Re: Vmware crashes if compress/misc.c scrolls?

Zachary Amsden
2007-08-04T14:33:55Z

Andi Kleen wrote:
>> In the boot decompressor for the kernel in the image Iouri provided, I
>>
>
> 32bit or 64bit image?
>
>
>> As you can plainly see, the call to memcpy (which is redefined in
>> boot/compressed/misc.c) is made using stack calling convention.
>> Unfortunately, the compiler generated the memcpy function itself using
>> regparm(3) convention. I am guessing this happened because a leftover
>>
>
> I can't find any here grepping .i files and includes. None of the memcpy
> prototypes in include have a __fastcall
>
> Are you sure this still happens in mainline?
>
> When I look at my scroll it also looks correct:
>
> c0: 0f af f8 imul %eax,%edi
> c3: 01 c0 add %eax,%eax
> c5: 89 c2 mov %eax,%edx
> c7: 01 f2 add %esi,%edx
> c9: 89 45 f0 mov %eax,0xfffffff0(%ebp)
> cc: 89 f0 mov %esi,%eax
> ce: 89 f9 mov %edi,%ecx
> d0: e8 7b ff ff ff call 50 <memcpy>
>
>
>
>> Does anyone recall compiler problems (I noticed this VM was booting a
>> 64-bit kernel,
>>
>
> Ok 64bit, that was 32bit above.
>
> Since some time the decompressor is 64bit and 64bit always uses
> regparms. 64bit Scroll is ok too:
>
> 92: 0f af eb imul %ebx,%ebp
> 95: 01 db add %ebx,%ebx
> 97: 48 63 f3 movslq %ebx,%rsi
> 9a: 4c 01 ee add %r13,%rsi
> 9d: 89 ea mov %ebp,%edx
> 9f: e8 9c ff ff ff callq 40 <memcpy>
>
>
>
>> but the decompressor was 32-bit code,
>>
>
> That must be a old kernel.
>
> Can you people please verify this all still happens with a mainline or
> 2.6.22 kernel?
>
>
>> so perhaps at some
>> time the 64-bit makefile or toolchain for Linux had some kind of
>> compiler bug).
>>
>
> I'm not aware of any such bugs.
>

It was 2.6.21.4, so it is fairly recent, but with 32-bit decompress
stage. GCC was 4.2.0.

Sounds like a gcc bug, to me.

Zach