m32r: convert to generic sys_ptrace

Convert m32r to the generic sys_ptrace.  The conversion requires an
architecture hook after ptrace_attach which this patch adds.  The hook
will also be needed for a conersion of ia64 to the generic ptrace code.

Thanks to Hirokazu Takata for fixing a bug in the first version of this
code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/m32r/kernel/ptrace.c

@@ -570,7 +570,7 @@ withdraw_debug_trap(struct pt_regs *regs)
 	}
 }
 
-static void
+void
 init_debug_traps(struct task_struct *child)
 {
 	struct debug_trap *p = &child->thread.debug_trap;
@@ -593,8 +593,8 @@ void ptrace_disable(struct task_struct *child)
 	/* nothing to do.. */
 }
 
-static int
-do_ptrace(long request, struct task_struct *child, long addr, long data)
+long
+arch_ptrace(struct task_struct *child, long request, long addr, long data)
 {
 	int ret;
 
@@ -720,42 +720,6 @@ do_ptrace(long request, struct task_struct *child, long addr, long data)
 	return ret;
 }
 
-asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
-{
-	struct task_struct *child;
-	int ret;
-
-	lock_kernel();
-	if (request == PTRACE_TRACEME) {
-		ret = ptrace_traceme();
-		goto out;
-	}
-
-	child = ptrace_get_task_struct(pid);
-	if (IS_ERR(child)) {
-		ret = PTR_ERR(child);
-		goto out;
-	}
-
-	if (request == PTRACE_ATTACH) {
-		ret = ptrace_attach(child);
-		if (ret == 0)
-			init_debug_traps(child);
-		goto out_tsk;
-	}
-
-	ret = ptrace_check_attach(child, request == PTRACE_KILL);
-	if (ret == 0)
-		ret = do_ptrace(request, child, addr, data);
-
-out_tsk:
-	put_task_struct(child);
-out:
-	unlock_kernel();
-
-	return ret;
-}
-
 /* notification of system call entry/exit
  * - triggered by current->work.syscall_trace
  */

include/asm-m32r/ptrace.h

@@ -120,7 +120,10 @@ struct pt_regs {
 
 #include <asm/m32r.h>		/* M32R_PSW_BSM, M32R_PSW_BPM */
 
-#define __ARCH_SYS_PTRACE	1
+struct task_struct;
+extern void init_debug_traps(struct task_struct *);
+#define arch_ptrace_attach(child) \
+	init_debug_traps(child)
 
 #if defined(CONFIG_ISA_M32R2) || defined(CONFIG_CHIP_VDEC2)
 #define user_mode(regs) ((M32R_PSW_BPM & (regs)->psw) != 0)

kernel/ptrace.c

@@ -453,6 +453,10 @@ struct task_struct *ptrace_get_task_struct(pid_t pid)
 	return child;
 }
 
+#ifndef arch_ptrace_attach
+#define arch_ptrace_attach(child)	do { } while (0)
+#endif
+
 #ifndef __ARCH_SYS_PTRACE
 asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
 {
@@ -476,6 +480,12 @@ asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
 
 	if (request == PTRACE_ATTACH) {
 		ret = ptrace_attach(child);
+		/*
+		 * Some architectures need to do book-keeping after
+		 * a ptrace attach.
+		 */
+		if (!ret)
+			arch_ptrace_attach(child);
 		goto out_put_task_struct;
 	}