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.

7 files changed, 98 insertions, 16 deletions

diff --git a/runtime/sym.c b/runtime/sym.c
index d0c5d9fd..ecd64fee 100644
--- a/runtime/sym.c
+++ b/runtime/sym.c
@@ -106,8 +106,8 @@ static unsigned long _stp_module_relocate(const char *module, const char *sectio
 }
 
 
-/* Return module owner and fills in closest section of the address
-   if found, return NULL otherwise.
+/* Return module owner and, if sec != NULL, fills in closest section
+   of the address if found, return NULL otherwise.
    XXX: needs to be address-space-specific. */
 static struct _stp_module *_stp_mod_sec_lookup(unsigned long addr,
 					       struct task_struct *task,
@@ -151,7 +151,8 @@ static struct _stp_module *_stp_mod_sec_lookup(unsigned long addr,
 	    {
 	      closest_section_offset = this_section_offset;
 	      m = _stp_modules[midx];
-	      *sec = & m->sections[secidx];
+	      if (sec)
+		*sec = & m->sections[secidx];
 	    }
 	}
       }
@@ -338,8 +339,15 @@ static int _stp_func_print(unsigned long address, int verbose, int exact)
 	return 0;
 }
 
+/** Puts symbolic information of an address in a string.
+ * @param src The string to fill in.
+ * @param len The length of the given src string.
+ * @param address The address to lookup.
+ * @param add_mod Whether to include module name information if found.
+ */
+
 static void _stp_symbol_snprint(char *str, size_t len, unsigned long address,
-			 struct task_struct *task)
+			 struct task_struct *task, int add_mod)
 {
 	const char *modname;
 	const char *name;
@@ -347,9 +355,13 @@ static void _stp_symbol_snprint(char *str, size_t len, unsigned long address,
 
 	name = _stp_kallsyms_lookup(address, &size, &offset, &modname, NULL,
 				    task);
-	if (name)
-		strlcpy(str, name, len);
-	else
+	if (name) {
+		if (add_mod && modname && *modname)
+			_stp_printf("%s %s+%#lx/%#lx\n",
+				    name, modname, offset, size);
+		else
+			strlcpy(str, name, len);
+	} else
 		_stp_snprintf(str, len, "%p", (int64_t) address);
 }
 
diff --git a/tapset/context-symbols.stp b/tapset/context-symbols.stp
index 4c200aa8..66d9fea2 100644
--- a/tapset/context-symbols.stp
+++ b/tapset/context-symbols.stp
@@ -66,7 +66,7 @@ function probefunc:string () %{ /* pure */
 #else
 		((unsigned long)REG_IP(CONTEXT->regs) >= (unsigned long)PAGE_OFFSET)) {
 #endif
-		_stp_symbol_snprint(THIS->__retvalue, MAXSTRINGLEN, REG_IP(CONTEXT->regs), current);
+		_stp_symbol_snprint(THIS->__retvalue, MAXSTRINGLEN, REG_IP(CONTEXT->regs), current, 0);
        	         if (THIS->__retvalue[0] == '.')  /* powerpc symbol has a dot*/
        	         	strlcpy(THIS->__retvalue,THIS->__retvalue + 1,MAXSTRINGLEN);
 	} else {
@@ -89,13 +89,59 @@ function probemod:string () %{ /* pure */
 		while (*ptr != '"' && --len && *ptr)
 			*dst++ = *ptr++;
 		*dst = 0;
-	} else {
-		/* XXX: need a PC- and symbol-table-based fallback. */
-		THIS->__retvalue[0] = '\0';
-	}
+	} else if (CONTEXT->regs) {
+		struct _stp_module *m;
+		m = _stp_mod_sec_lookup (REG_IP(CONTEXT->regs), current, NULL);
+		if (m && m->name)
+			strlcpy (THIS->__retvalue, m->name, MAXSTRINGLEN);
+		else
+			strlcpy (THIS->__retvalue, "<unknown>", MAXSTRINGLEN);
+	} else
+		strlcpy (THIS->__retvalue, "<unknown>", MAXSTRINGLEN);
 %}
 
-function symbolname:string (addr:long) %{ /* pure */
+/**
+ * sfunction modname - Return the kernel module name loaded at the address.
+ * @addr: The address.
+ *
+ * Description: Returns the module name associated with the given
+ * address if known. If not known it will return the string "<unknown>".
+ * If the address was not in a kernel module, but in the kernel itself,
+ * then the string "kernel" will be returned.
+ */
+function modname:string (addr: long) %{ /* pure */
+	struct _stp_module *m;
+	m = _stp_mod_sec_lookup (THIS->addr, current, NULL);
+	if (m && m->name)
+          strlcpy (THIS->__retvalue, m->name, MAXSTRINGLEN);
+	else
+	  strlcpy (THIS->__retvalue, "<unknown>", MAXSTRINGLEN);
+%}
+
+/**
+ * sfunction symname - Return the symbol associated with the given address.
+ * @addr: The address to translate.
+ *
+ * Description: Returns the (function) symbol name associated with the
+ * given address if known. If not known it will return the hex string
+ * representation of addr.
+ */
+function symname:string (addr: long) %{ /* pure */
+	 _stp_symbol_snprint(THIS->__retvalue, MAXSTRINGLEN, THIS->addr,
+			     current, 0);
+%}
+
+/**
+ * sfunction symdata - Return the symbol and module offset for the address.
+ * @addr: The address to translate.
+ *
+ * Description: Returns the (function) symbol name associated with the
+ * given address if known, plus the module name (between brackets) and
+ * the offset inside the module, plus the size of the symbol function.
+ * If any element is not known it will be ommitted and if the symbol name
+ * is unknown it will return the hex string for the given address.
+ */
+function symdata:string (addr: long) %{ /* pure */
 	 _stp_symbol_snprint(THIS->__retvalue, MAXSTRINGLEN, THIS->addr,
-	                     current);
+			     current, 1);
 %}
diff --git a/tapset/context-unwind.stp b/tapset/context-unwind.stp
index a976f8b6..b3d19e29 100644
--- a/tapset/context-unwind.stp
+++ b/tapset/context-unwind.stp
@@ -57,7 +57,7 @@ function caller:string() %{ /* pure */
         if (CONTEXT->pi) 
 		_stp_symbol_snprint( THIS->__retvalue, MAXSTRINGLEN, 
 			(unsigned long)_stp_ret_addr_r(CONTEXT->pi),
-                        current);
+                        current, 0);
         else
 		strlcpy(THIS->__retvalue,"unknown",MAXSTRINGLEN);
 %}
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 */