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615d6e87 DB |
1 | /* |
2 | * Copyright (C) 2014 Davidlohr Bueso. | |
3 | */ | |
4 | #include <linux/sched.h> | |
5 | #include <linux/mm.h> | |
6 | #include <linux/vmacache.h> | |
7 | ||
615d6e87 DB |
8 | /* |
9 | * This task may be accessing a foreign mm via (for example) | |
10 | * get_user_pages()->find_vma(). The vmacache is task-local and this | |
11 | * task's vmacache pertains to a different mm (ie, its own). There is | |
12 | * nothing we can do here. | |
13 | * | |
14 | * Also handle the case where a kernel thread has adopted this mm via use_mm(). | |
15 | * That kernel thread's vmacache is not applicable to this mm. | |
16 | */ | |
17 | static bool vmacache_valid_mm(struct mm_struct *mm) | |
18 | { | |
19 | return current->mm == mm && !(current->flags & PF_KTHREAD); | |
20 | } | |
21 | ||
22 | void vmacache_update(unsigned long addr, struct vm_area_struct *newvma) | |
23 | { | |
24 | if (vmacache_valid_mm(newvma->vm_mm)) | |
25 | current->vmacache[VMACACHE_HASH(addr)] = newvma; | |
26 | } | |
27 | ||
28 | static bool vmacache_valid(struct mm_struct *mm) | |
29 | { | |
30 | struct task_struct *curr; | |
31 | ||
32 | if (!vmacache_valid_mm(mm)) | |
33 | return false; | |
34 | ||
35 | curr = current; | |
36 | if (mm->vmacache_seqnum != curr->vmacache_seqnum) { | |
37 | /* | |
38 | * First attempt will always be invalid, initialize | |
39 | * the new cache for this task here. | |
40 | */ | |
41 | curr->vmacache_seqnum = mm->vmacache_seqnum; | |
42 | vmacache_flush(curr); | |
43 | return false; | |
44 | } | |
45 | return true; | |
46 | } | |
47 | ||
48 | struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr) | |
49 | { | |
50 | int i; | |
51 | ||
52 | if (!vmacache_valid(mm)) | |
53 | return NULL; | |
54 | ||
4f115147 DB |
55 | count_vm_vmacache_event(VMACACHE_FIND_CALLS); |
56 | ||
615d6e87 DB |
57 | for (i = 0; i < VMACACHE_SIZE; i++) { |
58 | struct vm_area_struct *vma = current->vmacache[i]; | |
59 | ||
50f5aa8a LT |
60 | if (!vma) |
61 | continue; | |
62 | if (WARN_ON_ONCE(vma->vm_mm != mm)) | |
63 | break; | |
4f115147 DB |
64 | if (vma->vm_start <= addr && vma->vm_end > addr) { |
65 | count_vm_vmacache_event(VMACACHE_FIND_HITS); | |
615d6e87 | 66 | return vma; |
4f115147 | 67 | } |
615d6e87 DB |
68 | } |
69 | ||
70 | return NULL; | |
71 | } | |
72 | ||
73 | #ifndef CONFIG_MMU | |
74 | struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm, | |
75 | unsigned long start, | |
76 | unsigned long end) | |
77 | { | |
78 | int i; | |
79 | ||
80 | if (!vmacache_valid(mm)) | |
81 | return NULL; | |
82 | ||
4f115147 DB |
83 | count_vm_vmacache_event(VMACACHE_FIND_CALLS); |
84 | ||
615d6e87 DB |
85 | for (i = 0; i < VMACACHE_SIZE; i++) { |
86 | struct vm_area_struct *vma = current->vmacache[i]; | |
87 | ||
4f115147 DB |
88 | if (vma && vma->vm_start == start && vma->vm_end == end) { |
89 | count_vm_vmacache_event(VMACACHE_FIND_HITS); | |
615d6e87 | 90 | return vma; |
4f115147 | 91 | } |
615d6e87 DB |
92 | } |
93 | ||
94 | return NULL; | |
95 | } | |
96 | #endif |