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author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-06-30 10:24:09 -0300 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-12-28 08:40:38 -0300 |
commit | 063f9ba220f434c7f30dd65c4cff17c0c458a7cf (patch) | |
tree | 00737e23f3b48e8d8dd338f16fc8cb98f0e6c051 /elf/tst-auditmod19b.c | |
parent | 8c0664e2b861fd3789602cc0b0b1922b0e20cb3a (diff) | |
download | glibc-063f9ba220f434c7f30dd65c4cff17c0c458a7cf.tar.gz glibc-063f9ba220f434c7f30dd65c4cff17c0c458a7cf.tar.xz glibc-063f9ba220f434c7f30dd65c4cff17c0c458a7cf.zip |
elf: Avoid unnecessary slowdown from profiling with audit (BZ#15533)
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>
Diffstat (limited to 'elf/tst-auditmod19b.c')
-rw-r--r-- | elf/tst-auditmod19b.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/elf/tst-auditmod19b.c b/elf/tst-auditmod19b.c new file mode 100644 index 0000000000..e2248b2a75 --- /dev/null +++ b/elf/tst-auditmod19b.c @@ -0,0 +1,46 @@ +/* Audit module for tst-audit18b. + Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#include <link.h> +#include <string.h> +#include <stdio.h> + +unsigned int +la_version (unsigned int version) +{ + return LAV_CURRENT; +} + +unsigned int +la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie) +{ + return LA_FLG_BINDTO | LA_FLG_BINDFROM; +} + +uintptr_t +#if __ELF_NATIVE_CLASS == 32 +la_symbind32 (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook, + uintptr_t *defcook, unsigned int *flags, const char *symname) +#else +la_symbind64 (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook, + uintptr_t *defcook, unsigned int *flags, const char *symname) +#endif +{ + fprintf (stderr, "la_symbind: %s\n", symname); + return sym->st_value; +} |