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91181954f9
To enable building glibc with branch protection, assembly code needs BTI landing pads and ELF object file markings in the form of a GNU property note. The landing pads are unconditionally added to all functions that may be indirectly called. When the code segment is not mapped with PROT_BTI these instructions are nops. They are kept in the code when BTI is not supported so that the layout of performance critical code is unchanged across configurations. The GNU property notes are only added when there is support for BTI in the toolchain, because old binutils does not handle the notes right. (Does not know how to merge them nor to put them in PT_GNU_PROPERTY segment instead of PT_NOTE, and some versions of binutils emit warnings about the unknown GNU property. In such cases the produced libc binaries would not have valid ELF marking so BTI would not be enabled.) Note: functions using ENTRY or ENTRY_ALIGN now start with an additional BTI c, so alignment of the following code changes, but ENTRY_ALIGN_AND_PAD was fixed so there is no change to the existing code layout. Some string functions may need to be tuned for optimal performance after this commit. Co-authored-by: Szabolcs Nagy <szabolcs.nagy@arm.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
55 lines
1.7 KiB
ArmAsm
55 lines
1.7 KiB
ArmAsm
/* Memset for falkor.
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Copyright (C) 2017-2020 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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#include <sysdep.h>
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#include <memset-reg.h>
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/* Reading dczid_el0 is expensive on falkor so move it into the ifunc
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resolver and assume ZVA size of 64 bytes. The IFUNC resolver takes care to
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use this function only when ZVA is enabled. */
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#if IS_IN (libc)
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.macro zva_macro
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.p2align 4
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/* Write the first and last 64 byte aligned block using stp rather
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than using DC ZVA. This is faster on some cores. */
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str q0, [dst, 16]
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stp q0, q0, [dst, 32]
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bic dst, dst, 63
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stp q0, q0, [dst, 64]
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stp q0, q0, [dst, 96]
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sub count, dstend, dst /* Count is now 128 too large. */
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sub count, count, 128+64+64 /* Adjust count and bias for loop. */
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add dst, dst, 128
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1: dc zva, dst
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add dst, dst, 64
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subs count, count, 64
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b.hi 1b
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stp q0, q0, [dst, 0]
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stp q0, q0, [dst, 32]
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stp q0, q0, [dstend, -64]
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stp q0, q0, [dstend, -32]
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ret
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.endm
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# define ZVA_MACRO zva_macro
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# define MEMSET __memset_falkor
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# include <sysdeps/aarch64/memset.S>
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#endif
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