[PATCH 04/11] Define the virtual space of KASan's shadow region
From: linux@armlinux.org.uk (Russell King - ARM Linux)
Date: 2017-10-19 12:41:19
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linux-mm, lkml
On Mon, Oct 16, 2017 at 11:42:05AM +0000, Liuwenliang (Lamb) wrote:
quoted hunk ↗ jump to hunk
On 10/16/2017 07:03 PM, Abbott Liu wrote:quoted
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 modequoted
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
We can surely do better than this with macros and condition support - we can build-time test in the assembler whether TASK_SIZE can fit in a normal "mov", whether we can use the movw/movt instructions, or fall back to ldr if necessary. I'd rather we avoided "ldr" here where possible.
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@@ -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
Same sort of thing goes for here - we can select the instruction at runtime using the assembler's macros and condition support. We know that TASK_SIZE is going to be one of a limited set of values. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up According to speedtest.net: 8.21Mbps down 510kbps up