1 /* 2 * High memory support for Xtensa architecture 3 * 4 * This file is subject to the terms and conditions of the GNU General 5 * Public License. See the file "COPYING" in the main directory of 6 * this archive for more details. 7 * 8 * Copyright (C) 2014 Cadence Design Systems Inc. 9 */ 10 11 #include <linux/export.h> 12 #include <linux/highmem.h> 13 #include <asm/tlbflush.h> 14 15 static pte_t *kmap_pte; 16 17 #if DCACHE_WAY_SIZE > PAGE_SIZE 18 unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS]; 19 wait_queue_head_t pkmap_map_wait_arr[DCACHE_N_COLORS]; 20 21 static void __init kmap_waitqueues_init(void) 22 { 23 unsigned int i; 24 25 for (i = 0; i < ARRAY_SIZE(pkmap_map_wait_arr); ++i) 26 init_waitqueue_head(pkmap_map_wait_arr + i); 27 } 28 #else 29 static inline void kmap_waitqueues_init(void) 30 { 31 } 32 #endif 33 34 static inline enum fixed_addresses kmap_idx(int type, unsigned long color) 35 { 36 return (type + KM_TYPE_NR * smp_processor_id()) * DCACHE_N_COLORS + 37 color; 38 } 39 40 void *kmap_atomic(struct page *page) 41 { 42 enum fixed_addresses idx; 43 unsigned long vaddr; 44 45 pagefault_disable(); 46 if (!PageHighMem(page)) 47 return page_address(page); 48 49 idx = kmap_idx(kmap_atomic_idx_push(), 50 DCACHE_ALIAS(page_to_phys(page))); 51 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 52 #ifdef CONFIG_DEBUG_HIGHMEM 53 BUG_ON(!pte_none(*(kmap_pte + idx))); 54 #endif 55 set_pte(kmap_pte + idx, mk_pte(page, PAGE_KERNEL_EXEC)); 56 57 return (void *)vaddr; 58 } 59 EXPORT_SYMBOL(kmap_atomic); 60 61 void __kunmap_atomic(void *kvaddr) 62 { 63 if (kvaddr >= (void *)FIXADDR_START && 64 kvaddr < (void *)FIXADDR_TOP) { 65 int idx = kmap_idx(kmap_atomic_idx(), 66 DCACHE_ALIAS((unsigned long)kvaddr)); 67 68 /* 69 * Force other mappings to Oops if they'll try to access this 70 * pte without first remap it. Keeping stale mappings around 71 * is a bad idea also, in case the page changes cacheability 72 * attributes or becomes a protected page in a hypervisor. 73 */ 74 pte_clear(&init_mm, kvaddr, kmap_pte + idx); 75 local_flush_tlb_kernel_range((unsigned long)kvaddr, 76 (unsigned long)kvaddr + PAGE_SIZE); 77 78 kmap_atomic_idx_pop(); 79 } 80 81 pagefault_enable(); 82 } 83 EXPORT_SYMBOL(__kunmap_atomic); 84 85 void __init kmap_init(void) 86 { 87 unsigned long kmap_vstart; 88 89 /* cache the first kmap pte */ 90 kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN); 91 kmap_pte = kmap_get_fixmap_pte(kmap_vstart); 92 kmap_waitqueues_init(); 93 } 94