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Commit 9641c7cc authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[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: default avatarHyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 002547b4

arch/arm/kernel/armksyms.c

+5 −2
Original line number Diff line number Diff line
@@ -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);

arch/arm/kernel/vmlinux.lds.S

+8 −0
Original line number Diff line number Diff line
@@ -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 = .;



		/*

arch/arm/lib/Makefile

+8 −5
Original line number Diff line number Diff line
@@ -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

include/asm-arm/uaccess.h

+87 −52
Original line number Diff line number Diff line
@@ -40,13 +40,22 @@ struct exception_table_entry 


extern int fixup_exception(struct pt_regs *regs);



/*

 * These two are intentionally not defined anywhere - if the kernel

 * code generates any references to them, that's a bug.

 */

extern int __get_user_bad(void);

extern int __put_user_bad(void);



/*

 * Note that this is actually 0x1,0000,0000

 */

#define KERNEL_DS	0x00000000

#define USER_DS		TASK_SIZE



#define get_ds()	(KERNEL_DS)



#ifdef CONFIG_MMU



#define USER_DS		TASK_SIZE

#define get_fs()	(current_thread_info()->addr_limit)



static inline void set_fs(mm_segment_t fs)
@@ -75,8 +84,6 @@ static inline void set_fs (mm_segment_t fs) 
		: "cc"); \

	flag; })



#define access_ok(type,addr,size)	(__range_ok(addr,size) == 0)



/*

 * Single-value transfer routines.  They automatically use the right

 * size if we just have the right pointer type.  Note that the functions
@@ -87,20 +94,10 @@ static inline void set_fs (mm_segment_t fs) 
 * fixup code, but there are a few places where it intrudes on the

 * main code path.  When we only write to user space, there is no

 * problem.

 *

 * The "__xxx" versions of the user access functions do not verify the

 * address space - it must have been done previously with a separate

 * "access_ok()" call.

 *

 * The "xxx_error" versions set the third argument to EFAULT if an

 * error occurs, and leave it unchanged on success.  Note that these

 * versions are void (ie, don't return a value as such).

 */



extern int __get_user_1(void *);

extern int __get_user_2(void *);

extern int __get_user_4(void *);

extern int __get_user_bad(void);



#define __get_user_x(__r2,__p,__e,__s,__i...)				\

	   __asm__ __volatile__ (					\
@@ -131,6 +128,74 @@ extern int __get_user_bad(void); 
		__e;							\

	})



extern int __put_user_1(void *, unsigned int);

extern int __put_user_2(void *, unsigned int);

extern int __put_user_4(void *, unsigned int);

extern int __put_user_8(void *, unsigned long long);



#define __put_user_x(__r2,__p,__e,__s)					\

	   __asm__ __volatile__ (					\

		__asmeq("%0", "r0") __asmeq("%2", "r2")			\

		"bl	__put_user_" #__s				\

		: "=&r" (__e)						\

		: "0" (__p), "r" (__r2)					\

		: "ip", "lr", "cc")



#define put_user(x,p)							\

	({								\

		const register typeof(*(p)) __r2 asm("r2") = (x);	\

		const register typeof(*(p)) __user *__p asm("r0") = (p);\

		register int __e asm("r0");				\

		switch (sizeof(*(__p))) {				\

		case 1:							\

			__put_user_x(__r2, __p, __e, 1);		\

			break;						\

		case 2:							\

			__put_user_x(__r2, __p, __e, 2);		\

			break;						\

		case 4:							\

			__put_user_x(__r2, __p, __e, 4);		\

			break;						\

		case 8:							\

			__put_user_x(__r2, __p, __e, 8);		\

			break;						\

		default: __e = __put_user_bad(); break;			\

		}							\

		__e;							\

	})



#else /* CONFIG_MMU */



/*

 * uClinux has only one addr space, so has simplified address limits.

 */

#define USER_DS			KERNEL_DS



#define segment_eq(a,b)		(1)

#define __addr_ok(addr)		(1)

#define __range_ok(addr,size)	(0)

#define get_fs()		(KERNEL_DS)



static inline void set_fs(mm_segment_t fs)

{

}



#define get_user(x,p)	__get_user(x,p)

#define put_user(x,p)	__put_user(x,p)



#endif /* CONFIG_MMU */



#define access_ok(type,addr,size)	(__range_ok(addr,size) == 0)



/*

 * The "__xxx" versions of the user access functions do not verify the

 * address space - it must have been done previously with a separate

 * "access_ok()" call.

 *

 * The "xxx_error" versions set the third argument to EFAULT if an

 * error occurs, and leave it unchanged on success.  Note that these

 * versions are void (ie, don't return a value as such).

 */

#define __get_user(x,ptr)						\

({									\

	long __gu_err = 0;						\
@@ -212,43 +277,6 @@ do { \ 
	: "r" (addr), "i" (-EFAULT)				\

	: "cc")



extern int __put_user_1(void *, unsigned int);

extern int __put_user_2(void *, unsigned int);

extern int __put_user_4(void *, unsigned int);

extern int __put_user_8(void *, unsigned long long);

extern int __put_user_bad(void);



#define __put_user_x(__r2,__p,__e,__s)					\

	   __asm__ __volatile__ (					\

		__asmeq("%0", "r0") __asmeq("%2", "r2")			\

		"bl	__put_user_" #__s				\

		: "=&r" (__e)						\

		: "0" (__p), "r" (__r2)					\

		: "ip", "lr", "cc")



#define put_user(x,p)							\

	({								\

		const register typeof(*(p)) __r2 asm("r2") = (x);	\

		const register typeof(*(p)) __user *__p asm("r0") = (p);\

		register int __e asm("r0");				\

		switch (sizeof(*(__p))) {				\

		case 1:							\

			__put_user_x(__r2, __p, __e, 1);		\

			break;						\

		case 2:							\

			__put_user_x(__r2, __p, __e, 2);		\

			break;						\

		case 4:							\

			__put_user_x(__r2, __p, __e, 4);		\

			break;						\

		case 8:							\

			__put_user_x(__r2, __p, __e, 8);		\

			break;						\

		default: __e = __put_user_bad(); break;			\

		}							\

		__e;							\

	})



#define __put_user(x,ptr)						\

({									\

	long __pu_err = 0;						\
@@ -354,9 +382,16 @@ do { \ 
	: "cc")





#ifdef CONFIG_MMU

extern unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n);

extern unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n);

extern unsigned long __clear_user(void __user *addr, unsigned long n);

#else

#define __copy_from_user(to,from,n)	(memcpy(to, (void __force *)from, n), 0)

#define __copy_to_user(to,from,n)	(memcpy((void __force *)to, from, n), 0)

#define __clear_user(addr,n)		(memset((void __force *)addr, 0, n), 0)

#endif



extern unsigned long __strncpy_from_user(char *to, const char __user *from, unsigned long count);

extern unsigned long __strnlen_user(const char __user *s, long n);