From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
m68k has the thread_info structure embedded in its task struct. Therefore
its not possible to implement current_thread_info() by looking at the stack
pointer and do some simple calculations like most other architectures do it.
To return the thread_info pointer for a task two defines are used. This works
until the spinlock function bodies get moved into an own header file and
CONFIG_SPINLOCK_DEBUG is turned on. That results into this compile error:
In file included from include/linux/spinlock.h:378,
from include/linux/seqlock.h:29,
from include/linux/time.h:8,
from include/linux/timex.h:56,
from include/linux/sched.h:54,
from arch/m68k/kernel/asm-offsets.c:12:
include/linux/spinlock_api_smp.h: In function '__spin_unlock_irq':
include/linux/spinlock_api_smp.h:371: error: 'current' undeclared (first use in this function)
include/linux/spinlock_api_smp.h:371: error: (Each undeclared identifier is reported only once
include/linux/spinlock_api_smp.h:371: error: for each function it appears in.)
Including asm/current.h to asm-offsets.c wouldn't help since the definition
of struct task is needed. So we end up with ugly header file include
dependencies.
To solve this calculate the offset of the thread_info structure into the
task struct in asm-offsets.h and use the offset in task_thread_info().
This works just like it does for IA64 as well.
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
---
arch/m68k/include/asm/thread_info_mm.h | 11 ++++++++++-
arch/m68k/kernel/asm-offsets.c | 5 +++++
2 files changed, 15 insertions(+), 1 deletion(-)
Index: linux-2.6/arch/m68k/include/asm/thread_info_mm.h
===================================================================
--- linux-2.6.orig/arch/m68k/include/asm/thread_info_mm.h
+++ linux-2.6/arch/m68k/include/asm/thread_info_mm.h
@@ -1,6 +1,10 @@
#ifndef _ASM_M68K_THREAD_INFO_H
#define _ASM_M68K_THREAD_INFO_H
+#ifndef ASM_OFFSETS_C
+#include <asm/asm-offsets.h>
+#endif
+#include <asm/current.h>
#include <asm/types.h>
#include <asm/page.h>
@@ -31,7 +35,12 @@ struct thread_info {
#define init_thread_info (init_task.thread.info)
#define init_stack (init_thread_union.stack)
-#define task_thread_info(tsk) (&(tsk)->thread.info)
+#ifdef ASM_OFFSETS_C
+#define task_thread_info(tsk) ((struct thread_info *) NULL)
+#else
+#define task_thread_info(tsk) ((struct thread_info *)((char *)tsk+TASK_TINFO))
+#endif
+
#define task_stack_page(tsk) ((tsk)->stack)
#define current_thread_info() task_thread_info(current)
Index: linux-2.6/arch/m68k/kernel/asm-offsets.c
===================================================================
--- linux-2.6.orig/arch/m68k/kernel/asm-offsets.c
+++ linux-2.6/arch/m68k/kernel/asm-offsets.c
@@ -8,6 +8,8 @@
* #defines from the assembly-language output.
*/
+#define ASM_OFFSETS_C
+
#include <linux/stddef.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
@@ -27,6 +29,9 @@ int main(void)
DEFINE(TASK_INFO, offsetof(struct task_struct, thread.info));
DEFINE(TASK_MM, offsetof(struct task_struct, mm));
DEFINE(TASK_ACTIVE_MM, offsetof(struct task_struct, active_mm));
+#ifdef CONFIG_MMU
+ DEFINE(TASK_TINFO, offsetof(struct task_struct, thread.info));
+#endif
/* offsets into the thread struct */
DEFINE(THREAD_KSP, offsetof(struct thread_struct, ksp));
--
--
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