PR6580: Implement symname, symdata and modname context functions.

This adds a couple of the suggested context/stack revamp functions
from PR6580. In particular it replaces the symbolname() function that
sneaked in with the pr6866 branch merge with the suggested symname().

* runtime/sym.c (_stp_mod_sec_lookup): Make section optional.
  (_stp_symbol_snprint): Provide a way to get optional module info.
* tapset/context-symbols.stp: Replace symbolname() with symname(),
  add modname() and symdata().
  (probemod): Implement pc based fallback.
* tapset/context-unwind.stp (caller): Adjust for _stp_symbol_snprint
  change.
* testsuite/systemtap.context/usymbols.exp: Use new symname.
* testsuite/buildok/modname.stp: New test.
* testsuite/buildok/symdata.stp: Likewise.
* testsuite/buildok/symname.stp: Likewise.

4 files changed, 25 insertions, 1 deletions

diff --git a/testsuite/buildok/modname.stp b/testsuite/buildok/modname.stp
new file mode 100755
index 00000000..02229301
--- /dev/null
+++ b/testsuite/buildok/modname.stp
@@ -0,0 +1,8 @@
+#! stap -p4
+#
+# Test the translatability for modname()
+#
+probe begin
+{
+   log(modname(0))
+}
diff --git a/testsuite/buildok/symdata.stp b/testsuite/buildok/symdata.stp
new file mode 100755
index 00000000..d7e803a9
--- /dev/null
+++ b/testsuite/buildok/symdata.stp
@@ -0,0 +1,8 @@
+#! stap -p4
+#
+# Test the translatability for symdata()
+#
+probe begin
+{
+   log(symdata(0))
+}
diff --git a/testsuite/buildok/symname.stp b/testsuite/buildok/symname.stp
new file mode 100755
index 00000000..e082d1a5
--- /dev/null
+++ b/testsuite/buildok/symname.stp
@@ -0,0 +1,8 @@
+#! stap -p4
+#
+# Test the translatability for symname()
+#
+probe begin
+{
+   log(symname(0))
+}
diff --git a/testsuite/systemtap.context/usymbols.exp b/testsuite/systemtap.context/usymbols.exp
index 82f68b67..8af20126 100644
--- a/testsuite/systemtap.context/usymbols.exp
+++ b/testsuite/systemtap.context/usymbols.exp
@@ -35,7 +35,7 @@ set testscript {
     probe syscall.rt_sigaction {
       if (pid() == target() && execname() == "%s") {
 	  handler = $act->sa_handler;
-	  printf("handler: %%s\n", symbolname(handler));
+	  printf("handler: %%s\n", symname(handler));
       }
     }
     /* track through uprobes, so as to make sure we have the symbols */