The original implementation could clobber registers under certain conditions.
The Xtensa processor architecture uses windowed registers and the original
implementation was using a4 as a temporary register, which under certain
conditions could be register a0 of the oldest window frame, and didn't always
restore the content correctly.
By moving the _spill_registers routine inside the fast system call, it frees
up one more register (the return address is not required anymore) for the
spill routine.
Signed-off-by: Chris Zankel <chris@zankel.net>
/* Check for overflow/underflow exception, jump if overflow. */
- _bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow
+ bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow
/*
* Restart window underflow exception.
EXPORT_SYMBOL(insl);
extern long common_exception_return;
-extern long _spill_registers;
EXPORT_SYMBOL(common_exception_return);
-EXPORT_SYMBOL(_spill_registers);
#ifdef CONFIG_FUNCTION_TRACER
EXPORT_SYMBOL(_mcount);