On Sat, Aug 07, 2021 at 04:04:29PM +0800, Huang Pei wrote:
> Borrow from ARM64
>
> MIPS64 CPU has enough direct mapped memory space to access all
> physical memory. In case of no cache alias, bypass both k*map_atomic
> and k*map_coherent for better real-time performance.
>
> Signed-off-by: Huang Pei <huangpei@xxxxxxxxxxx>
> ---
> arch/mips/mm/init.c | 39 ++++++++++++++++++++++++++-------------
> 1 file changed, 26 insertions(+), 13 deletions(-)
>
> diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
> index 19347dc6bbf8..1f5bdd18ae7c 100644
> --- a/arch/mips/mm/init.c
> +++ b/arch/mips/mm/init.c
> @@ -171,22 +171,35 @@ void copy_user_highpage(struct page *to, struct page *from,
> {
> void *vfrom, *vto;
>
> - vto = kmap_atomic(to);
> - if (cpu_has_dc_aliases &&
> - page_mapcount(from) && !Page_dcache_dirty(from)) {
> - vfrom = kmap_coherent(from, vaddr);
> + if (IS_ENABLED(CONFIG_64BIT) && !cpu_has_dc_aliases) {
> + vfrom = page_address(from);
> + vto = page_address(to);
> copy_page(vto, vfrom);
> - kunmap_coherent();
> + /*
> + * even without cache alias, still need to maintain
> + * coherence between icache and dcache
> + */
> + if (!cpu_has_ic_fills_f_dc)
> + flush_data_cache_page((unsigned long)vto);
> +
> } else {
> - vfrom = kmap_atomic(from);
> - copy_page(vto, vfrom);
> - kunmap_atomic(vfrom);
> + vto = kmap_atomic(to);
> + if (cpu_has_dc_aliases &&
> + page_mapcount(from) && !Page_dcache_dirty(from)) {
please fix indentation and place page_mapping() to same column as
cpu_has_dc_aliases()
> + vfrom = kmap_coherent(from, vaddr);
> + copy_page(vto, vfrom);
> + kunmap_coherent();
> + } else {
> + vfrom = kmap_atomic(from);
> + copy_page(vto, vfrom);
> + kunmap_atomic(vfrom);
> + }
> + if ((!cpu_has_ic_fills_f_dc) ||
> + pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
same here
> + flush_data_cache_page((unsigned long)vto);
> + kunmap_atomic(vto);
> + /* Make sure this page is cleared on other CPU's too before using it */
this comment should stay in front of the smp_wmb()
> }
> - if ((!cpu_has_ic_fills_f_dc) ||
> - pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
> - flush_data_cache_page((unsigned long)vto);
> - kunmap_atomic(vto);
> - /* Make sure this page is cleared on other CPU's too before using it */
> smp_wmb();
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
