[Xen-devel] [PATCH v2 1/2] xen: add config option to include failing condition in BUG_ON() message

[Juergen Gross <jgross@xxxxxxxx>]

Today a triggering BUG_ON() will only print source file and line
information. Add the possibility to print the triggering condition like
ASSERT().

Do that by introducing BUG_ON_VERBOSE() and add a Kconfig option to
make BUG_ON use BUG_ON_VERBOSE().

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 xen/Kconfig.debug         | 6 ++++++
 xen/include/asm-x86/bug.h | 5 +++--
 xen/include/xen/lib.h     | 5 +++++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
index b3511e81a2..dfbcac575a 100644
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -81,6 +81,12 @@ config PERF_ARRAYS
        ---help---
          Enables software performance counter array histograms.
 
+config DEBUG_BUGVERBOSE
+       bool "Verbose BUG_ON messages"
+       default DEBUG
+       ---help---
+         In case a BUG_ON triggers additionally print the triggering
+         condition on the console.
 
 config VERBOSE_DEBUG
        bool "Verbose debug messages"
diff --git a/xen/include/asm-x86/bug.h b/xen/include/asm-x86/bug.h
index 9bb4a19420..46d282777f 100644
--- a/xen/include/asm-x86/bug.h
+++ b/xen/include/asm-x86/bug.h
@@ -60,10 +60,11 @@ struct bug_frame {
 
 
 #define WARN() BUG_FRAME(BUGFRAME_warn, __LINE__, __FILE__, 0, NULL)
-#define BUG() do {                                              \
-    BUG_FRAME(BUGFRAME_bug,  __LINE__, __FILE__, 0, NULL);      \
+#define BUG_VERBOSE(msg) do {                                   \
+    BUG_FRAME(BUGFRAME_bug,  __LINE__, __FILE__, 0, msg);       \
     unreachable();                                              \
 } while (0)
+#define BUG() BUG_VERBOSE(NULL)
 
 #define run_in_exception_handler(fn) BUG_FRAME(BUGFRAME_run_fn, 0, fn, 0, NULL)
 
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index 8fbe84032d..e7770b0d24 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -8,7 +8,12 @@
 #include <xen/string.h>
 #include <asm/bug.h>
 
+#define BUG_ON_VERBOSE(p) do { if (unlikely(p)) BUG_VERBOSE(#p);  } while (0)
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+#define BUG_ON(p)  BUG_ON_VERBOSE(p)
+#else
 #define BUG_ON(p)  do { if (unlikely(p)) BUG();  } while (0)
+#endif
 #define WARN_ON(p) do { if (unlikely(p)) WARN(); } while (0)
 
 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
-- 
2.16.4


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