+2012-07-27 Gary Benson <gbenson@redhat.com>
+
+ [BZ #14298]
+ * elf/rtld.c: Include <stap-probe.h>.
+ (dl_main): Added static probes "init_start" and "init_complete".
+ * elf/dl-load.c: Include <stap-probe.h>.
+ (lose): Take new parameter "nsid".
+ Added static probe "map_failed".
+ (_dl_map_object_from_fd): Pass namespace id to lose.
+ Added static probe "map_start".
+ (open_verify): Pass namespace id to lose.
+ * elf/dl-open.c: Include <stap-probe.h>.
+ (dl_open_worker) Added static probes "map_complete", "reloc_start"
+ and "reloc_complete".
+ * elf/dl-close.c: Include <stap-probe.h>.
+ (_dl_close_worker): Added static probes "unmap_start" and
+ "unmap_complete".
+ * elf/rtld-debugger-interface.txt: New file documenting the above.
+
2012-07-26 Roland McGrath <roland@hack.frob.com>
* sunrpc/rpc_hout.c (pdeclaration): Call f_print with a "%s" format
* The following bugs are resolved with this release:
- 6778, 6808, 14042, 14151, 14154, 14157, 14173, 14283, 14328, 14331, 14337,
- 14347, 14349
+ 6778, 6808, 14042, 14151, 14154, 14157, 14173, 14283, 14298, 14328, 14331,
+ 14337, 14347, 14349
* Support for STT_GNU_IFUNC symbols added for s390 and s390x.
Optimized versions of memcpy, memset, and memcmp added for System z10 and
returning NULL if running in a SUID/SGID process. This function replaces
the internal function __secure_getenv.
+* SystemTap static probes have been added into the dynamic linker.
+ Implemented by Gary Benson.
+
\f
Version 2.16
#include <sys/mman.h>
#include <sysdep-cancel.h>
#include <tls.h>
+#include <stap-probe.h>
/* Type of the constructor functions. */
struct r_debug *r = _dl_debug_initialize (0, nsid);
r->r_state = RT_DELETE;
_dl_debug_state ();
+ LIBC_PROBE (unmap_start, 2, nsid, r);
if (unload_global)
{
/* Notify the debugger those objects are finalized and gone. */
r->r_state = RT_CONSISTENT;
_dl_debug_state ();
+ LIBC_PROBE (unmap_complete, 2, nsid, r);
/* Recheck if we need to retry, release the lock. */
out:
#include <stackinfo.h>
#include <caller.h>
#include <sysdep.h>
+#include <stap-probe.h>
#include <dl-dst.h>
static void
__attribute__ ((noreturn, noinline))
lose (int code, int fd, const char *name, char *realname, struct link_map *l,
- const char *msg, struct r_debug *r)
+ const char *msg, struct r_debug *r, Lmid_t nsid)
{
/* The file might already be closed. */
if (fd != -1)
{
r->r_state = RT_CONSISTENT;
_dl_debug_state ();
+ LIBC_PROBE (map_failed, 2, nsid, r);
}
_dl_signal_error (code, name, NULL, msg);
errval = errno;
call_lose:
lose (errval, fd, name, realname, l, errstring,
- make_consistent ? r : NULL);
+ make_consistent ? r : NULL, nsid);
}
/* Look again to see if the real name matched another already loaded. */
linking has not been used before. */
r->r_state = RT_ADD;
_dl_debug_state ();
+ LIBC_PROBE (map_start, 2, nsid, r);
make_consistent = true;
}
else
name = strdupa (realname);
free (realname);
}
- lose (errval, fd, name, NULL, NULL, errstring, NULL);
+ lose (errval, fd, name, NULL, NULL, errstring, NULL, 0);
}
/* See whether the ELF header is what we expect. */
#include <caller.h>
#include <sysdep-cancel.h>
#include <tls.h>
+#include <stap-probe.h>
#include <dl-dst.h>
struct r_debug *r = _dl_debug_initialize (0, args->nsid);
r->r_state = RT_CONSISTENT;
_dl_debug_state ();
+ LIBC_PROBE (map_complete, 3, args->nsid, r, new);
/* Print scope information. */
if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES, 0))
}
}
+ int relocation_in_progress = 0;
+
for (size_t i = nmaps; i-- > 0; )
{
l = maps[i];
+ if (! relocation_in_progress)
+ {
+ /* Notify the debugger that relocations are about to happen. */
+ LIBC_PROBE (reloc_start, 2, args->nsid, r);
+ relocation_in_progress = 1;
+ }
+
#ifdef SHARED
if (__builtin_expect (GLRO(dl_profile) != NULL, 0))
{
}
}
+ /* Notify the debugger all new objects have been relocated. */
+ if (relocation_in_progress)
+ LIBC_PROBE (reloc_complete, 3, args->nsid, r, new);
+
/* Run the initializer functions of new objects. */
_dl_init (new, args->argc, args->argv, args->env);
--- /dev/null
+Standard debugger interface
+===========================
+
+The run-time linker exposes a rendezvous structure to allow debuggers
+to interface with it. This structure, r_debug, is defined in link.h.
+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 r_debug structure contains (amongst others) the following fields:
+
+ struct link_map *r_map:
+ A linked list of loaded objects.
+
+ enum { RT_CONSISTENT, RT_ADD, RT_DELETE } r_state:
+ The current state of the r_map list. RT_CONSISTENT means that r_map
+ is not currently being modified and may safely be inspected. RT_ADD
+ means that an object is being added to r_map, and that the list is
+ not guaranteed to be consistent. Likewise RT_DELETE means that an
+ object is being removed from the list.
+
+ ElfW(Addr) r_brk:
+ The address of a function internal to the run-time linker which is
+ called whenever r_state is changed. The debugger should set a
+ breakpoint at this address if it wants to notice mapping changes.
+
+This protocol is widely supported, but somewhat limited in that it
+has no provision to provide access to multiple namespaces, and that
+the notifications (via r_brk) only refer to changes to r_map--the
+debugger is notified that a new object has been added, for instance,
+but there is no way for the debugger to discover whether any of the
+objects in the link-map have been relocated or not.
+
+
+Probe-based debugger interface
+==============================
+
+Systemtap is a dynamic tracing/instrumenting tool available on Linux.
+Probes that are not fired at run time have close to zero overhead.
+glibc contains a number of probes that debuggers can set breakpoints
+on in order to notice certain events.
+
+All rtld probes have the following arguments:
+
+ arg1: Lmid_t lmid:
+ The link-map ID of the link-map list that the object was loaded
+ into. This will be LM_ID_BASE for the application's main link-map
+ list, or some other value for different namespaces.
+
+ arg2: struct r_debug *r_debug:
+ A pointer to the r_debug structure containing the link-map list
+ that the object was loaded into. This will be the value stored in
+ DT_DEBUG for the application's main link-map list, or some other
+ value for different namespaces.
+
+map_complete and reloc_complete may have the following additional
+argument:
+
+ arg3: struct link_map *new:
+ A pointer which, if not NULL, points to the entry in the specified
+ r_debug structure's link-map list corresponding to the first new
+ object to have been mapped or relocated, with new->l_next pointing
+ to the link-map of the next new object to have been mapped or
+ relocated, and so on. Note that because `new' is an entry in a
+ larger list, new->l_prev (if not NULL) will point to what was the
+ last link-map in the link-map list prior to the new objects being
+ mapped or relocated.
+
+The following probes are available:
+
+ init_start:
+ This is called once, when the linker is about to fill in the main
+ r_debug structure at application startup. init_start always has
+ lmid set to LM_ID_BASE and r_debug set to the value stored in
+ DT_DEBUG. r_debug is not guaranteed to be consistent until
+ init_complete is fired.
+
+ init_complete:
+ This is called once, when the linker has filled in the main
+ r_debug structure at application startup. init_complete always
+ has lmid set to LM_ID_BASE and r_debug set to the value stored
+ in DT_DEBUG. The r_debug structure is consistent and may be
+ inspected, and all objects in the link-map are guaranteed to
+ have been relocated.
+
+ map_start:
+ The linker is about to map new objects into the specified
+ namespace. The namespace's r_debug structure is not guaranteed
+ to be consistent until a corresponding map_complete is fired.
+
+ map_complete:
+ The linker has finished mapping new objects into the specified
+ namespace. The namespace's r_debug structure is consistent and
+ may be inspected, although objects in the namespace's link-map
+ are not guaranteed to have been relocated.
+
+ map_failed:
+ The linker failed while attempting to map new objects into
+ the specified namespace. The namespace's r_debug structure
+ is consistent and may be inspected.
+
+ reloc_start:
+ The linker is about to relocate all unrelocated objects in the
+ specified namespace. The namespace's r_debug structure is not
+ guaranteed to be consistent until a corresponding reloc_complete
+ is fired.
+
+ reloc_complete:
+ The linker has relocated all objects in the specified namespace.
+ The namespace's r_debug structure is consistent and may be
+ inspected, and all objects in the namespace's link-map are
+ guaranteed to have been relocated.
+
+ unmap_start:
+ The linker is about to remove objects from the specified
+ namespace. The namespace's r_debug structure is not guaranteed to
+ be consistent until a corresponding unmap_complete is fired.
+
+ unmap_complete:
+ The linker has finished removing objects into the specified
+ namespace. The namespace's r_debug structure is consistent and
+ may be inspected.
#include <dl-osinfo.h>
#include <dl-procinfo.h>
#include <tls.h>
+#include <stap-probe.h>
#include <stackinfo.h>
#include <assert.h>
/* We start adding objects. */
r->r_state = RT_ADD;
_dl_debug_state ();
+ LIBC_PROBE (init_start, 2, LM_ID_BASE, r);
/* Auditing checkpoint: we are ready to signal that the initial map
is being constructed. */
r = _dl_debug_initialize (0, LM_ID_BASE);
r->r_state = RT_CONSISTENT;
_dl_debug_state ();
+ LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
#ifndef MAP_COPY
/* We must munmap() the cache file. */
projects / platform / upstream / glibc.git / commitdiff