f82e9672ad
Now that LD_HWCAP_MASK (or glibc.tune.hwcap_mask) is read early enough to influence cpu feature check in aarch64, use it to influence multiarch selection. Setting LD_HWCAP_MASK such that it clears HWCAP_CPUID will now disable multiarch for the binary. HWCAP_CPUID is also now set in HWCAP_IMPORTANT so that it is set by default. With this patch, this feature is only usable with dyanmically linked binaries because LD_HWCAP_MASK is not read for static binaries. A future patch fixes that. * sysdeps/unix/sysv/linux/aarch64/cpu-features.c (init_cpu_features): Use glibc.tune.hwcap_mask. * sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h: New file.
38 lines
1.2 KiB
C
38 lines
1.2 KiB
C
/* Initialize CPU feature data. AArch64 version.
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This file is part of the GNU C Library.
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Copyright (C) 2017 Free Software Foundation, Inc.
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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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<http://www.gnu.org/licenses/>. */
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#include <cpu-features.h>
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#include <sys/auxv.h>
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#include <elf/dl-hwcaps.h>
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static inline void
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init_cpu_features (struct cpu_features *cpu_features)
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{
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uint64_t hwcap_mask = GET_HWCAP_MASK();
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uint64_t hwcap = GLRO (dl_hwcap) & hwcap_mask;
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if (hwcap & HWCAP_CPUID)
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{
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register uint64_t id = 0;
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asm volatile ("mrs %0, midr_el1" : "=r"(id));
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cpu_features->midr_el1 = id;
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}
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else
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cpu_features->midr_el1 = 0;
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}
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