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: Petr Tesarik <ptesarik@xxxxxxx>
---
ptrace.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 59 insertions(+)
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index d8c9864..76cc4d4 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -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.
+ */
+static 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)
{
@@ -1520,6 +1577,8 @@ sys_ptrace (long request, pid_t pid, uns
if (request == PTRACE_ATTACH) {
ret = ptrace_attach(child);
+ if (ret == 0)
+ ptrace_attach_sync_user_rbs(child);
goto out_tsk;
}
-
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