* Patched longjmp to be context-switch safe
longjmp modifies the windowbase and windowstart
registers, which isn't safe if a context switch
occurs during the modification. After a context
switch, windowstart and windowbase will be
different, leading to a wrongly set windowstart
bit due to longjmp writing it based on the
windowbase before the context switch. This
corrupts the registers at the next window
overflow reaching that wrongly set bit.
The solution is to disable interrupts during
this code. It is only 6 instructions long,
the impact shouldn't be significant.
The fix is implemented as a wrapper which
replaces the original first instructions of
longjmp which are buggy. Then, it jumps back
to execute the rest of the original longjmp
function.
Added a comparably reliable test to the
test apps.
