From 03a4ec63de7060914b01320f6e840e0bc2d0beda Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mjw@redhat.com>
Date: Wed, 21 Apr 2010 11:21:07 +0200
Subject: [PATCH] PR11514 Only use kallsyms_on_each_symbol speedup when
 available.

* runtime/autoconf-kallsyms-on-each-symbol.c: New check.
* buildrun.cxx (compile_pass): Add new check to output_autoconf.
* tapsets.cxx (kprobe_derived_probe_group::emit_module_decls): Only declare
  kprobe_resolve when STAPCONF_KALLSYMS_ON_EACH_SYMBOL defined.
  (kprobe_derived_probe_group::emit_module_init): Check whether to invoke
  kallsyms_on_each_symbol optimization.
---
 buildrun.cxx                               |  1 +
 runtime/autoconf-kallsyms-on-each-symbol.c |  5 +++++
 tapsets.cxx                                | 13 +++++++++++--
 3 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 runtime/autoconf-kallsyms-on-each-symbol.c

diff --git a/buildrun.cxx b/buildrun.cxx
index 89fa01777..c4703978b 100644
--- a/buildrun.cxx
+++ b/buildrun.cxx
@@ -193,6 +193,7 @@ compile_pass (systemtap_session& s)
   output_autoconf(s, o, "autoconf-asm-syscall.c",
 		  "STAPCONF_ASM_SYSCALL_H", NULL);
   output_autoconf(s, o, "autoconf-ring_buffer-flags.c", "STAPCONF_RING_BUFFER_FLAGS", NULL);
+  output_autoconf(s, o, "autoconf-kallsyms-on-each-symbol.c", "STAPCONF_KALLSYMS_ON_EACH_SYMBOL", NULL);
 
   o << module_cflags << " += -include $(STAPCONF_HEADER)" << endl;
 
diff --git a/runtime/autoconf-kallsyms-on-each-symbol.c b/runtime/autoconf-kallsyms-on-each-symbol.c
new file mode 100644
index 000000000..c0005e185
--- /dev/null
+++ b/runtime/autoconf-kallsyms-on-each-symbol.c
@@ -0,0 +1,5 @@
+#include <linux/kallsyms.h>
+
+void foo (void) {
+   (void) kallsyms_on_each_symbol(NULL, NULL);
+}
diff --git a/tapsets.cxx b/tapsets.cxx
index d624042b2..e1151e547 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -5477,6 +5477,7 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "return 0;";
   s.op->newline(-1) << "}";
 
+  s.op->newline() << "#ifdef STAPCONF_KALLSYMS_ON_EACH_SYMBOL";
   s.op->newline() << "static int kprobe_resolve(void *data, const char *name,";
   s.op->newline() << "                          struct module *owner,";
   s.op->newline() << "                          unsigned long val) {";
@@ -5489,28 +5490,36 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline(-3) << "}";
   s.op->newline() << "return 0;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#endif";
 }
 
 
 void
 kprobe_derived_probe_group::emit_module_init (systemtap_session& s)
 {
+  s.op->newline() << "#ifdef STAPCONF_KALLSYMS_ON_EACH_SYMBOL";
   s.op->newline() << "kallsyms_on_each_symbol(kprobe_resolve, NULL);";
+  s.op->newline() << "#endif";
 
   s.op->newline() << "for (i=0; i<" << probes_by_module.size() << "; i++) {";
   s.op->newline(1) << "struct stap_dwarfless_probe *sdp = & stap_dwarfless_probes[i];";
   s.op->newline() << "struct stap_dwarfless_kprobe *kp = & stap_dwarfless_kprobes[i];";
   s.op->newline() << "void *addr = (void *) sdp->address;";
+  s.op->newline() << "const char *symbol_name = addr ? NULL : sdp->symbol_string;";
+
+  s.op->newline() << "#ifdef STAPCONF_KALLSYMS_ON_EACH_SYMBOL";
   s.op->newline() << "if (! addr) {";
   s.op->newline(1) << "sdp->registered_p = 0;";
   s.op->newline() << "if (!sdp->optional_p)";
   s.op->newline(1) << "_stp_warn (\"probe %s registration error (symbol not found)\", probe_point);";
   s.op->newline(-1) << "continue;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#endif";
+
   s.op->newline() << "probe_point = sdp->pp;"; // for error messages
   s.op->newline() << "if (sdp->return_p) {";
   s.op->newline(1) << "kp->u.krp.kp.addr = addr;";
-  s.op->newline() << "kp->u.krp.kp.symbol_name = NULL;";
+  s.op->newline() << "kp->u.krp.kp.symbol_name = (char *) symbol_name;";
   s.op->newline() << "if (sdp->maxactive_p) {";
   s.op->newline(1) << "kp->u.krp.maxactive = sdp->maxactive_val;";
   s.op->newline(-1) << "} else {";
@@ -5534,7 +5543,7 @@ kprobe_derived_probe_group::emit_module_init (systemtap_session& s)
   s.op->newline(-1) << "} else {";
   // to ensure safeness of bspcache, always use aggr_kprobe on ia64
   s.op->newline(1) << "kp->u.kp.addr = addr;";
-  s.op->newline() << "kp->u.kp.symbol_name = NULL;";
+  s.op->newline() << "kp->u.kp.symbol_name = (char *) symbol_name;";
   s.op->newline() << "kp->u.kp.pre_handler = &enter_kprobe2_probe;";
   s.op->newline() << "#ifdef __ia64__";
   s.op->newline() << "kp->dummy.pre_handler = NULL;";
-- 
2.43.5