Commit e38361d0 authored by Daniel Thompson's avatar Daniel Thompson Committed by Russell King
Browse files

ARM: 8091/2: add get_user() support for 8 byte types 



Recent contributions, including to DRM and binder, introduce 64-bit
values in their interfaces. A common motivation for this is to allow
the same ABI for 32- and 64-bit userspaces (and therefore also a shared
ABI for 32/64 hybrid userspaces). Anyhow, the developers would like to
avoid gotchas like having to use copy_from_user().

This feature is already implemented on x86-32 and the majority of other
32-bit architectures. The current list of get_user_8 hold out
architectures are: arm, avr32, blackfin, m32r, metag, microblaze,
mn10300, sh.

Credit:

    My name sits rather uneasily at the top of this patch. The v1 and
    v2 versions of the patch were written by Rob Clark and to produce v4
    I mostly copied code from Russell King and H. Peter Anvin. However I
    have mangled the patch sufficiently that *blame* is rightfully mine
    even if credit should more widely shared.

Changelog:

v5: updated to use the ret macro (requested by Russell King)
v4: remove an inlined add on big endian systems (spotted by Russell King),
    used __ARMEB__ rather than BIG_ENDIAN (to match rest of file),
    cleared r3 on EFAULT during __get_user_8.
v3: fix a couple of checkpatch issues
v2: pass correct size to check_uaccess, and better handling of narrowing
    double word read with __get_user_xb() (Russell King's suggestion)
v1: original

Signed-off-by: default avatarRob Clark <robdclark@gmail.com>
Signed-off-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent bc994c77

arch/arm/include/asm/uaccess.h

+19 −1
Original line number Diff line number Diff line
@@ -107,6 +107,8 @@ static inline void set_fs(mm_segment_t fs) 
extern int __get_user_1(void *);

extern int __get_user_2(void *);

extern int __get_user_4(void *);

extern int __get_user_lo8(void *);

extern int __get_user_8(void *);



#define __GUP_CLOBBER_1	"lr", "cc"

#ifdef CONFIG_CPU_USE_DOMAINS
@@ -115,6 +117,8 @@ extern int __get_user_4(void *); 
#define __GUP_CLOBBER_2 "lr", "cc"

#endif

#define __GUP_CLOBBER_4	"lr", "cc"

#define __GUP_CLOBBER_lo8 "lr", "cc"

#define __GUP_CLOBBER_8	"lr", "cc"



#define __get_user_x(__r2,__p,__e,__l,__s)				\

	   __asm__ __volatile__ (					\
@@ -125,11 +129,19 @@ extern int __get_user_4(void *); 
		: "0" (__p), "r" (__l)					\

		: __GUP_CLOBBER_##__s)



/* narrowing a double-word get into a single 32bit word register: */

#ifdef __ARMEB__

#define __get_user_xb(__r2, __p, __e, __l, __s)				\

	__get_user_x(__r2, __p, __e, __l, lo8)

#else

#define __get_user_xb __get_user_x

#endif



#define __get_user_check(x,p)							\

	({								\

		unsigned long __limit = current_thread_info()->addr_limit - 1; \

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

		register unsigned long __r2 asm("r2");			\

		register typeof(x) __r2 asm("r2");			\

		register unsigned long __l asm("r1") = __limit;		\

		register int __e asm("r0");				\

		switch (sizeof(*(__p))) {				\
@@ -142,6 +154,12 @@ extern int __get_user_4(void *); 
		case 4:							\

			__get_user_x(__r2, __p, __e, __l, 4);		\

			break;						\

		case 8:							\

			if (sizeof((x)) < 8)				\

				__get_user_xb(__r2, __p, __e, __l, 4);	\

			else						\

				__get_user_x(__r2, __p, __e, __l, 8);	\

			break;						\

		default: __e = __get_user_bad(); break;			\

		}							\

		x = (typeof(*(p))) __r2;				\

arch/arm/lib/getuser.S

+36 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ 
 * Inputs:	r0 contains the address

 *		r1 contains the address limit, which must be preserved

 * Outputs:	r0 is the error code

 *		r2 contains the zero-extended value

 *		r2, r3 contains the zero-extended value

 *		lr corrupted

 *

 * No other registers must be altered.  (see <asm/uaccess.h>
@@ -66,15 +66,50 @@ ENTRY(__get_user_4) 
	ret	lr

ENDPROC(__get_user_4)



ENTRY(__get_user_8)

	check_uaccess r0, 8, r1, r2, __get_user_bad

#ifdef CONFIG_THUMB2_KERNEL

5: TUSER(ldr)	r2, [r0]

6: TUSER(ldr)	r3, [r0, #4]

#else

5: TUSER(ldr)	r2, [r0], #4

6: TUSER(ldr)	r3, [r0]

#endif

	mov	r0, #0

	ret	lr

ENDPROC(__get_user_8)



#ifdef __ARMEB__

ENTRY(__get_user_lo8)

	check_uaccess r0, 8, r1, r2, __get_user_bad

#ifdef CONFIG_CPU_USE_DOMAINS

	add	r0, r0, #4

7:	ldrt	r2, [r0]

#else

7:	ldr	r2, [r0, #4]

#endif

	mov	r0, #0

	ret	lr

ENDPROC(__get_user_lo8)

#endif



__get_user_bad8:

	mov	r3, #0

__get_user_bad:

	mov	r2, #0

	mov	r0, #-EFAULT

	ret	lr

ENDPROC(__get_user_bad)

ENDPROC(__get_user_bad8)



.pushsection __ex_table, "a"

	.long	1b, __get_user_bad

	.long	2b, __get_user_bad

	.long	3b, __get_user_bad

	.long	4b, __get_user_bad

	.long	5b, __get_user_bad8

	.long	6b, __get_user_bad8

#ifdef __ARMEB__

	.long   7b, __get_user_bad

#endif

.popsection

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