forked from rpms/glibc
450 lines
15 KiB
Diff
450 lines
15 KiB
Diff
Added $(objpfx)tst-audit19a: $(libdl) to elf/Makefile since
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we still need $(libdl) in RHEL8.
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commit 063f9ba220f434c7f30dd65c4cff17c0c458a7cf
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Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Date: Wed Jun 30 10:24:09 2021 -0300
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elf: Avoid unnecessary slowdown from profiling with audit (BZ#15533)
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The rtld-audit interfaces introduces a slowdown due to enabling
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profiling instrumentation (as if LD_AUDIT implied LD_PROFILE).
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However, instrumenting is only necessary if one of audit libraries
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provides PLT callbacks (la_pltenter or la_pltexit symbols). Otherwise,
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the slowdown can be avoided.
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The following patch adjusts the logic that enables profiling to iterate
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over all audit modules and check if any of those provides a PLT hook.
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To keep la_symbind to work even without PLT callbacks, _dl_fixup now
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calls the audit callback if the modules implements it.
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Co-authored-by: Alexander Monakov <amonakov@ispras.ru>
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Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
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Reviewed-by: Florian Weimer <fweimer@redhat.com>
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Conflicts:
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elf/Makefile
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diff --git a/elf/Makefile b/elf/Makefile
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index 08a32a712a34f2cc..0cc03ffe2984ee50 100644
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--- a/elf/Makefile
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+++ b/elf/Makefile
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@@ -221,12 +221,14 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
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tst-dlmopen-gethostbyname \
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tst-audit17 \
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tst-audit18 \
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+ tst-audit19b \
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# reldep9
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tests-internal += loadtest unload unload2 circleload1 \
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neededtest neededtest2 neededtest3 neededtest4 \
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tst-tls3 tst-tls6 tst-tls7 tst-tls8 tst-dlmopen2 \
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tst-ptrguard1 tst-stackguard1 tst-libc_dlvsym \
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- tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split
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+ tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split \
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+ tst-audit19a
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tests-container += tst-pldd tst-preload-pthread-libc
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ifeq ($(build-hardcoded-path-in-tests),yes)
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tests += tst-dlopen-aout
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@@ -358,6 +360,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
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tst-dlmopen-gethostbyname-mod \
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tst-auditmod18 \
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tst-audit18mod \
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+ tst-auditmod19a \
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+ tst-auditmod19b \
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+ tst-audit19bmod \
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# Most modules build with _ISOMAC defined, but those filtered out
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# depend on internal headers.
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@@ -1548,6 +1553,14 @@ $(objpfx)tst-audit18.out: $(objpfx)tst-auditmod18.so \
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$(objpfx)tst-audit18mod.so
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tst-audit18-ARGS = -- $(host-test-program-cmd)
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+$(objpfx)tst-audit19a: $(libdl)
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+$(objpfx)tst-audit19a.out: $(objpfx)tst-auditmod19a.so
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+tst-audit19a-ENV = LD_AUDIT=$(objpfx)tst-auditmod19a.so
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+
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+$(objpfx)tst-audit19b.out: $(objpfx)tst-auditmod19b.so
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+$(objpfx)tst-audit19b: $(objpfx)tst-audit19bmod.so
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+tst-audit19b-ARGS = -- $(host-test-program-cmd)
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+
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# tst-sonamemove links against an older implementation of the library.
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LDFLAGS-tst-sonamemove-linkmod1.so = \
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-Wl,--version-script=tst-sonamemove-linkmod1.map \
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diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c
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index 19de5de067a5ef07..7a84b1fa8c3a7fdd 100644
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--- a/elf/dl-reloc.c
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+++ b/elf/dl-reloc.c
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@@ -178,12 +178,28 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
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int skip_ifunc = reloc_mode & __RTLD_NOIFUNC;
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#ifdef SHARED
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+ bool consider_symbind = false;
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/* If we are auditing, install the same handlers we need for profiling. */
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if ((reloc_mode & __RTLD_AUDIT) == 0)
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- consider_profiling |= GLRO(dl_audit) != NULL;
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+ {
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+ struct audit_ifaces *afct = GLRO(dl_audit);
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+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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+ {
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+ /* Profiling is needed only if PLT hooks are provided. */
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+ if (afct->ARCH_LA_PLTENTER != NULL
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+ || afct->ARCH_LA_PLTEXIT != NULL)
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+ consider_profiling = 1;
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+ if (afct->symbind != NULL)
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+ consider_symbind = true;
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+
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+ afct = afct->next;
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+ }
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+ }
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#elif defined PROF
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/* Never use dynamic linker profiling for gprof profiling code. */
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# define consider_profiling 0
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+#else
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+# define consider_symbind 0
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#endif
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if (l->l_relocated)
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@@ -278,7 +294,7 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
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ELF_DYNAMIC_RELOCATE (l, scope, lazy, consider_profiling, skip_ifunc);
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#ifndef PROF
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- if (__glibc_unlikely (consider_profiling)
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+ if ((consider_profiling || consider_symbind)
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&& l->l_info[DT_PLTRELSZ] != NULL)
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{
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/* Allocate the array which will contain the already found
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diff --git a/elf/dl-runtime.c b/elf/dl-runtime.c
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index ec0b2164825fa538..71ec65264ff780fb 100644
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--- a/elf/dl-runtime.c
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+++ b/elf/dl-runtime.c
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@@ -123,6 +123,37 @@ _dl_fixup (
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&& __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0))
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value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value));
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+#ifdef SHARED
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+ /* Auditing checkpoint: we have a new binding. Provide the auditing
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+ libraries the possibility to change the value and tell us whether further
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+ auditing is wanted.
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+ The l_reloc_result is only allocated if there is an audit module which
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+ provides a la_symbind. */
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+ if (l->l_reloc_result != NULL)
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+ {
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+ /* This is the address in the array where we store the result of previous
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+ relocations. */
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+ struct reloc_result *reloc_result
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+ = &l->l_reloc_result[reloc_index (pltgot, reloc_arg, sizeof (PLTREL))];
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+ unsigned int init = atomic_load_acquire (&reloc_result->init);
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+ if (init == 0)
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+ {
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+ _dl_audit_symbind (l, reloc_result, sym, &value, result);
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+
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+ /* Store the result for later runs. */
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+ if (__glibc_likely (! GLRO(dl_bind_not)))
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+ {
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+ reloc_result->addr = value;
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+ /* Guarantee all previous writes complete before init is
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+ updated. See CONCURRENCY NOTES below. */
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+ atomic_store_release (&reloc_result->init, 1);
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+ }
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+ }
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+ else
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+ value = reloc_result->addr;
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+ }
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+#endif
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+
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/* Finally, fix up the plt itself. */
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if (__glibc_unlikely (GLRO(dl_bind_not)))
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return value;
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diff --git a/elf/rtld.c b/elf/rtld.c
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index 767acd122262b824..2994578ba3a5f911 100644
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--- a/elf/rtld.c
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+++ b/elf/rtld.c
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@@ -1027,13 +1027,7 @@ ERROR: audit interface '%s' requires version %d (maximum supported version %d);
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"la_objsearch\0"
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"la_objopen\0"
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"la_preinit\0"
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-#if __ELF_NATIVE_CLASS == 32
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- "la_symbind32\0"
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-#elif __ELF_NATIVE_CLASS == 64
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- "la_symbind64\0"
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-#else
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-# error "__ELF_NATIVE_CLASS must be defined"
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-#endif
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+ LA_SYMBIND "\0"
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#define STRING(s) __STRING (s)
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"la_" STRING (ARCH_LA_PLTENTER) "\0"
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"la_" STRING (ARCH_LA_PLTEXIT) "\0"
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diff --git a/elf/tst-audit19a.c b/elf/tst-audit19a.c
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new file mode 100644
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index 0000000000000000..035cde9351c2711b
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--- /dev/null
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+++ b/elf/tst-audit19a.c
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@@ -0,0 +1,38 @@
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+/* Check if DT_AUDIT a module without la_plt{enter,exit} symbols does not incur
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+ in profiling (BZ#15533).
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <link.h>
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+#include <support/xdlfcn.h>
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+#include <support/check.h>
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+
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+static int
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+do_test (void)
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+{
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+ void *h = xdlopen ("tst-auditmod19a.so", RTLD_NOW);
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+
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+ struct link_map *lmap;
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+ TEST_VERIFY_EXIT (dlinfo (h, RTLD_DI_LINKMAP, &lmap) == 0);
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+
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+ /* The internal array is only allocated if profiling is enabled. */
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+ TEST_VERIFY (lmap->l_reloc_result == NULL);
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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diff --git a/elf/tst-audit19b.c b/elf/tst-audit19b.c
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new file mode 100644
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index 0000000000000000..da015734f24e0d79
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--- /dev/null
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+++ b/elf/tst-audit19b.c
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@@ -0,0 +1,94 @@
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+/* Check if DT_AUDIT a module with la_plt{enter,exit} call la_symbind
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+ for lazy resolution.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <getopt.h>
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+#include <support/capture_subprocess.h>
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+#include <support/check.h>
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+#include <support/xstdio.h>
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+#include <stdlib.h>
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+#include <string.h>
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+#include <stdbool.h>
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+
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+static int restart;
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+#define CMDLINE_OPTIONS \
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+ { "restart", no_argument, &restart, 1 },
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+
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+int tst_audit18bmod1_func (void);
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+
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+static int
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+handle_restart (void)
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+{
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+ TEST_COMPARE (tst_audit18bmod1_func (), 10);
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+ return 0;
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+}
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+
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+static inline bool
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+startswith (const char *str, const char *pre)
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+{
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+ size_t lenpre = strlen (pre);
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+ size_t lenstr = strlen (str);
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+ return lenstr < lenpre ? false : memcmp (pre, str, lenpre) == 0;
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+}
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+
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+static int
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+do_test (int argc, char *argv[])
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+{
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+ /* We must have either:
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+ - One our fource parameters left if called initially:
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+ + path to ld.so optional
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+ + "--library-path" optional
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+ + the library path optional
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+ + the application name */
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+
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+ if (restart)
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+ return handle_restart ();
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+
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+ char *spargv[9];
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+ int i = 0;
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+ for (; i < argc - 1; i++)
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+ spargv[i] = argv[i + 1];
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+ spargv[i++] = (char *) "--direct";
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+ spargv[i++] = (char *) "--restart";
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+ spargv[i] = NULL;
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+
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+ setenv ("LD_AUDIT", "tst-auditmod18b.so", 0);
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+ struct support_capture_subprocess result
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+ = support_capture_subprogram (spargv[0], spargv);
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+ support_capture_subprocess_check (&result, "tst-audit18b", 0, sc_allow_stderr);
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+
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+ bool find_symbind = false;
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+
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+ FILE *out = fmemopen (result.err.buffer, result.err.length, "r");
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+ TEST_VERIFY (out != NULL);
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+ char *buffer = NULL;
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+ size_t buffer_length = 0;
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+ while (xgetline (&buffer, &buffer_length, out))
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+ if (startswith (buffer, "la_symbind: tst_audit18bmod1_func") == 0)
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+ find_symbind = true;
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+
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+ TEST_COMPARE (find_symbind, true);
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+
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+ free (buffer);
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+ xfclose (out);
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+
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+ return 0;
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+}
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+
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+#define TEST_FUNCTION_ARGV do_test
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+#include <support/test-driver.c>
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diff --git a/elf/tst-audit19bmod.c b/elf/tst-audit19bmod.c
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new file mode 100644
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index 0000000000000000..9ffdcd8f3ffbc38e
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--- /dev/null
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+++ b/elf/tst-audit19bmod.c
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@@ -0,0 +1,23 @@
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+/* Extra module for tst-audit18b.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+int
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+tst_audit18bmod1_func (void)
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+{
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+ return 10;
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+}
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diff --git a/elf/tst-auditmod19a.c b/elf/tst-auditmod19a.c
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new file mode 100644
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index 0000000000000000..f58204099457743d
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--- /dev/null
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+++ b/elf/tst-auditmod19a.c
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@@ -0,0 +1,25 @@
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+/* Audit module for tst-audit18a.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <link.h>
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+
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+unsigned int
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+la_version (unsigned int version)
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+{
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+ return LAV_CURRENT;
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+}
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diff --git a/elf/tst-auditmod19b.c b/elf/tst-auditmod19b.c
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new file mode 100644
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index 0000000000000000..e2248b2a75946746
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--- /dev/null
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+++ b/elf/tst-auditmod19b.c
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@@ -0,0 +1,46 @@
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+/* Audit module for tst-audit18b.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <link.h>
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+#include <string.h>
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+#include <stdio.h>
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+
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+unsigned int
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+la_version (unsigned int version)
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+{
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+ return LAV_CURRENT;
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+}
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+
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+unsigned int
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+la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie)
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+{
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+ return LA_FLG_BINDTO | LA_FLG_BINDFROM;
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+}
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+
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+uintptr_t
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+#if __ELF_NATIVE_CLASS == 32
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+la_symbind32 (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
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+ uintptr_t *defcook, unsigned int *flags, const char *symname)
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+#else
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+la_symbind64 (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
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+ uintptr_t *defcook, unsigned int *flags, const char *symname)
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+#endif
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+{
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+ fprintf (stderr, "la_symbind: %s\n", symname);
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+ return sym->st_value;
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+}
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diff --git a/include/link.h b/include/link.h
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index cdd011f59445e490..dd491989beb41353 100644
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--- a/include/link.h
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+++ b/include/link.h
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@@ -353,8 +353,10 @@ struct link_map
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#if __ELF_NATIVE_CLASS == 32
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# define symbind symbind32
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+# define LA_SYMBIND "la_symbind32"
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#elif __ELF_NATIVE_CLASS == 64
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# define symbind symbind64
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+# define LA_SYMBIND "la_symbind64"
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#else
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# error "__ELF_NATIVE_CLASS must be defined"
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#endif
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