Implement detailed syscall event probe

[lttng-modules.git] / probes / lttng-kprobes.c

diff --git a/probes/lttng-kprobes.c b/probes/lttng-kprobes.c
index 9dd3569b4a794d59f5a7cbec2a060fb1d3cd9a6f..8e1ae832cd82abb14d0413a1aee5b13cb1cd9fc8 100644 (file)
--- a/probes/lttng-kprobes.c
+++ b/probes/lttng-kprobes.c
@@ -25,9 +25,14 @@ int lttng_kprobes_handler_pre(struct kprobe *p, struct pt_regs *regs)
        int ret;
        unsigned long data = (unsigned long) p->addr;
 
-       if (!ACCESS_ONCE(chan->session->active))
+       if (unlikely(!ACCESS_ONCE(chan->session->active)))
                return 0;
-       lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, sizeof(data),
+       if (unlikely(!ACCESS_ONCE(chan->enabled)))
+               return 0;
+       if (unlikely(!ACCESS_ONCE(event->enabled)))
+               return 0;
+
+       lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(data),
                                 ltt_alignof(data), -1);
        ret = chan->ops->event_reserve(&ctx, event->id);
        if (ret < 0)
@@ -67,7 +72,7 @@ int lttng_create_kprobe_event(const char *name, struct ltt_event *event)
        field->type.atype = atype_integer;
        field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
        field->type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
-       field->type.u.basic.integer.signedness = 0;
+       field->type.u.basic.integer.signedness = is_signed_type(unsigned long);
        field->type.u.basic.integer.reverse_byte_order = 0;
        field->type.u.basic.integer.base = 16;
        field->type.u.basic.integer.encoding = lttng_encode_none;
@@ -91,22 +96,28 @@ int lttng_kprobes_register(const char *name,
 {
        int ret;
 
+       /* Kprobes expects a NULL symbol name if unused */
+       if (symbol_name[0] == '\0')
+               symbol_name = NULL;
+
        ret = lttng_create_kprobe_event(name, event);
        if (ret)
                goto error;
        memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
        event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
-       event->u.kprobe.symbol_name =
-               kzalloc(LTTNG_SYM_NAME_LEN * sizeof(char),
-                       GFP_KERNEL);
-       if (!event->u.kprobe.symbol_name) {
-               ret = -ENOMEM;
-               goto name_error;
+       if (symbol_name) {
+               event->u.kprobe.symbol_name =
+                       kzalloc(LTTNG_SYM_NAME_LEN * sizeof(char),
+                               GFP_KERNEL);
+               if (!event->u.kprobe.symbol_name) {
+                       ret = -ENOMEM;
+                       goto name_error;
+               }
+               memcpy(event->u.kprobe.symbol_name, symbol_name,
+                      LTTNG_SYM_NAME_LEN * sizeof(char));
+               event->u.kprobe.kp.symbol_name =
+                       event->u.kprobe.symbol_name;
        }
-       memcpy(event->u.kprobe.symbol_name, symbol_name,
-              LTTNG_SYM_NAME_LEN * sizeof(char));
-       event->u.kprobe.kp.symbol_name =
-               event->u.kprobe.symbol_name;
        event->u.kprobe.kp.offset = offset;
        event->u.kprobe.kp.addr = (void *) addr;