Restore the binary compatibility for link_map l_addr.

Keep link_map l_addr binary layout compatible, rename l_addr to l_base
where rtld returns map base.  Provide relocbase in newly added l_addr.

This effectively reverts the patch to the initial version of D24918.

Reported by: antoine (portmgr)
Reviewed by:	jhb, markj
Tested by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D24946

4 files changed, 19 insertions, 8 deletions

diff --git a/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c b/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c
index cd9294998454a..836eeccb8274a 100644
--- a/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c
+++ b/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c
@@ -143,12 +143,18 @@ dtrace_dof_init(void)
 		return;
 	}
 
+#ifdef __FreeBSD__
+	elf = (void *)lmp->l_base;
+#else
 	elf = (void *)lmp->l_addr;
+#endif
 
 	dh.dofhp_dof = (uintptr_t)dof;
-	dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
 #ifdef __FreeBSD__
+	dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_base : 0;
 	dh.dofhp_pid = getpid();
+#else
+	dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
 #endif
 
 	if (lmid == 0) {
diff --git a/lib/libc/gen/dlinfo.3 b/lib/libc/gen/dlinfo.3
index 7a6551dfe9ee2..a801b0bd005d3 100644
--- a/lib/libc/gen/dlinfo.3
+++ b/lib/libc/gen/dlinfo.3
@@ -105,17 +105,16 @@ structure is defined in
 .In link.h
 and has the following members:
 .Bd -literal -offset indent
-caddr_t         l_addr;    /* Load Offset of library */
+caddr_t         l_base;    /* Base Address of library */
 const char      *l_name;   /* Absolute Path to Library */
 const void      *l_ld;     /* Pointer to .dynamic in memory */
 struct link_map *l_next,   /* linked list of mapped libs */
                 *l_prev;
+caddr_t         l_addr;     /* Load Offset of library */
 .Ed
 .Bl -tag -width ".Va l_addr"
-.It Va l_addr
-The load offset of the object, that is, the difference between
-the actual load address and the base virtual address the object
-was linked at.
+.It Va l_base
+The base address of the object loaded into memory.
 .It Va l_name
 The full name of the loaded shared object.
 .It Va l_ld
@@ -130,6 +129,10 @@ structure on the link-map list.
 The previous
 .Vt Link_map
 structure on the link-map list.
+.It Va l_addr
+The load offset of the object, that is, the difference between
+the actual load address and the base virtual address the object
+was linked at.
 .El
 .It Dv RTLD_DI_SERINFO
 Retrieve the library search paths associated with the given
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 1af83f5dc18a3..1799d1893d281 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -4032,8 +4032,9 @@ linkmap_add(Obj_Entry *obj)
     struct link_map *prev;
 
     obj->linkmap.l_name = obj->path;
-    obj->linkmap.l_addr = obj->relocbase;
+    obj->linkmap.l_base = obj->mapbase;
     obj->linkmap.l_ld = obj->dynamic;
+    obj->linkmap.l_addr = obj->relocbase;
 
     if (r_debug.r_map == NULL) {
 	r_debug.r_map = l;
diff --git a/sys/sys/link_elf.h b/sys/sys/link_elf.h
index 52ef4c84ea07a..7ea1b4e69ebcd 100644
--- a/sys/sys/link_elf.h
+++ b/sys/sys/link_elf.h
@@ -57,13 +57,14 @@
 #define	LA_SER_SECURE	0x80	/* default (secure) path prepended */
 
 typedef struct link_map {
-	caddr_t		l_addr;			/* Load Offset of library */
+	caddr_t		l_base;			/* Base Address of library */
 #ifdef __mips__
 	caddr_t		l_xxx;			/* unused */
 #endif
 	const char	*l_name;		/* Absolute Path to Library */
 	const void	*l_ld;			/* Pointer to .dynamic in memory */
 	struct link_map	*l_next, *l_prev;	/* linked list of of mapped libs */
+	caddr_t		l_addr;			/* Load Offset of library */
 } Link_map;
 
 struct r_debug {