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Date:   Mon, 1 Feb 2021 11:43:38 +0100
From:   Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To:     Tiezhu Yang <yangtiezhu@loongson.cn>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>, linux-mips@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        David Daney <david.daney@cavium.com>,
        Ralf Baechle <ralf@linux-mips.org>,
        Archer Yan <ayan@wavecomp.com>
Subject: Re: [PATCH 1/3] MIPS: kernel: Support extracting off-line stack
 traces from user-space with perf
Message-ID: <20210201104338.GA6484@alpha.franken.de>
References: <1609246561-5474-1-git-send-email-yangtiezhu@loongson.cn>
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On Tue, Dec 29, 2020 at 08:55:59PM +0800, Tiezhu Yang wrote:
> +++ b/arch/mips/include/uapi/asm/perf_regs.h
> @@ -0,0 +1,42 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +#ifndef _ASM_MIPS_PERF_REGS_H
> +#define _ASM_MIPS_PERF_REGS_H
> +
> +enum perf_event_mips_regs {
> +	PERF_REG_MIPS_PC,
> +	PERF_REG_MIPS_R1,
> +	PERF_REG_MIPS_R2,
> +	PERF_REG_MIPS_R3,
> +	PERF_REG_MIPS_R4,
> +	PERF_REG_MIPS_R5,
> +	PERF_REG_MIPS_R6,
> +	PERF_REG_MIPS_R7,
> +	PERF_REG_MIPS_R8,
> +	PERF_REG_MIPS_R9,
> +	PERF_REG_MIPS_R10,
> +	PERF_REG_MIPS_R11,
> +	PERF_REG_MIPS_R12,
> +	PERF_REG_MIPS_R13,
> +	PERF_REG_MIPS_R14,
> +	PERF_REG_MIPS_R15,
> +	PERF_REG_MIPS_R16,
> +	PERF_REG_MIPS_R17,
> +	PERF_REG_MIPS_R18,
> +	PERF_REG_MIPS_R19,
> +	PERF_REG_MIPS_R20,
> +	PERF_REG_MIPS_R21,
> +	PERF_REG_MIPS_R22,
> +	PERF_REG_MIPS_R23,
> +	PERF_REG_MIPS_R24,
> +	PERF_REG_MIPS_R25,
> +	/*
> +	 * 26 and 27 are k0 and k1, they are always clobbered thus not
> +	 * stored.
> +	 */

haveing this hole here make all code more complicated. Does it hurt
to have R26 and R27 in the list ?

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]