[thirdparty/kernel/stable.git] / mm / vmacache.c

// 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>
#include <asm/pgtable.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 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
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
615d6e87 DB	2	/*
	3	* Copyright (C) 2014 Davidlohr Bueso.
	4	*/
3f07c014	5	#include <linux/sched/signal.h>
9164bb4a	6	#include <linux/sched/task.h>
615d6e87 DB	7	#include <linux/mm.h>
615d6e87 DB	8	#include <linux/vmacache.h>
ddbf369c DR	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)
615d6e87	21
615d6e87 DB	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	*/
a2c1aad3	31	static inline bool vmacache_valid_mm(struct mm_struct *mm)
615d6e87 DB	32	{
	33	return current->mm == mm && !(current->flags & PF_KTHREAD);
	34	}
	35
	36	void vmacache_update(unsigned long addr, struct vm_area_struct *newvma)
	37	{
	38	if (vmacache_valid_mm(newvma->vm_mm))
314ff785	39	current->vmacache.vmas[VMACACHE_HASH(addr)] = newvma;
615d6e87 DB	40	}
	41
	42	static 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;
314ff785	50	if (mm->vmacache_seqnum != curr->vmacache.seqnum) {
615d6e87 DB	51	/*
	52	* First attempt will always be invalid, initialize
	53	* the new cache for this task here.
	54	*/
314ff785	55	curr->vmacache.seqnum = mm->vmacache_seqnum;
615d6e87 DB	56	vmacache_flush(curr);
	57	return false;
	58	}
	59	return true;
	60	}
	61
	62	struct vm_area_struct vmacache_find(struct mm_struct mm, unsigned long addr)
	63	{
ddbf369c	64	int idx = VMACACHE_HASH(addr);
615d6e87 DB	65	int i;
615d6e87 DB	66
131ddc5c AD	67	count_vm_vmacache_event(VMACACHE_FIND_CALLS);
131ddc5c AD	68
615d6e87 DB	69	if (!vmacache_valid(mm))
	70	return NULL;
	71
	72	for (i = 0; i < VMACACHE_SIZE; i++) {
ddbf369c	73	struct vm_area_struct *vma = current->vmacache.vmas[idx];
615d6e87	74
ddbf369c DR	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	}
4f115147	84	}
ddbf369c DR	85	if (++idx == VMACACHE_SIZE)
ddbf369c DR	86	idx = 0;
615d6e87 DB	87	}
	88
	89	return NULL;
	90	}
	91
	92	#ifndef CONFIG_MMU
	93	struct vm_area_struct vmacache_find_exact(struct mm_struct mm,
	94	unsigned long start,
	95	unsigned long end)
	96	{
ddbf369c	97	int idx = VMACACHE_HASH(start);
615d6e87 DB	98	int i;
615d6e87 DB	99
131ddc5c AD	100	count_vm_vmacache_event(VMACACHE_FIND_CALLS);
131ddc5c AD	101
615d6e87 DB	102	if (!vmacache_valid(mm))
	103	return NULL;
	104
	105	for (i = 0; i < VMACACHE_SIZE; i++) {
ddbf369c	106	struct vm_area_struct *vma = current->vmacache.vmas[idx];
615d6e87	107
4f115147 DB	108	if (vma && vma->vm_start == start && vma->vm_end == end) {
4f115147 DB	109	count_vm_vmacache_event(VMACACHE_FIND_HITS);
615d6e87	110	return vma;
4f115147	111	}
ddbf369c DR	112	if (++idx == VMACACHE_SIZE)
ddbf369c DR	113	idx = 0;
615d6e87 DB	114	}
	115
	116	return NULL;
	117	}
	118	#endif