Commit Graph

90 Commits

Author SHA1 Message Date
kib
cafa79dcef Remove Obj_Entry textsize member.
It is unused after r340102, and more important, I do not see how to
define textsize in both practically useful and correct way, for binaries
with more that one executable segments.

Sponsored by:	The FreeBSD Foundation
2018-11-04 00:32:28 +00:00
arichardson
b885decb3c rtld-elf: compile with WANRS=4 warnings other than -Wcast-align
Reviewed By:	kib
Approved By:	brooks (mentor)
Differential Revision: https://reviews.freebsd.org/D17153
2018-10-29 21:08:19 +00:00
arichardson
ea67da5f83 rtld-elf: make it compile with WARNS=3
Reviewed By:	kib
Approved By:	brooks (mentor)
Differential Revision: https://reviews.freebsd.org/D17150
2018-10-29 21:08:11 +00:00
marius
d9ac9c210e o Let rtld(1) set up psABI user trap handlers prior to executing the
objects' init functions instead of doing the setup via a constructor
  in libc as the init functions may already depend on these handlers
  to be in place. This gets us rid of:
  - the undefined order in which libc constructors as __guard_setup()
    and jemalloc_constructor() are executed WRT __sparc_utrap_setup(),
  - the requirement to link libc last so __sparc_utrap_setup() gets
    called prior to constructors in other libraries (see r122883).
  For static binaries, crt1.o still sets up the user trap handlers.
o Move misplaced prototypes for MD functions in to the MD prototype
  section of rtld.h.
o Sprinkle nitems().
2018-02-03 23:14:11 +00:00
pfg
fab328f17f libexec: adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.
2017-11-27 15:25:02 +00:00
jhb
3783785a2f Handle relocations for newer non-PIC MIPS ABI.
Newer binutils supports extensions to the MIPS ABI for non-PIC code
that is used when compiling O32 binaries with clang 5 (but not used
for N64 oddly enough).  These extensions require support for
R_MIPS_COPY relocations as well as a second PLT GOT using
R_MIPS_JUMP_SLOT relocations.

For R_MIPS_COPY, use the same approach as on other architectures where
fixups are deferred to the MD do_copy_relocations.

The additional PLT GOT for jump slots is located in a .got.plt section
which is identified by a DT_MIPS_PLTGOT dynamic entry.  This GOT also
requires fixups for the first two GOT entries just as the normal GOT.
However, the entry point for this second GOT uses a different calling
convention. Rather than passing an offset into the GOT, it passes an
offset into the .rel.plt section.  This requires a second entry point
(_rtld_pltbind_start) which calls the normal _rtld_bind() rather than
_mips_rtld_bind().  This also means providing a real version of
reloc_jmpslot() which is used by _rtld_bind().

In addition, add real implementions of reloc_plt() and
reloc_jmpslots() which walk .rel.plt handling R_MIPS_JUMP_SLOT
relocations.

Reviewed by:	kib
Sponsored by:	DARPA / AFRL
Differential Revision:	https://reviews.freebsd.org/D12326
2017-09-12 17:46:30 +00:00
kib
3d8511bbc4 Implement LD_BIND_NOT knob for rtld.
From the manpage:
When set to a nonempty string, prevents modifications of the PLT slots
when doing bindings.  As result, each call of the PLT-resolved
function is resolved.  In combination with debug output, this provides
complete account of all bind actions at runtime.

Same feature exists on Linux and Solaris.

Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2017-03-15 21:11:57 +00:00
markj
3ff2e66ecb rtld: Ensure that dlopen() cannot obtain a reference on a doomed object.
rtld drops the bind lock to call fini functions in an object prior to
unmapping it. The new "doomed" state flag prevents the acquisition of new
references for an object while the lock is dropped.

Reviewed by:	kib
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
2016-12-22 17:41:32 +00:00
markj
adc0aca204 rtld: Fix a race between dl_iterate_phdr() and dlclose().
Add a transient reference count to ensure that the phdr argument to the
callback remains valid while the bind lock is dropped.

Reviewed by:	kib
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
2016-12-22 17:37:39 +00:00
kib
df6afadf79 Adjust r308689 to make rtld compilable with either in-tree or
(hopefully) stock gcc 4.2.1 on i386 and other arches.

In particular:
- Do not use %ebx in the asm constraints on i386, since rtld is
  compiled with -fPIC and gcc cannot handle GOT-base register reload
  (clang and newer gcc can).
- Avoid direct use of [static N] construct in the function
  declaration/definion.  In-tree gcc was patched to support this, but
  stock 4.2.1 cannot handle the feature.

Requested by:	bde
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-11-21 14:13:57 +00:00
kib
be68c0b10a Pass CPUID[1] %edx (cpu_feature), %ecx (cpu_feature2) and
CPUID[7].%ebx (cpu_stdext_feature), %ecx (cpu_stdext_feature2) to the
ifunc resolvers on x86.

It is much more clean to use CPUID instruction in usermode to retrieve
this information than to pass AT_HWCAP aux vector from kernel, on
x86.  Still, the change does allow for use of AT_HWCAP on arches where it is
needed, by passing aux array to ifunc_init() initializer which should
prepare arguments for ifunc resolvers.

Current signature for resolvers on x86 is
	func_t iresolve(uint32_t cpu_feature, uint32_t cpu_feature2,
	    uint32_t cpu_stdext_feature, uint32_t cpu_stdext_feature2);
where arguments have identical meaning as the kernel variables of the
same name.  The ABIs allow to use resolvers with the void or shortened
list of arguments.

Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D8448
2016-11-15 09:43:26 +00:00
kib
a45b6b4d9c Fix handling of DT_TEXTREL for an object with more than one read-only
segment.  According to gABI spec, presence of the tag indicates that
dynamic linker must be prepared to handle relocations against any
read-only segment, not only the segment which we, somewhat arbitrary,
declared the text.

For each read-only segment, add write permission before relocs are
processed, and return to the mapping mode requested by the phdr, after
relocs are done.

Reported, tested, and reviewed by:	emaste
PR:	207631
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2016-03-02 16:36:24 +00:00
kib
5f1c6d1039 Do not call callbacks for dl_iterate_phdr(3) with the rtld bind and
phdr locks locked.  This allows to call rtld services from the
callback, which is only reasonable for dlopen(path, RTLD_NOLOAD) to
test existence of the library in the image, and for dlsym().  The
later might still be not quite safe, due to the lazy resolution of
filters.

To allow dropping the locks around iteration in dl_iterate_phdr(3), we
insert markers to track current position between relocks.  The global
objects list is converted to tailq and all iterators skip markers,
globallist_next() and globallist_curr() helpers are added.

Reported and tested by:	davide
Reviewed by:	kan
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
2016-01-20 07:21:33 +00:00
emaste
202862da9c Revert r293201, r293202 (rtld: populate DT_DEBUG iff DYNAMIC segment is writable)
It turns out MIPS binaries may have other oddities that can trigger a
fault at startup.

PR:		206017
Reported by:	ray
2016-01-08 00:56:41 +00:00
emaste
189b511555 rtld: populate DT_DEBUG iff DYNAMIC segment is writable
rtld.h was accidentally missed in r293201
2016-01-05 15:55:45 +00:00
nwhitehorn
4bced8674e Provide support for ELFv2 userland if using a newer compiler (recent clang
or gcc) and binutils >= 2.24. Not enabled by default.
2015-12-03 00:10:57 +00:00
imp
0d0aa50ab4 Move all the paths into a new path.h to centralize them. 2015-10-31 04:39:28 +00:00
kib
788163adc0 Implement support -z global linker option. It marks the shared object
as always participating in the global symbols namespace, regardless of
the way the object was brought into the process address space.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-04-15 08:16:34 +00:00
emaste
d9fc1f13c2 Make die available as rtld_die for use by MD relocation code
Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D2213
2015-04-02 21:35:36 +00:00
kib
563a44c171 Change compiler setting to make default visibility of the symbols for
rtld on x86 to be hidden.  This is a micro-optimization, which allows
intrinsic references inside rtld to be handled without indirection
through PLT.  The visibility of rtld symbols for other objects in the
symbol namespace is controlled by a version script.

Reviewed by:	kan, jilles
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2015-03-29 18:53:21 +00:00
kib
7ac15f4b4c Add rtld private interface for dso to detect dynamic loading
vs. static linking.

Tested by:	pho, antoine (exp-run)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-01-03 18:09:53 +00:00
kib
359d218e65 Optimize r270798, only do the second pass over non-plt relocations
when the first pass found IFUNCs.

Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2014-08-29 10:43:56 +00:00
kib
c51525766a IFUNC symbol type shall be processed for non-PLT relocations,
e.g. when a global variable is initialized with a pointer to ifunc.
Add symbol type check and call resolver for STT_GNU_IFUNC symbol types
when processing non-PLT relocations, but only after non-IFUNC
relocations are done.  The two-phase proceessing is required since
resolvers may reference other symbols, which must be ready to use when
resolver calls are done.

Restructure reloc_non_plt() on x86 to call find_symdef() and handle
IFUNC in single place.

For non-x86 reloc_non_plt(), check for call for IFUNC relocation and
do nothing, to avoid processing relocs twice.

PR:	193048
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2014-08-29 09:29:10 +00:00
alc
5f3ef7ae53 Before calling mmap() on a shared library's text and data sections, rtld
first calls mmap() with the arguments PROT_NONE and MAP_ANON to reserve a
single, contiguous range of virtual addresses for the entire shared library.
Later, rtld calls mmap() with the the shared library's file descriptor
and the argument MAP_FIXED to place the text and data sections within the
reserved range.  The rationale for mapping shared libraries in this way is
explained in the commit message for Revision 190885.  However, this approach
does have an unintended, negative consequence.  Since the first call to
mmap() specifies MAP_ANON and not the shared library's file descriptor, the
kernel has no idea what alignment the vm object backing the file prefers.
As a result, the reserved range's alignment is unlikely to be the same as
the vm object's, and so mapping with superpages becomes impossible.  To
address this problem, this revision adds the argument MAP_ALIGNED_SUPER to
the first call to mmap() if the text section is larger than the smallest
superpage size.

To determine if the text section is larger than the smallest superpage
size, rtld must always fetch the page size information.  As a result, the
private code for fetching the base page size in rtld's builtin malloc is
redundant.  Eliminate it.  Requested by: kib

Tested by:	zbb (on arm)
Reviewed by:	kib (an earlier version)
Discussed with:	jhb
2014-04-11 16:55:25 +00:00
kib
18ee928407 Build an allocator for the aligned memory on top of the rtld-private
malloc.

Reviewed by:	kan
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2013-12-06 21:30:31 +00:00
kib
c727c7bc75 Implement support for the interpose dso flag.
Requested by:	bf
Reviewed by:	kan
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (glebius)
2013-10-07 08:19:30 +00:00
kib
a78a2e3c36 Import the DragonFly BSD commit 4f0bc915b65fcf5a23214f6d221d65c80be68ad4
by John Marino <draco@marino.st>, with the following (edited) commit
message
Date: Sat, 24 Mar 2012 06:40:50 +0100
Subject: [PATCH 1/1] rtld: Implement DT_RUNPATH and -z nodefaultlib

DT_RUNPATH is incorrectly being considered as an alias of DT_RPATH.  The
purpose of DT_RUNPATH is to have two different types of rpath: one that
can be overridden by the environment variable LD_LIBRARY_PATH and one that
can't.  With the currently implementation, LD_LIBRARY_PATH will always
trump any embedded rpath or runpath tags.

Current path search order by rtld:
==================================
LD_LIBRARY_PATH
DT_RPATH / DT_RUNPATH (always the same)
ldconfig hints file (default: /var/run/ld-elf.so.hints)
/usr/lib

New path search order by rtld:
==============================
DT_RPATH of the calling object if no DT_RUNPATH
DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
LD_LIBRARY_PATH
DT_RUNPATH
ldconfig hints file
/usr/lib

The new path search matches how the linux runtime loader works.  The other
major added feature is support for linker flag "-z nodefaultlib".  When
this flag is passed to the linker, rtld will skip all references to the
standard library search path ("/usr/lib" in this case but it could handle
more color delimited paths) except in DT_RPATH and DT_RUNPATH.

New path search order by rtld with -z nodefaultlib flag set:
============================================================
DT_RPATH of the calling object if no DT_RUNPATH
DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
LD_LIBRARY_PATH
DT_RUNPATH
ldconfig hints file (skips all references to /usr/lib)

FreeBSD notes:
- we fixed some bugs which were submitted to DragonFly and merged there
  as commit 1ff8a2bd3eb6e5587174c6a983303ea3a79e0002;
- we added LD_LIBRARY_PATH_RPATH environment variable to switch to
  the previous behaviour of considering DT_RPATH a synonym for DT_RUNPATH;
- the FreeBSD default search path is /lib:/usr/lib and not /usr/lib.

Reviewed by:   kan
MFC after:     1 month
MFC note:      flip the ld_library_path_rpath default value for stable/9
2012-07-15 10:53:48 +00:00
kib
14c0cbcf62 Add GNU hash support for rtld.
Based on dragonflybsd support for GNU hash by John Marino <draco marino st>
Reviewed by:	kan
Tested by:	bapt
MFC after:	2 weeks
2012-04-30 13:31:10 +00:00
kib
8de997e052 Split the symlook_obj1 into a loop iterating over the ELF object symbol
hash elements, and a helper matched_symbol() which match the given hash
entry and request, performing needed type and version checks.

Based on dragonflybsd support for GNU hash by John Marino <draco marino st>
Reviewed by:	kan
Tested by:	bapt
MFC after:	2 weeks
2012-04-30 13:29:21 +00:00
kib
4d91f78223 Prevent rtld_verify_object_versions() from being called several times
for the same object. This can happen when object is a dependency of the
dlopen()ed dso. When called several times, we waste time due to unneeded
processing, and memory, because obj->vertab is allocated anew on each
iteration.

Reviewed by:	kan
MFC after:	2 weeks
2012-03-27 14:10:15 +00:00
kib
758ec7e7c3 Remove superfluous extern keywords.
MFC after:	   2 weeks
2012-03-23 12:13:31 +00:00
kib
625402758b Use xmalloc() instead of malloc() in the places where malloc() calls
are assumed to not fail.

Make the xcalloc() calling conventions follow the calloc(3) calling
conventions and replace unchecked calls to calloc() with calls to
xcalloc().

Remove redundand declarations from xmalloc.c, which are already
present in rtld.h.

Reviewed by:	kan
Discussed with:	bde
MFC after:	2 weeks
2012-03-22 14:20:51 +00:00
kib
c49b39491d Fix several problems with our ELF filters implementation.
Do not relocate twice an object which happens to be needed by loaded
binary (or dso) and some filtee opened due to symbol resolution when
relocating need objects.  Record the state of the relocation
processing in Obj_Entry and short-circuit relocate_objects() if
current object already processed.

Do not call constructors for filtees loaded during the early
relocation processing before image is initialized enough to run
user-provided code.  Filtees are loaded using dlopen_object(), which
normally performs relocation and initialization.  If filtee is
lazy-loaded during the relocation of dso needed by the main object,
dlopen_object() runs too earlier, when most runtime services are not
yet ready.

Postpone the constructors call to the time when main binary and
depended libraries constructors are run, passing the new flag
RTLD_LO_EARLY to dlopen_object().  Symbol lookups callers inform
symlook_* functions about early stage of initialization with
SYMLOOK_EARLY.  Pass flags through all functions participating in
object relocation.

Use the opportunity and fix flags argument to find_symdef() in
arch-specific reloc.c to use proper name SYMLOOK_IN_PLT instead of
true, which happen to have the same numeric value.

Reported and tested by:	theraven
Reviewed by:	kan
MFC after:	2 weeks
2012-03-20 13:20:49 +00:00
kib
6232e80d5b Rtld on diet 3.
Stop using strerror(3) in rtld, which brings in msgcat and stdio.
Directly access sys_errlist array of errno messages with private
rtld_strerror() function.

Now,
$ size /libexec/ld-elf.so.1
   text    data     bss     dec     hex filename
  96983    2480    8744  108207   1a6af /libexec/ld-elf.so.1

Reviewed by:	dim, kan
MFC after:	2 weeks
2012-03-14 15:39:59 +00:00
kib
95d1e3d11b Add support for preinit, init and fini arrays. Some ABIs, in
particular on ARM, do require working init arrays.

Traditional FreeBSD crt1 calls _init and _fini of the binary, instead
of allowing runtime linker to arrange the calls.  This was probably
done to have the same crt code serve both statically and dynamically
linked binaries.  Since ABI mandates that first is called preinit
array functions, then init, and then init array functions, the init
have to be called from rtld now.

To provide binary compatibility to old FreeBSD crt1, which calls _init
itself, rtld only calls intializers and finalizers for main binary if
binary has a note indicating that new crt was used for linking.  Add
parsing of ELF notes to rtld, and cache p_osrel value since we parsed
it anyway.

The patch is inspired by init_array support for DragonflyBSD, written
by John Marino.

Reviewed by:	kan
Tested by:	andrew (arm, previous version), flo (sparc64, previous version)
MFC after:	3 weeks
2012-03-11 20:03:09 +00:00
kib
e6736c915b Add support for GNU RELRO.
Submitted by:	John Marino <draco marino st>
MFC after:	2 weeks
2012-01-30 19:52:17 +00:00
uqs
8ecda3ab53 Spelling fixes for libexec/ 2012-01-07 16:09:54 +00:00
kib
a95b8e72c8 Add support for STT_GNU_IFUNC and R_MACHINE_IRELATIVE GNU extensions to
rtld on 386 and amd64. This adds runtime bits neccessary for the use
of the dispatch functions from the dynamically-linked executables and
shared libraries.

To allow use of external references from the dispatch function, resolution
of the R_MACHINE_IRESOLVE relocations in PLT is postponed until GOT entries
for PLT are prepared, and normal resolution of the GOT entries is finished.
Similar to how it is done by GNU, IRELATIVE relocations are resolved in
advance, instead of normal lazy handling for PLT.

Move the init_pltgot() call before the relocations for the object are
processed.

MFC after:	3 weeks
2011-12-12 11:03:14 +00:00
kib
512a0c1728 Typo.
MFC after:	3 days
2011-12-09 20:40:24 +00:00
kib
6a79063187 Rtld links with the specially built pic static libc library to get some
C runtime services, like printf(). Unfortunately, the multithread-safeness
measures in the libc do not work in rtld environment.

Rip the kernel printf() implementation and use it in the rtld instead of
libc version. This printf does not require any shared global data and thus
is mt-safe. Systematically use rtld_printf() and related functions, remove
the calls to err(3).

Note that stdio is still pulled from libc due to libmap implementaion using
fopen(). This is safe but unoptimal, and can be changed later.

Reported and tested by:	pgj
Diagnosed and reviewed by:	kan (previous version)
Approved by:	re (bz)
2011-08-24 20:05:13 +00:00
kib
2d3fe26ede Use sigsetjmp/siglongjmp with disabled signal mask access for
lock upgrade in rtld. There is no need to care about the mask,
which causes a lot of unneeded sigprocmask(2) calls during each
symbol lookup.
2011-02-09 09:20:27 +00:00
kib
5cec74bed9 In rtld, read the initial stack access mode from AT_STACKPROT as set
by kernel, and parse PT_GNU_STACK phdr from linked and loaded dsos.

If the loaded dso requires executable stack, as specified by PF_X bit
of p_flags of PT_GNU_STACK phdr, but current stack protection does not
permit execution, the __pthread_map_stacks_exec symbol is looked up
and called. It should be implemented in libc or threading library and
change the protection mode of all thread stacks to be executable.

Provide a private interface _rtld_get_stack_prot() to export the stack
access mode as calculated by rtld.

Reviewed by:	   kan
2011-01-08 17:11:49 +00:00
kib
cefd8b2a41 Implement support for ELF filters in rtld. Both normal and auxillary
filters are implemented.

Filtees are loaded on demand, unless LD_LOADFLTR environment variable
is set or -z loadfltr was specified during the linking. This forces
rtld to upgrade read-locked rtld_bind_lock to write lock when it
encounters an object with filter during symbol lookup.

Consolidate common arguments of the symbol lookup functions in the
SymLook structure.  Track the state of the rtld locks in the
RtldLockState structure. Pass local RtldLockState through the rtld
symbol lookup calls to allow lock upgrades.

Reviewed by:	kan
Tested by:	Mykola Dzham <i levsha me>, nwhitehorn (powerpc)
2010-12-25 08:51:20 +00:00
kib
6ddde2168b If dlopen() is called for the dso that has been already loaded as a
dependency, then the dso never has its DAG initialized. Empty DAG
makes ref_dag() call in dlopen() a nop, and the dso refcount is off
by one.

Initialize the DAG on the first dlopen() call, using a boolean flag
to prevent double initialization.

From the PR (edited):
Assume we have a library liba.so, containing a function a(), and a
library libb.so, containing function b(). liba.so needs functionality
from libb.so, so liba.so links in libb.so.

An application doesn't know about the relation between these libraries,
but needs to call a() and b(). It dlopen()s liba.so and obtains a
pointer to a(), then it dlopen()s libb.so and obtains a pointer to b().

As soon as the application doesn't need a() anymore, it dlclose()s liba.so.

Expected result: the pointer to b() is still valid and can be called
Actual result: the pointer to b() has become invalid, even though the
application did not dlclose() the handle to libb.so. On calling b(), the
application crashes with a segmentation fault.

PR:	misc/151861
Based on patch by:	jh
Reviewed by:	kan
Tested by:	Arjan van Leeuwen <freebsd-maintainer opera com>
MFC after:	1 week
2010-11-03 09:23:08 +00:00
nwhitehorn
6701006626 Check for undefined weak symbols during PLT binding on powerpc64, and do
not attempt to copy NULL function descriptors. This fixes LD_BIND_NOW on
powerpc64 after r211706.

Reviewed by:	kib
2010-09-12 17:04:51 +00:00
kib
d9873126f6 Allow to load not-openable dso when tracing. This fixes ldd on such dso or
dso linked to non-openable object.
Remove '\n' at the end of error message.
End comments with dot.

MFC after:	3 weeks (together with r199829)
2009-11-28 14:29:32 +00:00
kib
8f8a9dcd17 Implement rtld part of the support for -z nodlopen (see ld(1)).
Reviewed by:	kan
MFC after:	3 weeks
2009-11-26 13:57:20 +00:00
kan
51b981d72b Allow order of initialization of loaded shared objects to be
altered through their .init code. This might happen if init
vector calls dlopen on its own and that dlopen causes some not
yet initialized object to be initialized earlier as part of that
dlopened DAG.

Do not reset module reference counts to zero on final fini vector
run when process is exiting. Just add an additional parameter to
force fini vector invocation regardless of current reference count
value if object was not destructed yet. This allows dlclose called
from fini vector to proceed normally instead of failing with handle
validation error.

Reviewed by:	kib
Reported by:	venki kaps
2009-06-20 14:16:41 +00:00
dfr
954b6f0f3b Increase the size of the static TLS area slightly (required for the NVidia's
OpenGL driver on amd64).
2009-05-27 18:54:31 +00:00
kib
566c4f31f1 Implement support for RTLD_NODELETE flag for dlopen() and -z nodelete
static linker option. Do it by incrementing reference count on the loaded
object and its dependencies.

Reviewed by:	davidxu, kan
2009-03-30 08:47:28 +00:00