diff options
Diffstat (limited to 'Documentation/core-api/cachetlb.rst')
| -rw-r--r-- | Documentation/core-api/cachetlb.rst | 55 |
1 files changed, 27 insertions, 28 deletions
diff --git a/Documentation/core-api/cachetlb.rst b/Documentation/core-api/cachetlb.rst index 5c0552e78c58..889fc84ccd1b 100644 --- a/Documentation/core-api/cachetlb.rst +++ b/Documentation/core-api/cachetlb.rst @@ -88,13 +88,17 @@ changes occur: This is used primarily during fault processing. -5) ``void update_mmu_cache(struct vm_area_struct *vma, - unsigned long address, pte_t *ptep)`` +5) ``void update_mmu_cache_range(struct vm_fault *vmf, + struct vm_area_struct *vma, unsigned long address, pte_t *ptep, + unsigned int nr)`` - At the end of every page fault, this routine is invoked to - tell the architecture specific code that a translation - now exists at virtual address "address" for address space - "vma->vm_mm", in the software page tables. + At the end of every page fault, this routine is invoked to tell + the architecture specific code that translations now exists + in the software page tables for address space "vma->vm_mm" + at virtual address "address" for "nr" consecutive pages. + + This routine is also invoked in various other places which pass + a NULL "vmf". A port may use this information in any way it so chooses. For example, it could use this event to pre-load TLB @@ -269,7 +273,7 @@ maps this page at its virtual address. If D-cache aliasing is not an issue, these two routines may simply call memcpy/memset directly and do nothing more. - ``void flush_dcache_page(struct page *page)`` + ``void flush_dcache_folio(struct folio *folio)`` This routines must be called when: @@ -277,7 +281,7 @@ maps this page at its virtual address. and / or in high memory b) the kernel is about to read from a page cache page and user space shared/writable mappings of this page potentially exist. Note - that {get,pin}_user_pages{_fast} already call flush_dcache_page + that {get,pin}_user_pages{_fast} already call flush_dcache_folio on any page found in the user address space and thus driver code rarely needs to take this into account. @@ -291,7 +295,7 @@ maps this page at its virtual address. The phrase "kernel writes to a page cache page" means, specifically, that the kernel executes store instructions that dirty data in that - page at the page->virtual mapping of that page. It is important to + page at the kernel virtual mapping of that page. It is important to flush here to handle D-cache aliasing, to make sure these kernel stores are visible to user space mappings of that page. @@ -302,21 +306,22 @@ maps this page at its virtual address. If D-cache aliasing is not an issue, this routine may simply be defined as a nop on that architecture. - There is a bit set aside in page->flags (PG_arch_1) as "architecture + There is a bit set aside in folio->flags (PG_arch_1) as "architecture private". The kernel guarantees that, for pagecache pages, it will clear this bit when such a page first enters the pagecache. - This allows these interfaces to be implemented much more efficiently. - It allows one to "defer" (perhaps indefinitely) the actual flush if - there are currently no user processes mapping this page. See sparc64's - flush_dcache_page and update_mmu_cache implementations for an example - of how to go about doing this. + This allows these interfaces to be implemented much more + efficiently. It allows one to "defer" (perhaps indefinitely) the + actual flush if there are currently no user processes mapping this + page. See sparc64's flush_dcache_folio and update_mmu_cache_range + implementations for an example of how to go about doing this. - The idea is, first at flush_dcache_page() time, if page_file_mapping() - returns a mapping, and mapping_mapped on that mapping returns %false, - just mark the architecture private page flag bit. Later, in - update_mmu_cache(), a check is made of this flag bit, and if set the - flush is done and the flag bit is cleared. + The idea is, first at flush_dcache_folio() time, if + folio_flush_mapping() returns a mapping, and mapping_mapped() on that + mapping returns %false, just mark the architecture private page + flag bit. Later, in update_mmu_cache_range(), a check is made + of this flag bit, and if set the flush is done and the flag bit + is cleared. .. important:: @@ -326,12 +331,6 @@ maps this page at its virtual address. dirty. Again, see sparc64 for examples of how to deal with this. - ``void flush_dcache_folio(struct folio *folio)`` - This function is called under the same circumstances as - flush_dcache_page(). It allows the architecture to - optimise for flushing the entire folio of pages instead - of flushing one page at a time. - ``void copy_to_user_page(struct vm_area_struct *vma, struct page *page, unsigned long user_vaddr, void *dst, void *src, int len)`` ``void copy_from_user_page(struct vm_area_struct *vma, struct page *page, @@ -352,7 +351,7 @@ maps this page at its virtual address. When the kernel needs to access the contents of an anonymous page, it calls this function (currently only - get_user_pages()). Note: flush_dcache_page() deliberately + get_user_pages()). Note: flush_dcache_folio() deliberately doesn't work for an anonymous page. The default implementation is a nop (and should remain so for all coherent architectures). For incoherent architectures, it should flush @@ -369,7 +368,7 @@ maps this page at its virtual address. ``void flush_icache_page(struct vm_area_struct *vma, struct page *page)`` All the functionality of flush_icache_page can be implemented in - flush_dcache_page and update_mmu_cache. In the future, the hope + flush_dcache_folio and update_mmu_cache_range. In the future, the hope is to remove this interface completely. The final category of APIs is for I/O to deliberately aliased address |