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-rw-r--r--arch/ia64/kernel/ptrace.c139
1 files changed, 139 insertions, 0 deletions
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 2e96f17..331d676 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -547,6 +547,129 @@ ia64_sync_user_rbs (struct task_struct *child, struct switch_stack *sw,
return 0;
}
+static long
+ia64_sync_kernel_rbs (struct task_struct *child, struct switch_stack *sw,
+ unsigned long user_rbs_start, unsigned long user_rbs_end)
+{
+ unsigned long addr, val;
+ long ret;
+
+ /* now copy word for word from user rbs to kernel rbs: */
+ for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) {
+ if (access_process_vm(child, addr, &val, sizeof(val), 0)
+ != sizeof(val))
+ return -EIO;
+
+ ret = ia64_poke(child, sw, user_rbs_end, addr, val);
+ if (ret < 0)
+ return ret;
+ }
+ return 0;
+}
+
+typedef long (*syncfunc_t)(struct task_struct *, struct switch_stack *,
+ unsigned long, unsigned long);
+
+static void do_sync_rbs(struct unw_frame_info *info, void *arg)
+{
+ struct pt_regs *pt;
+ unsigned long urbs_end;
+ syncfunc_t fn = arg;
+
+ if (unw_unwind_to_user(info) < 0)
+ return;
+ pt = task_pt_regs(info->task);
+ urbs_end = ia64_get_user_rbs_end(info->task, pt, NULL);
+
+ fn(info->task, info->sw, pt->ar_bspstore, urbs_end);
+}
+
+/*
+ * when a thread is stopped (ptraced), debugger might change thread's user
+ * stack (change memory directly), and we must avoid the RSE stored in kernel
+ * to override user stack (user space's RSE is newer than kernel's in the
+ * case). To workaround the issue, we copy kernel RSE to user RSE before the
+ * task is stopped, so user RSE has updated data. we then copy user RSE to
+ * kernel after the task is resummed from traced stop and kernel will use the
+ * newer RSE to return to user. TIF_RESTORE_RSE is the flag to indicate we need
+ * synchronize user RSE to kernel.
+ */
+void ia64_ptrace_stop(void)
+{
+ if (test_and_set_tsk_thread_flag(current, TIF_RESTORE_RSE))
+ return;
+ tsk_set_notify_resume(current);
+ unw_init_running(do_sync_rbs, ia64_sync_user_rbs);
+}
+
+/*
+ * This is called to read back the register backing store.
+ */
+void ia64_sync_krbs(void)
+{
+ clear_tsk_thread_flag(current, TIF_RESTORE_RSE);
+ tsk_clear_notify_resume(current);
+
+ 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)
{
@@ -1422,6 +1545,7 @@ sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data)
struct task_struct *child;
struct switch_stack *sw;
long ret;
+ struct unw_frame_info info;
lock_kernel();
ret = -EPERM;
@@ -1453,6 +1577,8 @@ sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data)
if (request == PTRACE_ATTACH) {
ret = ptrace_attach(child);
+ if (!ret)
+ arch_ptrace_attach(child);
goto out_tsk;
}
@@ -1481,6 +1607,11 @@ sys_ptrace (long request, pid_t pid, unsigned long addr, unsigned long data)
/* write the word at location addr */
urbs_end = ia64_get_user_rbs_end(child, pt, NULL);
ret = ia64_poke(child, sw, urbs_end, addr, data);
+
+ /* Make sure user RBS has the latest data */
+ unw_init_from_blocked_task(&info, child);
+ do_sync_rbs(&info, ia64_sync_user_rbs);
+
goto out_tsk;
case PTRACE_PEEKUSR:
@@ -1634,6 +1765,10 @@ syscall_trace_enter (long arg0, long arg1, long arg2, long arg3,
&& (current->ptrace & PT_PTRACED))
syscall_trace();
+ /* copy user rbs to kernel rbs */
+ if (test_thread_flag(TIF_RESTORE_RSE))
+ ia64_sync_krbs();
+
if (unlikely(current->audit_context)) {
long syscall;
int arch;
@@ -1671,4 +1806,8 @@ syscall_trace_leave (long arg0, long arg1, long arg2, long arg3,
|| test_thread_flag(TIF_SINGLESTEP))
&& (current->ptrace & PT_PTRACED))
syscall_trace();
+
+ /* copy user rbs to kernel rbs */
+ if (test_thread_flag(TIF_RESTORE_RSE))
+ ia64_sync_krbs();
}
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