winedbg: Respect Thumb mode when adjusting PC on ARM

[Eric Pouech]

Le 11/03/2012 09:18, Eric Pouech a écrit :
> Le 10/03/2012 18:26, André Hentschel a écrit :
>> ---
>>   programs/winedbg/be_arm.c |   10 ++++++----
>>   1 files changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/programs/winedbg/be_arm.c b/programs/winedbg/be_arm.c
>> index c39043c..6c1cc05 100644
>> --- a/programs/winedbg/be_arm.c
>> +++ b/programs/winedbg/be_arm.c
>> @@ -205,13 +205,15 @@ static void be_arm_clear_watchpoint(CONTEXT* 
>> ctx, unsigned idx)
>>
>>   static int be_arm_adjust_pc_for_break(CONTEXT* ctx, BOOL way)
>>   {
>> +    INT step = (ctx->Cpsr&  0x20) ? 2 : 4;
> hmm
> the way winedbg works might put us in trouble here...
>
> when winedbg is entered with a break exception:
> 1/ winedbg calls adjust_pc_for_break(..., TRUE) to get the PC to the 
> real location of the break insn (and not after, as most CPU report in 
> break exception handler)
> 2/ user interacts with winedbg
> 3/ user resumes execution, and winedbg calls again 
> adjust_pc_for_break(..., FALSE)
>
> but, the ctx passed here is the context used to resume execution... 
> and in ARM case Cpsr could have been changed by user in step 2/
> leading to wrong PC computation in 3/
>
> therefore, if we want to plug that hole, I'd suggest having two 
> context used in winedbg (the incoming one (never being changed), and 
> the current/outgoing one), and that we pass the two contexts in 
> winedbg to do the right thing here
>
> A+
>
and I forgot my question... is it possible for the user to change the 
cpsr value?
A+

-- 
Eric Pouech
"The problem with designing something completely foolproof is to underestimate the ingenuity of a complete idiot." (Douglas Adams)