@@ -104,27 +104,30 @@ handle_vcei:
__FINIT
- .align 5 /* 32 byte rollback region */
+ .align 5
LEAF(__r4k_wait)
.set push
.set noreorder
- /* start of rollback region */
- LONG_L t0, TI_FLAGS($28)
- nop
- andi t0, _TIF_NEED_RESCHED
- bnez t0, 1f
- nop
- nop
- nop
-#ifdef CONFIG_CPU_MICROMIPS
- nop
- nop
- nop
- nop
-#endif
+ /* start of idle interrupt region */
+ MFC0 t0, CP0_STATUS
+ /* Enable Interrput */
+ ori t0, 0x1f
+ xori t0, 0x1e
+ MTC0 t0, CP0_STATUS
+ _ssnop
+ _ssnop
+ _ssnop
+ _ehb
.set MIPS_ISA_ARCH_LEVEL_RAW
+ /*
+ * If an interrupt lands here, between enabling interrupts above and
+ * going idle on the next instruction, we must *NOT* go idle since the
+ * interrupt could have set TIF_NEED_RESCHED or caused a timer to need
+ * resched. Fall through -- see rollback_handler below -- and have
+ * the idle loop take care of things.
+ */
wait
- /* end of rollback region (the region size must be power of two) */
+ /* end of rollback region */
1:
jr ra
nop
@@ -136,9 +139,10 @@ LEAF(__r4k_wait)
.set push
.set noat
MFC0 k0, CP0_EPC
- PTR_LA k1, __r4k_wait
- ori k0, 0x1f /* 32 byte rollback region */
- xori k0, 0x1f
+ PTR_LA k1, 1b
+ /* 36 byte idle interrupt region */
+ ori k0, 0x1f
+ PTR_ADDIU k0, 5
bne k0, k1, \handler
MTC0 k0, CP0_EPC
.set pop
@@ -37,7 +37,6 @@ static void __cpuidle r3081_wait(void)
void __cpuidle r4k_wait(void)
{
- raw_local_irq_enable();
__r4k_wait();
raw_local_irq_disable();
}
MIPS re-enables interrupts on its idle routine and performs a TIF_NEED_RESCHED check afterwards before putting the CPU to sleep. The IRQs firing between the check and the 'wait' instruction may set the TIF_NEED_RESCHED flag. In order to deal with this possible race, IRQs interrupting __r4k_wait() rollback their return address to the beginning of __r4k_wait() so that TIF_NEED_RESCHED is checked again before going back to sleep. However idle IRQs can also queue timers that may require a tick reprogramming through a new generic idle loop iteration but those timers would go unnoticed here because __r4k_wait() only checks TIF_NEED_RESCHED. It doesn't check for pending timers. Fix this with fast-forwarding idle IRQs return address to the end of the idle routine instead of the beginning, so that the generic idle loop handles both TIF_NEED_RESCHED and pending timers. CONFIG_CPU_MICROMIPS has been removed along with the nop instructions. There, NOPs are 2 byte in size, so change the code with 3 _ssnop which are always 4 byte and remove the ifdef. Added ehb to make sure the hazard is always cleared. Signed-off-by: Marco Crivellari <marco.crivellari@suse.com> --- arch/mips/kernel/genex.S | 42 ++++++++++++++++++++++------------------ arch/mips/kernel/idle.c | 1 - 2 files changed, 23 insertions(+), 20 deletions(-)