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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2014 Davidlohr Bueso.
4 */
5#include <linux/sched/signal.h>
6#include <linux/sched/task.h>
7#include <linux/mm.h>
8#include <linux/vmacache.h>
9#include <asm/pgtable.h>
10
11/*
12 * Hash based on the pmd of addr if configured with MMU, which provides a good
13 * hit rate for workloads with spatial locality. Otherwise, use pages.
14 */
15#ifdef CONFIG_MMU
16#define VMACACHE_SHIFT PMD_SHIFT
17#else
18#define VMACACHE_SHIFT PAGE_SHIFT
19#endif
20#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK)
21
22/*
23 * This task may be accessing a foreign mm via (for example)
24 * get_user_pages()->find_vma(). The vmacache is task-local and this
25 * task's vmacache pertains to a different mm (ie, its own). There is
26 * nothing we can do here.
27 *
28 * Also handle the case where a kernel thread has adopted this mm via use_mm().
29 * That kernel thread's vmacache is not applicable to this mm.
30 */
31static inline bool vmacache_valid_mm(struct mm_struct *mm)
32{
33 return current->mm == mm && !(current->flags & PF_KTHREAD);
34}
35
36void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
37{
38 if (vmacache_valid_mm(newvma->vm_mm))
39 current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma;
40}
41
42static bool vmacache_valid(struct mm_struct *mm)
43{
44 struct task_struct *curr;
45
46 if (!vmacache_valid_mm(mm))
47 return false;
48
49 curr = current;
50 if (mm->vmacache_seqnum != curr->vmacache.seqnum) {
51 /*
52 * First attempt will always be invalid, initialize
53 * the new cache for this task here.
54 */
55 curr->vmacache.seqnum = mm->vmacache_seqnum;
56 vmacache_flush(curr);
57 return false;
58 }
59 return true;
60}
61
62struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
63{
64 int idx = VMACACHE_HASH(addr);
65 int i;
66
67 count_vm_vmacache_event(VMACACHE_FIND_CALLS);
68
69 if (!vmacache_valid(mm))
70 return NULL;
71
72 for (i = 0; i < VMACACHE_SIZE; i++) {
73 struct vm_area_struct *vma = current->vmacache.vmas[idx];
74
75 if (vma) {
76#ifdef CONFIG_DEBUG_VM_VMACACHE
77 if (WARN_ON_ONCE(vma->vm_mm != mm))
78 break;
79#endif
80 if (vma->vm_start <= addr && vma->vm_end > addr) {
81 count_vm_vmacache_event(VMACACHE_FIND_HITS);
82 return vma;
83 }
84 }
85 if (++idx == VMACACHE_SIZE)
86 idx = 0;
87 }
88
89 return NULL;
90}
91
92#ifndef CONFIG_MMU
93struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
94 unsigned long start,
95 unsigned long end)
96{
97 int idx = VMACACHE_HASH(start);
98 int i;
99
100 count_vm_vmacache_event(VMACACHE_FIND_CALLS);
101
102 if (!vmacache_valid(mm))
103 return NULL;
104
105 for (i = 0; i < VMACACHE_SIZE; i++) {
106 struct vm_area_struct *vma = current->vmacache.vmas[idx];
107
108 if (vma && vma->vm_start == start && vma->vm_end == end) {
109 count_vm_vmacache_event(VMACACHE_FIND_HITS);
110 return vma;
111 }
112 if (++idx == VMACACHE_SIZE)
113 idx = 0;
114 }
115
116 return NULL;
117}
118#endif
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2014 Davidlohr Bueso.
4 */
5#include <linux/sched/signal.h>
6#include <linux/sched/task.h>
7#include <linux/mm.h>
8#include <linux/vmacache.h>
9
10/*
11 * Hash based on the pmd of addr if configured with MMU, which provides a good
12 * hit rate for workloads with spatial locality. Otherwise, use pages.
13 */
14#ifdef CONFIG_MMU
15#define VMACACHE_SHIFT PMD_SHIFT
16#else
17#define VMACACHE_SHIFT PAGE_SHIFT
18#endif
19#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK)
20
21/*
22 * This task may be accessing a foreign mm via (for example)
23 * get_user_pages()->find_vma(). The vmacache is task-local and this
24 * task's vmacache pertains to a different mm (ie, its own). There is
25 * nothing we can do here.
26 *
27 * Also handle the case where a kernel thread has adopted this mm via
28 * kthread_use_mm(). That kernel thread's vmacache is not applicable to this mm.
29 */
30static inline bool vmacache_valid_mm(struct mm_struct *mm)
31{
32 return current->mm == mm && !(current->flags & PF_KTHREAD);
33}
34
35void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
36{
37 if (vmacache_valid_mm(newvma->vm_mm))
38 current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma;
39}
40
41static bool vmacache_valid(struct mm_struct *mm)
42{
43 struct task_struct *curr;
44
45 if (!vmacache_valid_mm(mm))
46 return false;
47
48 curr = current;
49 if (mm->vmacache_seqnum != curr->vmacache.seqnum) {
50 /*
51 * First attempt will always be invalid, initialize
52 * the new cache for this task here.
53 */
54 curr->vmacache.seqnum = mm->vmacache_seqnum;
55 vmacache_flush(curr);
56 return false;
57 }
58 return true;
59}
60
61struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr)
62{
63 int idx = VMACACHE_HASH(addr);
64 int i;
65
66 count_vm_vmacache_event(VMACACHE_FIND_CALLS);
67
68 if (!vmacache_valid(mm))
69 return NULL;
70
71 for (i = 0; i < VMACACHE_SIZE; i++) {
72 struct vm_area_struct *vma = current->vmacache.vmas[idx];
73
74 if (vma) {
75#ifdef CONFIG_DEBUG_VM_VMACACHE
76 if (WARN_ON_ONCE(vma->vm_mm != mm))
77 break;
78#endif
79 if (vma->vm_start <= addr && vma->vm_end > addr) {
80 count_vm_vmacache_event(VMACACHE_FIND_HITS);
81 return vma;
82 }
83 }
84 if (++idx == VMACACHE_SIZE)
85 idx = 0;
86 }
87
88 return NULL;
89}
90
91#ifndef CONFIG_MMU
92struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm,
93 unsigned long start,
94 unsigned long end)
95{
96 int idx = VMACACHE_HASH(start);
97 int i;
98
99 count_vm_vmacache_event(VMACACHE_FIND_CALLS);
100
101 if (!vmacache_valid(mm))
102 return NULL;
103
104 for (i = 0; i < VMACACHE_SIZE; i++) {
105 struct vm_area_struct *vma = current->vmacache.vmas[idx];
106
107 if (vma && vma->vm_start == start && vma->vm_end == end) {
108 count_vm_vmacache_event(VMACACHE_FIND_HITS);
109 return vma;
110 }
111 if (++idx == VMACACHE_SIZE)
112 idx = 0;
113 }
114
115 return NULL;
116}
117#endif