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authorPetr Tesarik <ptesarik@suse.cz>2007-12-12 15:24:25 +0100
committerTony Luck <tony.luck@intel.com>2008-02-08 12:01:29 -0800
commitaa91a2e90044b88228bdb0620e771f2ea7798804 (patch)
tree935056068de330e73eaf39ba8284ae33ad6e145e /arch
parent[IA64] Synchronize kernel RSE to user-space and back (diff)
downloadlinux-dev-aa91a2e90044b88228bdb0620e771f2ea7798804.tar.xz
linux-dev-aa91a2e90044b88228bdb0620e771f2ea7798804.zip
[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: Petr Tesarik <ptesarik@suse.cz> CC: Roland McGrath <roland@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/ia64/kernel/ptrace.c57
1 files changed, 57 insertions, 0 deletions
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 2de5a524a0ee..331d6768b5d5 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.
+ */
+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)
{