[PATCH 18 of 36] x86/paravirt: add debugging for missing operations

Jeremy Fitzhardinge
2008-06-25T04:48:15Z

Rather than just jumping to 0 when there's a missing operation, raise a BUG.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/Kconfig | 7 +++++++
include/asm-x86/paravirt.h | 8 ++++++++
2 files changed, 15 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -433,6 +433,13 @@
the kernel is theoretically slower and slightly larger.

endif
+
+config PARAVIRT_DEBUG
+ bool "paravirt-ops debugging"
+ depends on PARAVIRT && DEBUG_KERNEL
+ help
+ Enable to debug paravirt_ops internals. Specifically, BUG if
+ a paravirt_op is missing when it is called.

config MEMTEST
bool "Memtest"
diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -460,10 +460,17 @@
#define VEXTRA_CLOBBERS , "rax", "r8", "r9", "r10", "r11"
#endif

+#ifdef CONFIG_PARAVIRT_DEBUG
+#define PVOP_TEST_NULL(op) BUG_ON(op == NULL)
+#else
+#define PVOP_TEST_NULL(op) ((void)op)
+#endif
+
#define __PVOP_CALL(rettype, op, pre, post, ...) \
({ \
rettype __ret; \
PVOP_CALL_ARGS; \
+ PVOP_TEST_NULL(op); \
/* This is 32-bit specific, but is okay in 64-bit */ \
/* since this condition will never hold */ \
if (sizeof(rettype) > sizeof(unsigned long)) { \
@@ -492,6 +499,7 @@
#define __PVOP_VCALL(op, pre, post, ...) \
({ \
PVOP_VCALL_ARGS; \
+ PVOP_TEST_NULL(op); \
asm volatile(pre \
paravirt_alt(PARAVIRT_CALL) \
post \