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* Fix elf/tst-audit25a with default bind now toolchainsSzabolcs Nagy2022-02-021-0/+1
| | | | | This test relies on lazy binding for the executable so request that explicitly in case the toolchain defaults to bind now.
* elf: Issue la_symbind for bind-now (BZ #23734)Adhemerval Zanella2022-02-011-1/+88
| | | | | | | | | | | | | | | | | | | | | | | The audit symbind callback is not called for binaries built with -Wl,-z,now or when LD_BIND_NOW=1 is used, nor the PLT tracking callbacks (plt_enter and plt_exit) since this would change the expected program semantics (where no PLT is expected) and would have performance implications (such as for BZ#15533). LAV_CURRENT is also bumped to indicate the audit ABI change (where la_symbind flags are set by the loader to indicate no possible PLT trace). To handle powerpc64 ELFv1 function descriptor, _dl_audit_symbind requires to know whether bind-now is used so the symbol value is updated to function text segment instead of the OPD (for lazy binding this is done by PPC64_LOAD_FUNCPTR on _dl_runtime_resolve). Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, powerpc64-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
* elf: Fix initial-exec TLS access on audit modules (BZ #28096)Adhemerval Zanella2022-02-011-0/+8
| | | | | | | | | | | | | | | | | For audit modules and dependencies with initial-exec TLS, we can not set the initial TLS image on default loader initialization because it would already be set by the audit setup. However, subsequent thread creation would need to follow the default behaviour. This patch fixes it by setting l_auditing link_map field not only for the audit modules, but also for all its dependencies. This is used on _dl_allocate_tls_init to avoid the static TLS initialization at load time. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
* elf: Add la_activity during application exitAdhemerval Zanella2022-02-011-0/+7
| | | | | | | | | | la_activity is not called during application exit, even though la_objclose is. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
* Fix elf/loadfail test build dependenciesSzabolcs Nagy2022-01-281-1/+3
| | | | | | | | | | There was no direct or indirect make dependency on testobj3.so so the test could fail with /B/elf/loadfail: failed to load shared object: testobj3.so: cannot open shared object file: No such file or directory Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* Fix glibc 2.34 ABI omission (missing GLIBC_2.34 in dynamic loader)Florian Weimer2022-01-271-0/+1
| | | | | | | | | | | | | The glibc 2.34 release really should have added a GLIBC_2.34 symbol to the dynamic loader. With it, we could move functions such as dlopen or pthread_key_create that work on process-global state into the dynamic loader (once we have fixed a longstanding issue with static linking). Without the GLIBC_2.34 symbol, yet another new symbol version would be needed because old glibc will fail to load binaries due to the missing symbol version in ld.so that newly linked programs will require. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* Guard tst-valgrind-smoke.out with run-built-testsMark Wielaard2022-01-261-0/+2
| | | | | | Prevent tst-valgrind-smoke from running when run-built-tests is not yes. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Replace tst-p_alignmod1-editX with a python scriptAdhemerval Zanella2022-01-261-10/+4
| | | | | | | | This avoid the cross-compiling breakage when the test should not run ($(run-built-tests) equal to no). Checked on x86_64-linux-gnu and i686-linux-gnu as well with a cross compile to aarch64-linux-gnu and powerpc64-linux-gnu.
* elf: Add a test for PT_LOAD segments with invalid p_align [BZ #28688]H.J. Lu2022-01-241-0/+9
| | | | | | | Build tst-p_alignmod3.so with 256 byte page size and verify that it is rejected with a proper error message. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Add a test for PT_LOAD segments with p_align == 1 [BZ #28688]H.J. Lu2022-01-241-0/+13
| | | | | | | | Add tst-p_alignmod2-edit to edit the copy of tst-p_alignmod-base.so to set p_align of the first PT_LOAD segment to 1 and verify that the shared library can be loaded normally. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Add a test for PT_LOAD segments with mixed p_align [BZ #28676]H.J. Lu2022-01-241-0/+17
| | | | | | | | Add tst-p_alignmod1-edit to edit the copy of tst-p_alignmod-base.so to reduce p_align of the first PT_LOAD segment by half and verify that the shared library is mapped with the maximum p_align of all PT_LOAD segments. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Add and use link-test-modules-rpath-link [BZ #28455]H.J. Lu2022-01-241-0/+7
| | | | | | | | | | | | | DT_RUNPATH is only used to find the immediate dependencies of the executable or shared object containing the DT_RUNPATH entry: 1. Define link-test-modules-rpath-link if $(build-hardcoded-path-in-tests) is yes. 2. Use $(link-test-modules-rpath-link) in build-module-helper so that test modules can dlopen modules with DT_RUNPATH. 3. Add a test to show why link-test-modules-rpath-link is needed. This partially fixes BZ #28455.
* Add valgrind smoke testAlexandra Hájková2022-01-221-0/+7
| | | | | | | | | | Check if whether valgrind is available in the test environment. If not, skip the test. Run smoke tests with valgrind to verify dynamic loader. First, check if algrind works with the system ld.so in the test environment. Then run the actual test inside the test environment, using the just build ld.so and new libraries. Co-authored-by: Mark Wielaard <mark@klomp.org>
* elf: Move _dl_setup_hash to its own fileFlorian Weimer2022-01-181-0/+2
| | | | | | | | | And compile it with the early CFLAGS. _dl_setup_hash is called very early for the ld.so link map, so it should be compiled differently. Reviewed-by: Stefan Liebler <stli@linux.ibm.com> Tested-by: Stefan Liebler <stli@linux.ibm.com>
* elf: Reinstate tst-audit17Adhemerval Zanella2022-01-171-0/+1
| | | | | 9926f6e2eeb3 ("elf: Skip tst-auditlogmod-* if the linker doesn't support --depaudit [BZ #28 151]") dropped the test by mistake.
* Add --with-rtld-early-cflags configure optionFlorian Weimer2022-01-141-0/+8
| | | | | Reviewed-by: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* elf: Split dl-printf.c from dl-misc.cFlorian Weimer2022-01-141-0/+1
| | | | | | | This allows to use different compiler flags for the diagnostics code. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* elf/Makefile: Reflow and sort most variable assignmentsFlorian Weimer2022-01-141-102/+318
| | | | Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* elf: Add a comment after trailing backslashesH.J. Lu2022-01-041-0/+4
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* elf: Also try DT_RUNPATH for LD_AUDIT dlopen [BZ #28455]H.J. Lu2022-01-041-3/+8
| | | | | | | | | | | DT_RUNPATH is only used to find the immediate dependencies of the executable or shared object containing the DT_RUNPATH entry. Update LD_AUDIT dlopen call to try the DT_RUNPATH entry of the executable. Add tst-audit14a, which is copied from tst-audit14, to DT_RUNPATH and build tst-audit14 with -Wl,--disable-new-dtags to test DT_RPATH. This partially fixes BZ #28455.
* elf: Fix tst-linkall-static link when pthread is not in libcSamuel Thibault2022-01-041-0/+4
| | | | In that case we want to link in libanl.a, thus providing getaddrinfo_a.
* elf: Sort tests and modules-namesH.J. Lu2022-01-031-147/+405
| | | | Sort tests and modules-names to reduce future conflicts.
* Remove stale reference to libanl.aAdhemerval Zanella2022-01-031-1/+0
| | | | | Since dbb949f53d4 ("resolv: Move libanl into libc (if libpthread is in libc)") libanl.a is empty, so linking against it no longer necessary.
* Update copyright dates with scripts/update-copyrightsPaul Eggert2022-01-011-1/+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 7061 files FOO. I then removed trailing white space from math/tgmath.h, support/tst-support-open-dev-null-range.c, and sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following obscure pre-commit check failure diagnostics from Savannah. I don't know why I run into these diagnostics whereas others evidently do not. remote: *** 912-#endif remote: *** 913: remote: *** 914- remote: *** error: lines with trailing whitespace found ... remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
* elf: Add _dl_find_object functionFlorian Weimer2021-12-281-4/+51
| | | | | | | | | | | | | | | | | | | | | | | | | It can be used to speed up the libgcc unwinder, and the internal _dl_find_dso_for_object function (which is used for caller identification in dlopen and related functions, and in dladdr). _dl_find_object is in the internal namespace due to bug 28503. If libgcc switches to _dl_find_object, this namespace issue will be fixed. It is located in libc for two reasons: it is necessary to forward the call to the static libc after static dlopen, and there is a link ordering issue with -static-libgcc and libgcc_eh.a because libc.so is not a linker script that includes ld.so in the glibc build tree (so that GCC's internal -lc after libgcc_eh.a does not pick up ld.so). It is necessary to do the i386 customization in the sysdeps/x86/bits/dl_find_object.h header shared with x86-64 because otherwise, multilib installations are broken. The implementation uses software transactional memory, as suggested by Torvald Riegel. Two copies of the supporting data structures are used, also achieving full async-signal-safety. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Do not fail for failed dlmopen on audit modules (BZ #28061)Adhemerval Zanella2021-12-281-0/+5
| | | | | | | | | | | | | | | | | | | | | The dl_main sets the LM_ID_BASE to RT_ADD just before starting to add load new shared objects. The state is set to RT_CONSISTENT just after all objects are loaded. However if a audit modules tries to dlmopen an inexistent module, the _dl_open will assert that the namespace is in an inconsistent state. This is different than dlopen, since first it will not use LM_ID_BASE and second _dl_map_object_from_fd is the sole responsible to set and reset the r_state value. So the assert on _dl_open can not really be seen if the state is consistent, since _dt_main resets it. This patch removes the assert. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Issue audit la_objopen for vDSOAdhemerval Zanella2021-12-281-0/+5
| | | | | | | | | | | | | | | The vDSO is is listed in the link_map chain, but is never the subject of an la_objopen call. A new internal flag __RTLD_VDSO is added that acts as __RTLD_OPENEXEC to allocate the required 'struct auditstate' extra space for the 'struct link_map'. The return value from the callback is currently ignored, since there is no PLT call involved by glibc when using the vDSO, neither the vDSO are exported directly. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Add audit tests for modules with TLSDESCAdhemerval Zanella2021-12-281-0/+16
| | | | | | Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Avoid unnecessary slowdown from profiling with audit (BZ#15533)Adhemerval Zanella2021-12-281-1/+13
| | | | | | | | | | | | | | | | | | | The rtld-audit interfaces introduces a slowdown due to enabling profiling instrumentation (as if LD_AUDIT implied LD_PROFILE). However, instrumenting is only necessary if one of audit libraries provides PLT callbacks (la_pltenter or la_pltexit symbols). Otherwise, the slowdown can be avoided. The following patch adjusts the logic that enables profiling to iterate over all audit modules and check if any of those provides a PLT hook. To keep la_symbind to work even without PLT callbacks, _dl_fixup now calls the audit callback if the modules implements it. Co-authored-by: Alexander Monakov <amonakov@ispras.ru> Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Add _dl_audit_objopenAdhemerval Zanella2021-12-281-1/+1
| | | | | | | | It consolidates the code required to call la_objopen audit callback. Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* Add a testcase to check alignment of PT_LOAD segment [BZ #28676]H.J. Lu2021-12-101-2/+12
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* elf: Install a symbolic link to ld.so as /usr/bin/ld.soFlorian Weimer2021-12-101-1/+6
| | | | | | | | This makes ld.so features such as --preload, --audit, and --list-diagnostics more accessible to end users because they do not need to know the ABI name of the dynamic loader. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* elf: execve statically linked programs instead of crashing [BZ #28648]Florian Weimer2021-12-051-0/+3
| | | | | | | | | | | | | | | Programs without dynamic dependencies and without a program interpreter are now run via execve. Previously, the dynamic linker either crashed while attempting to read a non-existing dynamic segment (looking for DT_AUDIT/DT_DEPAUDIT data), or the self-relocated in the static PIE executable crashed because the outer dynamic linker had already applied RELRO protection. <dl-execve.h> is needed because execve is not available in the dynamic loader on Hurd. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
* elf: Move la_activity (LA_ACT_ADD) after _dl_add_to_namespace_list() (BZ #28062)Adhemerval Zanella2021-11-181-1/+8
| | | | | | | | It ensures that the the namespace is guaranteed to not be empty. Checked on x86_64-linux-gnu. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Introduce GLRO (dl_libc_freeres), called from __libc_freeresFlorian Weimer2021-11-171-1/+1
| | | | | | | This will be used to deallocate memory allocated using the non-minimal malloc. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Use a temporary file to generate Makefile fragments [BZ #28550]H.J. Lu2021-11-161-2/+8
| | | | | | | | | | | | 1. Use a temporary file to generate Makefile fragments for DSO sorting tests and use -include on them. 2. Add Makefile fragments to postclean-generated so that a "make clean" removes the autogenerated fragments and a subsequent "make" regenerates them. This partially fixes BZ #28550. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Move LAV_CURRENT to link_lavcurrent.hAdhemerval Zanella2021-11-151-1/+1
| | | | No functional change.
* elf: Use the minimal malloc on tunables_strdupAdhemerval Zanella2021-11-091-1/+6
| | | | | | | | | | | | | | | | | | | | The rtld_malloc functions are moved to its own file so it can be used on csu code. Also, the functiosn are renamed to __minimal_* (since there are now used not only on loader code). Using the __minimal_malloc on tunables_strdup() avoids potential issues with sbrk() calls while processing the tunables (I see sporadic elf/tst-dso-ordering9 on powerpc64le with different tests failing due ASLR). Also, using __minimal_malloc over plain mmap optimizes the memory allocation on both static and dynamic case (since it will any unused space in either the last page of data segments, avoiding mmap() call, or from the previous mmap() call). Checked on x86_64-linux-gnu, i686-linux-gnu, and powerpc64le-linux-gnu. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
* elf: Do not run DSO sorting if tunables is not enabledAdhemerval Zanella2021-11-031-0/+2
| | | | | | Since the argorithm selection requires tunables. Checked on x86_64-linux-gnu with --enable-tunables=no.
* elf: Disable ifuncmain{1,5,5pic,5pie} when using LLDAdhemerval Zanella2021-10-291-4/+13
| | | | | | | | | These tests takes the address of a protected symbol (foo_protected) and lld does not support copy relocations on protected data symbols. Checked on x86_64-linux-gnu. Reviewed-by: Fangrui Song <maskray@google.com>
* elf: Make global.out depend on reldepmod4.so [BZ #28457]H.J. Lu2021-10-251-1/+1
| | | | | | The global test is linked with globalmod1.so which dlopens reldepmod4.so. Make global.out depend on reldepmod4.so. This fixes BZ #28457. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Testing infrastructure for ld.so DSO sorting (BZ #17645)Chung-Lin Tang2021-10-211-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the first of a 2-part patch set that fixes slow DSO sorting behavior in the dynamic loader, as reported in BZ #17645. In order to facilitate such a large modification to the dynamic loader, this first patch implements a testing framework for validating shared object sorting behavior, to enable comparison between old/new sorting algorithms, and any later enhancements. This testing infrastructure consists of a Python script scripts/dso-ordering-test.py' which takes in a description language, consisting of strings that describe a set of link dependency relations between DSOs, and generates testcase programs and Makefile fragments to automatically test the described situation, for example: a->b->c->d # four objects linked one after another a->[bc]->d;b->c # a depends on b and c, which both depend on d, # b depends on c (b,c linked to object a in fixed order) a->b->c;{+a;%a;-a} # a, b, c serially dependent, main program uses # dlopen/dlsym/dlclose on object a a->b->c;{}!->[abc] # a, b, c serially dependent; multiple tests generated # to test all permutations of a, b, c ordering linked # to main program (Above is just a short description of what the script can do, more documentation is in the script comments.) Two files containing several new tests, elf/dso-sort-tests-[12].def are added, including test scenarios for BZ #15311 and Redhat issue #1162810 [1]. Due to the nature of dynamic loader tests, where the sorting behavior and test output occurs before/after main(), generating testcases to use support/test-driver.c does not suffice to control meaningful timeout for ld.so. Therefore a new utility program 'support/test-run-command', based on test-driver.c/support_test_main.c has been added. This does the same testcase control, but for a program specified through a command-line rather than at the source code level. This utility is used to run the dynamic loader testcases generated by dso-ordering-test.py. [1] https://bugzilla.redhat.com/show_bug.cgi?id=1162810 Signed-off-by: Chung-Lin Tang <cltang@codesourcery.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Update audit tests to not depend on stdoutStafford Horne2021-10-121-0/+14
| | | | | | | | | | | | | | The tst-audit14, tst-audit15 and tst-audit16 tests all have audit modules that write to stdout; the test reads from stdout to confirm what was written. This assumes the stdout is a file which is not the case when run over ssh. This patch updates the tests to use a post run cmp command to compare the output against and .exp file. This is similar to how many other tests work and it fixes the stdout limitation. Also, this means the test code can be greatly simplified. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* Avoid warning: overriding recipe for .../tst-ro-dynamic-mod.soH.J. Lu2021-09-251-2/+3
| | | | | | | | Add tst-ro-dynamic-mod to modules-names-nobuild to avoid ../Makerules:767: warning: ignoring old recipe for target '.../elf/tst-ro-dynamic-mod.so' This updates BZ #28340 fix.
* ld.so: Replace DL_RO_DYN_SECTION with dl_relocate_ld [BZ #28340]H.J. Lu2021-09-221-2/+9
| | | | | | | | | | | | | | | | | We can't relocate entries in dynamic section if it is readonly: 1. Add a l_ld_readonly field to struct link_map to indicate if dynamic section is readonly and set it based on p_flags of PT_DYNAMIC segment. 2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic section should be relocated. 3. Remove DL_RO_DYN_TEMP_CNT. 4. Don't use a static dynamic section to make readonly dynamic section in vDSO writable. 5. Remove the temp argument from elf_get_dynamic_info. This fixes BZ #28340. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
* Extend struct r_debug to support multiple namespaces [BZ #15971]H.J. Lu2021-09-191-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Glibc does not provide an interface for debugger to access libraries loaded in multiple namespaces via dlmopen. The current rtld-debugger interface is described in the file: elf/rtld-debugger-interface.txt under the "Standard debugger interface" heading. This interface only provides access to the first link-map (LM_ID_BASE). 1. Bump r_version to 2 when multiple namespaces are used. This triggers the GDB bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28236 2. Add struct r_debug_extended to extend struct r_debug into a linked-list, where each element correlates to an unique namespace. 3. Initialize the r_debug_extended structure. Bump r_version to 2 for the new namespace and add the new namespace to the namespace linked list. 4. Add _dl_debug_update to return the address of struct r_debug' of a namespace. 5. Add a hidden symbol, _r_debug_extended, for struct r_debug_extended. 6. Provide the symbol, _r_debug, with size of struct r_debug, as an alias of _r_debug_extended, for programs which reference _r_debug. This fixes BZ #15971. Reviewed-by: Florian Weimer <fweimer@redhat.com>
* elf: Skip tst-auditlogmod-* if the linker doesn't support --depaudit [BZ #28151]Fangrui Song2021-08-241-1/+3
| | | | | | gold and ld.lld do not support --audit or --depaudit. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* elf: Drop elf/tls-macros.h in favor of __thread and tls_model attributes [BZ ↵Fangrui Song2021-08-161-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | #28152] [BZ #28205] elf/tls-macros.h was added for TLS testing when GCC did not support __thread. __thread and tls_model attributes are mature now and have been used by many newer tests. Also delete tst-tls2.c which tests .tls_common (unused by modern GCC and unsupported by Clang/LLD). .tls_common and .tbss definition are almost identical after linking, so the runtime test doesn't add additional coverage. Assembler and linker tests should be on the binutils side. When LLD 13.0.0 is allowed in configure.ac (https://sourceware.org/pipermail/libc-alpha/2021-August/129866.html), `make check` result is on par with glibc built with GNU ld on aarch64 and x86_64. As a future clean-up, TLS_GD/TLS_LD/TLS_IE/TLS_IE macros can be removed from sysdeps/*/tls-macros.h. We can add optional -mtls-dialect={gnu2,trad} tests to ensure coverage. Tested on aarch64-linux-gnu, powerpc64le-linux-gnu, and x86_64-linux-gnu. Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
* elf: Fix audit regressionAdhemerval Zanella2021-07-301-1/+11
| | | | | | | Commit 03e187a41d9 added a regression when an audit module does not have libc as DT_NEEDED (although unusual it is possible). Checked on x86_64-linux-gnu.
* Move malloc hooks into a compat DSOSiddhesh Poyarekar2021-07-221-9/+6
| | | | | | | | | | | | | | | | | | | | | | | | Remove all malloc hook uses from core malloc functions and move it into a new library libc_malloc_debug.so. With this, the hooks now no longer have any effect on the core library. libc_malloc_debug.so is a malloc interposer that needs to be preloaded to get hooks functionality back so that the debugging features that depend on the hooks, i.e. malloc-check, mcheck and mtrace work again. Without the preloaded DSO these debugging features will be nops. These features will be ported away from hooks in subsequent patches. Similarly, legacy applications that need hooks functionality need to preload libc_malloc_debug.so. The symbols exported by libc_malloc_debug.so are maintained at exactly the same version as libc.so. Finally, static binaries will no longer be able to use malloc debugging features since they cannot preload the debugging DSO. Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>