glibc/elf/tst-auditmod19b.c
Adhemerval Zanella 063f9ba220 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>
2021-12-28 08:40:38 -03:00

47 lines
1.4 KiB
C

/* 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;
}