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c94767712b
Currently gcc -pg -mbranch-protection=pac-ret passes signed return address to _mcount, so _mcount now has to always strip pac from the frompc since that's from user code that may be built with pac-ret. This is gcc PR target/94791: signed pointers should not escape and get passed across extern call boundaries, since that's an ABI break, but because existing gcc has this issue we work it around in glibc until that is resolved. This is compatible with a fixed gcc and it is a nop on systems without PAuth support. The bug was introduced in gcc-7 with -msign-return-address=non-leaf|all support which in gcc-9 got renamed to -mbranch-protection=pac-ret|pac-ret+leaf|standard. strip_pac uses inline asm instead of __builtin_aarch64_xpaclri since that is not a documented api and not available in all supported gccs. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
36 lines
1.5 KiB
C
36 lines
1.5 KiB
C
/* AArch64 definitions for profiling support.
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Copyright (C) 1996-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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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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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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/* Accept 'frompc' address as argument from the function that calls
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__mcount for profiling. Use __builtin_return_address (0)
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for the 'selfpc' address. */
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#include <sysdep.h>
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static void mcount_internal (u_long frompc, u_long selfpc);
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#define _MCOUNT_DECL(frompc, selfpc) \
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static inline void mcount_internal (u_long frompc, u_long selfpc)
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/* Note: strip_pac is needed for frompc because of gcc PR target/94791. */
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#define MCOUNT \
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void __mcount (void *frompc) \
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{ \
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mcount_internal ((u_long) strip_pac (frompc), (u_long) RETURN_ADDRESS (0)); \
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}
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