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Date: Wed, 30 Nov 2016 16:27:22 +0000 From: Dave Martin <Dave.Martin@....com> To: Suzuki K Poulose <suzuki.poulose@....com> Cc: linux-arm-kernel@...ts.infradead.org, mark.rutland@....com, ryan.arnold@...aro.org, sid@...erved-bit.com, aph@...hat.com, catalin.marinas@....com, will.deacon@....com, linux-kernel@...r.kernel.org, marc.zyngier@....com, adhemerval.zanella@...aro.org Subject: Re: [sample] A sample program for MRS emulation On Wed, Nov 30, 2016 at 03:15:01PM +0000, Suzuki K Poulose wrote: > Here is a sample program which demonstrates how to use mrs > emulation to fetch the ID registers. Are we planning to add this in Documentation/? If so, we might want some tweaks (noted below). > > ----8>---- > /* > * Sample program to demonstrate the MRS emulation > * ABI. overwrapped? > * Copyright (C) 2015-2016, ARM Ltd > * > * Author: Suzuki K Poulose <suzuki.poulose@....com> > * > * This program is free software; you can redistribute it and/or modify > * it under the terms of the GNU General Public License version 2 as > * published by the Free Software Foundation. > * > * This program 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 General Public License for more details. > * This program is free software; you can redistribute it and/or modify > * it under the terms of the GNU General Public License version 2 as > * published by the Free Software Foundation. > * > * This program 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 General Public License for more details. > */ > > #include <stdio.h> > > #define get_cpu_ftr(id) ({ \ > unsigned long long __val; \ > asm("mrs %0, "#id : "=r" (__val)); \ > printf("%-20s: 0x%016lx\n", #id, __val); \ > }) > > int main() (void) > { We don't wan't people using the MRS emulation without checking for its availability first. Something like this may work (untested), with the caveat that getauxval() is a GNU libc extension, and other environments may require a different mechanism to obtain the hwcaps. --8<-- #include <sys/auxv.h> #include <asm/hwcap.h> /* ... */ if (!getauxval(AT_HWCAP) & HWCAP_CPUID) { fputs("CPUID registers unavailable\n", stderr); return 1; } -->8-- Cheers ---Dave > > get_cpu_ftr(ID_AA64ISAR0_EL1); > get_cpu_ftr(ID_AA64ISAR1_EL1); > get_cpu_ftr(ID_AA64MMFR0_EL1); > get_cpu_ftr(ID_AA64MMFR1_EL1); > get_cpu_ftr(ID_AA64PFR0_EL1); > get_cpu_ftr(ID_AA64PFR1_EL1); > get_cpu_ftr(ID_AA64DFR0_EL1); > get_cpu_ftr(ID_AA64DFR1_EL1); > > get_cpu_ftr(MIDR_EL1); > get_cpu_ftr(MPIDR_EL1); > get_cpu_ftr(REVIDR_EL1); > return 0; > } > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@...ts.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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