glibc/sysdeps/x86/isa-level.c
H.J. Lu 339bf918ea x86: Set minimum x86-64 level marker [BZ #27318]
Since the full ISA set used in an ELF binary is unknown to compiler,
an x86-64 ISA level marker indicates the minimum, not maximum, ISA set
required to run such an ELF binary.  We never guarantee a library with
an x86-64 ISA level v3 marker doesn't contain other ISAs beyond x86-64
ISA level v3, like AVX VNNI.  We check the x86-64 ISA level marker for
the minimum ISA set.  Since -march=sandybridge enables only some ISAs
in x86-64 ISA level v3, we should set the needed ISA marker to v2.
Otherwise, libc is compiled with -march=sandybridge will fail to run on
Sandy Bridge:

$ ./elf/ld.so ./libc.so
./libc.so: (p) CPU ISA level is lower than required: needed: 7; got: 3

Set the minimum, instead of maximum, x86-64 ISA level marker should have
no impact on the glibc-hwcaps directory assignment logic in ldconfig nor
ld.so.
2021-03-06 07:49:30 -08:00

101 lines
3.5 KiB
C

/* ELF program property for x86 ISA level.
Copyright (C) 2020 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.
In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file with other
programs, and to distribute those programs without any restriction
coming from the use of this file. (The Lesser General Public
License restrictions do apply in other respects; for example, they
cover modification of the file, and distribution when not linked
into another program.)
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 <elf.h>
/* ELF program property for x86 ISA level. */
#ifdef INCLUDE_X86_ISA_LEVEL
# if defined __SSE__ && defined __SSE2__
/* NB: ISAs, excluding MMX, in x86-64 ISA level baseline are used. */
# define ISA_BASELINE GNU_PROPERTY_X86_ISA_1_BASELINE
# else
# define ISA_BASELINE 0
# endif
# if ISA_BASELINE && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 \
&& defined HAVE_X86_LAHF_SAHF && defined __POPCNT__ \
&& defined __SSE3__ && defined __SSSE3__ && defined __SSE4_1__ \
&& defined __SSE4_2__
/* NB: ISAs in x86-64 ISA level v2 are used. */
# define ISA_V2 GNU_PROPERTY_X86_ISA_1_V2
# else
# define ISA_V2 0
# endif
# if ISA_V2 && defined __AVX__ && defined __AVX2__ && defined __F16C__ \
&& defined __FMA__ && defined __LZCNT__ && defined HAVE_X86_MOVBE
/* NB: ISAs in x86-64 ISA level v3 are used. */
# define ISA_V3 GNU_PROPERTY_X86_ISA_1_V3
# else
# define ISA_V3 0
# endif
# if ISA_V3 && defined __AVX512F__ && defined __AVX512BW__ \
&& defined __AVX512CD__ && defined __AVX512DQ__ \
&& defined __AVX512VL__
/* NB: ISAs in x86-64 ISA level v4 are used. */
# define ISA_V4 GNU_PROPERTY_X86_ISA_1_V4
# else
# define ISA_V4 0
# endif
# ifndef ISA_LEVEL
# define ISA_LEVEL (ISA_BASELINE | ISA_V2 | ISA_V3 | ISA_V4)
# endif
# if ISA_LEVEL
# ifdef __LP64__
# define PROPERTY_ALIGN 3
# else
# define PROPERTY_ALIGN 2
# endif
# define note_stringify(arg) note_stringify_1(arg)
# define note_stringify_1(arg) #arg
asm(".pushsection \".note.gnu.property\",\"a\",@note\n"
" .p2align " note_stringify (PROPERTY_ALIGN)
/* name length. */
"\n .long 1f - 0f\n"
/* data length. */
" .long 4f - 1f\n"
/* note type: NT_GNU_PROPERTY_TYPE_0. */
" .long " note_stringify (NT_GNU_PROPERTY_TYPE_0)
/* vendor name. */
"\n0: .asciz \"GNU\"\n"
"1: .p2align " note_stringify (PROPERTY_ALIGN)
/* pr_type: GNU_PROPERTY_X86_ISA_1_NEEDED. */
"\n .long " note_stringify (GNU_PROPERTY_X86_ISA_1_NEEDED)
/* pr_datasz. */
"\n .long 3f - 2f\n"
/* GNU_PROPERTY_X86_ISA_1_V[234]. */
"2:\n .long " note_stringify (ISA_LEVEL)
"\n3:\n .p2align " note_stringify (PROPERTY_ALIGN)
"\n4:\n .popsection");
# endif /* ISA_LEVEL */
#endif /* INCLUDE_X86_ISA_LEVEL */