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SubjectRe: [PATCH] arm: get rid of hardcoded assumptions about kernel stack size
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@samsung.com>

Acked-by: Nicolas Pitre <nico@linaro.org>


> ---
> 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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