diff options
| author | Marco Crivellari <marco.crivellari@suse.com> | 2025-04-03 18:11:42 +0200 |
|---|---|---|
| committer | Thomas Bogendoerfer <tsbogend@alpha.franken.de> | 2025-04-27 10:12:03 +0200 |
| commit | 56651128e2fbad80f632f388d6bf1f39c928267a (patch) | |
| tree | 94d3676270eb5105b7d4f4c87f8d6b391a6b884c /arch/mips/include/asm | |
| parent | 0af2f6be1b4281385b618cb86ad946eded089ac8 (diff) | |
MIPS: Fix idle VS timer enqueue
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.
Fixes: c65a5480ff29 ("[MIPS] Fix potential latency problem due to non-atomic cpu_wait.")
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Diffstat (limited to 'arch/mips/include/asm')
| -rw-r--r-- | arch/mips/include/asm/idle.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/mips/include/asm/idle.h b/arch/mips/include/asm/idle.h index 0992cad9c632..2bc3678455ed 100644 --- a/arch/mips/include/asm/idle.h +++ b/arch/mips/include/asm/idle.h @@ -6,8 +6,7 @@ #include <linux/linkage.h> extern void (*cpu_wait)(void); -extern void r4k_wait(void); -extern asmlinkage void __r4k_wait(void); +extern asmlinkage void r4k_wait(void); extern void r4k_wait_irqoff(void); static inline int using_rollback_handler(void) |