[PATCH] Tell the user if UTS_VERSION does not match running kernel

[Timo Juhani Lindfors <timo.lindfors@iki.fi>]

The test is done before looking at build-id since build-id error
messages like

ERROR: Build-id mismatch: "kernel" vs. "vmlinux-2.6.32-5-amd64" byte 0 (0x5e vs 0xff)
Pass 5: run failed.  Try again with another '--vp 00001' option.

are not very user-friendly.
---
 buildrun.cxx                         |    1 +
 runtime/autoconf-generated-compile.c |    4 ++++
 translate.cxx                        |   17 +++++++++++++++++
 3 files changed, 22 insertions(+), 0 deletions(-)
 create mode 100644 runtime/autoconf-generated-compile.c

diff --git a/buildrun.cxx b/buildrun.cxx
index 0435403..f3dcda5 100644
--- a/buildrun.cxx
+++ b/buildrun.cxx
@@ -214,6 +214,7 @@ compile_pass (systemtap_session& s)
   o << "$(STAPCONF_HEADER):" << endl;
   o << "\t@echo -n > $@" << endl;
   output_autoconf(s, o, "autoconf-hrtimer-rel.c", "STAPCONF_HRTIMER_REL", NULL);
+  output_autoconf(s, o, "autoconf-generated-compile.c", "STAPCONF_GENERATED_COMPILE", NULL);
   output_autoconf(s, o, "autoconf-hrtimer-getset-expires.c", "STAPCONF_HRTIMER_GETSET_EXPIRES", NULL);
   output_autoconf(s, o, "autoconf-inode-private.c", "STAPCONF_INODE_PRIVATE", NULL);
   output_autoconf(s, o, "autoconf-constant-tsc.c", "STAPCONF_CONSTANT_TSC", NULL);
diff --git a/runtime/autoconf-generated-compile.c b/runtime/autoconf-generated-compile.c
new file mode 100644
index 0000000..abf0765
--- /dev/null
+++ b/runtime/autoconf-generated-compile.c
@@ -0,0 +1,4 @@
+#include <generated/compile.h>
+
+char* x = UTS_VERSION;
+
diff --git a/translate.cxx b/translate.cxx
index 8dc0995..0aff9d1 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -1162,6 +1162,9 @@ c_unparser::emit_module_init ()
   // just in case modversions didn't.
   o->newline() << "{";
   o->newline(1) << "const char* release = UTS_RELEASE;";
+  o->newline() << "#ifdef STAPCONF_GENERATED_COMPILE";
+  o->newline() << "const char* version = UTS_VERSION;";
+  o->newline() << "#endif";
 
   // NB: This UTS_RELEASE compile-time macro directly checks only that
   // the compile-time kbuild tree matches the compile-time debuginfo/etc.
@@ -1182,6 +1185,17 @@ c_unparser::emit_module_init ()
   o->newline() << "rc = -EINVAL;";
   o->newline(-1) << "}";
 
+  o->newline() << "#ifdef STAPCONF_GENERATED_COMPILE";
+  o->newline() << "if (strcmp (utsname()->version, version)) {";
+  o->newline(1) << "_stp_error (\"module version mismatch (%s vs %s), release %s\", "
+                << "version, "
+                << "utsname()->version, "
+                << "release"
+                << ");";
+  o->newline() << "rc = -EINVAL;";
+  o->newline(-1) << "}";
+  o->newline() << "#endif";
+
   // perform buildid-based checking if able
   o->newline() << "if (_stp_module_check()) rc = -EINVAL;";
 
@@ -5813,6 +5827,9 @@ translate_pass (systemtap_session& s)
       s.op->newline() << "#include <linux/utsname.h>";
       s.op->newline() << "#include <linux/version.h>";
       // s.op->newline() << "#include <linux/compile.h>";
+      s.op->newline() << "#ifdef STAPCONF_GENERATED_COMPILE";
+      s.op->newline() << "#include <generated/compile.h>";
+      s.op->newline() << "#endif";
       s.op->newline() << "#include \"loc2c-runtime.h\" ";
       s.op->newline() << "#include \"access_process_vm.h\" ";
 
-- 
1.7.2.5