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.poul...@arm.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;
> }
>
>
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