winedbg: Respect Thumb mode when adjusting PC on ARM

[Eric Pouech]

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+

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