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From: Nicholas Piggin <npiggin@gmail.com>
To: Huacai Chen <chenhuacai@loongson.cn>,
	Peter Zijlstra <peterz@infradead.org>
Cc: David Airlie <airlied@linux.ie>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>, Huacai Chen <chenhuacai@gmail.com>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	linux-arch@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
	Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 06/19] LoongArch: Add exception/interrupt handling
Date: Wed, 07 Jul 2021 23:56:37 +1000	[thread overview]
Message-ID: <1625665981.7hbs7yesxx.astroid@bobo.none> (raw)
In-Reply-To: <YOQ5UBa0xYf7kAjg@hirez.programming.kicks-ass.net>

Excerpts from Peter Zijlstra's message of July 6, 2021 9:06 pm:
> On Tue, Jul 06, 2021 at 12:18:07PM +0800, Huacai Chen wrote:
>> +	.align	5	/* 32 byte rollback region */
>> +SYM_FUNC_START(__arch_cpu_idle)
>> +	/* start of rollback region */
>> +	LONG_L	t0, tp, TI_FLAGS
>> +	nop
>> +	andi	t0, t0, _TIF_NEED_RESCHED
>> +	bnez	t0, 1f
>> +	nop
>> +	nop
>> +	nop
>> +	idle	0
>> +	/* end of rollback region */
>> +1:
>> +	jirl	zero, ra, 0
>> +SYM_FUNC_END(__arch_cpu_idle)
> 
>> +/*
>> + * Common Vectored Interrupt
>> + * Complete the register saves and invoke the do_vi() handler
>> + */
>> +SYM_FUNC_START(except_vec_vi_handler)
>> +	la	t1, __arch_cpu_idle
>> +	LONG_L  t0, sp, PT_EPC
>> +	/* 32 byte rollback region */
>> +	ori	t0, t0, 0x1f
>> +	xori	t0, t0, 0x1f
>> +	bne	t0, t1, 1f
>> +	LONG_S  t0, sp, PT_EPC
> 
> Seriously, you're having your interrupt handler recover from the idle
> race? On a *new* architecture?

It's heavily derived from MIPS (does that make the wholesale replacement 
of arch/mips copyright headers a bit questionable?).

I don't think it's such a bad trick though -- restartable sequences 
before they were cool. It can let you save an irq disable in some
cases (depending on the arch of course).

Thanks,
Nick

  reply	other threads:[~2021-07-07 13:56 UTC|newest]

Thread overview: 131+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-06  4:18 [PATCH 00/19] arch: Add basic LoongArch support Huacai Chen
2021-07-06  4:18 ` [PATCH 01/19] LoongArch: Add elf-related definitions Huacai Chen
2021-07-06  4:18 ` [PATCH 02/19] LoongArch: Add writecombine support for drm Huacai Chen
2021-07-06  4:18 ` [PATCH 03/19] LoongArch: Add build infrastructure Huacai Chen
2021-07-06 10:12   ` Arnd Bergmann
2021-07-19  1:26     ` Huacai Chen
2021-07-19  7:43       ` Arnd Bergmann
2021-07-19 13:02         ` Huacai Chen
2021-07-06 10:35   ` Arnd Bergmann
2021-07-07  0:00   ` Randy Dunlap
2021-07-19  1:28     ` Huacai Chen
2021-07-06  4:18 ` [PATCH 05/19] LoongArch: Add boot and setup routines Huacai Chen
2021-07-06 10:16   ` Arnd Bergmann
2021-07-27 11:53     ` Huacai Chen
2021-07-27 12:40       ` Arnd Bergmann
2021-07-27 12:51         ` Ard Biesheuvel
2021-07-27 13:14           ` Arnd Bergmann
2021-07-27 16:22             ` Ard Biesheuvel
2021-07-27 17:53               ` Arnd Bergmann
2021-07-28 10:24                 ` Huacai Chen
2021-07-06 10:55   ` Arnd Bergmann
2021-07-06  4:18 ` [PATCH 06/19] LoongArch: Add exception/interrupt handling Huacai Chen
2021-07-06 10:16   ` Arnd Bergmann
2021-07-06 10:56     ` Arnd Bergmann
2021-07-06 11:06   ` Peter Zijlstra
2021-07-07 13:56     ` Nicholas Piggin [this message]
2021-07-27 14:10       ` Peter Zijlstra
2021-07-27 15:08         ` Arnd Bergmann
2021-07-28 10:16           ` Huacai Chen
2021-07-28 12:23             ` Arnd Bergmann
2021-07-06  4:18 ` [PATCH 07/19] LoongArch: Add process management Huacai Chen
2021-07-06 10:16   ` Arnd Bergmann
2021-07-06 10:57     ` Arnd Bergmann
2021-07-06 11:09     ` Peter Zijlstra
2021-08-12 11:17       ` Huacai Chen
2021-08-12 12:29         ` Arnd Bergmann
2021-08-12 12:51           ` Huacai Chen
2021-07-06  4:18 ` [PATCH 08/19] LoongArch: Add memory management Huacai Chen
2021-07-06 10:16   ` Arnd Bergmann
2021-07-06 10:57     ` Arnd Bergmann
2021-08-12 11:20     ` Huacai Chen
2021-08-16  1:57   ` Guo Ren
2021-08-16  3:31     ` Huacai Chen
2021-07-06  4:18 ` [PATCH 09/19] LoongArch: Add system call support Huacai Chen
2021-07-06 10:17   ` Arnd Bergmann
2021-07-06 10:58     ` Arnd Bergmann
2021-07-07  4:24     ` Huacai Chen
2021-07-07  6:44       ` Arnd Bergmann
2021-07-07  7:00         ` Huacai Chen
2021-07-09  8:44         ` Huacai Chen
2021-07-06 13:51   ` Thomas Gleixner
2021-07-07  4:27     ` Huacai Chen
2021-08-12 12:40     ` Huacai Chen
2021-07-06  4:18 ` [PATCH 10/19] LoongArch: Add signal handling support Huacai Chen
2021-07-06 10:17   ` Arnd Bergmann
2021-07-06 10:59     ` Arnd Bergmann
2021-07-08 13:04     ` Huacai Chen
2021-07-08 13:23       ` Arnd Bergmann
2021-07-09  9:24         ` Huacai Chen
2021-07-09 10:22           ` Arnd Bergmann
2021-07-09 14:49             ` Eric W. Biederman
2021-07-09 15:59               ` Arnd Bergmann
2021-08-26 16:43   ` Xi Ruoyao
2021-08-27  4:23     ` Huacai Chen
2021-08-27  4:27       ` Xi Ruoyao
2021-07-06  4:18 ` [PATCH 11/19] LoongArch: Add elf and module support Huacai Chen
2021-07-06  4:18 ` [PATCH 12/19] LoongArch: Add misc common routines Huacai Chen
2021-07-06 10:17   ` Arnd Bergmann
2021-07-06 11:00     ` Arnd Bergmann
2021-07-23 10:41     ` Huacai Chen
2021-07-23 11:43       ` Arnd Bergmann
2021-07-24 12:53         ` Huacai Chen
2021-07-06  4:18 ` [PATCH 13/19] LoongArch: Add some library functions Huacai Chen
2021-07-06 10:17   ` Arnd Bergmann
2021-07-06 11:00     ` Arnd Bergmann
2021-08-12 11:22     ` Huacai Chen
2021-07-06  4:18 ` [PATCH 14/19] LoongArch: Add 64-bit Loongson platform Huacai Chen
2021-07-06  4:18 ` [PATCH 15/19] LoongArch: Add PCI controller support Huacai Chen
2021-07-06 10:17   ` Arnd Bergmann
2021-07-06 11:01     ` Arnd Bergmann
2021-08-12 11:29     ` Huacai Chen
2021-07-06  4:18 ` [PATCH 16/19] LoongArch: Add VDSO and VSYSCALL support Huacai Chen
2021-07-06 10:17   ` Arnd Bergmann
2021-07-06 11:02     ` Arnd Bergmann
2021-08-12 11:31     ` Huacai Chen
2021-07-06  4:18 ` [PATCH 17/19] LoongArch: Add multi-processor (SMP) support Huacai Chen
2021-07-06 10:17   ` Arnd Bergmann
2021-07-06 11:03     ` Arnd Bergmann
2021-07-06 11:32   ` Peter Zijlstra
2021-08-12 11:39     ` Huacai Chen
2021-07-06 11:56   ` Peter Zijlstra
2021-07-06 13:48   ` Peter Zijlstra
2021-08-12 11:41     ` Huacai Chen
2021-07-06 13:52   ` Peter Zijlstra
2021-07-06  4:18 ` [PATCH 18/19] LoongArch: Add Non-Uniform Memory Access (NUMA) support Huacai Chen
2021-07-06 10:18   ` Arnd Bergmann
2021-07-06 11:03     ` Arnd Bergmann
2021-08-12 11:46     ` Huacai Chen
2021-08-12 12:48       ` Arnd Bergmann
2021-07-06  4:18 ` [PATCH 19/19] LoongArch: Add Loongson-3 default config file Huacai Chen
2021-07-06 10:18   ` Arnd Bergmann
2021-07-06 11:04     ` Arnd Bergmann
2021-08-12 11:58     ` Huacai Chen
2021-08-12 12:50       ` Arnd Bergmann
2021-07-06 10:11 ` [PATCH 00/19] arch: Add basic LoongArch support Arnd Bergmann
2021-07-07  3:04   ` Huacai Chen
2021-07-07  7:28     ` Arnd Bergmann
2021-07-29 16:48       ` Huacai Chen
2021-07-30 20:50         ` Arnd Bergmann
2021-07-06 10:33 ` Arnd Bergmann
     [not found] ` <20210706041820.1536502-5-chenhuacai@loongson.cn>
2021-07-06 10:16   ` [PATCH 04/19] LoongArch: Add common headers Arnd Bergmann
2021-08-12 11:05     ` Huacai Chen
2021-08-12 12:45       ` Arnd Bergmann
2021-08-13  3:30         ` Huacai Chen
2021-08-13  7:05           ` Arnd Bergmann
2021-08-13  8:14             ` Huacai Chen
2021-08-13  9:08               ` Arnd Bergmann
2021-08-14  2:50                 ` Huacai Chen
2021-08-15  8:56                   ` Arnd Bergmann
2021-08-16  4:10                     ` Huacai Chen
2021-08-18  9:38                       ` Arnd Bergmann
2021-08-20  4:00                         ` Huacai Chen
2021-08-20  7:55                           ` Arnd Bergmann
2021-08-21  8:16                             ` Huacai Chen
2021-07-06 10:54   ` Arnd Bergmann
2021-07-06 10:57   ` Peter Zijlstra
2021-07-06 11:23   ` Peter Zijlstra
2021-07-06 12:59     ` Arnd Bergmann
2021-07-06 13:20       ` Peter Zijlstra
2021-07-06 13:37       ` Peter Zijlstra
2021-07-06 11:59   ` Peter Zijlstra

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