Introduce side ptrace hook

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/src/side.c b/src/side.c
index 43d342e26c1e54683502837b3726e5ffe5226ea2..ca48d2cfb5b7cf349a35dead705b952be6c8a716 100644 (file)
--- a/src/side.c
+++ b/src/side.c
@@ -11,21 +11,28 @@
 #include "list.h"
 #include "rculist.h"
 
-/* Top 8 bits reserved for kernel tracer use. */
+/* Top 8 bits reserved for shared tracer use. */
 #if SIDE_BITS_PER_LONG == 64
-# define SIDE_EVENT_ENABLED_KERNEL_MASK                        0xFF00000000000000ULL
-# define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK     0x8000000000000000ULL
+# define SIDE_EVENT_ENABLED_SHARED_MASK                        0xFF00000000000000ULL
+# define SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK     0x8000000000000000ULL
+# define SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK                 0x4000000000000000ULL
 
-/* Allow 2^56 tracer references on an event. */
-# define SIDE_EVENT_ENABLED_USER_MASK                  0x00FFFFFFFFFFFFFFULL
+/* Allow 2^56 private tracer references on an event. */
+# define SIDE_EVENT_ENABLED_PRIVATE_MASK               0x00FFFFFFFFFFFFFFULL
 #else
-# define SIDE_EVENT_ENABLED_KERNEL_MASK                        0xFF000000UL
-# define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK     0x80000000UL
+# define SIDE_EVENT_ENABLED_SHARED_MASK                        0xFF000000UL
+# define SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK     0x80000000UL
+# define SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK         0x40000000UL
 
-/* Allow 2^24 tracer references on an event. */
-# define SIDE_EVENT_ENABLED_USER_MASK                  0x00FFFFFFUL
+/* Allow 2^24 private tracer references on an event. */
+# define SIDE_EVENT_ENABLED_PRIVATE_MASK               0x00FFFFFFUL
 #endif
 
+/* Key 0x1 is reserved for user event. */
+#define SIDE_USER_EVENT_KEY                            ((void *)0x1UL)
+/* Key 0x2 is reserved for ptrace. */
+#define SIDE_PTRACE_KEY                                        ((void *)0x2UL)
+
 struct side_events_register_handle {
        struct side_list_node node;
        struct side_event_description **events;
@@ -90,6 +97,20 @@ static __thread void *filter_key;
  */
 const char side_empty_callback[sizeof(struct side_callback)];
 
+/*
+ * side_ptrace_hook is a place holder for a debugger breakpoint.
+ * var_struct is NULL if not variadic.
+ */
+void side_ptrace_hook(const struct side_event_state *event_state __attribute__((unused)),
+       const struct side_arg_vec *side_arg_vec __attribute__((unused)),
+       const struct side_arg_dynamic_struct *var_struct __attribute__((unused)))
+       __attribute__((noinline));
+void side_ptrace_hook(const struct side_event_state *event_state __attribute__((unused)),
+       const struct side_arg_vec *side_arg_vec __attribute__((unused)),
+       const struct side_arg_dynamic_struct *var_struct __attribute__((unused)))
+{
+}
+
 static
 void _side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec, void *key)
 {
@@ -107,8 +128,14 @@ void _side_call(const struct side_event_state *event_state, const struct side_ar
        es0 = side_container_of(event_state, const struct side_event_state_0, parent);
        assert(!(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC));
        enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
-       if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
-               // TODO: call kernel write.
+       if (side_unlikely(enabled & SIDE_EVENT_ENABLED_SHARED_MASK)) {
+               if ((enabled & SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK) &&
+                   (!key || key == SIDE_USER_EVENT_KEY)) {
+                       // TODO: call kernel write.
+               }
+               if ((enabled & SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK) &&
+                   (!key || key == SIDE_PTRACE_KEY))
+                       side_ptrace_hook(event_state, side_arg_vec, NULL);
        }
        side_rcu_read_begin(&event_rcu_gp, &rcu_read_state);
        for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call != NULL; side_cb++) {
@@ -150,8 +177,14 @@ void _side_call_variadic(const struct side_event_state *event_state,
        es0 = side_container_of(event_state, const struct side_event_state_0, parent);
        assert(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC);
        enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
-       if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
-               // TODO: call kernel write.
+       if (side_unlikely(enabled & SIDE_EVENT_ENABLED_SHARED_MASK)) {
+               if ((enabled & SIDE_EVENT_ENABLED_SHARED_USER_EVENT_MASK) &&
+                   (!key || key == SIDE_USER_EVENT_KEY)) {
+                       // TODO: call kernel write.
+               }
+               if ((enabled & SIDE_EVENT_ENABLED_SHARED_PTRACE_MASK) &&
+                   (!key || key == SIDE_PTRACE_KEY))
+                       side_ptrace_hook(event_state, side_arg_vec, var_struct);
        }
        side_rcu_read_begin(&event_rcu_gp, &rcu_read_state);
        for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call_variadic != NULL; side_cb++) {