Re: [PATCH] x86/asm/entry/64: Clean up entry_64.S

From: Andy Lutomirski
Date: Mon Jul 06 2015 - 14:35:50 EST


On Mon, Jul 6, 2015 at 10:41 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
> * Sasha Levin <sasha.levin@xxxxxxxxxx> wrote:
>
>> On 07/06/2015 01:20 PM, Andy Lutomirski wrote:
>> > On Mon, Jul 6, 2015 at 8:00 AM, Sasha Levin <sasha.levin@xxxxxxxxxx> wrote:
>> >> >
>> >> > --- entry.before.o.cmd 2015-07-06 10:48:32.110189938 -0400
>> >> > +++ entry.after.o.cmd 2015-07-06 10:48:23.509645442 -0400
>> >> > @@ -1,5 +1,5 @@
>> >> >
>> >> > -entry.before.o: file format elf64-x86-64
>> >> > +entry.after.o: file format elf64-x86-64
>> >> >
>> >> >
>> >> > Disassembly of section .entry.text:
>> >> > @@ -3961,8 +3961,8 @@
>> >> > 3b: 09 02 or %eax,(%rdx)
>> >> > ...
>> >> > 3d: R_X86_64_64 .entry.text
>> >> > - 45: 03 3a add (%rdx),%edi
>> >> > - 47: 01 3d 03 d6 00 c8 add %edi,-0x37ff29fd(%rip) # ffffffffc800d650 <ignore_sysret+0xffffffffc800b1f0>
>> >> > + 45: 03 33 add (%rbx),%esi
>> >> > + 47: 01 3d 03 d5 00 c8 add %edi,-0x37ff2afd(%rip) # ffffffffc800d550 <ignore_sysret+0xffffffffc800b0f0>
>> > What exactly are you doing to generate this diff? This all looks really weird.
>> >
>> >> > 4d: 44 91 rex.R xchg %eax,%ecx
>> >> > 4f: 93 xchg %eax,%ebx
>> >> > 50: 2f (bad)
>> > For example: what on earth is the asm above?
>>
>> objdump...
>
> Oh, so I'm using 'objdump -d' to compare - but you probably used 'objdump
> --disassemble-all', to disassemble .data sections as well?
>

I can reproduce the difference now. Give me a few minutes to see if I
can figure out what's causing it.

--Andy

> Thanks,
>
> Ingo



--
Andy Lutomirski
AMA Capital Management, LLC
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