m32r: use generic ptrace_resume code

Use the generic ptrace_resume code for PTRACE_SYSCALL, PTRACE_CONT,
PTRACE_KILL and PTRACE_SINGLESTEP.  This implies defining
arch_has_single_step in <asm/ptrace.h> and implementing the
user_enable_single_step and user_disable_single_step functions, which also
causes the breakpoint information to be cleared on fork, which could be
considered a bug fix.

Also the TIF_SYSCALL_TRACE thread flag is now cleared on PTRACE_KILL which
it previously wasn't, which is consistent with all architectures using the
modern ptrace code.

The old code only disables the breakpoints on PTRACE_KILL, while after
this patch this also happens for PTRACE_CONT and PTRACE_SYSCALL which
matches the behaviour of the other architetures.  I think this is a
bugfixes, but please double verify this is correct.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
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>

2 files changed, 31 insertions, 68 deletions

diff --git a/arch/m32r/include/asm/ptrace.h b/arch/m32r/include/asm/ptrace.h
index a0755b982028..840a1231edeb 100644
--- a/arch/m32r/include/asm/ptrace.h
+++ b/arch/m32r/include/asm/ptrace.h
@@ -120,6 +120,8 @@ struct pt_regs {
 
 #include <asm/m32r.h>           /* M32R_PSW_BSM, M32R_PSW_BPM */
 
+#define arch_has_single_step() (1)
+
 struct task_struct;
 extern void init_debug_traps(struct task_struct *);
 #define arch_ptrace_attach(child) \
diff --git a/arch/m32r/kernel/ptrace.c b/arch/m32r/kernel/ptrace.c
index 98682bba0ed9..e555091eb97c 100644
--- a/arch/m32r/kernel/ptrace.c
+++ b/arch/m32r/kernel/ptrace.c
@@ -580,6 +580,35 @@ init_debug_traps(struct task_struct *child)
         }
 }
 
+void user_enable_single_step(struct task_struct *child)
+{
+        unsigned long next_pc;
+        unsigned long pc, insn;
+
+        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+
+        /* Compute next pc.  */
+        pc = get_stack_long(child, PT_BPC);
+
+        if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
+            != sizeof(insn))
+                break;
+
+        compute_next_pc(insn, pc, &next_pc, child);
+        if (next_pc & 0x80000000)
+                break;
+
+        if (embed_debug_trap(child, next_pc))
+                break;
+
+        invalidate_cache();
+}
+
+void user_disable_single_step(struct task_struct *child)
+{
+        unregister_all_debug_traps(child);
+        invalidate_cache();
+}
 
 /*
  * Called by kernel/ptrace.c when detaching..
@@ -630,74 +659,6 @@ arch_ptrace(struct task_struct *child, long request, long addr, long data)
                 ret = ptrace_write_user(child, addr, data);
                 break;
 
-        /*
-         * continue/restart and stop at next (return from) syscall
-         */
-        case PTRACE_SYSCALL:
-        case PTRACE_CONT:
-                ret = -EIO;
-                if (!valid_signal(data))
-                        break;
-                if (request == PTRACE_SYSCALL)
-                        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-                else
-                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-                child->exit_code = data;
-                wake_up_process(child);
-                ret = 0;
-                break;
-
-        /*
-         * make the child exit.  Best I can do is send it a sigkill.
-         * perhaps it should be put in the status that it wants to
-         * exit.
-         */
-        case PTRACE_KILL: {
-                ret = 0;
-                unregister_all_debug_traps(child);
-                invalidate_cache();
-                if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
-                        break;
-                child->exit_code = SIGKILL;
-                wake_up_process(child);
-                break;
-        }
-
-        /*
-         * execute single instruction.
-         */
-        case PTRACE_SINGLESTEP: {
-                unsigned long next_pc;
-                unsigned long pc, insn;
-
-                ret = -EIO;
-                if (!valid_signal(data))
-                        break;
-                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-
-                /* Compute next pc.  */
-                pc = get_stack_long(child, PT_BPC);
-
-                if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
-                    != sizeof(insn))
-                        break;
-
-                compute_next_pc(insn, pc, &next_pc, child);
-                if (next_pc & 0x80000000)
-                        break;
-
-                if (embed_debug_trap(child, next_pc))
-                        break;
-
-                invalidate_cache();
-                child->exit_code = data;
-
-                /* give it a chance to run. */
-                wake_up_process(child);
-                ret = 0;
-                break;
-        }
-
         case PTRACE_GETREGS:
                 ret = ptrace_getregs(child, (void __user *)data);
                 break;