[PATCH] m68k/uaccess: Fix asm constraints for userspace access

Geert Uytterhoeven
2013-06-13T11:59:44Z

When compiling a MMU kernel with CPU_HAS_ADDRESS_SPACES=n (e.g. "MMU=y
allnoconfig": "echo CONFIG_MMU=y > allno.config && make KCONFIG_ALLCONFIG=1
allnoconfig"), we use plain "move" instead of "moves", and I got:

CC arch/m68k/lib/uaccess.o
{standard input}: Assembler messages:
{standard input}:47: Error: operands mismatch -- statement `move.b %a0,(%a1)' ignored

This happens because plain "move" doesn't support byte transfers between
memory and address registers, while "moves" does.

Fix the asm constraints for __generic_copy_from_user(),
__generic_copy_to_user(), and __clear_user() to only use data registers
when accessing userspace.

Also, relax the asm constraints for 16-bit userspace accesses in
__put_user() and __get_user(), as both "move" and "moves" do support
such transfers between memory and address registers.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
arch/m68k/include/asm/uaccess_mm.h | 4 ++--
arch/m68k/lib/uaccess.c | 6 +++---
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/m68k/include/asm/uaccess_mm.h b/arch/m68k/include/asm/uaccess_mm.h
index 472c891..7aa681b 100644
--- a/arch/m68k/include/asm/uaccess_mm.h
+++ b/arch/m68k/include/asm/uaccess_mm.h
@@ -90,7 +90,7 @@ asm volatile ("\n" \
__put_user_asm(__pu_err, __pu_val, ptr, b, d, -EFAULT); \
break; \
case 2: \
- __put_user_asm(__pu_err, __pu_val, ptr, w, d, -EFAULT); \
+ __put_user_asm(__pu_err, __pu_val, ptr, w, r, -EFAULT); \
break; \
case 4: \
__put_user_asm(__pu_err, __pu_val, ptr, l, r, -EFAULT); \
@@ -158,7 +158,7 @@ asm volatile ("\n" \
__get_user_asm(__gu_err, x, ptr, u8, b, d, -EFAULT); \
break; \
case 2: \
- __get_user_asm(__gu_err, x, ptr, u16, w, d, -EFAULT); \
+ __get_user_asm(__gu_err, x, ptr, u16, w, r, -EFAULT); \
break; \
case 4: \
__get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT); \
diff --git a/arch/m68k/lib/uaccess.c b/arch/m68k/lib/uaccess.c
index 5e97f2e..35d1442 100644
--- a/arch/m68k/lib/uaccess.c
+++ b/arch/m68k/lib/uaccess.c
@@ -52,7 +52,7 @@ unsigned long __generic_copy_from_user(void *to, const void __user *from,
" .long 3b,30b\n"
" .long 5b,50b\n"
" .previous"
- : "=d" (res), "+a" (from), "+a" (to), "=&r" (tmp)
+ : "=d" (res), "+a" (from), "+a" (to), "=&d" (tmp)
: "0" (n / 4), "d" (n & 3));

return res;
@@ -96,7 +96,7 @@ unsigned long __generic_copy_to_user(void __user *to, const void *from,
" .long 7b,50b\n"
" .long 8b,50b\n"
" .previous"
- : "=d" (res), "+a" (from), "+a" (to), "=&r" (tmp)
+ : "=d" (res), "+a" (from), "+a" (to), "=&d" (tmp)
: "0" (n / 4), "d" (n & 3));

return res;
@@ -141,7 +141,7 @@ unsigned long __clear_user(void __user *to, unsigned long n)
" .long 7b,40b\n"
" .previous"
: "=d" (res), "+a" (to)
- : "r" (0), "0" (n / 4), "d" (n & 3));
+ : "d" (0), "0" (n / 4), "d" (n & 3));

return res;
}
--
1.7.0.4