From f82e9672ad89ea1ef40bbe1af71478e255e87c5e Mon Sep 17 00:00:00 2001 From: Siddhesh Poyarekar Date: Tue, 25 Apr 2017 22:39:17 +0530 Subject: [PATCH] aarch64: Allow overriding HWCAP_CPUID feature check using HWCAP_MASK 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. --- ChangeLog | 4 ++ .../unix/sysv/linux/aarch64/cpu-features.c | 10 +++-- sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h | 44 +++++++++++++++++++ 3 files changed, 54 insertions(+), 4 deletions(-) create mode 100644 sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h diff --git a/ChangeLog b/ChangeLog index 5b4d842100..f0b25e31cc 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,9 @@ 2017-06-07 Siddhesh Poyarekar + * 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. + * elf/dl-hwcaps.h: New file. * elf/dl-hwcaps.c: Include it. (_dl_important_hwcaps)[HAVE_TUNABLES]: Read and update diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c index 702506249d..ef6eecd17e 100644 --- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c +++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c @@ -18,18 +18,20 @@ #include #include +#include static inline void init_cpu_features (struct cpu_features *cpu_features) { - if (GLRO(dl_hwcap) & HWCAP_CPUID) + uint64_t hwcap_mask = GET_HWCAP_MASK(); + uint64_t hwcap = GLRO (dl_hwcap) & hwcap_mask; + + if (hwcap & HWCAP_CPUID) { register uint64_t id = 0; asm volatile ("mrs %0, midr_el1" : "=r"(id)); cpu_features->midr_el1 = id; } else - { - cpu_features->midr_el1 = 0; - } + cpu_features->midr_el1 = 0; } diff --git a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h new file mode 100644 index 0000000000..7a60d72844 --- /dev/null +++ b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h @@ -0,0 +1,44 @@ +/* Processor capability information handling macros - aarch64 version. + Copyright (C) 2017 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 + . */ + +#ifndef _DL_PROCINFO_H +#define _DL_PROCINFO_H 1 + +#include + +/* We cannot provide a general printing function. */ +#define _dl_procinfo(type, word) -1 + +/* There are no hardware capabilities defined. */ +#define _dl_hwcap_string(idx) "" + +/* HWCAP_CPUID should be available by default to influence IFUNC as well as + library search. */ +#define HWCAP_IMPORTANT HWCAP_CPUID + +/* There're no platforms to filter out. */ +#define _DL_HWCAP_PLATFORM 0 + +/* We don't have any hardware capabilities. */ +#define _DL_HWCAP_COUNT 0 + +#define _dl_string_hwcap(str) (-1) + +#define _dl_string_platform(str) (-1) + +#endif /* dl-procinfo.h */