1/*
2 *  highmem.c: virtual kernel memory mappings for high memory
3 *
4 *  Provides kernel-static versions of atomic kmap functions originally
5 *  found as inlines in include/asm-sparc/highmem.h.  These became
6 *  needed as kmap_atomic() and kunmap_atomic() started getting
7 *  called from within modules.
8 *  -- Tomas Szepe <szepe@pinerecords.com>, September 2002
9 *
10 *  But kmap_atomic() and kunmap_atomic() cannot be inlined in
11 *  modules because they are loaded with btfixup-ped functions.
12 */
13
14#include <linux/mm.h>
15#include <linux/highmem.h>
16#include <asm/pgalloc.h>
17#include <asm/cacheflush.h>
18#include <asm/tlbflush.h>
19#include <asm/fixmap.h>
20
21void *kmap_atomic(struct page *page, enum km_type type)
22{
23	unsigned long idx;
24	unsigned long vaddr;
25
26	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
27	pagefault_disable();
28	if (!PageHighMem(page))
29		return page_address(page);
30
31	idx = type + KM_TYPE_NR*smp_processor_id();
32	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
33
34	flush_cache_all();
35
36#ifdef CONFIG_DEBUG_HIGHMEM
37	BUG_ON(!pte_none(*(kmap_pte-idx)));
38#endif
39	set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
40	flush_tlb_all();
41
42	return (void*) vaddr;
43}
44
45void kunmap_atomic(void *kvaddr, enum km_type type)
46{
47#ifdef CONFIG_DEBUG_HIGHMEM
48	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
49	unsigned long idx = type + KM_TYPE_NR*smp_processor_id();
50
51	if (vaddr < FIXADDR_START) {
52		pagefault_enable();
53		return;
54	}
55
56	BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));
57
58	flush_cache_all();
59
60	/*
61	 * force other mappings to Oops if they'll try to access
62	 * this pte without first remap it
63	 */
64	pte_clear(&init_mm, vaddr, kmap_pte-idx);
65	flush_tlb_all();
66#endif
67
68	pagefault_enable();
69}
70
71/* We may be fed a pagetable here by ptep_to_xxx and others. */
72struct page *kmap_atomic_to_page(void *ptr)
73{
74	unsigned long idx, vaddr = (unsigned long)ptr;
75	pte_t *pte;
76
77	if (vaddr < SRMMU_NOCACHE_VADDR)
78		return virt_to_page(ptr);
79	if (vaddr < PKMAP_BASE)
80		return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT);
81	BUG_ON(vaddr < FIXADDR_START);
82	BUG_ON(vaddr > FIXADDR_TOP);
83
84	idx = virt_to_fix(vaddr);
85	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
86	return pte_page(*pte);
87}
88