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Date:   Fri, 07 Oct 2022 10:47:55 -0700
From:   "H. Peter Anvin" <hpa@zytor.com>
To:     Peter Zijlstra <peterz@infradead.org>, Xin Li <xin3.li@intel.com>
CC:     linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com
Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_4/6=5D_x86/gsseg=3A_move_local=5Fir?= =?US-ASCII?Q?q=5Fsave/restore=28=29_into_asm=5Fload=5Fgs=5Findex=28=29?=
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References: <20221006154041.13001-1-xin3.li@intel.com> <20221006154041.13001-5-xin3.li@intel.com> <Y0A8mWvT0mLm3nVD@hirez.programming.kicks-ass.net>
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On October 7, 2022 7:50:01 AM PDT, Peter Zijlstra <peterz@infradead=2Eorg> =
wrote:
>On Thu, Oct 06, 2022 at 08:40:39AM -0700, Xin Li wrote:
>>  SYM_FUNC_START(asm_load_gs_index)
>>  	FRAME_BEGIN
>> +	pushf
>> +	pop	%rax
>> +	andl	$X86_EFLAGS_IF, %eax	/* Interrupts enabled? */
>> +	jz	1f
>> +	cli
>> +1:
>
>Why the pop,andl,jz ? AFAICT our arch_local_irq_save() doesn't even
>bother with that, why does this function=2E

They pop and and are needed for the sti anyway, and so might as well be le=
veraged here, too=2E