bb86bf28ae
Commit 351336929c (kernel.org) rsp.
b3594a089f1c17ff919f8f78505c3f20e1f6f8ce (linux-mips.org):
> From: Chris Dearman <chris@mips.com>
> Date: Wed, 19 Sep 2007 00:58:24 +0100
> Subject: [PATCH] [MIPS] Allow setting of the cache attribute at run time.
>
> Slightly tacky, but there is a precedent in the sparc archirecture code.
introduces the variable _page_cachable_default, which defaults to zero and.
is used to create the prototype PTE for __kmap_atomic in
arch/mips/mm/init.c:kmap_init before initialization in
arch/mips/mm/c-r4k.c:coherency_setup, so the default value of 0 will be
used as the CCA of kmap atomic pages which on many processors is not a
defined CCA value and may result in writes to kmap_atomic pages getting
corrupted. Debugged by Jon Fraser (jfraser@broadcom.com).
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
130 lines
2.9 KiB
C
130 lines
2.9 KiB
C
#include <linux/module.h>
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#include <linux/highmem.h>
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#include <asm/fixmap.h>
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#include <asm/tlbflush.h>
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static pte_t *kmap_pte;
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unsigned long highstart_pfn, highend_pfn;
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void *__kmap(struct page *page)
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{
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void *addr;
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might_sleep();
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if (!PageHighMem(page))
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return page_address(page);
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addr = kmap_high(page);
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flush_tlb_one((unsigned long)addr);
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return addr;
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}
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EXPORT_SYMBOL(__kmap);
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void __kunmap(struct page *page)
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{
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BUG_ON(in_interrupt());
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if (!PageHighMem(page))
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return;
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kunmap_high(page);
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}
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EXPORT_SYMBOL(__kunmap);
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/*
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* kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
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* no global lock is needed and because the kmap code must perform a global TLB
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* invalidation when the kmap pool wraps.
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*
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* However when holding an atomic kmap is is not legal to sleep, so atomic
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* kmaps are appropriate for short, tight code paths only.
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*/
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void *__kmap_atomic(struct page *page, enum km_type type)
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{
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enum fixed_addresses idx;
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unsigned long vaddr;
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/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
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pagefault_disable();
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if (!PageHighMem(page))
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return page_address(page);
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debug_kmap_atomic(type);
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idx = type + KM_TYPE_NR*smp_processor_id();
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vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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#ifdef CONFIG_DEBUG_HIGHMEM
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BUG_ON(!pte_none(*(kmap_pte - idx)));
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#endif
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set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
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local_flush_tlb_one((unsigned long)vaddr);
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return (void*) vaddr;
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}
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EXPORT_SYMBOL(__kmap_atomic);
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void __kunmap_atomic(void *kvaddr, enum km_type type)
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{
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#ifdef CONFIG_DEBUG_HIGHMEM
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unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
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enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
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if (vaddr < FIXADDR_START) { // FIXME
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pagefault_enable();
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return;
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}
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BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
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/*
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* force other mappings to Oops if they'll try to access
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* this pte without first remap it
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*/
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pte_clear(&init_mm, vaddr, kmap_pte-idx);
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local_flush_tlb_one(vaddr);
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#endif
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pagefault_enable();
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}
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EXPORT_SYMBOL(__kunmap_atomic);
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/*
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* This is the same as kmap_atomic() but can map memory that doesn't
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* have a struct page associated with it.
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*/
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void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
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{
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enum fixed_addresses idx;
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unsigned long vaddr;
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pagefault_disable();
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debug_kmap_atomic(type);
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idx = type + KM_TYPE_NR*smp_processor_id();
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vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
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flush_tlb_one(vaddr);
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return (void*) vaddr;
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}
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struct page *__kmap_atomic_to_page(void *ptr)
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{
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unsigned long idx, vaddr = (unsigned long)ptr;
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pte_t *pte;
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if (vaddr < FIXADDR_START)
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return virt_to_page(ptr);
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idx = virt_to_fix(vaddr);
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pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
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return pte_page(*pte);
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}
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void __init kmap_init(void)
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{
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unsigned long kmap_vstart;
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/* cache the first kmap pte */
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kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
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kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
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}
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