Re: 2.6.24-rc6-mm1

[Christoph Hellwig <hch@infradead.org>]

On Sun, Dec 23, 2007 at 12:57:35PM +0100, Ingo Molnar wrote:
> 
> * Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > Still.  The crash is 100% repeatable and is the same every time.  
> > Happens on both my i386 test boxes.
> > 
> > http://userweb.kernel.org/~akpm/config-sony.txt
> > http://userweb.kernel.org/~akpm/config-vmm.txt
> > 
> > and I bisected it down to e3c1b141.
> 
> ok, can reproduce it - the patch below fixes it for me.
> 
> 	Ingo
> 
> ------------------------->
> Subject: x86: fix system gate related crash
> From: Ingo Molnar <mingo@elte.hu>
> 
> on 32-bit, system gates are traps.
> 
> on 64-bit, they are interrupts (which disable hardirqs).
> 
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
>  include/asm-x86/desc.h |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> Index: linux-x86.q/include/asm-x86/desc.h
> ===================================================================
> --- linux-x86.q.orig/include/asm-x86/desc.h
> +++ linux-x86.q/include/asm-x86/desc.h
> @@ -310,7 +310,11 @@ static inline void set_trap_gate(unsigne
>  static inline void set_system_gate(unsigned int n, void *addr)
>  {
>  	BUG_ON((unsigned)n > 0xFF);
> +#ifdef CONFIG_X86_32
> +	_set_gate(n, GATE_TRAP, addr, 0x3, 0, __KERNEL_CS);
> +#else
>  	_set_gate(n, GATE_INTERRUPT, addr, 0x3, 0, __KERNEL_CS);
> +#endif
>  }
>
This would be a lot cleaner with entirely separate implementations
of set_system_gate for 32 vs 64 bit.  Especially if the file already
has a large ifdef block for 32 vs 64 already.
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