From: Dave.Martin@arm.com (Dave Martin)
To: linux-arm-kernel@lists.infradead.org
Subject: [sample] A sample program for MRS emulation
Date: Wed, 30 Nov 2016 16:27:22 +0000 [thread overview]
Message-ID: <20161130162720.GN1574@e103592.cambridge.arm.com> (raw)
In-Reply-To: <1480518901-18544-11-git-send-email-suzuki.poulose@arm.com>
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@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;
> }
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2016-11-30 16:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-30 15:14 [PATCH v2 0/9] arm64: Expose CPUID registers via emulation Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 1/9] arm64: cpufeature: treat unknown fields as RES0 Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 2/9] arm64: cpufeature: remove explicit RAZ fields Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 3/9] arm64: cpufeature: Cleanup feature bit tables Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 4/9] arm64: cpufeature: Document the rules of safe value for features Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 5/9] arm64: cpufeature: Define helpers for sys_reg id Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 6/9] arm64: Add helper to decode register from instruction Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 7/9] arm64: cpufeature: Track user visible fields Suzuki K Poulose
2016-11-30 15:14 ` [PATCH v2 8/9] arm64: cpufeature: Expose CPUID registers by emulation Suzuki K Poulose
2016-11-30 15:15 ` [PATCH v2 9/9] arm64: Documentation - Expose CPU feature registers Suzuki K Poulose
2016-11-30 15:15 ` [sample] A sample program for MRS emulation Suzuki K Poulose
2016-11-30 16:27 ` Dave Martin [this message]
2017-01-03 15:37 ` Suzuki K Poulose
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