trace: add some tcg tracing support

This adds a couple of tcg specific trace-events which are useful for
tracing execution though tcg generated blocks. It's been tested with
lttng user space tracing but is generic enough for all systems. The tcg
events are:

  * translate_block - when a subject block is translated
  * exec_tb - when a translated block is entered
  * exec_tb_exit - when we exit the translated code
  * exec_tb_nocache - special case translations

Of course we can only trace the entrance to the first block of a chain
as each block will jump directly to the next when it can. See the -d
nochain patch to allow more complete tracing at the expense of
performance.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/trace-events b/trace-events
index 11a17a8..dcc33dd 100644
--- a/trace-events
+++ b/trace-events
@@ -1265,6 +1265,15 @@
 kvm_failed_reg_get(uint64_t id, const char *msg) "Warning: Unable to retrieve ONEREG %" PRIu64 " from KVM: %s"
 kvm_failed_reg_set(uint64_t id, const char *msg) "Warning: Unable to set ONEREG %" PRIu64 " to KVM: %s"
 
+# TCG related tracing (mostly disabled by default)
+# cpu-exec.c
+disable exec_tb(void *tb, uintptr_t pc) "tb:%p pc=0x%"PRIxPTR
+disable exec_tb_nocache(void *tb, uintptr_t pc) "tb:%p pc=0x%"PRIxPTR
+disable exec_tb_exit(void *next_tb, unsigned int flags) "tb:%p flags=%x"
+
+# translate-all.c
+translate_block(void *tb, uintptr_t pc, uint8_t *tb_code) "tb:%p, pc:0x%"PRIxPTR", tb_code:%p"
+
 # memory.c
 memory_region_ops_read(void *mr, uint64_t addr, uint64_t value, unsigned size) "mr %p addr %#"PRIx64" value %#"PRIx64" size %u"
 memory_region_ops_write(void *mr, uint64_t addr, uint64_t value, unsigned size) "mr %p addr %#"PRIx64" value %#"PRIx64" size %u"