Re: [Xen-devel] x86_64: Fix double fault stack setup

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.05.12 at 16:59, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> x86_64: Fix double fault stack setup.
> 
> Dont forget to push error_code and entry_vector onto the stack for a double
> fault.  If it is missed, the register information printed looks like
> 
> (XEN) CPU:    0
> (XEN) RIP:    0246:[<000000000000e008>] ???
> (XEN) RFLAGS: ffff82c480287eb8
> (XEN) rax: 0000000000000282   rbx: ffff82c480242dd0   rcx: 0000000000000282
> (XEN) rdx: 0000000000000000   rsi: 0000000000000282   rdi: 0000000000000031
> (XEN) rbp: 0000000000000031   rsp: 0000000000000000   r8:  ffff83007ee52488
> (XEN) r9:  ffff83007ee61088   r10: 0000000000000007   r11: ffff82c480116460
> (XEN) r12: 0000000000000000   r13: ffff82c4802c37e0   r14: 00026501a9ced0b8
> (XEN) r15: ffff82c4802c37c0    cs: 0000000000000246    ss: 0000000000000000
> 
> which incorrectly displays cs, rip, rflags and rsp; the useful pieces of
> information when trying to identify the cause of a double fault.

Is this from an actual double fault, or from one of your INT 08
attempts to simulate one? An actual exception pushes an error
code, so I'm afraid the change below is wrong.

Jan

> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> diff -r 69c3ae25bb1d xen/arch/x86/x86_64/entry.S
> --- a/xen/arch/x86/x86_64/entry.S
> +++ b/xen/arch/x86/x86_64/entry.S
> @@ -595,6 +595,8 @@ ENTRY(spurious_interrupt_bug)
>          jmp   handle_exception
>  
>  ENTRY(double_fault)
> +        pushq $0
> +        movl $TRAP_double_fault,4(%rsp)
>          SAVE_ALL
>          movq  %rsp,%rdi
>          call  do_double_fault
> 
> -- 
> Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
> T: +44 (0)1223 225 900, http://www.citrix.com 




_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel