On Wed 2010-02-03 12:44:26, Daniel Jacobowitz wrote:

On Wed, Feb 03, 2010 at 05:23:01PM +0000, Jamie Lokier wrote:

quoted

Daniel Jacobowitz wrote:

quoted

Thankfully, both branches into IT blocks and branches
leaving IT blocks not at the last instruction are forbidden.

Forbidden as in throws a fault, or forbidden as in "can we use this to
break out of GDB single-stepping to give third-parties a hard time
tracing my secret code"?

Forbidden as in "the architecture documentation says it has
unpredictable behavior".

That's generally where I draw the line at trying to handle bad code.
In practice, I will make a wild guess that current processors fault
branches during an IT block and don't do anything fancy for branches
into an IT block, or else it messes up in some hard-to-reproduce way.

So it seems the second kind of forbidden :-(.
									Pavel

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