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117 lines
2.7 KiB
117 lines
2.7 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2014 Davidlohr Bueso. |
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*/ |
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#include <linux/sched/signal.h> |
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#include <linux/sched/task.h> |
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#include <linux/mm.h> |
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#include <linux/vmacache.h> |
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/* |
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* Hash based on the pmd of addr if configured with MMU, which provides a good |
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* hit rate for workloads with spatial locality. Otherwise, use pages. |
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*/ |
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#ifdef CONFIG_MMU |
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#define VMACACHE_SHIFT PMD_SHIFT |
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#else |
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#define VMACACHE_SHIFT PAGE_SHIFT |
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#endif |
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#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK) |
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/* |
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* This task may be accessing a foreign mm via (for example) |
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* get_user_pages()->find_vma(). The vmacache is task-local and this |
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* task's vmacache pertains to a different mm (ie, its own). There is |
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* nothing we can do here. |
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* |
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* Also handle the case where a kernel thread has adopted this mm via |
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* kthread_use_mm(). That kernel thread's vmacache is not applicable to this mm. |
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*/ |
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static inline bool vmacache_valid_mm(struct mm_struct *mm) |
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{ |
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return current->mm == mm && !(current->flags & PF_KTHREAD); |
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} |
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void vmacache_update(unsigned long addr, struct vm_area_struct *newvma) |
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{ |
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if (vmacache_valid_mm(newvma->vm_mm)) |
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current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma; |
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} |
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static bool vmacache_valid(struct mm_struct *mm) |
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{ |
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struct task_struct *curr; |
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if (!vmacache_valid_mm(mm)) |
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return false; |
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curr = current; |
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if (mm->vmacache_seqnum != curr->vmacache.seqnum) { |
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/* |
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* First attempt will always be invalid, initialize |
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* the new cache for this task here. |
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*/ |
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curr->vmacache.seqnum = mm->vmacache_seqnum; |
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vmacache_flush(curr); |
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return false; |
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} |
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return true; |
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} |
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struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr) |
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{ |
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int idx = VMACACHE_HASH(addr); |
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int i; |
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count_vm_vmacache_event(VMACACHE_FIND_CALLS); |
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if (!vmacache_valid(mm)) |
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return NULL; |
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for (i = 0; i < VMACACHE_SIZE; i++) { |
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struct vm_area_struct *vma = current->vmacache.vmas[idx]; |
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if (vma) { |
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#ifdef CONFIG_DEBUG_VM_VMACACHE |
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if (WARN_ON_ONCE(vma->vm_mm != mm)) |
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break; |
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#endif |
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if (vma->vm_start <= addr && vma->vm_end > addr) { |
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count_vm_vmacache_event(VMACACHE_FIND_HITS); |
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return vma; |
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} |
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} |
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if (++idx == VMACACHE_SIZE) |
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idx = 0; |
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} |
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return NULL; |
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} |
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#ifndef CONFIG_MMU |
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struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm, |
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unsigned long start, |
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unsigned long end) |
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{ |
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int idx = VMACACHE_HASH(start); |
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int i; |
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count_vm_vmacache_event(VMACACHE_FIND_CALLS); |
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if (!vmacache_valid(mm)) |
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return NULL; |
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for (i = 0; i < VMACACHE_SIZE; i++) { |
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struct vm_area_struct *vma = current->vmacache.vmas[idx]; |
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if (vma && vma->vm_start == start && vma->vm_end == end) { |
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count_vm_vmacache_event(VMACACHE_FIND_HITS); |
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return vma; |
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} |
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if (++idx == VMACACHE_SIZE) |
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idx = 0; |
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} |
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return NULL; |
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} |
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#endif
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