x86: Improve information from domain_crash_synchronous

As it currently stands, the string "domain_crash_sync called from entry.S" is
not helpful at identifying why the domain was crashed, and a debug build of
Xen doesn't help the matter

This patch improves the information printed, by pointing to where the crash
decision was made.

Specific improvements include:
 * Moving the ascii string "domain_crash_sync called from entry.S\n" away from
   some semi-hot code cache lines.
 * Moving the printk into C code (especially as this_cpu() is miserable to use
   in assembly code)
 * Undo the previous confusing situation of having the
   domain_crash_synchronous() as a macro in C code, yet a global symbol in
   assembly code.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/xen/include/asm-x86/asm_defns.h b/xen/include/asm-x86/asm_defns.h
index 25032d55eb..a4601bab32 100644
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -35,10 +35,14 @@ void ret_from_intr(void);
 #ifdef __ASSEMBLY__
 
 #define UNLIKELY_START(cond, tag) \
+        .Ldispatch.tag:           \
         j##cond .Lunlikely.tag;   \
         .subsection 1;            \
         .Lunlikely.tag:
 
+#define UNLIKELY_DISPATCH_LABEL(tag) \
+        .Ldispatch.tag
+
 #define UNLIKELY_DONE(cond, tag)  \
         j##cond .Llikely.tag