Hi Greg,
On Wed, Sep 9, 2020 at 4:18 AM Greg Ungerer <gerg@xxxxxxxxxxxxxx> 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.
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Greg Ungerer <gerg@xxxxxxxxxxxxxx>
Thanks for your patch!
rename from arch/m68k/include/asm/uaccess_mm.h
rename to arch/m68k/include/asm/uaccess.h
index 9ae9f8d05925..f98208ccbbcd 100644
--- a/arch/m68k/include/asm/uaccess_mm.h
+++ b/arch/m68k/include/asm/uaccess.h
@@ -2,12 +2,15 @@
#ifndef __M68K_UACCESS_H
#define __M68K_UACCESS_H
+#ifdef CONFIG_MMU
+
/*
* User space memory access functions
*/
#include <linux/compiler.h>
#include <linux/types.h>
#include <asm/segment.h>
+#include <asm/extable.h>
For a moment, I wondered where this new include came from...
Seems like git doesn't show what happened to the old
arch/m68k/include/asm/uaccess.h file, which was overwritten by the
rename:
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifdef __uClinux__
-#include <asm/uaccess_no.h>
-#else
-#include <asm/uaccess_mm.h>
-#endif
-#include <asm/extable.h>
There it is ;-)
Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
/* We let the MMU do all checking */
static inline int access_ok(const void __user *addr,
@@ -387,4 +390,8 @@ unsigned long __clear_user(void __user *to, unsigned long n);
#define clear_user __clear_user
+#else /* !CONFIG_MMU */
+#include <asm-generic/uaccess.h>
+#endif
+
#endif /* _M68K_UACCESS_H */
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
