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From: Dave Jiang <dave.jiang@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: vkoul@kernel.org, tglx@linutronix.de, mingo@redhat.com,
	dan.j.williams@intel.com, tony.luck@intel.com,
	jing.lin@intel.com, ashok.raj@intel.com,
	sanjay.k.kumar@intel.com, fenghua.yu@intel.com,
	kevin.tian@intel.com, dmaengine@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/5] x86/asm: move the raw asm in iosubmit_cmds512() to special_insns.h
Date: Wed, 23 Sep 2020 08:43:11 -0700	[thread overview]
Message-ID: <c38406b7-f1d1-35d8-8015-bacce7a52226@intel.com> (raw)
In-Reply-To: <20200923104158.GG28545@zn.tnic>



On 9/23/2020 3:41 AM, Borislav Petkov wrote:
>> Subject: Re: [PATCH v4 1/5] x86/asm: move the raw asm in iosubmit_cmds512() to special_insns.h
> 
> Start patch name with a capital letter: "Move the asm definition.."
> 
> Also, calling stuff "raw" and "core" is misleading in the kernel context
> - you wanna say simply: "Carve out a generic movdir64b() helper... "

Ok I will update

> 
> On Thu, Sep 17, 2020 at 02:15:16PM -0700, Dave Jiang wrote:
>> diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
>> index 59a3e13204c3..7bc8e714f37e 100644
>> --- a/arch/x86/include/asm/special_insns.h
>> +++ b/arch/x86/include/asm/special_insns.h
>> @@ -234,6 +234,23 @@ static inline void clwb(volatile void *__p)
>>   
>>   #define nop() asm volatile ("nop")
>>   
>> +static inline void movdir64b(void *__dst, const void *src)
> 
> Make __dst be the function local variable name and keep "dst", i.e.,
> without the underscores, the function parameter name.

Ok will fix

> 
>> +	/*
>> +	 * Note that this isn't an "on-stack copy", just definition of "dst"
>> +	 * as a pointer to 64-bytes of stuff that is going to be overwritten.
>> +	 * In the MOVDIR64B case that may be needed as you can use the
>> +	 * MOVDIR64B instruction to copy arbitrary memory around. This trick
>> +	 * lets the compiler know how much gets clobbered.
>> +	 */
>> +	volatile struct { char _[64]; } *dst = __dst;
>> +
>> +	/* MOVDIR64B [rdx], rax */
>> +	asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
>> +		     : "=m" (dst)
>> +		     : "d" (src), "a" (dst));
>> +}
>> +
>>   #endif /* __KERNEL__ */
>>   
>>   #endif /* _ASM_X86_SPECIAL_INSNS_H */
>>
> 

  reply	other threads:[~2020-09-23 15:43 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-17 21:15 [PATCH v4 0/5] Add shared workqueue support for idxd driver Dave Jiang
2020-09-17 21:15 ` [PATCH v4 1/5] x86/asm: move the raw asm in iosubmit_cmds512() to special_insns.h Dave Jiang
2020-09-23 10:41   ` Borislav Petkov
2020-09-23 15:43     ` Dave Jiang [this message]
2020-09-23 16:00       ` David Laight
2020-09-17 21:15 ` [PATCH v4 2/5] x86/asm: add enqcmds() to support ENQCMDS instruction Dave Jiang
2020-09-23 11:08   ` Borislav Petkov
2020-09-23 15:47     ` Dave Jiang
2020-09-17 21:15 ` [PATCH v4 4/5] dmaengine: idxd: clean up descriptors with fault error Dave Jiang
2020-09-17 21:15 ` [PATCH v4 5/5] dmaengine: idxd: add ABI documentation for shared wq Dave Jiang
2020-09-17 23:43 ` [PATCH v4 0/5] Add shared workqueue support for idxd driver Randy Dunlap
2020-09-17 23:51   ` Dave Jiang
2020-09-17 23:56     ` Randy Dunlap

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