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kernel: mmu: make k_mem_unmap() work with demand paging

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If a page is paged out or paged in but unaccessible for the purpose of
tracking the "accessed" flag then k_mem_unmap() may fails. Add the code
needed to support those cases.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This commit is contained in:
Nicolas Pitre 2024-06-10 17:00:41 -04:00 committed by Henrik Brix Andersen
parent 30c9f5eaa5
commit 0313091287
1 changed files with 32 additions and 1 deletions
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33
kernel/mmu.c
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@ -689,8 +689,39 @@ void k_mem_unmap_phys_guard(void *addr, size_t size, bool is_anon)
if (is_anon) {
/* Unmapping anonymous memory */
VIRT_FOREACH(addr, size, pos) {
ret = arch_page_phys_get(pos, &phys);
#ifdef CONFIG_DEMAND_PAGING
enum arch_page_location status;
uintptr_t location;
status = arch_page_location_get(pos, &location);
switch (status) {
case ARCH_PAGE_LOCATION_PAGED_OUT:
/*
* No pf is associated with this mapping.
* Simply get rid of the MMU entry and free
* corresponding backing store.
*/
arch_mem_unmap(pos, CONFIG_MMU_PAGE_SIZE);
k_mem_paging_backing_store_location_free(location);
continue;
case ARCH_PAGE_LOCATION_PAGED_IN:
/*
* The page is in memory but it may not be
* accessible in order to manage tracking
* of the ARCH_DATA_PAGE_ACCESSED flag
* meaning arch_page_phys_get() could fail.
* Still, we know the actual phys address.
*/
phys = location;
ret = 0;
break;
default:
ret = arch_page_phys_get(pos, &phys);
break;
}
#else
ret = arch_page_phys_get(pos, &phys);
#endif
__ASSERT(ret == 0,
"%s: cannot unmap an unmapped address %p",
__func__, pos);