[Xen-devel] [PATCH v2] xen: make tracebuffer configurable

Baodong Chen posted 1 patch 14 weeks ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/xen tags/patchew/1559639503-1705-1-git-send-email-chenbaodong@mxnavi.com
xen/common/Kconfig      | 12 ++++++++++++
xen/common/Makefile     |  2 +-
xen/include/xen/trace.h | 26 ++++++++++++++++++++++++++
3 files changed, 39 insertions(+), 1 deletion(-)

[Xen-devel] [PATCH v2] xen: make tracebuffer configurable

Posted by Baodong Chen 14 weeks ago
Xen internal running status(trace event) will be saved to
trace memory when enabled. trace event data and config params can be
read/changed by system control hypercall at run time.

Can be disabled for smaller code footprint.

Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
---
 xen/common/Kconfig      | 12 ++++++++++++
 xen/common/Makefile     |  2 +-
 xen/include/xen/trace.h | 26 ++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index c838506..3459f56 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -368,4 +368,16 @@ config DOM0_MEM
 
 	  Leave empty if you are not sure what to specify.
 
+config TRACEBUFFER
+	bool "Enable trace event logs"  if EXPERT = "y"
+	---help---
+	  Xen internal running status(trace event) will be saved to trace memory
+	  when enabled. trace event data and config params can be read/changed
+	  by system control hypercall at run time.
+
+	  This is used to record xen internal running status.
+	  with a litte performance overhead.
+	  Can be set to 'N' if you dont want this function.
+	  When not configured, 'XEN_STSCTL_tbuf_op' command will result 'ENOSYS'.
+
 endmenu
diff --git a/xen/common/Makefile b/xen/common/Makefile
index bca48e6..9fd1bd2 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -56,7 +56,7 @@ obj-y += sysctl.o
 obj-y += tasklet.o
 obj-y += time.o
 obj-y += timer.o
-obj-y += trace.o
+obj-$(CONFIG_TRACEBUFFER) += trace.o
 obj-y += version.o
 obj-y += virtual_region.o
 obj-y += vm_event.o
diff --git a/xen/include/xen/trace.h b/xen/include/xen/trace.h
index 12966ea..fad92c7 100644
--- a/xen/include/xen/trace.h
+++ b/xen/include/xen/trace.h
@@ -21,12 +21,18 @@
 #ifndef __XEN_TRACE_H__
 #define __XEN_TRACE_H__
 
+/* Put 'tb_init_done' here because 'asm/trace.h' may use it */
+#ifdef CONFIG_TRACEBUFFER
 extern int tb_init_done;
+#else
+#define tb_init_done false
+#endif
 
 #include <public/sysctl.h>
 #include <public/trace.h>
 #include <asm/trace.h>
 
+#ifdef CONFIG_TRACEBUFFER
 /* Used to initialise trace buffer functionality */
 void init_trace_bufs(void);
 
@@ -47,6 +53,26 @@ static inline void trace_var(u32 event, int cycles, int extra,
 void __trace_hypercall(uint32_t event, unsigned long op,
                        const xen_ulong_t *args);
 
+#else
+static inline void init_trace_bufs(void) {}
+static inline int tb_control(struct xen_sysctl_tbuf_op *tbc)
+{
+    return -ENOSYS;
+}
+
+static inline int trace_will_trace_event(uint32_t event)
+{
+    return 0;
+}
+
+static inline void trace_var(uint32_t event, int cycles, int extra,
+                             const void *extra_data) {}
+static inline void __trace_var(uint32_t event, bool cycles, unsigned int extra,
+                               const void *extra_data) {}
+static inline void __trace_hypercall(uint32_t event, unsigned long op,
+                                     const xen_ulong_t *args) {}
+#endif
+
 /* Convenience macros for calling the trace function. */
 #define TRACE_0D(_e)                            \
     do {                                        \
-- 
2.7.4


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel