# Commit f72cb6bbc10348f4f7671428e5db509731e9e6a5
# Date 2013-10-17 11:35:26 +0200
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86: print relevant (tail) part of filename for warnings and crashes

In particular when the origin construct is in a header file (and
hence the file name is an absolute path instead of just the file name
portion) the information can otherwise become rather useless when the
build tree isn't sitting relatively close to the file system root.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -953,7 +953,7 @@ void do_invalid_op(struct cpu_user_regs 
 {
     struct bug_frame bug;
     struct bug_frame_str bug_str;
-    const char *p, *filename, *predicate, *eip = (char *)regs->eip;
+    const char *p, *prefix = "", *filename, *predicate, *eip = (char *)regs->eip;
     unsigned long fixup;
     int id, lineno;
 
@@ -995,12 +995,19 @@ void do_invalid_op(struct cpu_user_regs 
     }
 
     /* WARN, BUG or ASSERT: decode the filename pointer and line number. */
-    filename = p;
+    fixup = strlen(p);
+    if ( fixup > 50 )
+    {
+        filename = p + fixup - 47;
+        prefix = "...";
+    }
+    else
+        filename = p;
     lineno = bug.id >> 2;
 
     if ( id == BUGFRAME_warn )
     {
-        printk("Xen WARN at %.50s:%d\n", filename, lineno);
+        printk("Xen WARN at %s%s:%d\n", prefix, filename, lineno);
         show_execution_state(regs);
         regs->eip = (unsigned long)eip;
         return;
@@ -1008,10 +1015,10 @@ void do_invalid_op(struct cpu_user_regs 
 
     if ( id == BUGFRAME_bug )
     {
-        printk("Xen BUG at %.50s:%d\n", filename, lineno);
+        printk("Xen BUG at %s%s:%d\n", prefix, filename, lineno);
         DEBUGGER_trap_fatal(TRAP_invalid_op, regs);
         show_execution_state(regs);
-        panic("Xen BUG at %.50s:%d\n", filename, lineno);
+        panic("Xen BUG at %s%s:%d\n", prefix, filename, lineno);
     }
 
     /* ASSERT: decode the predicate string pointer. */
@@ -1025,12 +1032,12 @@ void do_invalid_op(struct cpu_user_regs 
 
     if ( !is_kernel(predicate) )
         predicate = "<unknown>";
-    printk("Assertion '%s' failed at %.50s:%d\n",
-           predicate, filename, lineno);
+    printk("Assertion '%s' failed at %s%s:%d\n",
+           predicate, prefix, filename, lineno);
     DEBUGGER_trap_fatal(TRAP_invalid_op, regs);
     show_execution_state(regs);
-    panic("Assertion '%s' failed at %.50s:%d\n",
-          predicate, filename, lineno);
+    panic("Assertion '%s' failed at %s%s:%d\n",
+          predicate, prefix, filename, lineno);
 
  die:
     if ( (fixup = search_exception_table(regs->eip)) != 0 )