[PATCH] arm: task_pt_regs()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/arm/kernel/process.c

@@ -355,10 +355,9 @@ int
 copy_thread(int nr, unsigned long clone_flags, unsigned long stack_start,
 	    unsigned long stk_sz, struct task_struct *p, struct pt_regs *regs)
 {
-	struct thread_info *thread = p->thread_info;
-	struct pt_regs *childregs;
+	struct thread_info *thread = task_thread_info(p);
+	struct pt_regs *childregs = task_pt_regs(p);
 
-	childregs = (void *)thread + THREAD_START_SP - sizeof(*regs);
 	*childregs = *regs;
 	childregs->ARM_r0 = 0;
 	childregs->ARM_sp = stack_start;

arch/arm/kernel/ptrace.c

@@ -54,23 +54,6 @@
 #define BREAKINST_THUMB	0xde01
 #endif
 
-/*
- * Get the address of the live pt_regs for the specified task.
- * These are saved onto the top kernel stack when the process
- * is not running.
- *
- * Note: if a user thread is execve'd from kernel space, the
- * kernel stack will not be empty on entry to the kernel, so
- * ptracing these tasks will fail.
- */
-static inline struct pt_regs *
-get_user_regs(struct task_struct *task)
-{
-	return (struct pt_regs *)
-		((unsigned long)task->thread_info + THREAD_SIZE -
-				 8 - sizeof(struct pt_regs));
-}
-
 /*
  * this routine will get a word off of the processes privileged stack.
  * the offset is how far from the base addr as stored in the THREAD.
@@ -79,7 +62,7 @@ get_user_regs(struct task_struct *task)
  */
 static inline long get_user_reg(struct task_struct *task, int offset)
 {
-	return get_user_regs(task)->uregs[offset];
+	return task_pt_regs(task)->uregs[offset];
 }
 
 /*
@@ -91,7 +74,7 @@ static inline long get_user_reg(struct task_struct *task, int offset)
 static inline int
 put_user_reg(struct task_struct *task, int offset, long data)
 {
-	struct pt_regs newregs, *regs = get_user_regs(task);
+	struct pt_regs newregs, *regs = task_pt_regs(task);
 	int ret = -EINVAL;
 
 	newregs = *regs;
@@ -421,7 +404,7 @@ void ptrace_set_bpt(struct task_struct *child)
 	u32 insn;
 	int res;
 
-	regs = get_user_regs(child);
+	regs = task_pt_regs(child);
 	pc = instruction_pointer(regs);
 
 	if (thumb_mode(regs)) {
@@ -572,7 +555,7 @@ static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
  */
 static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
 {
-	struct pt_regs *regs = get_user_regs(tsk);
+	struct pt_regs *regs = task_pt_regs(tsk);
 
 	return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
 }
@@ -587,7 +570,7 @@ static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
 
 	ret = -EFAULT;
 	if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
-		struct pt_regs *regs = get_user_regs(tsk);
+		struct pt_regs *regs = task_pt_regs(tsk);
 
 		ret = -EINVAL;
 		if (valid_user_regs(&newregs)) {

include/asm-arm/processor.h

@@ -85,9 +85,11 @@ unsigned long get_wchan(struct task_struct *p);
  */
 extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
-#define KSTK_REGS(tsk)	(((struct pt_regs *)(THREAD_START_SP + (unsigned long)(tsk)->thread_info)) - 1)
-#define KSTK_EIP(tsk)	KSTK_REGS(tsk)->ARM_pc
-#define KSTK_ESP(tsk)	KSTK_REGS(tsk)->ARM_sp
+#define task_pt_regs(p) \
+	((struct pt_regs *)(THREAD_START_SP + (void *)(p)->thread_info) - 1)
+
+#define KSTK_EIP(tsk)	task_pt_regs(tsk)->ARM_pc
+#define KSTK_ESP(tsk)	task_pt_regs(tsk)->ARM_sp
 
 /*
  * Prefetching support - only ARMv5.