2009/8/14 David Miller <davem@xxxxxxxxxxxxx>:
> From: hyl <heyongli@xxxxxxxxx>
> Date: Wed, 12 Aug 2009 09:53:01 +0800
>
> Please post all Sparc patches and questions CC:'d to
> sparclinux@xxxxxxxxxxxxxxx otherwise no Sparc experts are going to see
thank you.
> it.
>
>> --- a/arch/sparc/kernel/sun4v_tlb_miss.S
>> +++ b/arch/sparc/kernel/sun4v_tlb_miss.S
>> @@ -124,7 +124,7 @@ sun4v_dtlb_load:
>> mov %g3, %o2 ! PTE
>> mov HV_MMU_DMMU, %o3 ! flags
>> ta HV_MMU_MAP_ADDR_TRAP
>> - brnz,pn %o0, sun4v_dtlb_error
>> + brnz,pn %o0, sun4v_dtlb_prot
>> mov %g2, %o1 ! restore %o1
>> mov %g1, %o0 ! restore %o0
>> mov %g5, %o2 ! restore %o2
>>
>>
>>
>> am i miss understanding the merged sparc/spar64?
>>
>> this problem found on sparc64, via a simple module just access address 0
>> via copy_from_user. another simple test is kgdb, issue a cmd:
>> x 0
>
> That condition should never trigger, the problem is caused
> elsewhere.
>
> If the HV_MMU_MAP_ADDR_TRAP hypervisor call gives an error it means:
>
> 1) The PTE passed in is invalid
>
> 2) The PTE passed in translates to addresses outside of the
> range accessible to the guest
the problem seem due to this reason. the test step and trigger flow is:
1. connect the kgdb (or simple modules just copy_from_user with
address 0xffff fff0)
kddb "x 0xfffffff0" command processed by probe_kernel_read() ->
__copy_from_user_inatomic.
2. then a tlb miss triggered
3. then cpu go to entry: sun4v_dtlb_miss ( should be)
4. --> sun4v_dtlb_load (very sure, verified)
5. --->halt in sun4v_dtlb_error (very sure, ) emit message in
console is: (access the address 0xffff fff0 )
SUN4V-DTLB: Error at TPC[5f2cc8], tl 1
SUN4V-DTLB: TPC<memcpy_user_stub+0x8/0x40>
SUN4V-DTLB: O7[4af23c]
SUN4V-DTLB: O7<probe_kernel_read+0x3c/0xa0>
SUN4V-DTLB: vaddr[ffffffffffffe000] ctx[0] pte[800007ffffffe743] error[2]
the problem is :
this DTLB fault can be fixed by search extable, by fall to the
do_sparc64_fault, my draft proposal can verify this: with this patch, this kind
of fault is recovery, so enable copy_from_user return error instead of halt.
in addition, it is triggered in kernel space, search the extable is mandatory .
fix me
Pauli He
>
> 3) The virtual address is invalid
>
> And the kernel should never have such an illegal address or
> PTE mapping here.
>
> You need to figure out how the bad mapping gets into the kernel page
> tables and/or translations in the first place.
>
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