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kernel: mmu: z_backing_store* to k_mem_paging_backing_store*

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These functions are those that need be implemented by backing
store outside kernel. Promote them from z_* so these can be
included in documentation.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2021-05-13 11:57:54 -07:00 • committed by Anas Nashif
commit dfa4b7e375
7 changed files with 168 additions and 151 deletions
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30
subsys/demand_paging/backing_store/ram.c
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@ -26,16 +26,18 @@
* large to hold clean copies of all mapped memory.
*
* This backing store is an example of the latter case. However, locations
* are freed as soon as pages are paged in, in z_backing_store_page_finalize().
* are freed as soon as pages are paged in, in
* k_mem_paging_backing_store_page_finalize().
* This implies that all data pages are treated as dirty as
* Z_PAGE_FRAME_BACKED is never set, even if the data page was paged out before
* and not modified since then.
*
* An optimization a real backing store will want is have
* z_backing_store_page_finalize() note the storage location of a paged-in
* data page in a custom field of its associated z_page_frame, and set the
* Z_PAGE_FRAME_BACKED bit. Invocations of z_backing_store_location_get() will
* have logic to return the previous clean page location instead of allocating
* k_mem_paging_backing_store_page_finalize() note the storage location of
* a paged-in data page in a custom field of its associated z_page_frame, and
* set the Z_PAGE_FRAME_BACKED bit. Invocations of
* k_mem_paging_backing_store_location_get() will have logic to return
* the previous clean page location instead of allocating
* a new one if Z_PAGE_FRAME_BACKED is set.
*
* This will, however, require the implementation of a clean page
@ -79,8 +81,9 @@ static uintptr_t slab_to_location(void *slab)
return offset;
}
int z_backing_store_location_get(struct z_page_frame *pf, uintptr_t *location,
bool page_fault)
int k_mem_paging_backing_store_location_get(struct z_page_frame *pf,
uintptr_t *location,
bool page_fault)
{
int ret;
void *slab;
@ -98,7 +101,7 @@ int z_backing_store_location_get(struct z_page_frame *pf, uintptr_t *location,
return 0;
}
void z_backing_store_location_free(uintptr_t location)
void k_mem_paging_backing_store_location_free(uintptr_t location)
{
void *slab = location_to_slab(location);
@ -106,24 +109,25 @@ void z_backing_store_location_free(uintptr_t location)
free_slabs++;
}
void z_backing_store_page_out(uintptr_t location)
void k_mem_paging_backing_store_page_out(uintptr_t location)
{
(void)memcpy(location_to_slab(location), Z_SCRATCH_PAGE,
CONFIG_MMU_PAGE_SIZE);
}
void z_backing_store_page_in(uintptr_t location)
void k_mem_paging_backing_store_page_in(uintptr_t location)
{
(void)memcpy(Z_SCRATCH_PAGE, location_to_slab(location),
CONFIG_MMU_PAGE_SIZE);
}
void z_backing_store_page_finalize(struct z_page_frame *pf, uintptr_t location)
void k_mem_paging_backing_store_page_finalize(struct z_page_frame *pf,
uintptr_t location)
{
z_backing_store_location_free(location);
k_mem_paging_backing_store_location_free(location);
}
void z_backing_store_init(void)
void k_mem_paging_backing_store_init(void)
{
k_mem_slab_init(&backing_slabs, backing_store, CONFIG_MMU_PAGE_SIZE,
CONFIG_BACKING_STORE_RAM_PAGES);