On Wed, Sep 09, 2020 at 12:18:31PM +1000, Greg Ungerer wrote:
Switch to using the asm-generic/uaccess functions for non-MMU builds.
Remove all the m68knommu local specific uaccess defines and macros.
There is nothing so special about the m68knommu targets that they cannot
use all of the asm-generic uaccess support. Using the asm-generic
uaccess definitions also resolves some of the existing problems with
missing __user annotations in the m68knommu specific functions.
The elimination of all of the contents of uaccess_no.h means we can fold
the uaccess_mm.h back into uaccess.h - and just have the single file
now.
The resulting generated code ends up being slightly smaller (by a few
hundred bytes) due to the compilers ability to better optimize load
and stores without forcing its hand with asm statements.
Specifically trivial cases like this contrived example:
get_user(x, ptr);
x++;
put_user(x, ptr);
end up now being optimized to a single instruction on m68k. More
generally the compiler can avoid using a temporary register in many
cases as well.
This looks great!
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
