Author: kib
Date: Wed May 27 21:56:45 2020
New Revision: 361564
URL: https://svnweb.freebsd.org/changeset/base/361564
Log:
MFC r361303, r361349, r361394, r361398, r361537:
Change link_map::l_addr to mean load offset in ABI-compatible way.
Add link_map::l_refname.
Add rtld feature indicators.
Modified:
stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c
stable/12/lib/libc/gen/dlinfo.3
stable/12/libexec/rtld-elf/Symbol.map
stable/12/libexec/rtld-elf/rtld.1
stable/12/libexec/rtld-elf/rtld.c
stable/12/sys/sys/link_elf.h
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c
==============================================================================
--- stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c Wed May
27 21:44:26 2020 (r361563)
+++ stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c Wed May
27 21:56:45 2020 (r361564)
@@ -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) {
Modified: stable/12/lib/libc/gen/dlinfo.3
==============================================================================
--- stable/12/lib/libc/gen/dlinfo.3 Wed May 27 21:44:26 2020
(r361563)
+++ stable/12/lib/libc/gen/dlinfo.3 Wed May 27 21:56:45 2020
(r361564)
@@ -25,7 +25,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd February 14, 2003
+.Dd May 21, 2020
.Dt DLINFO 3
.Os
.Sh NAME
@@ -105,14 +105,16 @@ structure is defined in
.In link.h
and has the following members:
.Bd -literal -offset indent
-caddr_t l_addr; /* Base Address 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 */
+const char *l_refname; /* Object this one filters for */
.Ed
.Bl -tag -width ".Va l_addr"
-.It Va l_addr
+.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.
@@ -128,6 +130,15 @@ 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.
+.It Va l_refname
+A name of the object this object filters for, if any.
+If there are more then one filtee, a name from the first
+.Dv DT_FILTER
+dynamic entry is supplied.
.El
.It Dv RTLD_DI_SERINFO
Retrieve the library search paths associated with the given
Modified: stable/12/libexec/rtld-elf/Symbol.map
==============================================================================
--- stable/12/libexec/rtld-elf/Symbol.map Wed May 27 21:44:26 2020
(r361563)
+++ stable/12/libexec/rtld-elf/Symbol.map Wed May 27 21:56:45 2020
(r361564)
@@ -32,4 +32,6 @@ FBSDprivate_1.0 {
_rtld_get_stack_prot;
_rtld_is_dlopened;
_r_debug_postinit;
+ _rtld_version__FreeBSD_version;
+ _rtld_version_laddr_offset;
};
Modified: stable/12/libexec/rtld-elf/rtld.1
==============================================================================
--- stable/12/libexec/rtld-elf/rtld.1 Wed May 27 21:44:26 2020
(r361563)
+++ stable/12/libexec/rtld-elf/rtld.1 Wed May 27 21:56:45 2020
(r361564)
@@ -355,6 +355,54 @@ ignores
and is naturally prone to race conditions.
Environments which rely on such restrictions are weak
and breakable on their own.
+.Sh VERSIONING
+Newer
+.Nm
+might provide some features or changes in runtime behavior that cannot be
+easily detected at runtime by checking of the normal exported symbols.
+Note that it is almost always wrong to verify
+.Dv __FreeBSD_version
+in userspace to detect features, either at compile or at run time,
+because either kernel, or libc, or environment variables could not
+match the running
+.Nm .
+.Pp
+To solve the problem,
+.Nm
+exports some feature indicators in the
+.Fx
+private symbols namespace
+.Dv FBSDprivate_1.0 .
+Symbols start with the
+.Dv _rtld_version
+prefix.
+Current list of defined symbols and corresponding features is:
+.Bl -tag -width indent
+.It Dv _rtld_version__FreeBSD_version
+Symbol exports the value of the
+.Dv __FreeBSD_version
+definition as it was provided during the
+.Nm
+build.
+The symbol is always present since the
+.Dv _rtld_version
+facility was introduced.
+.It Dv _rtld_version_laddr_offset
+The
+.Va l_addr
+member of the
+.Vt link_map
+structure contains the load offset of the shared object.
+Before that,
+.Va l_addr
+contained the base address of the library.
+See
+.Xr dlinfo 3 .
+.Pp
+Also it indicates the presence of
+.Va l_refname
+member of the structure.
+.El
.Sh FILES
.Bl -tag -width ".Pa /var/run/ld-elf32.so.hints" -compact
.It Pa /var/run/ld-elf.so.hints
@@ -369,6 +417,7 @@ The libmap configuration file for 32-bit binaries on 6
.Sh SEE ALSO
.Xr ld 1 ,
.Xr ldd 1 ,
+.Xr dlinfo 3 ,
.Xr capsicum 4 ,
.Xr elf 5 ,
.Xr libmap.conf 5 ,
Modified: stable/12/libexec/rtld-elf/rtld.c
==============================================================================
--- stable/12/libexec/rtld-elf/rtld.c Wed May 27 21:44:26 2020
(r361563)
+++ stable/12/libexec/rtld-elf/rtld.c Wed May 27 21:56:45 2020
(r361564)
@@ -1171,6 +1171,9 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_D
*needed_filtees_tail = nep;
needed_filtees_tail = &nep->next;
+
+ if (obj->linkmap.l_refname == NULL)
+ obj->linkmap.l_refname = (char *)dynp->d_un.d_val;
}
break;
@@ -1353,6 +1356,10 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_D
}
obj->dynsymcount += obj->symndx_gnu;
}
+
+ if (obj->linkmap.l_refname != NULL)
+ obj->linkmap.l_refname = obj->strtab + (unsigned long)obj->
+ linkmap.l_refname;
}
static bool
@@ -3981,52 +3988,50 @@ rtld_dirname_abs(const char *path, char *base)
static void
linkmap_add(Obj_Entry *obj)
{
- struct link_map *l = &obj->linkmap;
- struct link_map *prev;
+ struct link_map *l, *prev;
- obj->linkmap.l_name = obj->path;
- obj->linkmap.l_addr = obj->mapbase;
- obj->linkmap.l_ld = obj->dynamic;
-#ifdef __mips__
- /* GDB needs load offset on MIPS to use the symbols */
- obj->linkmap.l_offs = obj->relocbase;
-#endif
+ l = &obj->linkmap;
+ l->l_name = obj->path;
+ l->l_base = obj->mapbase;
+ l->l_ld = obj->dynamic;
+ l->l_addr = obj->relocbase;
- if (r_debug.r_map == NULL) {
- r_debug.r_map = l;
- return;
- }
+ if (r_debug.r_map == NULL) {
+ r_debug.r_map = l;
+ return;
+ }
- /*
- * Scan to the end of the list, but not past the entry for the
- * dynamic linker, which we want to keep at the very end.
- */
- for (prev = r_debug.r_map;
- prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
- prev = prev->l_next)
- ;
+ /*
+ * Scan to the end of the list, but not past the entry for the
+ * dynamic linker, which we want to keep at the very end.
+ */
+ for (prev = r_debug.r_map;
+ prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
+ prev = prev->l_next)
+ ;
- /* Link in the new entry. */
- l->l_prev = prev;
- l->l_next = prev->l_next;
- if (l->l_next != NULL)
- l->l_next->l_prev = l;
- prev->l_next = l;
+ /* Link in the new entry. */
+ l->l_prev = prev;
+ l->l_next = prev->l_next;
+ if (l->l_next != NULL)
+ l->l_next->l_prev = l;
+ prev->l_next = l;
}
static void
linkmap_delete(Obj_Entry *obj)
{
- struct link_map *l = &obj->linkmap;
+ struct link_map *l;
- if (l->l_prev == NULL) {
- if ((r_debug.r_map = l->l_next) != NULL)
- l->l_next->l_prev = NULL;
- return;
- }
+ l = &obj->linkmap;
+ if (l->l_prev == NULL) {
+ if ((r_debug.r_map = l->l_next) != NULL)
+ l->l_next->l_prev = NULL;
+ return;
+ }
- if ((l->l_prev->l_next = l->l_next) != NULL)
- l->l_next->l_prev = l->l_prev;
+ if ((l->l_prev->l_next = l->l_next) != NULL)
+ l->l_next->l_prev = l->l_prev;
}
/*
@@ -5775,3 +5780,9 @@ realloc(void *cp, size_t nbytes)
return (__crt_realloc(cp, nbytes));
}
+
+extern int _rtld_version__FreeBSD_version __exported;
+int _rtld_version__FreeBSD_version = __FreeBSD_version;
+
+extern char _rtld_version_laddr_offset __exported;
+char _rtld_version_laddr_offset;
Modified: stable/12/sys/sys/link_elf.h
==============================================================================
--- stable/12/sys/sys/link_elf.h Wed May 27 21:44:26 2020
(r361563)
+++ stable/12/sys/sys/link_elf.h Wed May 27 21:56:45 2020
(r361564)
@@ -57,13 +57,15 @@
#define LA_SER_SECURE 0x80 /* default (secure) path prepended */
typedef struct link_map {
- caddr_t l_addr; /* Base Address of library */
+ caddr_t l_base; /* Base Address of library */
#ifdef __mips__
- caddr_t l_offs; /* Load Offset of library */
+ 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 */
+ const char *l_refname; /* object we are filtering for
*/
} Link_map;
struct r_debug {
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