alpha: convert to generic sys_ptrace

This patch converts alpha to the generic sys_ptrace.  We use
force_successful_syscall_return to avoid having to pass the pt_regs pointer
down to the function.  I think the removal of the assemly stub is correct,
but I could only compile-test this patch, so please give it a spin before
commiting :)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/alpha/kernel/entry.S

@@ -916,15 +916,6 @@ sys_pipe:
 	ret
 .end sys_pipe
 
-	.align	4
-	.globl	sys_ptrace
-	.ent	sys_ptrace
-sys_ptrace:
-	.prologue 0
-	mov	$sp, $20
-	jmp	$31, do_sys_ptrace
-.end sys_ptrace
-
 	.align	4
 	.globl	sys_execve
 	.ent	sys_execve

arch/alpha/kernel/ptrace.c

@@ -260,38 +260,12 @@ void ptrace_disable(struct task_struct *child)
 	ptrace_cancel_bpt(child);
 }
 
-asmlinkage long
-do_sys_ptrace(long request, long pid, long addr, long data,
-	      struct pt_regs *regs)
+long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 {
-	struct task_struct *child;
 	unsigned long tmp;
 	size_t copied;
 	long ret;
 
-	lock_kernel();
-	DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",
-		      request, pid, addr, data));
-	if (request == PTRACE_TRACEME) {
-		ret = ptrace_traceme();
-		goto out_notsk;
-	}
-
-	child = ptrace_get_task_struct(pid);
-	if (IS_ERR(child)) {
-		ret = PTR_ERR(child);
-		goto out_notsk;
-	}
-
-	if (request == PTRACE_ATTACH) {
-		ret = ptrace_attach(child);
-		goto out;
-	}
-
-	ret = ptrace_check_attach(child, request == PTRACE_KILL);
-	if (ret < 0)
-		goto out;
-
 	switch (request) {
 	/* When I and D space are separate, these will need to be fixed.  */
 	case PTRACE_PEEKTEXT: /* read word at location addr. */
@@ -301,13 +275,13 @@ do_sys_ptrace(long request, long pid, long addr, long data,
 		if (copied != sizeof(tmp))
 			break;
 		
-		regs->r0 = 0;	/* special return: no errors */
+		force_successful_syscall_return();
 		ret = tmp;
 		break;
 
 	/* Read register number ADDR. */
 	case PTRACE_PEEKUSR:
-		regs->r0 = 0;	/* special return: no errors */
+		force_successful_syscall_return();
 		ret = get_reg(child, addr);
 		DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret));
 		break;
@@ -353,7 +327,7 @@ do_sys_ptrace(long request, long pid, long addr, long data,
 		/* make sure single-step breakpoint is gone. */
 		ptrace_cancel_bpt(child);
 		wake_up_process(child);
-		goto out;
+		break;
 
 	case PTRACE_SINGLESTEP:  /* execute single instruction. */
 		ret = -EIO;
@@ -366,16 +340,12 @@ do_sys_ptrace(long request, long pid, long addr, long data,
 		wake_up_process(child);
 		/* give it a chance to run. */
 		ret = 0;
-		goto out;
+		break;
 
 	default:
 		ret = ptrace_request(child, request, addr, data);
-		goto out;
+		break;
 	}
- out:
-	put_task_struct(child);
- out_notsk:
-	unlock_kernel();
 	return ret;
 }
 

include/asm-alpha/ptrace.h

@@ -68,8 +68,6 @@ struct switch_stack {
 
 #ifdef __KERNEL__
 
-#define __ARCH_SYS_PTRACE	1
-
 #define user_mode(regs) (((regs)->ps & 8) != 0)
 #define instruction_pointer(regs) ((regs)->pc)
 #define profile_pc(regs) instruction_pointer(regs)