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// SPDX-License-Identifier: GPL-2.0
/*
* DAMON Primitives for The Physical Address Space
*
* Author: SeongJae Park <sj@kernel.org>
*/
#define pr_fmt(fmt) "damon-pa: " fmt
#include <linux/mmu_notifier.h>
#include <linux/page_idle.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include "prmtv-common.h"
static bool __damon_pa_mkold(struct page *page, struct vm_area_struct *vma,
unsigned long addr, void *arg)
{
struct page_vma_mapped_walk pvmw = {
.page = page,
.vma = vma,
.address = addr,
};
while (page_vma_mapped_walk(&pvmw)) {
addr = pvmw.address;
if (pvmw.pte)
damon_ptep_mkold(pvmw.pte, vma->vm_mm, addr);
else
damon_pmdp_mkold(pvmw.pmd, vma->vm_mm, addr);
}
return true;
}
static void damon_pa_mkold(unsigned long paddr)
{
struct page *page = damon_get_page(PHYS_PFN(paddr));
struct rmap_walk_control rwc = {
.rmap_one = __damon_pa_mkold,
.anon_lock = page_lock_anon_vma_read,
};
bool need_lock;
if (!page)
return;
if (!page_mapped(page) || !page_rmapping(page)) {
set_page_idle(page);
goto out;
}
need_lock = !PageAnon(page) || PageKsm(page);
if (need_lock && !trylock_page(page))
goto out;
rmap_walk(page, &rwc);
if (need_lock)
unlock_page(page);
out:
put_page(page);
}
static void __damon_pa_prepare_access_check(struct damon_ctx *ctx,
struct damon_region *r)
{
r->sampling_addr = damon_rand(r->ar.start, r->ar.end);
damon_pa_mkold(r->sampling_addr);
}
void damon_pa_prepare_access_checks(struct damon_ctx *ctx)
{
struct damon_target *t;
struct damon_region *r;
damon_for_each_target(t, ctx) {
damon_for_each_region(r, t)
__damon_pa_prepare_access_check(ctx, r);
}
}
struct damon_pa_access_chk_result {
unsigned long page_sz;
bool accessed;
};
static bool __damon_pa_young(struct page *page, struct vm_area_struct *vma,
unsigned long addr, void *arg)
{
struct damon_pa_access_chk_result *result = arg;
struct page_vma_mapped_walk pvmw = {
.page = page,
.vma = vma,
.address = addr,
};
result->accessed = false;
result->page_sz = PAGE_SIZE;
while (page_vma_mapped_walk(&pvmw)) {
addr = pvmw.address;
if (pvmw.pte) {
result->accessed = pte_young(*pvmw.pte) ||
!page_is_idle(page) ||
mmu_notifier_test_young(vma->vm_mm, addr);
} else {
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
result->accessed = pmd_young(*pvmw.pmd) ||
!page_is_idle(page) ||
mmu_notifier_test_young(vma->vm_mm, addr);
result->page_sz = ((1UL) << HPAGE_PMD_SHIFT);
#else
WARN_ON_ONCE(1);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
}
if (result->accessed) {
page_vma_mapped_walk_done(&pvmw);
break;
}
}
/* If accessed, stop walking */
return !result->accessed;
}
static bool damon_pa_young(unsigned long paddr, unsigned long *page_sz)
{
struct page *page = damon_get_page(PHYS_PFN(paddr));
struct damon_pa_access_chk_result result = {
.page_sz = PAGE_SIZE,
.accessed = false,
};
struct rmap_walk_control rwc = {
.arg = &result,
.rmap_one = __damon_pa_young,
.anon_lock = page_lock_anon_vma_read,
};
bool need_lock;
if (!page)
return false;
if (!page_mapped(page) || !page_rmapping(page)) {
if (page_is_idle(page))
result.accessed = false;
else
result.accessed = true;
put_page(page);
goto out;
}
need_lock = !PageAnon(page) || PageKsm(page);
if (need_lock && !trylock_page(page)) {
put_page(page);
return NULL;
}
rmap_walk(page, &rwc);
if (need_lock)
unlock_page(page);
put_page(page);
out:
*page_sz = result.page_sz;
return result.accessed;
}
static void __damon_pa_check_access(struct damon_ctx *ctx,
struct damon_region *r)
{
static unsigned long last_addr;
static unsigned long last_page_sz = PAGE_SIZE;
static bool last_accessed;
/* If the region is in the last checked page, reuse the result */
if (ALIGN_DOWN(last_addr, last_page_sz) ==
ALIGN_DOWN(r->sampling_addr, last_page_sz)) {
if (last_accessed)
r->nr_accesses++;
return;
}
last_accessed = damon_pa_young(r->sampling_addr, &last_page_sz);
if (last_accessed)
r->nr_accesses++;
last_addr = r->sampling_addr;
}
unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
{
struct damon_target *t;
struct damon_region *r;
unsigned int max_nr_accesses = 0;
damon_for_each_target(t, ctx) {
damon_for_each_region(r, t) {
__damon_pa_check_access(ctx, r);
max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
}
}
return max_nr_accesses;
}
bool damon_pa_target_valid(void *t)
{
return true;
}
void damon_pa_set_primitives(struct damon_ctx *ctx)
{
ctx->primitive.init = NULL;
ctx->primitive.update = NULL;
ctx->primitive.prepare_access_checks = damon_pa_prepare_access_checks;
ctx->primitive.check_accesses = damon_pa_check_accesses;
ctx->primitive.reset_aggregated = NULL;
ctx->primitive.target_valid = damon_pa_target_valid;
ctx->primitive.cleanup = NULL;
ctx->primitive.apply_scheme = NULL;
}
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