x86, xen: record and display initiator of each multicall when debugging

Store the caller for each multicall so we can report it on failure.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index c738644b5435..82f2513e9758 100644
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -39,6 +39,7 @@ struct mc_buffer {
         struct multicall_entry entries[MC_BATCH];
 #if MC_DEBUG
         struct multicall_entry debug[MC_BATCH];
+        void *caller[MC_BATCH];
 #endif
         unsigned char args[MC_ARGS];
         struct callback {
@@ -154,11 +155,12 @@ void xen_mc_flush(void)
                                ret, smp_processor_id());
                         dump_stack();
                         for (i = 0; i < b->mcidx; i++) {
-                                printk(KERN_DEBUG "  call %2d/%d: op=%lu arg=[%lx] result=%ld\n",
+                                printk(KERN_DEBUG "  call %2d/%d: op=%lu arg=[%lx] result=%ld\t%pF\n",
                                        i+1, b->mcidx,
                                        b->debug[i].op,
                                        b->debug[i].args[0],
-                                       b->entries[i].result);
+                                       b->entries[i].result,
+                                       b->caller[i]);
                         }
                 }
 #endif
@@ -197,6 +199,9 @@ struct multicall_space __xen_mc_entry(size_t args)
         }
 
         ret.mc = &b->entries[b->mcidx];
+#ifdef MC_DEBUG
+        b->caller[b->mcidx] = __builtin_return_address(0);
+#endif
         b->mcidx++;
         ret.args = &b->args[argidx];
         b->argidx = argidx + args;