[ARM] nommu: uaccess tweaks

MMUless systems have only one address space for all threads, so
both the usual access_ok() checks, and the exception handling do
not make much sense.

Hence, discard the fixup and exception tables at link time, use
memcpy/memset for the user copy/clearing functions, and define
the permission check macros to be constants.

Some of this patch was derived from the equivalent patch by
Hyok S. Choi.

Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 21 insertions, 7 deletions

diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c
index f8bb7abd3e9b..da69e660574b 100644
--- a/arch/arm/kernel/armksyms.c
+++ b/arch/arm/kernel/armksyms.c
@@ -109,11 +109,13 @@ EXPORT_SYMBOL(memchr);
 EXPORT_SYMBOL(__memzero);
 
         /* user mem (segment) */
+EXPORT_SYMBOL(__strnlen_user);
+EXPORT_SYMBOL(__strncpy_from_user);
+
+#ifdef CONFIG_MMU
 EXPORT_SYMBOL(__copy_from_user);
 EXPORT_SYMBOL(__copy_to_user);
 EXPORT_SYMBOL(__clear_user);
-EXPORT_SYMBOL(__strnlen_user);
-EXPORT_SYMBOL(__strncpy_from_user);
 
 EXPORT_SYMBOL(__get_user_1);
 EXPORT_SYMBOL(__get_user_2);
@@ -123,6 +125,7 @@ EXPORT_SYMBOL(__put_user_1);
 EXPORT_SYMBOL(__put_user_2);
 EXPORT_SYMBOL(__put_user_4);
 EXPORT_SYMBOL(__put_user_8);
+#endif
 
         /* crypto hash */
 EXPORT_SYMBOL(sha_transform);
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 2b254e88595c..2df9688a7028 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -80,6 +80,10 @@ SECTIONS
                 *(.exit.text)
                 *(.exit.data)
                 *(.exitcall.exit)
+#ifndef CONFIG_MMU
+                *(.fixup)
+                *(__ex_table)
+#endif
         }
 
         .text : {                       /* Real text segment            */
@@ -87,7 +91,9 @@ SECTIONS
                         *(.text)
                         SCHED_TEXT
                         LOCK_TEXT
+#ifdef CONFIG_MMU
                         *(.fixup)
+#endif
                         *(.gnu.warning)
                         *(.rodata)
                         *(.rodata.*)
@@ -142,7 +148,9 @@ SECTIONS
                  */
                 . = ALIGN(32);
                 __start___ex_table = .;
+#ifdef CONFIG_MMU
                 *(__ex_table)
+#endif
                 __stop___ex_table = .;
 
                 /*
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index 7b726b627ea5..30351cd4560d 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -6,28 +6,31 @@
 
 lib-y           := backtrace.o changebit.o csumipv6.o csumpartial.o   \
                    csumpartialcopy.o csumpartialcopyuser.o clearbit.o \
-                   copy_page.o delay.o findbit.o memchr.o memcpy.o    \
+                   delay.o findbit.o memchr.o memcpy.o                \
                    memmove.o memset.o memzero.o setbit.o              \
                    strncpy_from_user.o strnlen_user.o                 \
                    strchr.o strrchr.o                                 \
                    testchangebit.o testclearbit.o testsetbit.o        \
-                   getuser.o putuser.o clear_user.o                   \
                    ashldi3.o ashrdi3.o lshrdi3.o muldi3.o             \
                    ucmpdi2.o lib1funcs.o div64.o sha1.o               \
                    io-readsb.o io-writesb.o io-readsl.o io-writesl.o
 
+mmu-y   := clear_user.o copy_page.o getuser.o putuser.o
+
 # the code in uaccess.S is not preemption safe and
 # probably faster on ARMv3 only
 ifeq ($(CONFIG_PREEMPT),y)
-  lib-y += copy_from_user.o copy_to_user.o
+  mmu-y += copy_from_user.o copy_to_user.o
 else
 ifneq ($(CONFIG_CPU_32v3),y)
-  lib-y += copy_from_user.o copy_to_user.o
+  mmu-y += copy_from_user.o copy_to_user.o
 else
-  lib-y += uaccess.o
+  mmu-y += uaccess.o
 endif
 endif
 
+lib-$(CONFIG_MMU) += $(mmu-y)
+
 ifeq ($(CONFIG_CPU_32v3),y)
   lib-y += io-readsw-armv3.o io-writesw-armv3.o
 else