + if (!PageHighMem(page)) + return page_address(page); + return kmap_high(page); +} +EXPORT_SYMBOL(kmap); + +void kunmap(struct page *page) +{ + BUG_ON(in_interrupt()); + if (!PageHighMem(page)) + return; + kunmap_high(page); +} +EXPORT_SYMBOL(kunmap); + +/* + * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because + * no global lock is needed and because the kmap code must perform a global TLB + * invalidation when the kmap pool wraps. + * + * 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 fixed_addresses idx; + unsigned long vaddr; + int type; + + /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ + pagefault_disable(); + if (!PageHighMem(page)) + return page_address(page); + + type = kmap_atomic_idx_push(); + idx = type + KM_TYPE_NR * smp_processor_id(); + vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); +#ifdef CONFIG_DEBUG_HIGHMEM + BUG_ON(!pte_none(*(kmap_pte - idx))); +#endif + set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL)); + + return (void *)vaddr; +} +EXPORT_SYMBOL(kmap_atomic); + +void __kunmap_atomic(void *kvaddr) +{ + unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; + int idx, type; + + if (kvaddr >= (void *)FIXADDR_START) { + type = kmap_atomic_idx(); + idx = type + KM_TYPE_NR * smp_processor_id(); + + /* + * Force other mappings to Oops if they'll try to access this + * pte without first remap it. Keeping stale mappings around + * is a bad idea also, in case the page changes cacheability + * attributes or becomes a protected page in a hypervisor. + */ + pte_clear(&init_mm, vaddr, kmap_pte-idx); + flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); + + kmap_atomic_idx_pop(); + } + + pagefault_enable(); +} +EXPORT_SYMBOL(__kunmap_atomic); + +/* + * This is the same as kmap_atomic() but can map memory that doesn't + * have a struct page associated with it. + */ +void *kmap_atomic_pfn(unsigned long pfn) +{ + enum fixed_addresses idx; + unsigned long vaddr; + int type; + + pagefault_disable(); + + type = kmap_atomic_idx_push(); + idx = type + KM_TYPE_NR * smp_processor_id(); + vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); +#ifdef CONFIG_DEBUG_HIGHMEM + BUG_ON(!pte_none(*(kmap_pte - idx))); +#endif + set_pte(kmap_pte - idx, pfn_pte(pfn, PAGE_KERNEL)); + flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); + + return (void *)vaddr; +} + +struct page *kmap_atomic_to_page(void *ptr) +{ + unsigned long vaddr = (unsigned long)ptr; + int idx; + pte_t *pte; + + if (vaddr < FIXADDR_START) + return virt_to_page(ptr); + + idx = virt_to_fix(vaddr); + pte = kmap_pte - (idx - FIX_KMAP_BEGIN); + return pte_page(*pte); +} + +void __init kmap_init(void) +{ + unsigned long kmap_vstart; + + /* cache the first kmap pte */ + kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN); + kmap_pte = kmap_get_fixmap_pte(kmap_vstart); +} |