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SubjectRe: [PATCH 04/11] Define the virtual space of KASan's shadow region
Date
On 10/16/2017 07:03 PM, Abbott Liu wrote:
>arch/arm/kernel/entry-armv.S:348: Error: selected processor does not support `movw r1,
#:lower16:((((0xC0000000-0x01000000)>>3)+((0xC0000000-0x01000000)-(1<<29))))' in ARM mode
>arch/arm/kernel/entry-armv.S:348: Error: selected processor does not support `movt r1,
#:upper16:((((0xC0000000-0x01000000)>>3)+((0xC0000000-0x01000000)-(1<<29))))' in ARM mode

Thanks for building test. This error can be solved by following code:
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -188,8 +188,7 @@ ENDPROC(__und_invalid)
get_thread_info tsk
ldr r0, [tsk, #TI_ADDR_LIMIT]
#ifdef CONFIG_KASAN
- movw r1, #:lower16:TASK_SIZE
- movt r1, #:upper16:TASK_SIZE
+ ldr r1, =TASK_SIZE
#else
mov r1, #TASK_SIZE
#endif
@@ -446,7 +445,12 @@ ENDPROC(__fiq_abt)
@ if it was interrupted in a critical region. Here we
@ perform a quick test inline since it should be false
@ 99.9999% of the time. The rest is done out of line.
+#if CONFIG_KASAN
+ ldr r0, =TASK_SIZE
+ cmp r4, r0
+#else
cmp r4, #TASK_SIZE
+#endif
blhs kuser_cmpxchg64_fixup
#endif
#endif

movt,movw can only be used in ARMv6*, ARMv7 instruction set. But ldr can be used in ARMv4*, ARMv5T*, ARMv6*, ARMv7.
Maybe the performance is going to fall down by using ldr, but I think the influence of performance is very limited.

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