forked from mirrors/linux
2cb7c9cb42
The existing code relies on pagefault_disable() implicitly disabling preemption, so that no schedule will happen between kmap_atomic() and kunmap_atomic(). Let's make this explicit, to prepare for pagefault_disable() not touching preemption anymore. Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: benh@kernel.crashing.org Cc: bigeasy@linutronix.de Cc: borntraeger@de.ibm.com Cc: daniel.vetter@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: hocko@suse.cz Cc: hughd@google.com Cc: mst@redhat.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: schwidefsky@de.ibm.com Cc: yang.shi@windriver.com Link: http://lkml.kernel.org/r/1431359540-32227-5-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
95 lines
2.3 KiB
C
95 lines
2.3 KiB
C
/*
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* High memory support for Xtensa architecture
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*
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* This file is subject to the terms and conditions of the GNU General
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* Public License. See the file "COPYING" in the main directory of
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* this archive for more details.
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*
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* Copyright (C) 2014 Cadence Design Systems Inc.
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*/
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#include <linux/export.h>
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#include <linux/highmem.h>
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#include <asm/tlbflush.h>
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static pte_t *kmap_pte;
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#if DCACHE_WAY_SIZE > PAGE_SIZE
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unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
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wait_queue_head_t pkmap_map_wait_arr[DCACHE_N_COLORS];
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static void __init kmap_waitqueues_init(void)
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{
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(pkmap_map_wait_arr); ++i)
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init_waitqueue_head(pkmap_map_wait_arr + i);
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}
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#else
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static inline void kmap_waitqueues_init(void)
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{
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}
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#endif
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static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
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{
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return (type + KM_TYPE_NR * smp_processor_id()) * DCACHE_N_COLORS +
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color;
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}
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void *kmap_atomic(struct page *page)
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{
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enum fixed_addresses idx;
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unsigned long vaddr;
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preempt_disable();
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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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idx = kmap_idx(kmap_atomic_idx_push(),
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DCACHE_ALIAS(page_to_phys(page)));
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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_EXEC));
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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)
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{
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if (kvaddr >= (void *)FIXADDR_START &&
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kvaddr < (void *)FIXADDR_TOP) {
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int idx = kmap_idx(kmap_atomic_idx(),
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DCACHE_ALIAS((unsigned long)kvaddr));
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/*
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* Force other mappings to Oops if they'll try to access this
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* pte without first remap it. Keeping stale mappings around
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* is a bad idea also, in case the page changes cacheability
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* attributes or becomes a protected page in a hypervisor.
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*/
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pte_clear(&init_mm, kvaddr, kmap_pte + idx);
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local_flush_tlb_kernel_range((unsigned long)kvaddr,
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(unsigned long)kvaddr + PAGE_SIZE);
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kmap_atomic_idx_pop();
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}
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pagefault_enable();
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preempt_enable();
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}
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EXPORT_SYMBOL(__kunmap_atomic);
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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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kmap_waitqueues_init();
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}
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