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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /mm/vmacache.c | |
parent | Initial commit. (diff) | |
download | linux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.tar.xz linux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'mm/vmacache.c')
-rw-r--r-- | mm/vmacache.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/mm/vmacache.c b/mm/vmacache.c new file mode 100644 index 000000000..01a6e6688 --- /dev/null +++ b/mm/vmacache.c @@ -0,0 +1,117 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2014 Davidlohr Bueso. + */ +#include <linux/sched/signal.h> +#include <linux/sched/task.h> +#include <linux/mm.h> +#include <linux/vmacache.h> + +/* + * Hash based on the pmd of addr if configured with MMU, which provides a good + * hit rate for workloads with spatial locality. Otherwise, use pages. + */ +#ifdef CONFIG_MMU +#define VMACACHE_SHIFT PMD_SHIFT +#else +#define VMACACHE_SHIFT PAGE_SHIFT +#endif +#define VMACACHE_HASH(addr) ((addr >> VMACACHE_SHIFT) & VMACACHE_MASK) + +/* + * This task may be accessing a foreign mm via (for example) + * get_user_pages()->find_vma(). The vmacache is task-local and this + * task's vmacache pertains to a different mm (ie, its own). There is + * nothing we can do here. + * + * Also handle the case where a kernel thread has adopted this mm via + * kthread_use_mm(). That kernel thread's vmacache is not applicable to this mm. + */ +static inline bool vmacache_valid_mm(struct mm_struct *mm) +{ + return current->mm == mm && !(current->flags & PF_KTHREAD); +} + +void vmacache_update(unsigned long addr, struct vm_area_struct *newvma) +{ + if (vmacache_valid_mm(newvma->vm_mm)) + current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma; +} + +static bool vmacache_valid(struct mm_struct *mm) +{ + struct task_struct *curr; + + if (!vmacache_valid_mm(mm)) + return false; + + curr = current; + if (mm->vmacache_seqnum != curr->vmacache.seqnum) { + /* + * First attempt will always be invalid, initialize + * the new cache for this task here. + */ + curr->vmacache.seqnum = mm->vmacache_seqnum; + vmacache_flush(curr); + return false; + } + return true; +} + +struct vm_area_struct *vmacache_find(struct mm_struct *mm, unsigned long addr) +{ + int idx = VMACACHE_HASH(addr); + int i; + + count_vm_vmacache_event(VMACACHE_FIND_CALLS); + + if (!vmacache_valid(mm)) + return NULL; + + for (i = 0; i < VMACACHE_SIZE; i++) { + struct vm_area_struct *vma = current->vmacache.vmas[idx]; + + if (vma) { +#ifdef CONFIG_DEBUG_VM_VMACACHE + if (WARN_ON_ONCE(vma->vm_mm != mm)) + break; +#endif + if (vma->vm_start <= addr && vma->vm_end > addr) { + count_vm_vmacache_event(VMACACHE_FIND_HITS); + return vma; + } + } + if (++idx == VMACACHE_SIZE) + idx = 0; + } + + return NULL; +} + +#ifndef CONFIG_MMU +struct vm_area_struct *vmacache_find_exact(struct mm_struct *mm, + unsigned long start, + unsigned long end) +{ + int idx = VMACACHE_HASH(start); + int i; + + count_vm_vmacache_event(VMACACHE_FIND_CALLS); + + if (!vmacache_valid(mm)) + return NULL; + + for (i = 0; i < VMACACHE_SIZE; i++) { + struct vm_area_struct *vma = current->vmacache.vmas[idx]; + + if (vma && vma->vm_start == start && vma->vm_end == end) { + count_vm_vmacache_event(VMACACHE_FIND_HITS); + return vma; + } + if (++idx == VMACACHE_SIZE) + idx = 0; + } + + return NULL; +} +#endif |