Re: [PATCH] arm: get rid of hardcoded assumptions about kernel stack size

From: Andrey Ryabinin
Date: Wed Jun 18 2014 - 11:32:28 EST


On 06/18/14 18:40, Nicolas Pitre wrote:
> On Wed, 18 Jun 2014, Andrey Ryabinin wrote:
>
>> Changing kernel stack size on arm is not as simple as it should be:
>> 1) THRED_SIZE macro doen't respect PAGE_SIZE and THREAD_SIZE_ORDER
>> 2) stack size is hardcoded in get_thread_info macro
>>
>> This patch fixes it by caculating THREAD_SIZE and thread_info address
>> taking into account PAGE_SIZE and THREAD_SIZE_ORDER.
>>
>> Now changing stack size becomes simply changing THREAD_SIZE_ORDER.
>>
>> Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
>
> Acked-by: Nicolas Pitre <nico@xxxxxxxxxx>
>
>

Thanks. Patch with fixes in commit message pushed to Russel's patch tracking system, #8078/1.
http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8078/1


>> ---
>> arch/arm/include/asm/assembler.h | 8 +++++---
>> arch/arm/include/asm/thread_info.h | 3 ++-
>> 2 files changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
>> index 57f0584..906703a 100644
>> --- a/arch/arm/include/asm/assembler.h
>> +++ b/arch/arm/include/asm/assembler.h
>> @@ -24,6 +24,8 @@
>> #include <asm/domain.h>
>> #include <asm/opcodes-virt.h>
>> #include <asm/asm-offsets.h>
>> +#include <asm/page.h>
>> +#include <asm/thread_info.h>
>>
>> #define IOMEM(x) (x)
>>
>> @@ -179,10 +181,10 @@
>> * Get current thread_info.
>> */
>> .macro get_thread_info, rd
>> - ARM( mov \rd, sp, lsr #13 )
>> + ARM( mov \rd, sp, lsr #THREAD_SIZE_ORDER + PAGE_SHIFT )
>> THUMB( mov \rd, sp )
>> - THUMB( lsr \rd, \rd, #13 )
>> - mov \rd, \rd, lsl #13
>> + THUMB( lsr \rd, \rd, #THREAD_SIZE_ORDER + PAGE_SHIFT )
>> + mov \rd, \rd, lsl #THREAD_SIZE_ORDER + PAGE_SHIFT
>> .endm
>>
>> /*
>> diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
>> index f989d7c..f85d2b0 100644
>> --- a/arch/arm/include/asm/thread_info.h
>> +++ b/arch/arm/include/asm/thread_info.h
>> @@ -14,9 +14,10 @@
>>
>> #include <linux/compiler.h>
>> #include <asm/fpstate.h>
>> +#include <asm/page.h>
>>
>> #define THREAD_SIZE_ORDER 1
>> -#define THREAD_SIZE 8192
>> +#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
>> #define THREAD_START_SP (THREAD_SIZE - 8)
>>
>> #ifndef __ASSEMBLY__
>> --
>> 1.8.5.5
>>
>

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