[ARM] 3309/1: disable the pre-ARMv5 NPTL kernel helper in the non MMU case
Patch from Nicolas Pitre The cmpxchg emulation on pre-ARMv5 relies on user code executed from a kernel address. If the operation cannot complete atomically, it is aborted from the usr_entry macro by clearing the Z flag. This clearing of the Z flag is done whenever the user pc is above TASK_SIZE. However this "pc >= TASK_SIZE" test cannot work in the non MMU case. Worse: the current code will corrupt the Z flag on every entry to the kernel. Let's disable it in the non MMU case for now. Using NPTL on non MMU targets needs to be worked out anyway. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Showing
Please register or sign in to comment