Commit Graph

121 Commits

Author SHA1 Message Date
John Polstra
5f8aa32e1b Dillon's recent commits to the dynamic linker without running them
by me first have given me a good excuse to drop my MAINTAINERship.

MFC after:	1 week
2002-06-10 21:51:16 +00:00
Matthew Dillon
b08440e568 Correct a bug in the last commit. The whole point of creating a 'done:'
goto target was so the cache could be freed.  So free the cache after
done: rather then before done: (!)

Submitted by:	Gavin Atkinson <gavin@ury.york.ac.uk>
2002-06-10 21:15:50 +00:00
Matthew Dillon
b603db3019 In tracking down an installation seg fault with then openoffice port
Martin Blapp determined that the elf dynamic loader was at fault.  In
particular, the loader uses alloca() to allocate a symbol cache on the
stack.  Normally this would work just fine, but if the loader is called
from a threaded program and the object being loaded is fairly large the
alloca() can blow away the thread stack and effect other nearby thread
stacks as well.  My testing showed that the symbol cache can be as large
as 250KBytes during the openoffice port build and install sequence.  Martin
was able to work around the problem by disabling the symbol cache
(cache = NULL;).  However, this solution is not adequate for commit because
it can cause an enormous cpu burden for applications which do a lot of
dynamic loading (e.g. like konqueror).

The solution is to use anonymous mmap() to temporarily allocate space to
hold the symbol cache.  In testing I found that replacing the alloca()
with mmap() has no observable degredation in performance.

It should be noted that this bug does not necessarily cause an immediate
crash but can instead result in long term corruption and instability in
applications that load modules from threads.  The bug is almost certainly
responsible for some of the instabilities found in konqueror, for example,
and possibly netscape too.

Sleuthing work by: Martin Blapp <mb@imp.ch>
X-MFC after:	Before or after the 4.6 release depending on the release engineers
2002-06-10 18:52:31 +00:00
Marcel Moolenaar
5c8e25383a Include machine/ia64_cpu.h because we use ia64_mf().
Submitted by: ru
2002-05-21 00:04:08 +00:00
Marcel Moolenaar
2aba02382e Fix handling of weak references to undefined symbols on ia64:
o  Set st_shndx for sym_zero to SHN_UNDEF instead of SHN_ABS.
   This gives us something to reliably test against.
o  For weak references to undefined sysmbols (as indicated by
   having st_shndx equals SHN_UNDEF) in the context of OPDs,
   the address of the OPD is to be zero, not the address of
   the function it contains.
o  For weak references to undefined symbols in all other cases
   (only DIR64LSB at this time), the actual relocated value is
   to be zero, not the value prior to relocating.

Roughly speaking, weak references to undefined symbols are no-ops.

Tested on: i386, ia64
2002-04-27 05:32:51 +00:00
Marcel Moolenaar
c7e3bd1ce6 Now that local symbols aren't looked up with the symbol hash table,
binding works for local symbols. Remove the workaround...
2002-04-27 02:53:31 +00:00
Marcel Moolenaar
9d4f27148f Don't do symbol lookups for local symbols. The symbol index in the
relocation identifies the symbol to which we need to bind. This
solves a problem seen on ia64 where the symbol hash table does not
contain local symbols and thus resulted in unresolved symbols.

Tested on: alpha, i386, ia64
2002-04-27 02:48:29 +00:00
Peter Wemm
968253905e Fix a relocation bug in the ia64 ld.so. Weak function pointers in shared
objects were not being correctly set to zero.  Instead, the function
descriptor pointer was set to the load address of the .so object.  This
caused gcc generated binaries to segfault on exit when crtbegin.asm's
_fini code tested the __cxa_finalize() function pointer for zero.

This is a bit of a hack because of a problem nearby workaround for
find_symdef and its quirks (failures) for local symbols.  This still
needs to be fixed.
2002-04-07 04:16:35 +00:00
Jake Burkholder
2da08e795e Minor changes to make this work on sparc64.
Approved by:	jdp
Tested on:	alpha, i386, sparc64
2002-04-02 02:19:02 +00:00
Jake Burkholder
e4c9dc6770 rtld support for sparc64.
Largely obtained from:	netbsd
Submitted by:	jake, tmm
2002-03-13 02:40:39 +00:00
Dag-Erling Smørgrav
e211585c77 When searching an object that was opened with RTLD_GLOBAL, search its DAG too.
PR:		bin/25059
Approved by:	jdp
MFC after:	3 weeks
2002-02-27 23:44:50 +00:00
Peter Wemm
939bc65715 ld-elf.so.1 assumed a few too many things about the ordering of sections
produced by ld(8) (ie: that _DYNAMIC immediately follows the _GOT).
The new binutils import changed that, and the intial GOT relocation
broke.  Use a custom linker script to provide a real end-of-GOT symbol.

Update ld.so to deal with the new (faster) PLT format that gcc-3.1 and
binutils can produce.

This is probably incomplete, but appears to be working again.

Obtained from:  NetBSD
(And a fix to a silly mistake that I made by:  gallatin)
2002-02-18 02:24:10 +00:00
David E. O'Brien
2024994319 Add support such that if LD_TRACE_LOADED_OBJECTS_ALL is defined to a
non-empty string in the environment; we indicate which objects caused
each object to be loaded.

PR:		30908
Submitted-by:	Mike Meyer <mwm@mired.org>
2002-02-17 07:04:32 +00:00
Maxim Sobolev
c6de4ce791 Allow ldd(1) be used on shared libraries in addition to executables. 2002-02-04 10:33:48 +00:00
Kris Kennaway
8f23d50652 Mark a function as __printflike()
MFC after:	1 week
2002-02-04 01:41:35 +00:00
John Polstra
a7dcaa3441 Change the library search order so that LD_LIBRARY_PATH overrides
all others.

PR:		bin/28191
MFC after:	2 weeks
2002-01-25 16:35:43 +00:00
David Malone
98d1592458 Change brk's prototype from char *brk(const char *) to int brk(const void *)
and sbrk's prototype from char *sbrk(int) to void *sbrk(intptr_t).

This makes us more consistant with NetBSD and standards which include
these functions. Bruce pointed out that ptrdiff_t would probably
have been better than intptr_t, but this doesn't match other
implimentations.

Also remove local declarations of sbrk and unnecessary casting.

PR:		32296
Tested by:	Harti Brandt <brandt@fokus.gmd.de>
MFC after:	1 month
2002-01-24 12:11:31 +00:00
Ruslan Ermilov
bcf2b1b312 mdoc(7) police: tidy up. 2002-01-10 17:49:57 +00:00
Peter Wemm
14a55adf36 Update rtld for the "new" ia64 ABI. In the old toolchain, the
DT_INIT and DT_FINI tags pointed to fptr records.  In 2.11.2, it points
to the actuall address of the function.  On IA64 you cannot just take
an address of a function, store it in a function pointer variable and
call it.. the function pointers point to a fptr data block that has the
target gp and address in it.  This is absolutely necessary for using
the in-tree binutils toolchain, but (unfortunately) will not work with
old shared libraries.  Save your old ld-elf.so.1 if you want to use
old ones still.  Do not mix-and-match.

This is a no-op change for i386 and alpha.

Reviewed by:	dfr
2001-10-29 10:10:10 +00:00
Peter Wemm
d4cf88ddc4 Fix a dependency violation (branch after alloc) 2001-10-29 10:05:32 +00:00
Doug Rabson
b5393d9f78 Add ia64 support. Various adjustments were made to existing targets to
cope with a few interface changes required by the ia64. In particular,
function pointers on ia64 need special treatment in rtld.
2001-10-15 18:48:42 +00:00
Doug Rabson
97571220e2 The support for accelerating find_symdef() with a cache was broken. This
fixes the problem and improves startup times for large applications such
as KDE2 considerably.

Reviewed by:	jdp
MFC after:	1 week
2001-10-10 07:15:01 +00:00
Ruslan Ermilov
c4d9468ea0 mdoc(7) police:
Avoid using parenthesis enclosure macros (.Pq and .Po/.Pc) with plain text.
Not only this slows down the mdoc(7) processing significantly, but it also
has an undesired (in this case) effect of disabling hyphenation within the
entire enclosed block.
2001-08-07 15:48:51 +00:00
Sheldon Hearn
e1b4d8d074 Use STD{ERR,IN,OUT}_FILENO instead of their numeric values. The
definitions are more readable, and it's possible that they're
more portable to pathalogical platforms.

Submitted by:   David Hill <david@phobia.ms>
2001-07-26 11:02:39 +00:00
Ruslan Ermilov
0efe23d669 mdoc(7) police: removed HISTORY info from the .Os call. 2001-07-10 10:49:54 +00:00
Dima Dorfman
70d51341bf mdoc(7) police: remove extraneous .Pp before and/or after .Sh. 2001-07-09 09:54:33 +00:00
Ruslan Ermilov
5521ff5a4d mdoc(7) police: sort SEE ALSO xrefs (sort -b -f +2 -3 +1 -2). 2001-07-06 16:46:48 +00:00
Ruslan Ermilov
4cf39050cc Use new backup feature of install(1). 2001-05-28 16:58:35 +00:00
John Polstra
c15e7faad5 Performance improvements for the ELF dynamic linker. These
particularly help programs which load many shared libraries with
a lot of relocations.  Large C++ programs such as are found in KDE
are a prime example.

While relocating a shared object, maintain a vector of symbols
which have already been looked up, directly indexed by symbol
number.  Typically, symbols which are referenced by a relocation
entry are referenced by many of them.  This is the same optimization
I made to the a.out dynamic linker in 1995 (rtld.c revision 1.30).

Also, compare the first character of a sought-after symbol with its
symbol table entry before calling strcmp().

On a PII/400 these changes reduce the start-up time of a typical
KDE program from 833 msec (elapsed) to 370 msec.

MFC after:	5 days
2001-05-05 23:21:05 +00:00
David E. O'Brien
5e6220d9d0 * include/elf.h has been repo copied to include/elf-hints.h, and it no
longer includes machine/elf.h.
* consumers of elf.h now use the minimalist elf header possible.

This change is motivated by Binutils 2.11.0 and too much clashing over
our base elf headers and the Binutils elf headers.
2001-05-02 23:56:21 +00:00
Ruslan Ermilov
e5b5c66bca - Backout botched attempt to intoduce MANSECT feature.
- MAN[1-9] -> MAN.
2001-03-26 14:22:12 +00:00
Ruslan Ermilov
896eb7d10c Prepare for mdoc(7)NG. 2001-01-16 09:15:57 +00:00
John Polstra
27e2c03506 Fix a bug in which a program called dlclose from a destructor and
got an assert failure in the dynamic linker.
2001-01-05 04:36:17 +00:00
Ruslan Ermilov
58eaff2332 Prepare for mdoc(7)NG. 2000-12-20 13:26:01 +00:00
David E. O'Brien
1a37aa566b Add `_PATH_DEVZERO'.
Use _PATH_* where where possible.
2000-12-09 09:35:55 +00:00
John Polstra
c1ff193db4 Remove the superfluous call to _rtld_error() in symlook_default().
The function's callers generate the error message when appropriate.

This eliminates the message ``Undefined symbol "__register_frame_info"''
which was bogusly returned by dlerror() in some cases.
2000-11-07 22:41:53 +00:00
John Polstra
185db83c04 Add support for dlsym(RTLD_DEFAULT, ...). 2000-09-19 04:27:16 +00:00
John W. De Boskey
bde08d0072 Pass two pointer parameters to the r_debug_state() hook
function, thus allowing a debugger or other trace tool
to easily grab the addresses of the needed structures
off the stack.

This change is transparent to gdb, which locates the
link_map list and transfers it to debugger memory
for comparison purposes.

A sample program will be committed showing how this can
be used.

Reviewed by:    John Polstra <jdp@FreeBSD.org>
2000-08-26 05:13:29 +00:00
John Polstra
44a028c369 Revamp the code that calls shared libraries' init and fini functions.
Formerly the init functions were called in the opposite of the
order in which libraries were loaded, and libraries were loaded
according to a breadth-first traversal of the dependency graph.
That ordering came from SVR4.0, and it was easy to implement but
not always sensible.

Now we do a depth-first walk over the dependency graph and call
the init functions in an order such that each shared object's needed
objects are initialized before the shared object itself.  At the
same time we build a list of finalization (fini) functions in the
opposite order, to guarantee correct C++ destructor ordering whenever
possible.  (It may not be possible if dlopen and dlclose are used
in strange ways, but we come as close as one can come.)

The need for this renovation has become apparent as more programs
have started using multithreading.  The multithreaded C library
libc_r requires initialization, whereas the standard libc does not.
Since virtually every other object depends on the C library, it is
important that it get initialized first.
2000-07-26 04:24:40 +00:00
Brian Feldman
119fc1a3ce We shouldn't use cp to save the old ld-elf.so.1. Use the sanctioned tool
${INSTALL} with -C -p instead.
2000-07-20 08:00:02 +00:00
John Polstra
cf98e66403 Fix a bug which could cause programs with user threads packages to
lock against themselves, causing infinite spinning.  Brian Feldman
found this problem when testing with Mozilla and supplied the fix,
which I have revised slightly.

Here is the failure scenario.  A thread calls dlopen() and acquires
the writer lock.  While the thread still holds the lock, a signal
is delivered and caught.  The signal handler tries to call a function
which hasn't been bound yet.  It thus enters the dynamic linker
and tries to acquire the reader lock.  Since the writer lock is
already held, it will spin forever in the signal handler.  The
thread holding the lock won't be able to progress and release the
lock.

The solution is to block almost all signals while holding the
exclusive lock.

A similar problem could conceivably occur in the opposite order.
Namely, a thread is holding the reader lock and then a signal
handler calls dlopen() or dlclose() and spins waiting for the writer
lock.  We deal with this administratively by proclaiming that signal
handlers aren't allowed to call dlopen() or dlclose().  Actually
we don't have to proclaim a thing, since signal handlers aren't
allowed to call any system functions except those which are explicitly
permitted.

Submitted by:	Brian Fundakowski Feldman <green>
2000-07-17 17:18:13 +00:00
John Polstra
630df077ab Solve the dynamic linker's problems with multithreaded programs once
and for all (I hope).  Packages such as wine, JDK, and linuxthreads
should no longer have any problems with re-entering the dynamic
linker.

This commit replaces the locking used in the dynamic linker with a
new spinlock-based reader/writer lock implementation.  Brian
Fundakowski Feldman <green> argued for this from the very beginning,
but it took me a long time to come around to his point of view.
Spinlocks are the only kinds of locks that work with all thread
packages.  But on uniprocessor systems they can be inefficient,
because while a contender for the lock is spinning the holder of the
lock cannot make any progress toward releasing it.  To alleviate
this disadvantage I have borrowed a trick from Sleepycat's Berkeley
DB implementation.  When spinning for a lock, the requester does a
nanosleep() call for 1 usec. each time around the loop.  This will
generally yield the CPU to other threads, allowing the lock holder
to finish its business and release the lock.  I chose 1 usec. as the
minimum sleep which would with reasonable certainty not be rounded
down to 0.

The formerly machine-independent file "lockdflt.c" has been moved
into the architecture-specific subdirectories by repository copy.
It now contains the machine-dependent spinlocking code.  For the
spinlocks I used the very nifty "simple, non-scalable reader-preference
lock" which I found at

  <http://www.cs.rochester.edu/u/scott/synchronization/pseudocode/rw.html>

on all CPUs except the 80386 (the specific CPU model, not the
architecture).  The 80386 CPU doesn't support the necessary "cmpxchg"
instruction, so on that CPU a simple exclusive test-and-set lock
is used instead.  80386 CPUs are detected at initialization time by
trying to execute "cmpxchg" and catching the resulting SIGILL
signal.

To reduce contention for the locks, I have revamped a couple of
key data structures, permitting all common operations to be done
under non-exclusive (reader) locking.  The only operations that
require exclusive locking now are the rare intrusive operations
such as dlopen() and dlclose().

The dllockinit() interface is now deprecated.  It still exists,
but only as a do-nothing stub.  I plan to remove it as soon as is
reasonably possible.  (From the very beginning it was clearly
labeled as experimental and subject to change.)  As far as I know,
only the linuxthreads port uses dllockinit().  This interface turned
out to have several problems.  As one example, when the dynamic
linker called a client-supplied locking function, that function
sometimes needed lazy binding, causing re-entry into the dynamic
linker and a big looping mess.  And in any case, it turned out to be
too burdensome to require threads packages to register themselves
with the dynamic linker.
2000-07-08 04:10:38 +00:00
John Polstra
517191eede When installing the dynamic linker, save the previous version in
"ld-elf.so.1.old".  The dynamic linker is a critical component of
the system, and it is difficult to recover if it is damaged and
there isn't a working backup available.  For instance, parts of
the toolchain such as the assembler are dynamically linked, making
it impossible to build a new dynamic linker if the installed one
doesn't work.
2000-07-08 03:27:54 +00:00
Sheldon Hearn
cbe10916b3 Only punctuation is an allowed argument type for open-close macros
such as Po/Pc, as explained by phantom.

Reported by:	billf
2000-06-30 06:30:53 +00:00
Jake Burkholder
e39756439c Back out the previous change to the queue(3) interface.
It was not discussed and should probably not happen.

Requested by:		msmith and others
2000-05-26 02:09:24 +00:00
Jake Burkholder
740a1973a6 Change the way that the queue(3) structures are declared; don't assume that
the type argument to *_HEAD and *_ENTRY is a struct.

Suggested by:	phk
Reviewed by:	phk
Approved by:	mdodd
2000-05-23 20:41:01 +00:00
John Polstra
a0f2601e13 Eliminate unaligned accesses that occurred when relocating the
DWARF2 exception tables emitted by the compiler for C++ sources.
These tables are tightly packed, and they contain some relocated
addresses which are not well-aligned.
2000-05-22 16:31:18 +00:00
Sheldon Hearn
35add0e9a7 Cross-reference ldd(1) in rtld(1) and vice versa. 2000-03-28 09:01:04 +00:00
Bruce Evans
9d08570309 Fixed missing DPADDs.
Fixed some style bugs (some usual ones for LDADD, and misformatting of
$FreeBSD$).
2000-03-27 16:11:27 +00:00
John Polstra
ea5cc7f114 Add a manual page for the ELF dynamic linker. I initially created
rtld.1 by means of a repository copy from "src/libexec/rtld-aout/rtld.1".
Then I edited it to make it (more) accurate for the ELF dynamic
linker.
2000-01-29 03:16:54 +00:00