ARM: 8078/1: get rid of hardcoded assumptions about kernel stack size

Changing kernel stack size on arm is not as simple as it should be:
1) THREAD_SIZE macro doesn't respect PAGE_SIZE and THREAD_SIZE_ORDER
2) stack size is hardcoded in get_thread_info macro

This patch fixes it by calculating 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>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 7 insertions, 4 deletions

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 57f0584e8d97..906703a5b564 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 e4e4208a9130..fc44d3761f9e 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__