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ARM: 8137/1: fix get_user BE behavior for target variable with size o…
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…f 8 bytes

e38361d 'ARM: 8091/2: add get_user() support for 8 byte types' commit
broke V7 BE get_user call when target var size is 64 bit, but '*ptr' size
is 32 bit or smaller. e38361d changed type of __r2 from 'register
unsigned long' to 'register typeof(x) __r2 asm("r2")' i.e before the change
even when target variable size was 64 bit, __r2 was still 32 bit.
But after e38361d commit, for target var of 64 bit size, __r2 became 64
bit and now it should occupy 2 registers r2, and r3. The issue in BE case
that r3 register is least significant word of __r2 and r2 register is most
significant word of __r2. But __get_user_4 still copies result into r2 (most
significant word of __r2). Subsequent code copies from __r2 into x, but
for situation described it will pick up only garbage from r3 register.

Special __get_user_64t_(124) functions are introduced. They are similar to
corresponding __get_user_(124) function but result stored in r3 register
(lsw in case of 64 bit __r2 in BE image). Those function are used by
get_user macro in case of BE and target var size is 64bit.

Also changed __get_user_lo8 name into __get_user_32t_8 to get consistent
naming accross all cases.

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Victor Kamensky authored and Russell King committed Sep 12, 2014
1 parent e918a62 commit d998138
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Showing 2 changed files with 75 additions and 11 deletions.
48 changes: 39 additions & 9 deletions arch/arm/include/asm/uaccess.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -107,8 +107,11 @@ 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_32t_8(void *);
extern int __get_user_8(void *);
extern int __get_user_64t_1(void *);
extern int __get_user_64t_2(void *);
extern int __get_user_64t_4(void *);

#define __GUP_CLOBBER_1 "lr", "cc"
#ifdef CONFIG_CPU_USE_DOMAINS
Expand All @@ -117,7 +120,7 @@ extern int __get_user_8(void *);
#define __GUP_CLOBBER_2 "lr", "cc"
#endif
#define __GUP_CLOBBER_4 "lr", "cc"
#define __GUP_CLOBBER_lo8 "lr", "cc"
#define __GUP_CLOBBER_32t_8 "lr", "cc"
#define __GUP_CLOBBER_8 "lr", "cc"

#define __get_user_x(__r2,__p,__e,__l,__s) \
Expand All @@ -131,12 +134,30 @@ extern int __get_user_8(void *);

/* 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)
#define __get_user_x_32t(__r2, __p, __e, __l, __s) \
__get_user_x(__r2, __p, __e, __l, 32t_8)
#else
#define __get_user_xb __get_user_x
#define __get_user_x_32t __get_user_x
#endif

/*
* storing result into proper least significant word of 64bit target var,
* different only for big endian case where 64 bit __r2 lsw is r3:
*/
#ifdef __ARMEB__
#define __get_user_x_64t(__r2, __p, __e, __l, __s) \
__asm__ __volatile__ ( \
__asmeq("%0", "r0") __asmeq("%1", "r2") \
__asmeq("%3", "r1") \
"bl __get_user_64t_" #__s \
: "=&r" (__e), "=r" (__r2) \
: "0" (__p), "r" (__l) \
: __GUP_CLOBBER_##__s)
#else
#define __get_user_x_64t __get_user_x
#endif


#define __get_user_check(x,p) \
({ \
unsigned long __limit = current_thread_info()->addr_limit - 1; \
Expand All @@ -146,17 +167,26 @@ extern int __get_user_8(void *);
register int __e asm("r0"); \
switch (sizeof(*(__p))) { \
case 1: \
__get_user_x(__r2, __p, __e, __l, 1); \
if (sizeof((x)) >= 8) \
__get_user_x_64t(__r2, __p, __e, __l, 1); \
else \
__get_user_x(__r2, __p, __e, __l, 1); \
break; \
case 2: \
__get_user_x(__r2, __p, __e, __l, 2); \
if (sizeof((x)) >= 8) \
__get_user_x_64t(__r2, __p, __e, __l, 2); \
else \
__get_user_x(__r2, __p, __e, __l, 2); \
break; \
case 4: \
__get_user_x(__r2, __p, __e, __l, 4); \
if (sizeof((x)) >= 8) \
__get_user_x_64t(__r2, __p, __e, __l, 4); \
else \
__get_user_x(__r2, __p, __e, __l, 4); \
break; \
case 8: \
if (sizeof((x)) < 8) \
__get_user_xb(__r2, __p, __e, __l, 4); \
__get_user_x_32t(__r2, __p, __e, __l, 4); \
else \
__get_user_x(__r2, __p, __e, __l, 8); \
break; \
Expand Down
38 changes: 36 additions & 2 deletions arch/arm/lib/getuser.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,7 @@ ENTRY(__get_user_8)
ENDPROC(__get_user_8)

#ifdef __ARMEB__
ENTRY(__get_user_lo8)
ENTRY(__get_user_32t_8)
check_uaccess r0, 8, r1, r2, __get_user_bad
#ifdef CONFIG_CPU_USE_DOMAINS
add r0, r0, #4
Expand All @@ -90,7 +90,37 @@ ENTRY(__get_user_lo8)
#endif
mov r0, #0
ret lr
ENDPROC(__get_user_lo8)
ENDPROC(__get_user_32t_8)

ENTRY(__get_user_64t_1)
check_uaccess r0, 1, r1, r2, __get_user_bad8
8: TUSER(ldrb) r3, [r0]
mov r0, #0
ret lr
ENDPROC(__get_user_64t_1)

ENTRY(__get_user_64t_2)
check_uaccess r0, 2, r1, r2, __get_user_bad8
#ifdef CONFIG_CPU_USE_DOMAINS
rb .req ip
9: ldrbt r3, [r0], #1
10: ldrbt rb, [r0], #0
#else
rb .req r0
9: ldrb r3, [r0]
10: ldrb rb, [r0, #1]
#endif
orr r3, rb, r3, lsl #8
mov r0, #0
ret lr
ENDPROC(__get_user_64t_2)

ENTRY(__get_user_64t_4)
check_uaccess r0, 4, r1, r2, __get_user_bad8
11: TUSER(ldr) r3, [r0]
mov r0, #0
ret lr
ENDPROC(__get_user_64t_4)
#endif

__get_user_bad8:
Expand All @@ -111,5 +141,9 @@ ENDPROC(__get_user_bad8)
.long 6b, __get_user_bad8
#ifdef __ARMEB__
.long 7b, __get_user_bad
.long 8b, __get_user_bad8
.long 9b, __get_user_bad8
.long 10b, __get_user_bad8
.long 11b, __get_user_bad8
#endif
.popsection

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