[RFC] [PATCH 0/4] ARM: kprobes: Infrastructure to support probes in Thumb code

Tixy tixy at yxit.co.uk
Mon Mar 21 16:52:44 UTC 2011


On Mon, 2011-03-21 at 12:01 -0400, Nicolas Pitre wrote:
> Why not always using a 16-bit Thumb breakpoint instruction even in place 
> of a 32-bit Thumb instruction?  This way you sidestep all the issues 
> about atomically updating the instruction across two words.  The 
> instruction to emulate might still be 32-bit and therefore pc would be 
> advanced appropriately.

If the breakpoint is in an IT block and its execution condition is false
then the breakpoint may not cause an exception and the CPU will go on
and try and execute the other half of the instruction.

-- 
Tixy





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