lkml.org 
[lkml]   [2020]   [Mar]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 10/12] powerpc/entry32: Blacklist exception entry points for kprobe.
Christophe Leroy wrote:
>
>
> Le 30/03/2020 à 19:08, Naveen N. Rao a écrit :
>> Christophe Leroy wrote:
>>> kprobe does not handle events happening in real mode.
>>>
>>> As exception entry points are running with MMU disabled,
>>> blacklist them.
>>>
>>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>>> ---
>>>  arch/powerpc/kernel/entry_32.S | 7 +++++++
>>>  1 file changed, 7 insertions(+)
>>>
>>> diff --git a/arch/powerpc/kernel/entry_32.S
>>> b/arch/powerpc/kernel/entry_32.S
>>> index 94f78c03cb79..9a1a45d6038a 100644
>>> --- a/arch/powerpc/kernel/entry_32.S
>>> +++ b/arch/powerpc/kernel/entry_32.S
>>> @@ -51,6 +51,7 @@ mcheck_transfer_to_handler:
>>>      mfspr    r0,SPRN_DSRR1
>>>      stw    r0,_DSRR1(r11)
>>>      /* fall through */
>>> +_ASM_NOKPROBE_SYMBOL(mcheck_transfer_to_handler)
>>>
>>>      .globl    debug_transfer_to_handler
>>>  debug_transfer_to_handler:
>>> @@ -59,6 +60,7 @@ debug_transfer_to_handler:
>>>      mfspr    r0,SPRN_CSRR1
>>>      stw    r0,_CSRR1(r11)
>>>      /* fall through */
>>> +_ASM_NOKPROBE_SYMBOL(debug_transfer_to_handler)
>>>
>>>      .globl    crit_transfer_to_handler
>>>  crit_transfer_to_handler:
>>> @@ -94,6 +96,7 @@ crit_transfer_to_handler:
>>>      rlwinm    r0,r1,0,0,(31 - THREAD_SHIFT)
>>>      stw    r0,KSP_LIMIT(r8)
>>>      /* fall through */
>>> +_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)
>>>  #endif
>>>
>>>  #ifdef CONFIG_40x
>>> @@ -115,6 +118,7 @@ crit_transfer_to_handler:
>>>      rlwinm    r0,r1,0,0,(31 - THREAD_SHIFT)
>>>      stw    r0,KSP_LIMIT(r8)
>>>      /* fall through */
>>> +_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)
>>>  #endif
>>>
>>>  /*
>>> @@ -127,6 +131,7 @@ crit_transfer_to_handler:
>>>      .globl    transfer_to_handler_full
>>>  transfer_to_handler_full:
>>>      SAVE_NVGPRS(r11)
>>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler_full)
>>>      /* fall through */
>>>
>>>      .globl    transfer_to_handler
>>> @@ -286,6 +291,8 @@ reenable_mmu:
>>>      lwz    r2, GPR2(r11)
>>>      b    fast_exception_return
>>>  #endif
>>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler)
>>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler_cont)
>>
>> These are added after 'reenable_mmu', which is itself not blacklisted.
>> Is that intentional?
>
> Yes I put it as the complete end of the entry part, ie just before
> stack_ovf which is a function by itself.
>
> Note that reenable_mmu is inside an #ifdef CONFIG_TRACE_IRQFLAGS.
>
> I'm not completely sure where to put the _ASM_NOKPROBE_SYMBOL()s, that's
> the reason why I put it close to the symbol itself in my first series.

Ok, I see what you mean. 'reenable_mmu' can probably be moved after the
end of 'transfer_to_handler_cont' (as also removing what looks to be an
unused label '1' for the branch to trace_hardirqs_off), but that's a
minor thing. From the blacklisting point, this is not an issue.

- Naveen

\
 
 \ /
  Last update: 2020-03-31 08:14    [W:0.064 / U:2.672 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site