@@ -315,6 +315,13 @@ do { \
#define __get_user_asm_byte(x, addr, err) \
__get_user_asm(x, addr, err, ldrb)
+#if __LINUX_ARM_ARCH__ >= 6
+
+#define __get_user_asm_half(x, addr, err) \
+ __get_user_asm(x, addr, err, ldrh)
+
+#else
+
#ifndef __ARMEB__
#define __get_user_asm_half(x, __gu_addr, err) \
({ \
@@ -333,6 +340,8 @@ do { \
})
#endif
+#endif /* __LINUX_ARM_ARCH__ >= 6 */
+
#define __get_user_asm_word(x, addr, err) \
__get_user_asm(x, addr, err, ldr)
#endif
@@ -406,6 +415,13 @@ do { \
#define __put_user_asm_byte(x, __pu_addr, err) \
__put_user_asm(x, __pu_addr, err, strb)
+#if __LINUX_ARM_ARCH__ >= 6
+
+#define __put_user_asm_half(x, __pu_addr, err) \
+ __put_user_asm(x, __pu_addr, err, strh)
+
+#else
+
#ifndef __ARMEB__
#define __put_user_asm_half(x, __pu_addr, err) \
({ \
@@ -422,6 +438,8 @@ do { \
})
#endif
+#endif /* __LINUX_ARM_ARCH__ >= 6 */
+
#define __put_user_asm_word(x, __pu_addr, err) \
__put_user_asm(x, __pu_addr, err, str)
@@ -42,6 +42,12 @@ _ASM_NOKPROBE(__get_user_1)
ENTRY(__get_user_2)
check_uaccess r0, 2, r1, r2, __get_user_bad
+#if __LINUX_ARM_ARCH__ >= 6
+
+2: TUSER(ldrh) r2, [r0]
+
+#else
+
#ifdef CONFIG_CPU_USE_DOMAINS
rb .req ip
2: ldrbt r2, [r0], #1
@@ -56,6 +62,9 @@ rb .req r0
#else
orr r2, rb, r2, lsl #8
#endif
+
+#endif /* __LINUX_ARM_ARCH__ >= 6 */
+
mov r0, #0
ret lr
ENDPROC(__get_user_2)
@@ -145,7 +154,9 @@ _ASM_NOKPROBE(__get_user_bad8)
.pushsection __ex_table, "a"
.long 1b, __get_user_bad
.long 2b, __get_user_bad
+#if __LINUX_ARM_ARCH__ < 6
.long 3b, __get_user_bad
+#endif
.long 4b, __get_user_bad
.long 5b, __get_user_bad8
.long 6b, __get_user_bad8
@@ -41,16 +41,13 @@ ENDPROC(__put_user_1)
ENTRY(__put_user_2)
check_uaccess r0, 2, r1, ip, __put_user_bad
- mov ip, r2, lsr #8
-#ifdef CONFIG_THUMB2_KERNEL
-#ifndef __ARMEB__
-2: TUSER(strb) r2, [r0]
-3: TUSER(strb) ip, [r0, #1]
+#if __LINUX_ARM_ARCH__ >= 6
+
+2: TUSER(strh) r2, [r0]
+
#else
-2: TUSER(strb) ip, [r0]
-3: TUSER(strb) r2, [r0, #1]
-#endif
-#else /* !CONFIG_THUMB2_KERNEL */
+
+ mov ip, r2, lsr #8
#ifndef __ARMEB__
2: TUSER(strb) r2, [r0], #1
3: TUSER(strb) ip, [r0]
@@ -58,7 +55,8 @@ ENTRY(__put_user_2)
2: TUSER(strb) ip, [r0], #1
3: TUSER(strb) r2, [r0]
#endif
-#endif /* CONFIG_THUMB2_KERNEL */
+
+#endif /* __LINUX_ARM_ARCH__ >= 6 */
mov r0, #0
ret lr
ENDPROC(__put_user_2)
@@ -91,7 +89,9 @@ ENDPROC(__put_user_bad)
.pushsection __ex_table, "a"
.long 1b, __put_user_bad
.long 2b, __put_user_bad
+#if __LINUX_ARM_ARCH__ < 6
.long 3b, __put_user_bad
+#endif
.long 4b, __put_user_bad
.long 5b, __put_user_bad
.long 6b, __put_user_bad
getuser() and putuser() (and there underscored variants) use two strb[t]/ldrb[t] instructions when they are asked to get/put 16-bits. This means that the read/write is not atomic even when performed to a 16-bit-aligned address. This leads to problems with vhost: vhost uses __getuser() to read the vring's 16-bit avail.index field, and if it happens to observe a partial update of the index, wrong descriptors will be used which will lead to a breakdown of the virtio communication. A similar problem exists for __putuser() which is used to write to the vring's used.index field. The reason these functions use strb[t]/ldrb[t] is because strht/ldrht instructions did not exist until ARMv6T2/ARMv7. So we should be easily able to fix this on ARMv7. Also, since all ARMv6 processors also don't actually use the unprivileged instructions anymore for uaccess (since CONFIG_CPU_USE_DOMAINS is not used) we can easily fix them too. Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> --- arch/arm/include/asm/uaccess.h | 18 ++++++++++++++++++ arch/arm/lib/getuser.S | 11 +++++++++++ arch/arm/lib/putuser.S | 20 ++++++++++---------- 3 files changed, 39 insertions(+), 10 deletions(-)