On Thu, 15 Nov 2012, Rob Clark wrote:

From: Rob Clark rob@ti.com

A new atomic modeset/pageflip ioctl being developed in DRM requires get_user() to work for 64bit types (in addition to just put_user()).

v1: original v2: pass correct size to check_uaccess, and better handling of narrowing double word read with __get_user_xb() (Russell King's suggestion) v3: explain in comment about why this works for narrowing fetch to 1, 2, or 4 byte type on ARM.

Signed-off-by: Rob Clark rob@ti.com

Acked-by: Nicolas Pitre nico@linaro.org

---

arch/arm/include/asm/uaccess.h | 22 +++++++++++++++++++++- arch/arm/lib/getuser.S | 17 ++++++++++++++++- 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 7e1f760..4cfa793 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -100,6 +100,7 @@ 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_8(void *);

#define __GUP_CLOBBER_1 "lr", "cc" #ifdef CONFIG_CPU_USE_DOMAINS @@ -108,6 +109,7 @@ extern int __get_user_4(void *); #define __GUP_CLOBBER_2 "lr", "cc" #endif #define __GUP_CLOBBER_4 "lr", "cc" +#define __GUP_CLOBBER_8 "lr", "cc"

#define __get_user_x(__r2,__p,__e,__l,__s) \ __asm__ __volatile__ ( \ @@ -118,11 +120,23 @@ extern int __get_user_4(void *); : "0" (__p), "r" (__l) \ : __GUP_CLOBBER_##__s)

+/*

• • Narrowing a double-word get into a single 32bit word register, which works
• • for 1, 2, or 4 byte types on ARM because there are no integer registers
• • smaller than 32bit
• */

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

• __get_user_x(__r2,(uintptr_t)__p + 4,__e,__l,__s)

+#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))) { \

@@ -135,6 +149,12 @@ 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; \

diff --git a/arch/arm/lib/getuser.S b/arch/arm/lib/getuser.S index 9b06bb4..ed98707 100644 --- a/arch/arm/lib/getuser.S +++ b/arch/arm/lib/getuser.S @@ -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>

@@ -66,6 +66,19 @@ ENTRY(__get_user_4) mov pc, 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
• mov pc, lr

+ENDPROC(__get_user_8)

__get_user_bad: mov r2, #0 mov r0, #-EFAULT @@ -77,4 +90,6 @@ ENDPROC(__get_user_bad) .long 2b, __get_user_bad .long 3b, __get_user_bad .long 4b, __get_user_bad

• .long 5b, __get_user_bad
• .long 6b, __get_user_bad

.popsection

1.8.0

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