glibc/elf/tst-audit19a.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

39 lines
1.3 KiB
C

/* Check if DT_AUDIT a module without la_plt{enter,exit} symbols does not incur
in profiling (BZ#15533).
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 <support/xdlfcn.h>
#include <support/check.h>
static int
do_test (void)
{
void *h = xdlopen ("tst-auditmod19a.so", RTLD_NOW);
struct link_map *lmap;
TEST_VERIFY_EXIT (dlinfo (h, RTLD_DI_LINKMAP, &lmap) == 0);
/* The internal array is only allocated if profiling is enabled. */
TEST_VERIFY (lmap->l_reloc_result == NULL);
return 0;
}
#include <support/test-driver.c>