2006-11-26 Frank Ch. Eigler <fche@redhat.com>

	PRs 2685, 3596, toward 2725.
	* tapsets.cxx (common_probe_entryfn_prologue): Skip probe on
	insufficient stack.
	(build_blacklist): Add a slew of lock-related calls.
	(query_module): Check for debuginfo architecture match.
	* translate.cxx (translate_pass): Add default MINSTACKSPACE.
	* configure.ac: Link stap with -lebl too.
	* configure: Regenerated.
	* stap.1.in: Document MINSTACKSPACE parameter.

6 files changed, 179 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 1fe67b59..c71a8c27 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2006-11-26  Frank Ch. Eigler  <fche@redhat.com>
+
+	PRs 2685, 3596, toward 2725.
+	* tapsets.cxx (common_probe_entryfn_prologue): Skip probe on
+	insufficient stack.
+	(build_blacklist): Add a slew of lock-related calls.
+	(query_module): Check for debuginfo architecture match.
+	* translate.cxx (translate_pass): Add default MINSTACKSPACE.
+	* configure.ac: Link stap with -lebl too.
+	* configure: Regenerated.
+	* stap.1.in: Document MINSTACKSPACE parameter.
+
 2006-11-21  Frank Ch. Eigler  <fche@elastic.org>
 
 	* translate.cxx (emit_module_init): Adapt to 2.6.19 utsname().
diff --git a/configure b/configure
index 240df784..7cee7614 100755
--- a/configure
+++ b/configure
@@ -5859,13 +5859,94 @@ echo "$as_me: error: systemtap requires elfutils 0.123+" >&2;}
    { (exit 1); exit 1; }; }
 fi
 
+
+echo "$as_me:$LINENO: checking for ebl_openbackend in -lebl" >&5
+echo $ECHO_N "checking for ebl_openbackend in -lebl... $ECHO_C" >&6
+if test "${ac_cv_lib_ebl_ebl_openbackend+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lebl  $LIBS"
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+/* Override any gcc2 internal prototype to avoid an error.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+/* We use char because int might match the return type of a gcc2
+   builtin and then its argument prototype would still apply.  */
+char ebl_openbackend ();
+int
+main ()
+{
+ebl_openbackend ();
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+  (eval $ac_link) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_cxx_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest$ac_exeext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_lib_ebl_ebl_openbackend=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_lib_ebl_ebl_openbackend=no
+fi
+rm -f conftest.err conftest.$ac_objext \
+      conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+echo "$as_me:$LINENO: result: $ac_cv_lib_ebl_ebl_openbackend" >&5
+echo "${ECHO_T}$ac_cv_lib_ebl_ebl_openbackend" >&6
+if test $ac_cv_lib_ebl_ebl_openbackend = yes; then
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBEBL 1
+_ACEOF
+
+  LIBS="-lebl $LIBS"
+
+else
+
+    { { echo "$as_me:$LINENO: error: systemtap requires elfutils 0.123+" >&5
+echo "$as_me: error: systemtap requires elfutils 0.123+" >&2;}
+   { (exit 1); exit 1; }; }
+fi
+
   stap_LIBS="$LIBS"
   LIBS="$SAVE_LIBS"
 else
   # We built our own and stap_LDFLAGS points at the install.
-  stap_LIBS=-ldw
+  stap_LIBS="-ldw -lebl"
 fi
 
+{ echo "$as_me:$LINENO: stap will link $stap_LIBS" >&5
+echo "$as_me: stap will link $stap_LIBS" >&6;}
 
 date=`date +%Y-%m-%d`
 
diff --git a/configure.ac b/configure.ac
index 5ff48549..ea3b61da 100644
--- a/configure.ac
+++ b/configure.ac
@@ -101,13 +101,16 @@ if test $build_elfutils = no; then
   save_LIBS="$LIBS"
   AC_CHECK_LIB(dw, dwfl_module_getsym,,[
     AC_MSG_ERROR([systemtap requires elfutils 0.123+])])
+  AC_CHECK_LIB(ebl, ebl_openbackend,,[
+    AC_MSG_ERROR([systemtap requires elfutils 0.123+])])
   stap_LIBS="$LIBS"
   LIBS="$SAVE_LIBS"
 else
   # We built our own and stap_LDFLAGS points at the install.
-  stap_LIBS=-ldw
+  stap_LIBS="-ldw -lebl"
 fi
 AC_SUBST(stap_LIBS)
+AC_MSG_NOTICE([stap will link $stap_LIBS])
 
 dnl Plop in the build (configure) date
 date=`date +%Y-%m-%d`
diff --git a/stap.1.in b/stap.1.in
index 5b5cd3e6..3986c52b 100644
--- a/stap.1.in
+++ b/stap.1.in
@@ -746,7 +746,7 @@ script is translated again assuming the same conditions exist (same kernel
 version, same systemtap version, etc.).  Cached files are stored in
 the
 .I $SYSTEMTAP_DIR/cache
-directory.
+directory, which may be periodically cleaned/erased by the user.
 
 .SH SAFETY AND SECURITY
 Systemtap is an administrative tool.  It exposes kernel internal data
@@ -801,6 +801,11 @@ means that the first error will exit the script.
 .TP
 MAXSKIPPED
 Maximum number of skipped reentrant probes before an exit is triggered, default 100.
+.TP
+MINSTACKSPACE
+Minimum number of free kernel stack bytes required in order to
+run a probe handler, default 1024.  This number should be large enough
+for the probe handler's own needs, plus a safety margin.
 
 .PP
 In case something goes wrong with 
diff --git a/tapsets.cxx b/tapsets.cxx
index 55a53cca..852ef378 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -29,6 +29,7 @@ extern "C" {
 #include <fcntl.h>
 #include <elfutils/libdwfl.h>
 #include <elfutils/libdw.h>
+#include <elfutils/libebl.h>
 #include <dwarf.h>
 #include <elf.h>
 #include <obstack.h>
@@ -174,6 +175,16 @@ common_probe_entryfn_prologue (translator_output* o, string statestr)
 
   o->newline() << "local_irq_save (flags);";
 
+  // Check for enough free enough stack space
+  o->newline() << "if ((((unsigned long) (& c)) & (THREAD_SIZE-1))";
+  o->newline(1) << "< (THREAD_SIZE - MINSTACKSPACE - sizeof (struct task_struct))) {";
+  o->newline() << "if (atomic_inc_return (& skipped_count) > MAXSKIPPED) {";
+  o->newline(1) << "atomic_set (& session_state, STAP_SESSION_ERROR);";
+  o->newline() << "_stp_exit ();";
+  o->newline(-1) << "}";
+  o->newline() << "goto probe_epilogue;";
+  o->newline(-1) << "}";
+
   o->newline() << "if (atomic_read (&session_state) != " << statestr << ")";
   o->newline(1) << "goto probe_epilogue;";
   o->indent(-1);
@@ -717,7 +728,7 @@ struct dwflpp
 
 
   // NB: "rc == 0" means OK in this case
-  void dwfl_assert(string desc, int rc, string extra_msg = "")
+  static void dwfl_assert(string desc, int rc, string extra_msg = "")
   {
     string msg = "libdwfl failure (" + desc + "): ";
     if (rc < 0) msg += dwfl_errmsg (rc);
@@ -2037,6 +2048,18 @@ dwarf_query::build_blacklist()
   blacklisted_probes.insert("unhandled_fault");
   blacklisted_probes.insert("unknown_nmi_error");
 
+  blacklisted_probes.insert("_read_trylock");
+  blacklisted_probes.insert("_read_lock");
+  blacklisted_probes.insert("_read_unlock");
+  blacklisted_probes.insert("_write_trylock");
+  blacklisted_probes.insert("_write_lock");
+  blacklisted_probes.insert("_write_unlock");
+  blacklisted_probes.insert("_spin_lock");
+  blacklisted_probes.insert("_spin_lock_irqsave");
+  blacklisted_probes.insert("_spin_trylock");
+  blacklisted_probes.insert("_spin_unlock");
+  blacklisted_probes.insert("_spin_unlock_irqrestore");
+
   // __switch_to is only disallowed on x86_64
   if (sess.architecture == "x86_64")
     blacklisted_probes.insert("__switch_to");
@@ -2748,11 +2771,57 @@ query_module (Dwfl_Module *mod __attribute__ ((unused)),
       if (q->has_module && !q->dw.module_name_matches(q->module_val))
         return DWARF_CB_OK;
 
+      // Validate the machine code in this elf file against the
+      // session machine.  This is important, in case the wrong kind
+      // of debuginfo is being automagically processed by elfutils.
+      // Unfortunately, while we can tell i686 apart from x86-64,
+      // we can't help confusing i586 vs i686 (both EM_386).
+
+      Dwarf_Addr _junk;
+      Elf* elf = dwfl_module_getelf (mod, &_junk);
+      Ebl* ebl = ebl_openbackend (elf);
+      int elf_machine = ebl_get_elfmachine (ebl);
+      const char* debug_filename = "";
+      const char* main_filename = "";
+      (void) dwfl_module_info (mod, NULL, NULL, 
+                               NULL, NULL, NULL,
+                               & main_filename, 
+                               & debug_filename);
+      const string& sess_machine = q->sess.architecture;
+      string expect_machine;
+      switch (elf_machine)
+        {
+        case EM_386: expect_machine = "i686"; break;
+        case EM_X86_64: expect_machine = "x86_64"; break;
+        case EM_PPC: expect_machine = "ppc"; break;
+        case EM_PPC64: expect_machine = "ppc64"; break;
+        case EM_S390: expect_machine = "s390x"; break;
+        case EM_IA_64: expect_machine = "ia64"; break;
+          // XXX: fill in some more of these
+        default: expect_machine = "?"; break;
+        }
+     
+      if (! debug_filename) debug_filename = main_filename;
+      if (! debug_filename) debug_filename = name;
+
+      if (sess_machine != expect_machine)
+        {
+          stringstream msg;
+          msg << "ELF machine " << expect_machine << " (code " << elf_machine
+              << ") mismatch with target " << sess_machine
+              << " in '" << debug_filename << "'";
+          throw semantic_error(msg.str ());
+        }
+
       if (q->sess.verbose>2)
 	clog << "focused on module '" << q->dw.module_name
-	     << "' = [" << hex << q->dw.module_start
+	     << " = [" << hex << q->dw.module_start
 	     << "-" << q->dw.module_end
-	     << ", bias " << q->dw.module_bias << "]" << dec << "\n";
+	     << ", bias " << q->dw.module_bias << "]" << dec 
+             << " file " << debug_filename
+             << " ELF machine " << expect_machine
+             << " (code " << elf_machine << ")"
+             << "\n";
 
       if (q->has_inline_num || q->has_function_num || q->has_statement_num)
         {
diff --git a/translate.cxx b/translate.cxx
index 09c51a6e..f36280da 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -3984,6 +3984,9 @@ translate_pass (systemtap_session& s)
       s.op->newline() << "#ifndef MAXSKIPPED";
       s.op->newline() << "#define MAXSKIPPED 100";
       s.op->newline() << "#endif";
+      s.op->newline() << "#ifndef MINSTACKSPACE";
+      s.op->newline() << "#define MINSTACKSPACE 1024";
+      s.op->newline() << "#endif";
 
       // impedance mismatch
       // STP_STRING_SIZE defines the size of the buffer