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* elf: Clean up GLIBC_PRIVATE exports of internal libdl symbolsFlorian Weimer2021-07-071-12/+4
| | | | | | | | They are no longer needed after everything has been moved into libc. The _dl_vsym test has to be removed because the symbol cannot be used outside libc anymore. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Linux: Cleanups after librt moveFlorian Weimer2021-06-281-1/+3
| | | | | | | | | | | | librt.so is no longer installed for PTHREAD_IN_LIBC, and tests are not linked against it. $(librt) is introduced globally for shared tests that need to be linked for both PTHREAD_IN_LIBC and !PTHREAD_IN_LIBC. GLIBC_PRIVATE symbols that were needed during the transition are removed again. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* Install shared objects under their ABI namesFlorian Weimer2021-06-281-8/+2
| | | | | | | | | | | | | Previously, the installed objects were named like libc-2.33.so, and the ABI soname libc.so.6 was just a symbolic link. The Makefile targets to install these symbolic links are no longer needed after this, so they are removed with this commit. The more general $(make-link) command (which invokes scripts/rellns-sh) is retained because other symbolic links are still needed. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@rehdat.com>
* elf: Generalize name-based DSO recognition in ldconfigFlorian Weimer2021-06-281-1/+2
| | | | | | | | | This introduces <dl-is_dso.h> and the _dl_is_dso function. A test ensures that the official names of libc.so, ld.so, and their versioned names are recognized. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
* elf: Use _dl_catch_error from base namespace in dl-libc.c [BZ #27646]Florian Weimer2021-06-171-1/+4
| | | | | | | | | | | dlerrror_run in elf/dl-libc.c needs to call GLRO (dl_catch_error) from the base namespace, just like the exported dlerror implementation. Fixes commit b2964eb1d9a6b8ab1250e8a881cf406182da5875 ("dlfcn: Failures after dlmopen should not terminate process [BZ #24772]"). Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
* Remove stale references to libdl.aFlorian Weimer2021-06-091-6/+1
| | | | | | | | Since commit 0c1c3a771eceec46e66ce1183cf988e2303bd373 ("dlfcn: Move dlopen into libc") libdl.a is empty, so linking against it is no longer necessary. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Fix elf/tst-tls9-static after libdl cleanups.Stefan Liebler2021-06-091-2/+0
| | | | | | | | | | | | The testcase elf/tst-tls9-static sometimes fails with: cannot open 'tst-tlsmod5.so': tst-tlsmod5.so: cannot open shared object file: No such file or directory cannot open 'tst-tlsmod6.so': tst-tlsmod6.so: cannot open shared object file: No such file or directory After recent commit 6f1c701026287f6928d3bdd1aea7359308635abe "dlfcn: Cleanups after -ldl is no longer required" the libdl variable is not set anymore and thus the dependencies were missing.
* dlfcn: Cleanups after -ldl is no longer requiredFlorian Weimer2021-06-031-143/+29
| | | | | | | | | | | | This commit removes the ELF constructor and internal variables from dlfcn/dlfcn.c. The file now serves the same purpose as nptl/libpthread-compat.c, so it is renamed to dlfcn/libdl-compat.c. The use of libdl-shared-only-routines ensures that libdl.a is empty. This commit adjusts the test suite not to use $(libdl). The libdl.so symbolic link is no longer installed. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* dlfcn: Move dlsym into libcFlorian Weimer2021-06-031-1/+0
| | | | | | | | | | The symbol was moved using scripts/move-symbol-to-libc.py. In elf/Makefile, remove the $(libdl) dependency from testobj1.so because it the unused libdl DSO now causes elf/tst-unused-deps to fail. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Use custom NODELETE DSO for tst-dlopenfail, tst-dlopenfail-2Florian Weimer2021-05-211-2/+9
| | | | | | | Once libpthread is empty and no longer marked NODELETE, it no longer can be used for testing. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Partially initialize ld.so after static dlopen (bug 20802)Florian Weimer2021-05-171-3/+8
| | | | | | | | | | | | | | After static dlopen, a copy of ld.so is loaded into the inner namespace, but that copy is not initialized at all. Some architectures run into serious problems as result, which is why the _dl_var_init mechanism was invented. With libpthread moving into libc and parts into ld.so, more architectures impacted, so it makes sense to switch to a generic mechanism which performs the partial initialization. As a result, getauxval now works after static dlopen (bug 20802). Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Remove all usage of @BASH@ or ${BASH} in installed files, and hardcode ↵Romain GEISSLER2021-05-121-3/+1
| | | | | | | | | | | | | | | | | | | /bin/bash instead (FYI, this is a repost of https://sourceware.org/pipermail/libc-alpha/2019-July/105035.html now that FSF papers have been signed and confirmed on FSF side). This trivial patch attemps to fix BZ 24106. Basically the bash locally used when building glibc on the host shall not leak on the installed glibc, as the system where it is installed might be different and use another bash location. So I have looked for all occurences of @BASH@ or $(BASH) in installed files, and replaced it by /bin/bash. This was suggested by Florian Weimer in the bug report. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
* elf: Add test case for [BZ #19329]Szabolcs Nagy2021-05-111-2/+7
| | | | | | | | | | | | | Test concurrent dlopen and pthread_create when the loaded modules have TLS. This triggers dl-tls assertion failures more reliably than the nptl/tst-stack4 test. The dlopened module has 100 DT_NEEDED dependencies with TLS, they were reused from an existing TLS test. The number of created threads during dlopen depends on filesystem speed and hardware, but at most 3 threads are alive at a time to limit resource usage. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf, nptl: Resolve recursive lock implementation earlyFlorian Weimer2021-05-101-1/+2
| | | | | | | | | | | If libpthread is included in libc, it is not necessary to delay initialization of the lock/unlock function pointers until libpthread is loaded. This eliminates two unprotected function pointers from _rtld_global and removes some initialization code from libpthread. Tested-by: Carlos O'Donell <carlos@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* nptl: Consolidate async cancel enable/disable implementation in libcFlorian Weimer2021-05-051-2/+4
| | | | | | | | | | | | | | Previously, the source file nptl/cancellation.c was compiled multiple times, for libc, libpthread, librt. This commit switches to a single implementation, with new __pthread_enable_asynccancel@@GLIBC_PRIVATE, __pthread_disable_asynccancel@@GLIBC_PRIVATE exports. The almost-unused CANCEL_ASYNC and CANCEL_RESET macros are replaced by LIBC_CANCEL_ASYNC and LIBC_CANCEL_ASYNC macros. They call the __pthread_* functions unconditionally now. The macros are still needed because shared code uses them; Hurd has different definitions. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Introduce __tls_init_tp for second-phase TCB initializationFlorian Weimer2021-04-211-1/+1
| | | | | | | | | | TLS_INIT_TP is processor-specific, so it is not a good place to put thread library initialization code (it would have to be repeated for all CPUs). Introduce __tls_init_tp as a separate function, to be called immediately after TLS_INIT_TP. Move the existing stack list setup code for NPTL to this function. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* dlfcn: Failures after dlmopen should not terminate process [BZ #24772]Florian Weimer2021-04-211-2/+6
| | | | | | | | | | | | | | | | | | | Commit 9e78f6f6e7134a5f299cc8de77370218f8019237 ("Implement _dl_catch_error, _dl_signal_error in libc.so [BZ #16628]") has the side effect that distinct namespaces, as created by dlmopen, now have separate implementations of the rtld exception mechanism. This means that the call to _dl_catch_error from libdl in a secondary namespace does not actually install an exception handler because the thread-local variable catch_hook in the libc.so copy in the secondary namespace is distinct from that of the base namepace. As a result, a dlsym/dlopen/... failure in a secondary namespace terminates the process with a dynamic linker error because it looks to the exception handler mechanism as if no handler has been installed. This commit restores GLRO (dl_catch_error) and uses it to set the handler in the base namespace. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* nptl: Move __pthread_unwind_next into libcFlorian Weimer2021-04-211-0/+2
| | | | | | | | | | | | | | | | | | | It's necessary to stub out __libc_disable_asynccancel and __libc_enable_asynccancel via rtld-stubbed-symbols because the new direct references to the unwinder result in symbol conflicts when the rtld exception handling from libc is linked in during the construction of librtld.map. unwind-forcedunwind.c is merged into unwind-resume.c. libc now needs the functions that were previously only used in libpthread. The GLIBC_PRIVATE exports of __libc_longjmp and __libc_siglongjmp are no longer needed, so switch them to hidden symbols. The symbol __pthread_unwind_next has been moved using scripts/move-symbol-to-libc.py. Reviewed-by: Adhemerva Zanella <adhemerval.zanella@linaro.org>
* elf: Add a DTV setup test [BZ #27136]Szabolcs Nagy2021-04-151-1/+9
| | | | | | | | | | | The test dlopens a large number of modules with TLS, they are reused from an existing test. The test relies on the reuse of slotinfo entries after dlclose, without bug 27135 fixed this needs a failing dlopen. With a slotinfo list that has non-monotone increasing generation counters, bug 27136 can trigger. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Enhance setuid-tunables testSiddhesh Poyarekar2021-04-121-2/+0
| | | | | | | | | | Instead of passing GLIBC_TUNABLES via the environment, pass the environment variable from parent to child. This allows us to test multiple variables to ensure better coverage. The test list currently only includes the case that's already being tested. More tests will be added later. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* elf: Fix not compiling ifunc tests that need gcc ifunc supportSamuel Thibault2021-03-241-5/+12
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* Build libc-start with stack protector for SHAREDSiddhesh Poyarekar2021-03-151-4/+0
| | | | | | | | | | This does not change the emitted code since __libc_start_main does not return, but is important for formal flags compliance. This also cleans up the cosmetic inconsistency in the stack protector flags in csu, especially the incorrect value of STACK_PROTECTOR_LEVEL. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: ld.so --help calls _dl_init_paths without a main map [BZ #27577]Florian Weimer2021-03-151-2/+16
| | | | | | | | | | | In this case, use the link map of the dynamic loader itself as a replacement. This is more than just a hack: if we ever support DT_RUNPATH/DT_RPATH for the dynamic loader, reporting it for ld.so --help (without further command line arguments) would be the right thing to do. Fixes commit 332421312576bd7095e70589154af99b124dd2d1 ("elf: Always set l in _dl_init_paths (bug 23462)").
* elf: Always set l in _dl_init_paths (bug 23462)Carlos O'Donell2021-03-121-1/+4
| | | | | | | | | | | | | | | After d1d5471579eb0426671bf94f2d71e61dfb204c30 ("Remove dead DL_DST_REQ_STATIC code.") we always setup the link map l to make the static and shared cases the same. The bug is that in elf/dl-load.c (_dl_init_paths) we conditionally set l only in the #ifdef SHARED case, but unconditionally use it later. The simple solution is to remove the #ifdef SHARED conditional, because it's no longer needed, and unconditionally setup l for both the static and shared cases. A regression test is added to run a static binary with LD_LIBRARY_PATH='$ORIGIN' which crashes before the fix and runs after the fix. Co-Authored-By: Florian Weimer <fweimer@redhat.com>
* ld.so: Implement the --list-diagnostics optionFlorian Weimer2021-03-021-1/+4
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* elf: Build __dl_iterate_phdr with unwinding support [BZ #27498]Florian Weimer2021-03-021-1/+1
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* elf: Replace a --defsym trick with an object file to be compatible with LLDFangrui Song2021-02-011-7/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The existing code specifies -Wl,--defsym=malloc=0 and other malloc.os definitions before libc_pic.a so that libc_pic.a(malloc.os) is not fetched. This trick is used to avoid multiple definition errors which would happen as a chain result: dl-allobjs.os has an undefined __libc_scratch_buffer_set_array_size __libc_scratch_buffer_set_array_size fetches libc_pic.a(scratch_buffer_set_array_size.os) libc_pic.a(scratch_buffer_set_array_size.os) has an undefined free free fetches libc_pic.a(malloc.os) libc_pic.a(malloc.os) has an undefined __libc_message __libc_message fetches libc_pic.a(libc_fatal.os) libc_fatal.os will cause a multiple definition error (__GI___libc_fatal) >>> defined at dl-fxstatat64.c >>> /tmp/p/glibc/Release/elf/dl-allobjs.os:(__GI___libc_fatal) >>> defined at libc_fatal.c >>> libc_fatal.os:(.text+0x240) in archive /tmp/p/glibc/Release/libc_pic.a LLD processes --defsym after all input files, so this trick does not suppress multiple definition errors with LLD. Split the step into two and use an object file to make the intention more obvious and make LLD work. This is conceptually more appropriate because --defsym defines a SHN_ABS symbol while a normal definition is relative to the image base. See https://sourceware.org/pipermail/libc-alpha/2020-March/111910.html for discussions about the --defsym semantics. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* elf: Limit tst-prelink-cmp target archsMatheus Castanho2021-01-271-7/+2
| | | | | | | | | | | | | | elf/tst-prelink-cmp was initially added for x86 (commit fe534fe898) to validate the fix for Bug 19178, and later applied to all architectures that use GLOB_DAT relocations (commit 89569c8bb6). However, that bug only affected targets that handle GLOB_DAT relocations as ELF_TYPE_CLASS_EXTERN_PROTECTED_DATA, so the test should only apply to targets defining DL_EXTERN_PROTECTED_DATA, which gates the usage of the elf type class above. For all other targets not meeting that criteria, the test now returns with UNSUPPORTED status. Fixes the test on POWER10 processors, which started using R_PPC64_GLOB_DAT. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* ld.so: Add --list-tunables to print tunable valuesH.J. Lu2021-01-151-0/+11
| | | | | | Pass --list-tunables to ld.so to print tunables with min and max values. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* ifuncmain6pie: Remove the circular IFUNC dependency [BZ #20019]H.J. Lu2021-01-131-0/+2
| | | | | | | | | | | | | | | | On x86, ifuncmain6pie failed with: [hjl@gnu-cfl-2 build-i686-linux]$ ./elf/ifuncmain6pie --direct ./elf/ifuncmain6pie: IFUNC symbol 'foo' referenced in '/export/build/gnu/tools-build/glibc-32bit/build-i686-linux/elf/ifuncmod6.so' is defined in the executable and creates an unsatisfiable circular dependency. [hjl@gnu-cfl-2 build-i686-linux]$ readelf -rW elf/ifuncmod6.so | grep foo 00003ff4 00000706 R_386_GLOB_DAT 0000400c foo_ptr 00003ff8 00000406 R_386_GLOB_DAT 00000000 foo 0000400c 00000401 R_386_32 00000000 foo [hjl@gnu-cfl-2 build-i686-linux]$ Remove non-JUMP_SLOT relocations against foo in ifuncmod6.so, which trigger the circular IFUNC dependency, and build ifuncmain6pie with -Wl,-z,lazy.
* Update copyright dates with scripts/update-copyrightsPaul Eggert2021-01-021-1/+1
| | | | | | | | | | | | | | | | I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 6694 files FOO. I then removed trailing white space from benchtests/bench-pthread-locks.c and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this diagnostic from Savannah: remote: *** pre-commit check failed ... remote: *** error: lines with trailing whitespace found remote: error: hook declined to update refs/heads/master
* elf: Include libc.so.6 as main program in dependency sort (bug 20972)Florian Weimer2020-12-111-1/+1
| | | | | | | | | | | | | | | | | _dl_map_object_deps always sorts the initially loaded object first during dependency sorting. This means it is relocated last in dl_open_worker. This results in crashes in IFUNC resolvers without lazy bindings if libraries are preloaded that refer to IFUNCs in libc.so.6: the resolvers are called when libc.so.6 has not been relocated yet, so references to _rtld_global_ro etc. crash. The fix is to check against the libc.so.6 link map recorded by the __libc_early_init framework, and let it participate in the dependency sort. This fixes bug 20972. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* s390x: Add glibc-hwcaps supportFlorian Weimer2020-12-101-1/+1
| | | | | | | Subdirectories z13, z14, z15 can be selected, mostly based on the level of support for vector instructions. Co-Authored-By: Stefan Liebler <stli@linux.ibm.com>
* elf: Fix run-time dependencies of tst-dlopen-fail-2Florian Weimer2020-12-101-1/+1
| | | | | | | | The misattributed dependencies can cause failures in parallel testing if the dependencies have not been built yet. Fixes commit a332bd1518af518c984fad73eba6f46dc5b2b2d4 ("elf: Add elf/tst-dlopenfail-2 [BZ #25396]").
* powerpc64le: Add glibc-hwcaps supportFlorian Weimer2020-12-041-1/+1
| | | | | The "power10" and "power9" subdirectories are selected in a way that matches the -mcpu=power10 and -mcpu=power9 options of GCC.
* x86_64: Add glibc-hwcaps supportFlorian Weimer2020-12-041-1/+1
| | | | | | | | The subdirectories match those in the x86-64 psABI: https://gitlab.com/x86-psABIs/x86-64-ABI/-/commit/77566eb03bc6a326811cb7e9a6b9396884b67c7c Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Add glibc-hwcaps subdirectory support to ld.so cache processingFlorian Weimer2020-12-041-0/+18
| | | | | | | | | | | | | | This recognizes the DL_CACHE_HWCAP_EXTENSION flag in cache entries, and picks the supported cache entry with the highest priority. The elf/tst-glibc-hwcaps-prepend-cache test documents a non-desired aspect of the current cache implementation: If the cache selects a DSO that does not exist on disk, _dl_map_object falls back to open_path, which may or may not find an alternative implementation. This is an existing limitation that also applies to the legacy hwcaps processing for ld.so.cache. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Implement tail merging of strings in ldconfigFlorian Weimer2020-12-041-1/+2
| | | | | | | | | | | | | This simplifies the string table construction in elf/cache.c because there is no more need to keep track of offsets explicitly; the string table implementation does this internally. This change slightly reduces the size of the cache on disk. The file format does not change as a result. The strings are null-terminated, without explicit length, so tail merging is transparent to readers. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Implement a string table for ldconfig, with tail mergingFlorian Weimer2020-12-041-1/+1
| | | | | | | | | | | | | | | | This will be used in ldconfig to reduce the ld.so.cache size slightly. Tail merging is an optimization where a pointer points into another string if the first string is a suffix of the second string. The hash function FNV-1a was chosen because it is simple and achieves good dispersion even for short strings (so that the hash table bucket count can be a power of two). It is clearly superior to the hsearch hash and the ELF hash in this regard. The hash table uses chaining for collision resolution. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Add glibc-hwcaps support for LD_LIBRARY_PATHFlorian Weimer2020-12-041-5/+66
| | | | | | | | | | | | | | | | | | | | This hacks non-power-set processing into _dl_important_hwcaps. Once the legacy hwcaps handling goes away, the subdirectory handling needs to be reworked, but it is premature to do this while both approaches are still supported. ld.so supports two new arguments, --glibc-hwcaps-prepend and --glibc-hwcaps-mask. Each accepts a colon-separated list of glibc-hwcaps subdirectory names. The prepend option adds additional subdirectories that are searched first, in the specified order. The mask option restricts the automatically selected subdirectories to those listed in the option argument. For example, on systems where /usr/lib64 is on the library search path, --glibc-hwcaps-prepend=valgrind:debug causes the dynamic loader to search the directories /usr/lib64/glibc-hwcaps/valgrind and /usr/lib64/glibc-hwcaps/debug just before /usr/lib64 is searched. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Add {,sysdep-}ld-library-path make variableSamuel Thibault2020-11-161-2/+2
| | | | | | | | On GNU/Hurd we not only need $(common-objpfx) in LD_LIBRARY_PATH when loading dynamic objects, but also $(common-objpfx)/mach and $(common-objpfx)/hurd. This adds an ld-library-path variable to be used as LD_LIBRARY_PATH basis in Makefiles, and a sysdep-ld-library-path variable for sysdeps to add some more paths, here mach/ and hurd/.
* nptl: Move stack list variables into _rtld_globalFlorian Weimer2020-11-161-2/+4
| | | | | | | | | Now __thread_gscope_wait (the function behind THREAD_GSCOPE_WAIT, formerly __wait_lookup_done) can be implemented directly in ld.so, eliminating the unprotected GL (dl_wait_lookup_done) function pointer. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Print the full name of the dynamic loader in the ld.so help messageFlorian Weimer2020-10-081-1/+2
| | | | | | | | This requires defining a macro for the full path, matching the -Wl,--dynamic-link= arguments used for linking glibc programs, and ldd script. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Move ld.so error/help output to _dl_usageFlorian Weimer2020-10-081-1/+8
| | | | | | | Also add a comment to elf/Makefile, explaining why we cannot use config.status for autoconf template processing. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Revert "Fix missing redirects in testsuite targets"Andreas Schwab2020-10-081-1/+1
| | | | | This reverts commit d5afb38503. The log files are actually created by the various shell scripts that drive the tests.
* elf: Implement _dl_writeFlorian Weimer2020-10-071-1/+1
| | | | | | | | The generic version is parallel to _dl_writev. It cannot use _dl_writev directly because the errno value needs to be obtained under a lock. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Do not search HWCAP subdirectories in statically linked binariesFlorian Weimer2020-10-071-2/+2
| | | | | | | | | This functionality does not seem to be useful since static dlopen is mostly used for iconv/character set conversion and NSS support. gconv modules are loaded with full paths anyway, so that the HWCAP subdirectory logic does not apply. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* ld.so: add an --argv0 option [BZ #16124]Vincent Mihalkovic2020-09-291-2/+10
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* elf: Change TLS static surplus default back to 1664Florian Weimer2020-07-201-1/+3
| | | | | | | Make the computation in elf/dl-tls.c more transparent, and add an explicit test for the historic value. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* rtld: Avoid using up static TLS surplus for optimizations [BZ #25051]Szabolcs Nagy2020-07-081-2/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | On some targets static TLS surplus area can be used opportunistically for dynamically loaded modules such that the TLS access then becomes faster (TLSDESC and powerpc TLS optimization). However we don't want all surplus TLS to be used for this optimization because dynamically loaded modules with initial-exec model TLS can only use surplus TLS. The new contract for surplus static TLS use is: - libc.so can have up to 192 bytes of IE TLS, - other system libraries together can have up to 144 bytes of IE TLS. - Some "optional" static TLS is available for opportunistic use. The optional TLS is now tunable: rtld.optional_static_tls, so users can directly affect the allocated static TLS size. (Note that module unloading with dlclose does not reclaim static TLS. After the optional TLS runs out, TLS access is no longer optimized to use static TLS.) The default setting of rtld.optional_static_tls is 512 so the surplus TLS is 3*192 + 4*144 + 512 = 1664 by default, the same as before. Fixes BZ #25051. Tested on aarch64-linux-gnu and x86_64-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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