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
kmap_waitqueues_init(void)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
kmap_waitqueues_init(void)29 static inline void kmap_waitqueues_init(void)
30 {
31 }
32 #endif
33
kmap_idx(int type,unsigned long color)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
kmap_atomic(struct page * page)40 void *kmap_atomic(struct page *page)
41 {
42 enum fixed_addresses idx;
43 unsigned long vaddr;
44
45 preempt_disable();
46 pagefault_disable();
47 if (!PageHighMem(page))
48 return page_address(page);
49
50 idx = kmap_idx(kmap_atomic_idx_push(),
51 DCACHE_ALIAS(page_to_phys(page)));
52 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
53 #ifdef CONFIG_DEBUG_HIGHMEM
54 BUG_ON(!pte_none(*(kmap_pte + idx)));
55 #endif
56 set_pte(kmap_pte + idx, mk_pte(page, PAGE_KERNEL_EXEC));
57
58 return (void *)vaddr;
59 }
60 EXPORT_SYMBOL(kmap_atomic);
61
__kunmap_atomic(void * kvaddr)62 void __kunmap_atomic(void *kvaddr)
63 {
64 if (kvaddr >= (void *)FIXADDR_START &&
65 kvaddr < (void *)FIXADDR_TOP) {
66 int idx = kmap_idx(kmap_atomic_idx(),
67 DCACHE_ALIAS((unsigned long)kvaddr));
68
69 /*
70 * Force other mappings to Oops if they'll try to access this
71 * pte without first remap it. Keeping stale mappings around
72 * is a bad idea also, in case the page changes cacheability
73 * attributes or becomes a protected page in a hypervisor.
74 */
75 pte_clear(&init_mm, kvaddr, kmap_pte + idx);
76 local_flush_tlb_kernel_range((unsigned long)kvaddr,
77 (unsigned long)kvaddr + PAGE_SIZE);
78
79 kmap_atomic_idx_pop();
80 }
81
82 pagefault_enable();
83 preempt_enable();
84 }
85 EXPORT_SYMBOL(__kunmap_atomic);
86
kmap_init(void)87 void __init kmap_init(void)
88 {
89 unsigned long kmap_vstart;
90
91 /* cache the first kmap pte */
92 kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
93 kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
94 kmap_waitqueues_init();
95 }
96
