From: Jan Beulich <jbeulich@suse.com>
To: "Hu, Lin1" <lin1.hu@intel.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>, Binutils <binutils@sourceware.org>
Subject: Re: [PATCH] x86: allow 32-bit reg to be used with U{RD,WR}MSR
Date: Mon, 4 Dec 2023 08:17:44 +0100 [thread overview]
Message-ID: <8e02065b-e9fb-4a5c-8a49-f56b54913862@suse.com> (raw)
In-Reply-To: <SJ0PR11MB5940D57B799081597108FED0A686A@SJ0PR11MB5940.namprd11.prod.outlook.com>
On 04.12.2023 02:45, Hu, Lin1 wrote:
> I talked to the people involved. They found the eds description about "ignoring h32 bits of the MSR address for register variants" is a documentation bug. The right version is USER_MSR have a GP fault on h32 of the MSR address for the register version. So they update the description from #GP(0) If MSR_address[63:0] & 0x0000_0000_FFFF_C000 != 0
> to #GP(0) If MSR_address[63:0] & 0xFFFF_FFFF_FFFF_C000 != 0. And the source register will still be r64 in the spec.
What an unhelpful behavior. I'll need to revert the patch below then,
assuming they're not willing to re-think.
Jan
>> -----Original Message-----
>> From: Jan Beulich <jbeulich@suse.com>
>> Sent: Friday, November 24, 2023 5:18 PM
>> To: Binutils <binutils@sourceware.org>
>> Cc: H.J. Lu <hjl.tools@gmail.com>; Hu, Lin1 <lin1.hu@intel.com>
>> Subject: [PATCH] x86: allow 32-bit reg to be used with U{RD,WR}MSR
>>
>> ... as MSR index specifier: It is unreasonable to demand that people write
>> less readable / understandable code, just because the present
>> documentation mentions only Reg64. Whether to also adjust the
>> disassembler is a separate question, perhaps indeed more tightly tied to
>> what the spec says.
>>
>> --- a/gas/testsuite/gas/i386/x86-64-user_msr.s
>> +++ b/gas/testsuite/gas/i386/x86-64-user_msr.s
>> @@ -5,7 +5,7 @@ _start:
>> urdmsr %r14, %r12
>> urdmsr %r14, %rax
>> urdmsr %rdx, %r12
>> - urdmsr %rdx, %rax
>> + urdmsr %edx, %rax
>> urdmsr $51515151, %r12
>> urdmsr $51515151, %rax
>> urdmsr $0x7f, %r12
>> @@ -14,7 +14,7 @@ _start:
>> uwrmsr %r12, %r14
>> uwrmsr %rax, %r14
>> uwrmsr %r12, %rdx
>> - uwrmsr %rax, %rdx
>> + uwrmsr %rax, %edx
>> uwrmsr %r12, $51515151
>> uwrmsr %rax, $51515151
>> uwrmsr %r12, $0x7f
>> @@ -24,7 +24,7 @@ _start:
>> .intel_syntax noprefix
>> urdmsr r12, r14
>> urdmsr rax, r14
>> - urdmsr r12, rdx
>> + urdmsr r12, edx
>> urdmsr rax, rdx
>> urdmsr r12, 51515151
>> urdmsr rax, 51515151
>> @@ -33,7 +33,7 @@ _start:
>> urdmsr r12, 0x80000000
>> uwrmsr r14, r12
>> uwrmsr r14, rax
>> - uwrmsr rdx, r12
>> + uwrmsr edx, r12
>> uwrmsr rdx, rax
>> uwrmsr 51515151, r12
>> uwrmsr 51515151, rax
>> --- a/opcodes/i386-opc.tbl
>> +++ b/opcodes/i386-opc.tbl
>> @@ -3359,9 +3359,9 @@ eretu, 0xf30f01ca, FRED, NoSuf, {}
>>
>> // USER_MSR instructions.
>>
>> -urdmsr, 0xf20f38f8, USER_MSR, RegMem|NoSuf|NoRex64, { Reg64, Reg64 }
>> +urdmsr, 0xf20f38f8, USER_MSR, RegMem|NoSuf|NoRex64, { Reg32|Reg64,
>> +Reg64 }
>> urdmsr, 0xf2f8/0, USER_MSR, Modrm|Vex128|VexMap7|VexW0|NoSuf,
>> { Imm32, Reg64 } -uwrmsr, 0xf30f38f8, USER_MSR, Modrm|NoSuf|NoRex64,
>> { Reg64, Reg64 }
>> +uwrmsr, 0xf30f38f8, USER_MSR, Modrm|NoSuf|NoRex64, { Reg64,
>> Reg32|Reg64
>> +}
>> // Immediates want to be first; md_assemble() takes care of swapping
>> operands // accordingly.
>> uwrmsr, 0xf3f8/0, USER_MSR, Modrm|Vex128|VexMap7|VexW0|NoSuf,
>> { Imm32, Reg64 }
next prev parent reply other threads:[~2023-12-04 7:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-24 9:18 Jan Beulich
2023-12-04 1:45 ` Hu, Lin1
2023-12-04 7:17 ` Jan Beulich [this message]
2023-12-12 7:13 ` Hu, Lin1
2023-12-12 8:13 ` Jan Beulich
2023-12-12 8:51 ` Hu, Lin1
2023-12-12 9:20 ` Jan Beulich
2023-12-13 2:23 ` Hu, Lin1
2023-12-13 6:59 ` Jan Beulich
2023-12-13 8:40 ` Hu, Lin1
2023-12-13 8:50 ` Jan Beulich
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