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-rw-r--r--elf/Makefile7
-rw-r--r--elf/dl-close.c2
-rw-r--r--elf/dl-debug-symbols.S36
-rw-r--r--elf/dl-debug.c81
-rw-r--r--elf/dl-load.c2
-rw-r--r--elf/dl-open.c10
-rw-r--r--elf/dl-reloc-static-pie.c2
-rw-r--r--elf/link.h35
-rw-r--r--elf/rtld-debugger-interface.txt15
-rw-r--r--elf/rtld.c4
-rw-r--r--elf/tst-dlmopen4.c72
11 files changed, 226 insertions, 40 deletions
diff --git a/elf/Makefile b/elf/Makefile
index 9f3fadc37e..835b85bd7c 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -35,7 +35,8 @@ dl-routines = $(addprefix dl-,load lookup object reloc deps \
execstack open close trampoline \
exception sort-maps lookup-direct \
call-libc-early-init write \
- thread_gscope_wait tls_init_tp)
+ thread_gscope_wait tls_init_tp \
+ debug-symbols)
ifeq (yes,$(use-ldconfig))
dl-routines += dl-cache
endif
@@ -203,7 +204,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-tls16 tst-tls17 tst-tls18 tst-tls19 tst-tls-dlinfo \
tst-align tst-align2 \
tst-dlmodcount tst-dlopenrpath tst-deep1 \
- tst-dlmopen1 tst-dlmopen3 \
+ tst-dlmopen1 tst-dlmopen3 tst-dlmopen4 \
unload3 unload4 unload5 unload6 unload7 unload8 tst-global1 order2 \
tst-audit1 tst-audit2 tst-audit8 tst-audit9 \
tst-addr1 tst-thrlock \
@@ -1244,6 +1245,8 @@ $(objpfx)tst-dlmopen2.out: $(objpfx)tst-dlmopen1mod.so
$(objpfx)tst-dlmopen3.out: $(objpfx)tst-dlmopen1mod.so
+$(objpfx)tst-dlmopen4.out: $(objpfx)tst-dlmopen1mod.so
+
$(objpfx)tst-audit1.out: $(objpfx)tst-auditmod1.so
tst-audit1-ENV = LD_AUDIT=$(objpfx)tst-auditmod1.so
diff --git a/elf/dl-close.c b/elf/dl-close.c
index f39001cab9..93ff5c96e9 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -500,7 +500,7 @@ _dl_close_worker (struct link_map *map, bool force)
#endif
/* Notify the debugger we are about to remove some loaded objects. */
- struct r_debug *r = _dl_debug_initialize (0, nsid);
+ struct r_debug *r = _dl_debug_update (nsid);
r->r_state = RT_DELETE;
_dl_debug_state ();
LIBC_PROBE (unmap_start, 2, nsid, r);
diff --git a/elf/dl-debug-symbols.S b/elf/dl-debug-symbols.S
new file mode 100644
index 0000000000..b7e9f5d947
--- /dev/null
+++ b/elf/dl-debug-symbols.S
@@ -0,0 +1,36 @@
+/* Define symbols used to communicate dynamic linker state to the
+ debugger at runtime.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <rtld-sizes.h>
+
+/* Define 2 symbols, _r_debug_extended and _r_debug, which is an alias
+ of _r_debug_extended, but with the size of struct r_debug. */
+
+ .globl _r_debug
+ .type _r_debug, %object
+ .size _r_debug, R_DEBUG_SIZE
+ .hidden _r_debug_extended
+ .globl _r_debug_extended
+ .type _r_debug_extended, %object
+ .size _r_debug_extended, R_DEBUG_EXTENDED_SIZE
+ .section .bss
+ .balign R_DEBUG_EXTENDED_ALIGN
+_r_debug:
+_r_debug_extended:
+ .zero R_DEBUG_EXTENDED_SIZE
diff --git a/elf/dl-debug.c b/elf/dl-debug.c
index 2cd5f09753..f637d4bb8d 100644
--- a/elf/dl-debug.c
+++ b/elf/dl-debug.c
@@ -30,37 +30,80 @@ extern const int verify_link_map_members[(VERIFY_MEMBER (l_addr)
&& VERIFY_MEMBER (l_prev))
? 1 : -1];
-/* This structure communicates dl state to the debugger. The debugger
- normally finds it via the DT_DEBUG entry in the dynamic section, but in
- a statically-linked program there is no dynamic section for the debugger
- to examine and it looks for this particular symbol name. */
-struct r_debug _r_debug;
+/* Update the `r_map' member and return the address of `struct r_debug'
+ of the namespace NS. */
+struct r_debug *
+_dl_debug_update (Lmid_t ns)
+{
+ struct r_debug_extended *r;
+ if (ns == LM_ID_BASE)
+ r = &_r_debug_extended;
+ else
+ r = &GL(dl_ns)[ns]._ns_debug;
+ if (r->base.r_map == NULL)
+ atomic_store_release (&r->base.r_map,
+ (void *) GL(dl_ns)[ns]._ns_loaded);
+ return &r->base;
+}
-/* Initialize _r_debug if it has not already been done. The argument is
- the run-time load address of the dynamic linker, to be put in
- _r_debug.r_ldbase. Returns the address of _r_debug. */
+/* Initialize _r_debug_extended for the namespace NS. LDBASE is the
+ run-time load address of the dynamic linker, to be put in
+ _r_debug_extended.r_ldbase. Return the address of _r_debug. */
struct r_debug *
_dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
{
- struct r_debug *r;
+ struct r_debug_extended *r, **pp = NULL;
if (ns == LM_ID_BASE)
- r = &_r_debug;
- else
- r = &GL(dl_ns)[ns]._ns_debug;
+ {
+ r = &_r_debug_extended;
+ /* Initialize r_version to 1. */
+ if (_r_debug_extended.base.r_version == 0)
+ _r_debug_extended.base.r_version = 1;
+ }
+ else if (DL_NNS > 1)
+ {
+ r = &GL(dl_ns)[ns]._ns_debug;
+ if (r->base.r_brk == 0)
+ {
+ /* Add the new namespace to the linked list. After a namespace
+ is initialized, r_brk becomes non-zero. A namespace becomes
+ empty (r_map == NULL) when it is unused. But it is never
+ removed from the linked list. */
+ struct r_debug_extended *p;
+ for (pp = &_r_debug_extended.r_next;
+ (p = *pp) != NULL;
+ pp = &p->r_next)
+ ;
+
+ r->base.r_version = 2;
+ }
+ }
+
+ if (r->base.r_brk == 0)
+ {
+ /* Tell the debugger where to find the map of loaded objects.
+ This function is called from dlopen. Initialize the namespace
+ only once. */
+ r->base.r_ldbase = ldbase ?: _r_debug_extended.base.r_ldbase;
+ r->base.r_brk = (ElfW(Addr)) &_dl_debug_state;
+ r->r_next = NULL;
+ }
+
+ if (r->base.r_map == NULL)
+ atomic_store_release (&r->base.r_map,
+ (void *) GL(dl_ns)[ns]._ns_loaded);
- if (r->r_map == NULL || ldbase != 0)
+ if (pp != NULL)
{
- /* Tell the debugger where to find the map of loaded objects. */
- r->r_version = 1 /* R_DEBUG_VERSION XXX */;
- r->r_ldbase = ldbase ?: _r_debug.r_ldbase;
- r->r_map = (void *) GL(dl_ns)[ns]._ns_loaded;
- r->r_brk = (ElfW(Addr)) &_dl_debug_state;
+ atomic_store_release (pp, r);
+ /* Bump r_version to 2 for the new namespace. */
+ atomic_store_release (&_r_debug_extended.base.r_version, 2);
}
- return r;
+ return &r->base;
}
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 650e4edc35..39e0d074b4 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -949,7 +949,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
/* Initialize to keep the compiler happy. */
const char *errstring = NULL;
int errval = 0;
- struct r_debug *r = _dl_debug_initialize (0, nsid);
+ struct r_debug *r = _dl_debug_update (nsid);
bool make_consistent = false;
/* Get file information. To match the kernel behavior, do not fill
diff --git a/elf/dl-open.c b/elf/dl-open.c
index ec386626f9..a25443f6d1 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -574,7 +574,7 @@ dl_open_worker (void *a)
if ((mode & RTLD_GLOBAL) && new->l_global == 0)
add_to_global_update (new);
- assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
+ assert (_dl_debug_update (args->nsid)->r_state == RT_CONSISTENT);
return;
}
@@ -630,7 +630,7 @@ dl_open_worker (void *a)
#endif
/* Notify the debugger all new objects are now ready to go. */
- struct r_debug *r = _dl_debug_initialize (0, args->nsid);
+ struct r_debug *r = _dl_debug_update (args->nsid);
r->r_state = RT_CONSISTENT;
_dl_debug_state ();
LIBC_PROBE (map_complete, 3, args->nsid, r, new);
@@ -830,7 +830,7 @@ no more namespaces available for dlmopen()"));
++GL(dl_nns);
}
- _dl_debug_initialize (0, nsid)->r_state = RT_CONSISTENT;
+ _dl_debug_update (nsid)->r_state = RT_CONSISTENT;
}
/* Never allow loading a DSO in a namespace which is empty. Such
direct placements is only causing problems. Also don't allow
@@ -899,7 +899,7 @@ no more namespaces available for dlmopen()"));
the flag here. */
}
- assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
+ assert (_dl_debug_update (args.nsid)->r_state == RT_CONSISTENT);
/* Release the lock. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
@@ -908,7 +908,7 @@ no more namespaces available for dlmopen()"));
_dl_signal_exception (errcode, &exception, NULL);
}
- assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
+ assert (_dl_debug_update (args.nsid)->r_state == RT_CONSISTENT);
/* Release the lock. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
diff --git a/elf/dl-reloc-static-pie.c b/elf/dl-reloc-static-pie.c
index d5bd2f31e9..289651b341 100644
--- a/elf/dl-reloc-static-pie.c
+++ b/elf/dl-reloc-static-pie.c
@@ -51,7 +51,7 @@ _dl_relocate_static_pie (void)
ELF_DYNAMIC_RELOCATE (main_map, 0, 0, 0);
main_map->l_relocated = 1;
- /* Initialize _r_debug. */
+ /* Initialize _r_debug_extended. */
struct r_debug *r = _dl_debug_initialize (0, LM_ID_BASE);
r->r_state = RT_CONSISTENT;
diff --git a/elf/link.h b/elf/link.h
index ff3a85c847..200d40c9c6 100644
--- a/elf/link.h
+++ b/elf/link.h
@@ -34,14 +34,13 @@
#include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */
#include <bits/link.h>
-/* Rendezvous structure used by the run-time dynamic linker to communicate
- details of shared object loading to the debugger. If the executable's
- dynamic section has a DT_DEBUG element, the run-time linker sets that
- element's value to the address where this structure can be found. */
+/* The legacy rendezvous structure used by the run-time dynamic linker to
+ communicate details of shared object loading to the debugger. */
struct r_debug
{
- int r_version; /* Version number for this protocol. */
+ /* Version number for this protocol. It should be greater than 0. */
+ int r_version;
struct link_map *r_map; /* Head of the chain of loaded objects. */
@@ -63,16 +62,34 @@ struct r_debug
ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */
};
-/* This is the instance of that structure used by the dynamic linker. */
+/* This is the symbol of that structure provided by the dynamic linker. */
extern struct r_debug _r_debug;
+/* The extended rendezvous structure used by the run-time dynamic linker
+ to communicate details of shared object loading to the debugger. If
+ the executable's dynamic section has a DT_DEBUG element, the run-time
+ linker sets that element's value to the address where this structure
+ can be found. */
+
+struct r_debug_extended
+ {
+ struct r_debug base;
+
+ /* The following field is added by r_version == 2. */
+
+ /* Link to the next r_debug_extended structure. Each r_debug_extended
+ structure represents a different namespace. The first
+ r_debug_extended structure is for the default namespace. */
+ struct r_debug_extended *r_next;
+ };
+
/* This symbol refers to the "dynamic structure" in the `.dynamic' section
of whatever module refers to `_DYNAMIC'. So, to find its own
- `struct r_debug', a program could do:
+ `struct r_debug_extended', a program could do:
for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn)
if (dyn->d_tag == DT_DEBUG)
- r_debug = (struct r_debug *) dyn->d_un.d_ptr;
- */
+ r_debug_extended = (struct r_debug_extended *) dyn->d_un.d_ptr;
+ */
extern ElfW(Dyn) _DYNAMIC[];
/* Structure describing a loaded shared object. The `l_next' and `l_prev'
diff --git a/elf/rtld-debugger-interface.txt b/elf/rtld-debugger-interface.txt
index 61bc99e4b0..f3476d8308 100644
--- a/elf/rtld-debugger-interface.txt
+++ b/elf/rtld-debugger-interface.txt
@@ -9,6 +9,9 @@ structure can be found.
The r_debug structure contains (amongst others) the following fields:
+ int r_version:
+ Version number for this protocol. It should be greater than 0.
+
struct link_map *r_map:
A linked list of loaded objects.
@@ -32,6 +35,18 @@ but there is no way for the debugger to discover whether any of the
objects in the link-map have been relocated or not.
+Extension to the r_debug structure
+==================================
+
+The r_debug_extended structure is an extension of the r_debug interface.
+If r_version is 2, one additional field is available:
+
+ struct r_debug_extended *r_next;
+ Link to the next r_debug_extended structure. Each r_debug_extended
+ structure represents a different namespace. A namespace is active
+ if its r_map field isn't NULL. The first r_debug_extended structure
+ is for the default namespace.
+
Probe-based debugger interface
==============================
diff --git a/elf/rtld.c b/elf/rtld.c
index 878e6480f4..742c413c48 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1660,7 +1660,7 @@ dl_main (const ElfW(Phdr) *phdr,
objects. */
call_init_paths (&state);
- /* Initialize _r_debug. */
+ /* Initialize _r_debug_extended. */
struct r_debug *r = _dl_debug_initialize (GL(dl_rtld_map).l_addr,
LM_ID_BASE);
r->r_state = RT_CONSISTENT;
@@ -2491,7 +2491,7 @@ dl_main (const ElfW(Phdr) *phdr,
/* Notify the debugger all new objects are now ready to go. We must re-get
the address since by now the variable might be in another object. */
- r = _dl_debug_initialize (0, LM_ID_BASE);
+ r = _dl_debug_update (LM_ID_BASE);
r->r_state = RT_CONSISTENT;
_dl_debug_state ();
LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
diff --git a/elf/tst-dlmopen4.c b/elf/tst-dlmopen4.c
new file mode 100644
index 0000000000..3fe150e50b
--- /dev/null
+++ b/elf/tst-dlmopen4.c
@@ -0,0 +1,72 @@
+/* Test struct r_debug_extended via DT_DEBUG.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <link.h>
+#include <stdlib.h>
+#include <string.h>
+#include <gnu/lib-names.h>
+#include <support/xdlfcn.h>
+#include <support/check.h>
+#include <support/test-driver.h>
+
+#ifndef ELF_MACHINE_GET_R_DEBUG
+# define ELF_MACHINE_GET_R_DEBUG(d) \
+ (__extension__ ({ \
+ struct r_debug_extended *debug; \
+ if ((d)->d_tag == DT_DEBUG) \
+ debug = (struct r_debug_extended *) (d)->d_un.d_ptr; \
+ else \
+ debug = NULL; \
+ debug; }))
+#endif
+
+static int
+do_test (void)
+{
+ ElfW(Dyn) *d;
+ struct r_debug_extended *debug = NULL;
+
+ for (d = _DYNAMIC; d->d_tag != DT_NULL; ++d)
+ {
+ debug = ELF_MACHINE_GET_R_DEBUG (d);
+ if (debug != NULL)
+ break;
+ }
+
+ TEST_VERIFY_EXIT (debug != NULL);
+ TEST_COMPARE (debug->base.r_version, 1);
+ TEST_VERIFY_EXIT (debug->r_next == NULL);
+
+ void *h = xdlmopen (LM_ID_NEWLM, "$ORIGIN/tst-dlmopen1mod.so",
+ RTLD_LAZY);
+
+ TEST_COMPARE (debug->base.r_version, 2);
+ TEST_VERIFY_EXIT (debug->r_next != NULL);
+ TEST_VERIFY_EXIT (debug->r_next->r_next == NULL);
+ TEST_VERIFY_EXIT (debug->r_next->base.r_map != NULL);
+ TEST_VERIFY_EXIT (debug->r_next->base.r_map->l_name != NULL);
+ const char *name = basename (debug->r_next->base.r_map->l_name);
+ TEST_COMPARE_STRING (name, "tst-dlmopen1mod.so");
+
+ xdlclose (h);
+
+ return 0;
+}
+
+#include <support/test-driver.c>
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-20 04:36:46 +0000