2 files changed, 28 insertions, 2 deletions

diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 67ad3f152329..ad754d1e0b13 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -48,6 +48,7 @@
 #define PTRACE_SETREGSET        0x4205
 
 #define PTRACE_SEIZE            0x4206
+#define PTRACE_INTERRUPT        0x4207
 
 /* flags in @data for PTRACE_SEIZE */
 #define PTRACE_SEIZE_DEVEL      0x80000000 /* temp flag for development */
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index dcf9f974198c..6852c0f4a916 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -658,10 +658,12 @@ static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 int ptrace_request(struct task_struct *child, long request,
                    unsigned long addr, unsigned long data)
 {
+        bool seized = child->ptrace & PT_SEIZED;
         int ret = -EIO;
         siginfo_t siginfo;
         void __user *datavp = (void __user *) data;
         unsigned long __user *datalp = datavp;
+        unsigned long flags;
 
         switch (request) {
         case PTRACE_PEEKTEXT:
@@ -694,6 +696,27 @@ int ptrace_request(struct task_struct *child, long request,
                         ret = ptrace_setsiginfo(child, &siginfo);
                 break;
 
+        case PTRACE_INTERRUPT:
+                /*
+                 * Stop tracee without any side-effect on signal or job
+                 * control.  At least one trap is guaranteed to happen
+                 * after this request.  If @child is already trapped, the
+                 * current trap is not disturbed and another trap will
+                 * happen after the current trap is ended with PTRACE_CONT.
+                 *
+                 * The actual trap might not be PTRACE_EVENT_STOP trap but
+                 * the pending condition is cleared regardless.
+                 */
+                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
+                        break;
+
+                if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
+                        signal_wake_up(child, 0);
+
+                unlock_task_sighand(child, &flags);
+                ret = 0;
+                break;
+
         case PTRACE_DETACH:      /* detach a process that was attached. */
                 ret = ptrace_detach(child, data);
                 break;
@@ -819,7 +842,8 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
                 goto out_put_task_struct;
         }
 
-        ret = ptrace_check_attach(child, request == PTRACE_KILL);
+        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
+                                  request == PTRACE_INTERRUPT);
         if (ret < 0)
                 goto out_put_task_struct;
 
@@ -961,7 +985,8 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
                 goto out_put_task_struct;
         }
 
-        ret = ptrace_check_attach(child, request == PTRACE_KILL);
+        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
+                                  request == PTRACE_INTERRUPT);
         if (!ret)
                 ret = compat_arch_ptrace(child, request, addr, data);