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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>,
	"Jan Beulich" <JBeulich@suse.com>,
	Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 4/7] x86/asm: Remove opencoded uses of altinstruction_entry
Date: Mon, 12 Feb 2018 12:34:02 +0000	[thread overview]
Message-ID: <9250fcb6-f570-577e-0bd3-f690a545e4fa@citrix.com> (raw)
In-Reply-To: <20180212123044.2nih6z65fp254oyq@citrix.com>

On 12/02/18 12:30, Wei Liu wrote:
> On Mon, Feb 12, 2018 at 11:23:04AM +0000, Andrew Cooper wrote:
>> diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
>> index 58f652d..bd3819a 100644
>> --- a/xen/arch/x86/x86_64/entry.S
>> +++ b/xen/arch/x86/x86_64/entry.S
>> @@ -557,23 +557,9 @@ handle_exception_saved:
>>          testb $X86_EFLAGS_IF>>8,UREGS_eflags+1(%rsp)
>>          jz    exception_with_ints_disabled
>>  
>> -.Lcr4_pv32_orig:
>> -        jmp   .Lcr4_pv32_done
>> -        .skip (.Lcr4_pv32_alt_end - .Lcr4_pv32_alt) - (. - .Lcr4_pv32_orig), 0xcc
>> -        .pushsection .altinstr_replacement, "ax"
>> -.Lcr4_pv32_alt:
>> -        mov   VCPU_domain(%rbx),%rax
>> -.Lcr4_pv32_alt_end:
>> -        .section .altinstructions, "a"
>> -        altinstruction_entry .Lcr4_pv32_orig, .Lcr4_pv32_alt, \
>> -                             X86_FEATURE_XEN_SMEP, \
>> -                             (.Lcr4_pv32_alt_end - .Lcr4_pv32_alt), \
>> -                             (.Lcr4_pv32_alt_end - .Lcr4_pv32_alt)
>> -        altinstruction_entry .Lcr4_pv32_orig, .Lcr4_pv32_alt, \
>> -                             X86_FEATURE_XEN_SMAP, \
>> -                             (.Lcr4_pv32_alt_end - .Lcr4_pv32_alt), \
>> -                             (.Lcr4_pv32_alt_end - .Lcr4_pv32_alt)
>> -        .popsection
>> +        ALTERNATIVE_2 "jmp .Lcr4_pv32_done; .skip 2, 0x90", \
> This changed 0xcc to 0x90 but since it is just padding following an
> unconditional jmp so it shouldn't matter.
>
> Mostly looks fine. I'm a bit hesitant to give my Rb because reviewing
> the diff to assembly is a bit more difficult to than diff to C source.
>
> Do you have a branch somewhere?

http://xenbits.xen.org/gitweb/?p=people/andrewcoop/xen.git;a=shortlog;h=refs/heads/alternatives-v1

~Andrew

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  reply	other threads:[~2018-02-12 12:34 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-12 11:23 [PATCH 0/7] x86/alternatives: Support for automatic padding calculations Andrew Cooper
2018-02-12 11:23 ` [PATCH 1/7] x86/alt: Drop unused alternative infrastructure Andrew Cooper
2018-02-12 12:30   ` Wei Liu
2018-02-12 15:56   ` Roger Pau Monné
2018-02-12 15:58     ` Andrew Cooper
2018-02-13 14:22   ` Jan Beulich
2018-02-13 14:41     ` Andrew Cooper
2018-02-13 15:33       ` Jan Beulich
2018-02-14 10:02       ` Jan Beulich
2018-02-12 11:23 ` [PATCH 2/7] x86/alt: Clean up struct alt_instr and its users Andrew Cooper
2018-02-12 12:30   ` Wei Liu
2018-02-12 16:52   ` Roger Pau Monné
2018-02-12 17:18     ` Wei Liu
2018-02-12 17:53       ` Andrew Cooper
2018-02-13 14:26   ` Jan Beulich
2018-02-21 21:22   ` Konrad Rzeszutek Wilk
2018-02-12 11:23 ` [PATCH 3/7] x86/alt: Clean up the assembly used to generate alternatives Andrew Cooper
2018-02-12 12:30   ` Wei Liu
2018-02-12 17:26   ` Roger Pau Monné
2018-02-12 17:54     ` Andrew Cooper
2018-02-13 14:37   ` Jan Beulich
2018-02-23 14:03     ` Andrew Cooper
2018-02-23 15:12       ` Jan Beulich
2018-02-23 16:24         ` Andrew Cooper
2018-02-23 17:28           ` Jan Beulich
2018-02-12 11:23 ` [PATCH 4/7] x86/asm: Remove opencoded uses of altinstruction_entry Andrew Cooper
2018-02-12 12:30   ` Wei Liu
2018-02-12 12:34     ` Andrew Cooper [this message]
2018-02-13  9:56     ` Jan Beulich
2018-02-13 10:07       ` Andrew Cooper
2018-02-13 11:10         ` Jan Beulich
2018-02-12 12:52   ` Wei Liu
2018-02-12 17:46   ` Roger Pau Monné
2018-02-12 17:59     ` Andrew Cooper
2018-02-14  9:53   ` Jan Beulich
2018-02-12 11:23 ` [PATCH 5/7] x86/alt: Support for automatic padding calculations Andrew Cooper
2018-02-12 14:39   ` Wei Liu
2018-02-12 15:04     ` Andrew Cooper
2018-02-12 18:41       ` Roger Pau Monné
2018-02-12 18:45         ` Andrew Cooper
2018-02-12 18:09   ` Roger Pau Monné
2018-02-13  9:45   ` Roger Pau Monné
2018-02-13 10:09     ` Andrew Cooper
2018-02-13 10:26       ` Roger Pau Monné
2018-02-14  9:46   ` Jan Beulich
2018-02-12 11:23 ` [PATCH 6/7] x86/alt: Drop explicit padding of origin sites Andrew Cooper
2018-02-12 14:39   ` Wei Liu
2018-02-12 18:12   ` Roger Pau Monné
2018-02-14  9:53   ` Jan Beulich
2018-02-12 11:23 ` [PATCH 7/7] x86/build: Use new .nop directive when available Andrew Cooper
2018-02-12 14:40   ` Wei Liu
2018-02-13 11:08   ` Roger Pau Monné

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