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Commit aa91a2e9 authored by Petr Tesarik's avatar Petr Tesarik Committed by Tony Luck
Browse files

[IA64] Synchronize RBS on PTRACE_ATTACH 



When attaching to a stopped process, the RSE must be explicitly
synced to user-space, so the debugger can read the correct values.

Signed-off-by: default avatarPetr Tesarik <ptesarik@suse.cz>
CC: Roland McGrath <roland@redhat.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 3b2ce0b1

arch/ia64/kernel/ptrace.c

+57 −0
Original line number Diff line number Diff line
@@ -613,6 +613,63 @@ void ia64_sync_krbs(void) 
	unw_init_running(do_sync_rbs, ia64_sync_kernel_rbs);

}



/*

 * After PTRACE_ATTACH, a thread's register backing store area in user

 * space is assumed to contain correct data whenever the thread is

 * stopped.  arch_ptrace_stop takes care of this on tracing stops.

 * But if the child was already stopped for job control when we attach

 * to it, then it might not ever get into ptrace_stop by the time we

 * want to examine the user memory containing the RBS.

 */

void

ptrace_attach_sync_user_rbs (struct task_struct *child)

{

	int stopped = 0;

	struct unw_frame_info info;



	/*

	 * If the child is in TASK_STOPPED, we need to change that to

	 * TASK_TRACED momentarily while we operate on it.  This ensures

	 * that the child won't be woken up and return to user mode while

	 * we are doing the sync.  (It can only be woken up for SIGKILL.)

	 */



	read_lock(&tasklist_lock);

	if (child->signal) {

		spin_lock_irq(&child->sighand->siglock);

		if (child->state == TASK_STOPPED &&

		    !test_and_set_tsk_thread_flag(child, TIF_RESTORE_RSE)) {

			tsk_set_notify_resume(child);



			child->state = TASK_TRACED;

			stopped = 1;

		}

		spin_unlock_irq(&child->sighand->siglock);

	}

	read_unlock(&tasklist_lock);



	if (!stopped)

		return;



	unw_init_from_blocked_task(&info, child);

	do_sync_rbs(&info, ia64_sync_user_rbs);



	/*

	 * Now move the child back into TASK_STOPPED if it should be in a

	 * job control stop, so that SIGCONT can be used to wake it up.

	 */

	read_lock(&tasklist_lock);

	if (child->signal) {

		spin_lock_irq(&child->sighand->siglock);

		if (child->state == TASK_TRACED &&

		    (child->signal->flags & SIGNAL_STOP_STOPPED)) {

			child->state = TASK_STOPPED;

		}

		spin_unlock_irq(&child->sighand->siglock);

	}

	read_unlock(&tasklist_lock);

}



static inline int

thread_matches (struct task_struct *thread, unsigned long addr)

{

include/asm-ia64/ptrace.h

+4 −0
Original line number Diff line number Diff line
@@ -310,6 +310,10 @@ struct switch_stack { 
  #define arch_ptrace_stop_needed(code, info) \

	(!test_thread_flag(TIF_RESTORE_RSE))



  extern void ptrace_attach_sync_user_rbs (struct task_struct *);

  #define arch_ptrace_attach(child) \

	ptrace_attach_sync_user_rbs(child)



#endif /* !__KERNEL__ */



/* pt_all_user_regs is used for PTRACE_GETREGS PTRACE_SETREGS */