path: root/src/ldso
AgeCommit message (Collapse)AuthorLines
2012-11-25eliminate gdb complaints about missing Felker-1/+2
actually, the hard-coded name should be eliminated too, and replaced by a search for the soname in the headers, but that can be done separately later.
2012-11-17fix typo in dynamic linker path file loading codeRich Felker-1/+1
fortunately the memory corruption could not hurt anything, but it prevented clearing the final newline and thus prevented the last path element from working.
2012-11-17arg-skipping code for powerpc dynamic linkerRich Felker-0/+8
this allows using the dynamic linker as a command to load programs.
2012-11-16dynamic linking support for powerpcRich Felker-17/+16
incomplete but at least partly working. requires all files to be compiled in the new "secure" plt model, not the old one that put plt code in the data segment. TLS is untested but may work. invoking the dynamic linker explicitly to load a program does not yet handle argv correctly.
2012-11-14fix indention with spaces in powerpc asmRich Felker-27/+26
2012-11-14Merge remote-tracking branch 'ppc-port/ppc-squashed'Rich Felker-0/+31
2012-11-13PPC port cleaned up, static linking works well now.rofl0r-24/+24
2012-11-13import preliminary ppc work by rdp.Richard Pennington-0/+31
2012-11-09support ldso path files without final newlineRich Felker-2/+5
2012-11-08change ldso path file logic to replace rather than add to search pathRich Felker-2/+2
this change was originally intended just to avoid repeated attempts to open a nonexistant /etc/ls-musl-$(ARCH).path file, but I realized it also prevents the default paths from being searched when such a path file exists. despite the potential to break existing usage, I believe the new behavior is the right behavior, and it's better to fix it sooner rather than later. with the old behavior, it was impossible to inhibit search of default paths which might contain musl-incompatible libs (or even libs from a different cpu arch, on multi-arch machines).
2012-11-08fix dlsym asm for mipsRich Felker-1/+2
saving the return address from the delay slot is not valid -- by the time the instruction executes, the return address has already been replaced.
2012-11-01remove one unnecessary static var from dynamic linkerRich Felker-2/+2
2012-11-01fix more unused variable warningsRich Felker-3/+2
some of these were coming from stdio functions locking files without unlocking them. I believe it's useful for this to throw a warning, so I added a new macro that's self-documenting that the file will never be unlocked to avoid the warning in the few places where it's wrong.
2012-10-31add dl_iterate_phdr interfaceRich Felker-7/+87
patches by Alex Caudill (npx). the dynamic-linked version is almost identical to the final submitted patch; I just added a couple missing lines for saving the phdr address when the dynamic linker is invoked directly to run a program, and removed a couple to avoid introducing another unnecessary type. the static-linked version is based on npx's draft. it could use some improvements which are contingent on the startup code saving some additional information for later use.
2012-10-19support looking up thread-local objects with dlsymRich Felker-0/+6
2012-10-19fix breakage in dlsym for looking up RTLD_DEFAULT, etc.Rich Felker-2/+5
this was broken during the early dynamic-linked TLS commits, which rearranged some of the code for handling new relocation types.
2012-10-17fix microblaze asm relocations for shared libcRich Felker-3/+3
only @PLT relocations are considered functions for purposes of -Bsymbolic-functions, so always use @PLT. it should not hurt in the static-linked case.
2012-10-15add support for TLS variant I, presently needed for arm and mipsRich Felker-3/+32
despite documentation that makes it sound a lot different, the only ABI-constraint difference between TLS variants II and I seems to be that variant II stores the initial TLS segment immediately below the thread pointer (i.e. the thread pointer points to the end of it) and variant I stores the initial TLS segment above the thread pointer, requiring the thread descriptor to be stored below. the actual value stored in the thread pointer register also tends to have per-arch random offsets applied to it for silly micro-optimization purposes. with these changes applied, TLS should be basically working on all supported archs except microblaze. I'm still working on getting the necessary information and a working toolchain that can build TLS binaries for microblaze, but in theory, static-linked programs with TLS and dynamic-linked programs where only the main executable uses TLS should already work on microblaze. alignment constraints have not yet been heavily tested, so it's possible that this code does not always align TLS segments correctly on archs that need TLS variant I.
2012-10-14fix main program TLS alignment for dynamic-linked programsRich Felker-6/+5
this change brings the behavior in line with the static-linked code, which seems to be correct.
2012-10-13fix namespace clash (libc) in dynlink.cRich Felker-14/+13
this makes it so the #undef libc and __libc name are no longer needed, which were problematic because the "accessor function" mode for accessing the libc struct could not be used, breaking build on any compiler without (working) visibility.
2012-10-13remove dead code from dynamic linkerRich Felker-10/+0
2012-10-07clean up and refactor program initializationRich Felker-2/+2
the code in __libc_start_main is now responsible for parsing auxv, rather than duplicating the parsing all over the place. this should shave off a few cycles and some code size. __init_libc is left as an external-linkage function despite the fact that it could be static, to prevent it from being inlined and permanently wasting stack space when main is called. a few other minor changes are included, like eliminating per-thread ssp canaries (they were likely broken when combined with certain dlopen usages, and completely unnecessary) and some other unnecessary checks. since this code gets linked into every program, it should be as small and simple as possible.
2012-10-07fix breakage due to initializing thread pointer when loading libsRich Felker-1/+1
at initial program load, all libraries must be loaded before the thread pointer can be setup, since the TP-relative addresses of all initial TLS objects must be constant.
2012-10-06make new TLS setup block even implementation-internals signalsRich Felker-2/+1
this is needed to ensure async-cancel-safety, i.e. to make it safe to access TLS objects when async cancellation is enabled. otherwise, if cancellation were acter upon after the atomic fetch/add but before the thread saved the obtained memory, another access to the same TLS in the cancellation handler could end up performing the atomic fetch/add again, consuming more memory than is actually available and overflowing into other objects on the heap.
2012-10-06don't crash if TLS library is loaded into process with no thread pointerRich Felker-0/+5
2012-10-06fix symbol acceptance/rejection rules for TLSRich Felker-8/+14
symbol value of 0 is not "undefined" for TLS; it's the address of the first symbol in the TLS segment. however, non-definition TLS references also have values of 0, so check the section. hopefully the new logic is more clear, too.
2012-10-06TLS fixes, mainly alignment handlingRich Felker-39/+48
compute offsets from the thread pointer statically when loading the library, rather than repeating the logic on each thread creation. not only is the latter less efficient at runtime; it also fails to provide solid guarantees that the offsets will remain the same when the initial alignment of memory is different. the new alignment handling is both more rigorous and simpler. the old code was also clobbering TLS bss with random image data in some cases due to using tls_size (size of TLS segment) instead of tls_len (length of the TLS data image).
2012-10-05fix/improve shared library ctor/dtor handling, allow recursive dlopenRich Felker-7/+29
some libraries call dlopen from their constructors, resulting in recursive calls to dlopen. previously, this resulted in deadlock. I'm now unlocking the dlopen lock before running constructors (this is especially important since the lock also blocked pthread_create and was being held while application code runs!) and using a separate recursive mutex protecting the ctor/dtor state instead. in order to prevent the same ctor from being called more than once, a module is considered "constructed" just before the ctor runs. also, switch from using atexit to register each dtor to using a single atexit call to register the dynamic linker's dtor processing as just one handler. this is necessary because atexit performs allocation and may fail, but the library has already been loaded and cannot be backed-out at the time dtor registration is performed. this change also ensures that all dtors run after all atexit functions, rather than in mixed order.
2012-10-05small dynamic linker module search fixRich Felker-1/+2
libraries loaded more than once by pathname should not get shortnames that would cause them to later be used to satisfy non-pathname load requests.
2012-10-05support for TLS in dynamic-loaded (dlopen) modulesRich Felker-19/+81
unlike other implementations, this one reserves memory for new TLS in all pre-existing threads at dlopen-time, and dlopen will fail with no resources consumed and no new libraries loaded if memory is not available. memory is not immediately distributed to running threads; that would be too complex and too costly. instead, assurances are made that threads needing the new TLS can obtain it in an async-signal-safe way from a buffer belonging to the dynamic linker/new module (via atomic fetch-and-add based allocator). I've re-appropriated the lock that was previously used for __synccall (synchronizing set*id() syscalls between threads) as a general pthread_create lock. it's a "backwards" rwlock where the "read" operation is safe atomic modification of the live thread count, which multiple threads can perform at the same time, and the "write" operation is making sure the count does not increase during an operation that depends on it remaining bounded (__synccall or dlopen). in static-linked programs that don't use __synccall, this lock is a no-op and has no cost.
2012-10-05fix race condition in dlopenRich Felker-1/+3
orig_tail was being saved before the lock was obtained, allowing dlopen failure to roll-back other dlopens that had succeeded.
2012-10-04dynamic-linked TLS support for everything but dlopen'd libsRich Felker-38/+58
currently, only i386 is tested. x86_64 and arm should probably work. the necessary relocation types for mips and microblaze have not been added because I don't understand how they're supposed to work, and I'm not even sure if it's defined yet on microblaze. I may be able to reverse engineer the requirements out of gcc/binutils output.
2012-10-04remove freeing of dynamic linker data when dlopen/dlsym are not usedRich Felker-11/+0
this was an optimization to save/recover a minimal amount of extra memory for use by malloc, that's becoming increasingly costly to keep around. freeing this data: 1. breaks debugging with gdb (it can't find library symbols) 2. breaks thread-local storage in shared libraries it would be possible to disable freeing when TLS is used, but in addition to the above breakages, tracking whether dlopen/dlsym is used adds a cost to every symbol lookup, possibly making program startup slower for large programs. combined with the complexity, it's not worth it. we already save/recover plenty of memory in the dynamic linker with reclaim_gaps.
2012-10-04beginnings of full TLS support in shared librariesRich Felker-0/+10
this code will not work yet because the necessary relocations are not supported, and cannot be supported without some internal changes to how relocation processing works (coming soon).
2012-10-04partial TLS support for dynamic-linked programsRich Felker-22/+72
only TLS in the main program is supported so far; TLS defined in shared libraries will not work yet.
2012-10-04TLS (GNU/C11 thread-local storage) support for static-linked programsRich Felker-0/+10
the design for TLS in dynamic-linked programs is mostly complete too, but I have not yet implemented it. cost is nonzero but still low for programs which do not use TLS and/or do not use threads (a few hundred bytes of new code, plus dependency on memcpy). i believe it can be made smaller at some point by merging __init_tls and __init_security into __libc_start_main and avoiding duplicate auxv-parsing code. at the same time, I've also slightly changed the logic pthread_create uses to allocate guard pages to ensure that guard pages are not counted towards commit charge.
2012-09-29more close-on-exec fixes, mostly using new "e" flag to fopenRich Felker-1/+1
2012-09-29fix some more O_CLOEXEC/SOCK_CLOEXEC issuesRich Felker-2/+2
2012-09-29microblaze portRich Felker-0/+32
based on initial work by rdp, with heavy modifications. some features including threads are untested because qemu app-level emulation seems to be broken and I do not have a proper system image for testing.
2012-09-06use restrict everywhere it's required by c99 and/or posix 2008Rich Felker-4/+4
to deal with the fact that the public headers may be used with pre-c99 compilers, __restrict is used in place of restrict, and defined appropriately for any supported compiler. we also avoid the form [restrict] since older versions of gcc rejected it due to a bug in the original c99 standard, and instead use the form *restrict.
2012-08-27fix bug caused by main app & libc having map set; cannot free themRich Felker-1/+1
2012-08-26dladdr support for dynamic linker (nonstandard extension)Rich Felker-0/+95
based on patches submitted by boris brezillon. this commit also fixes the issue whereby the main application and libc don't have the address ranges of their mappings stored, which was theoretically a problem for RTLD_NEXT support in dlsym; it didn't actually matter because libc never calls dlsym, and it seemed to be doing the right thing (by chance) for symbols in the main program as well.
2012-08-25fix bug in gnu hash lookup on dlsym(handle, name) lookupsRich Felker-1/+1
wrong hash was being passed; just a copy/paste error. did not affect lookups in the global namespace; this is probably why it was not caught in testing.
2012-08-25clean up search_vec usage for vdsoRich Felker-2/+2
2012-08-25use new search_vec function to find vdso in dynamic linkerRich Felker-4/+2
2012-08-25ensure canary is setup if stack-prot libs are dlopen'd into non-ssp appRich Felker-1/+4
previously, this usage could lead to a crash if the thread pointer was still uninitialized, and otherwise would just cause the canary to be zero (less secure).
2012-08-25add gnu hash support in the dynamic linkerRich Felker-12/+85
based on the patches contributed by boris brezillon.
2012-08-18make dynamic linker report all failures before exitingRich Felker-2/+6
before, only the first library that failed to load or symbol that failed to resolve was reported, and then the dynamic linker immediately exited. when attempting to fix a library compatibility issue, this is about the worst possible behavior. now we print all errors as they occur and exit at the very end if errors were encountered.
2012-08-17fix bug computing argc when invoking progname ...Rich Felker-3/+3
2012-08-07fix bug dlsym bug that slipped in during dynamic linker cleanupRich Felker-1/+1