Re: PROBLEM: x86 alignment check bug

[Alan Cox]

On Mer, 2004-09-08 at 00:51, Zachary Amsden wrote:
> Exception reporting for alignment check violations on x86 is broken 
> (unfortunately, rather badly, and rather hard to fix).  Look at the trap 
> function which fills in the si_addr field during an unaligned memory 
> access, 2.6.8.1-mm4+, arch/i386/kernel/traps.c, Line 522:

So it fills in a value with random data that should be zero. Ok thats
hardly "badly". 

> Clearly, this is not correct.  Considering how difficult the fix is (the 
> kernel must disassemble the faulting instruction and use register 
> information to determine the faulting address)

It would be a nice extension although it would break other OS's if it
used %cr2 for this since they use it for thread id.


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