From 4ac1e0a9fcd00850e993635f146519ab766d2456 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@FreeBSD.org>
Date: Sun, 25 Jan 2015 12:11:50 +0000
Subject: [PATCH] Allow tracing dlfunc() / dlsym() events.

MFC after:	1 week
---
 libexec/rtld-elf/rtld.c | 17 +++++++++++++----
 usr.bin/kdump/kdump.c   |  9 +++++++++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 5f449c138e11..7b19f5aa65c2 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -266,6 +266,8 @@ bool ld_library_path_rpath = false;
 #define	UTRACE_PRELOAD_FINISHED		8
 #define	UTRACE_INIT_CALL		9
 #define	UTRACE_FINI_CALL		10
+#define	UTRACE_DLSYM_START		11
+#define	UTRACE_DLSYM_STOP		12
 
 struct utrace_rtld {
 	char sig[4];			/* 'RTLD' */
@@ -3099,6 +3101,7 @@ do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
     SymLook req;
     RtldLockState lockstate;
     tls_index ti;
+    void *sym;
     int res;
 
     def = NULL;
@@ -3108,6 +3111,7 @@ do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
     req.flags = flags | SYMLOOK_IN_PLT;
     req.lockstate = &lockstate;
 
+    LD_UTRACE(UTRACE_DLSYM_START, handle, NULL, 0, 0, name);
     rlock_acquire(rtld_bind_lock, &lockstate);
     if (sigsetjmp(lockstate.env, 0) != 0)
 	    lock_upgrade(rtld_bind_lock, &lockstate);
@@ -3117,6 +3121,7 @@ do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
 	if ((obj = obj_from_addr(retaddr)) == NULL) {
 	    _rtld_error("Cannot determine caller's shared object");
 	    lock_release(rtld_bind_lock, &lockstate);
+	    LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
 	    return NULL;
 	}
 	if (handle == NULL) {	/* Just the caller's shared object. */
@@ -3164,6 +3169,7 @@ do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
     } else {
 	if ((obj = dlcheck(handle)) == NULL) {
 	    lock_release(rtld_bind_lock, &lockstate);
+	    LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
 	    return NULL;
 	}
 
@@ -3207,19 +3213,22 @@ do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
 	 * symbol.
 	 */
 	if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
-	    return (make_function_pointer(def, defobj));
+	    sym = make_function_pointer(def, defobj);
 	else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
-	    return (rtld_resolve_ifunc(defobj, def));
+	    sym = rtld_resolve_ifunc(defobj, def);
 	else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
 	    ti.ti_module = defobj->tlsindex;
 	    ti.ti_offset = def->st_value;
-	    return (__tls_get_addr(&ti));
+	    sym = __tls_get_addr(&ti);
 	} else
-	    return (defobj->relocbase + def->st_value);
+	    sym = defobj->relocbase + def->st_value;
+	LD_UTRACE(UTRACE_DLSYM_STOP, handle, sym, 0, 0, name);
+	return (sym);
     }
 
     _rtld_error("Undefined symbol \"%s\"", name);
     lock_release(rtld_bind_lock, &lockstate);
+    LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
     return NULL;
 }
 
diff --git a/usr.bin/kdump/kdump.c b/usr.bin/kdump/kdump.c
index 0daf7373cd19..b8e5903a0c8a 100644
--- a/usr.bin/kdump/kdump.c
+++ b/usr.bin/kdump/kdump.c
@@ -1531,6 +1531,8 @@ ktrcsw(struct ktr_csw *cs)
 #define	UTRACE_PRELOAD_FINISHED		8
 #define	UTRACE_INIT_CALL		9
 #define	UTRACE_FINI_CALL		10
+#define	UTRACE_DLSYM_START		11
+#define	UTRACE_DLSYM_STOP		12
 
 struct utrace_rtld {
 	char sig[4];				/* 'RTLD' */
@@ -1610,6 +1612,13 @@ ktruser_rtld(int len, void *p)
 		printf("RTLD: fini %p for %p (%s)\n", ut->mapbase, ut->handle,
 		    ut->name);
 		break;
+	case UTRACE_DLSYM_START:
+		printf("RTLD: dlsym(%p, %s)\n", ut->handle, ut->name);
+		break;
+	case UTRACE_DLSYM_STOP:
+		printf("RTLD: %p = dlsym(%p, %s)\n", ut->mapbase, ut->handle,
+		    ut->name);
+		break;
 	default:
 		cp = p;
 		cp += 4;