glibc/sysdeps/unix/sysv/linux/powerpc/pointer_guard.h
Florian Weimer 88f4b6929c Introduce <pointer_guard.h>, extracted from <sysdep.h>
This allows us to define a generic no-op version of PTR_MANGLE and
PTR_DEMANGLE.  In the future, we can use PTR_MANGLE and PTR_DEMANGLE
unconditionally in C sources, avoiding an unintended loss of hardening
due to missing include files or unlucky header inclusion ordering.

In i386 and x86_64, we can avoid a <tls.h> dependency in the C
code by using the computed constant from <tcb-offsets.h>.  <sysdep.h>
no longer includes these definitions, so there is no cyclic dependency
anymore when computing the <tcb-offsets.h> constants.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-10-18 17:03:55 +02:00

56 lines
2.0 KiB
C

/* Pointer obfuscation implenentation. PowerpC version.
Copyright (C) 2005-2022 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/>. */
#ifndef POINTER_GUARD_H
#define POINTER_GUARD_H
#if IS_IN (rtld)
/* We cannot use the thread descriptor because in ld.so we use setjmp
earlier than the descriptor is initialized. */
# include <sysdeps/generic/pointer_guard.h>
#else
# ifdef __ASSEMBLER__
# if defined(__PPC64__) || defined(__powerpc64__)
# define LOAD ld
# define TPREG r13
# else
# define LOAD lwz
# define TPREG r2
# endif
# define PTR_MANGLE(reg, tmpreg) \
LOAD tmpreg,POINTER_GUARD(TPREG); \
xor reg,tmpreg,reg
# define PTR_MANGLE2(reg, tmpreg) \
xor reg,tmpreg,reg
# define PTR_MANGLE3(destreg, reg, tmpreg) \
LOAD tmpreg,POINTER_GUARD(TPREG); \
xor destreg,tmpreg,reg
# define PTR_DEMANGLE(reg, tmpreg) PTR_MANGLE (reg, tmpreg)
# define PTR_DEMANGLE2(reg, tmpreg) PTR_MANGLE2 (reg, tmpreg)
# define PTR_DEMANGLE3(destreg, reg, tmpreg) PTR_MANGLE3 (destreg, reg, tmpreg)
# else
# include <stdint.h>
# include <tls.h>
# define PTR_MANGLE(var) \
(var) = (__typeof (var)) ((uintptr_t) (var) ^ THREAD_GET_POINTER_GUARD ())
# define PTR_DEMANGLE(var) PTR_MANGLE (var)
# endif
#endif
#endif /* POINTER_GUARD_H */