linux-dev/arch/powerpc/kernel/time.c, branch linus/master

powerpc: Add missing headers

2022-05-08T12:15:40Z

Don't inherit headers "by chances" from asm/prom.h, asm/mpc52xx.h, asm/pci.h etc... Include the needed headers, and remove asm/prom.h when it was needed exclusively for pulling necessary headers. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/be8bdc934d152a7d8ee8d1a840d5596e2f7d85e0.1646767214.git.christophe.leroy@csgroup.eu

powerpc: fix typos in comments

2022-05-05T12:12:44Z

Various spelling mistakes in comments. Detected with the help of Coccinelle. Signed-off-by: Julia Lawall Reviewed-by: Joel Stanley Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220430185654.5855-1-Julia.Lawall@inria.fr

Merge tag 'v5.18-rc4' into next

2022-05-05T12:09:35Z

Merge master into next, to bring in commit 5f24d5a579d1 ("mm, hugetlb: allow for "high" userspace addresses"), which is needed as a prerequisite for the series converting powerpc to the generic mmap logic.

powerpc/time: Fix sparse warnings

2022-05-04T09:37:42Z

We found these warnings in arch/powerpc/kernel/time.c as follows: warning: symbol 'decrementer_max' was not declared. Should it be static? warning: symbol 'rtc_lock' was not declared. Should it be static? warning: symbol 'dtl_consumer' was not declared. Should it be static? Declare 'decrementer_max' in powerpc asm/time.h. Include linux/mc146818rtc.h in powerpc kernel/time.c where 'rtc_lock' is declared. And remove duplicated declaration of 'rtc_lock' in powerpc platforms/chrp/time.c because it has included linux/mc146818rtc.h. Move 'dtl_consumer' definition after "include " because it is declared there. Reported-by: Hulk Robot Signed-off-by: He Ying Reviewed-by: Christophe Leroy Reviewed-by: Alexandre Belloni Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210324090939.143477-1-heying24@huawei.com

powerpc/time: Always set decrementer in timer_interrupt()

2022-04-21T06:10:56Z

This is a partial revert of commit 0faf20a1ad16 ("powerpc/64s/interrupt: Don't enable MSR[EE] in irq handlers unless perf is in use"). Prior to that commit, we always set the decrementer in timer_interrupt(), to clear the timer interrupt. Otherwise we could end up continuously taking timer interrupts. When high res timers are enabled there is no problem seen with leaving the decrementer untouched in timer_interrupt(), because it will be programmed via hrtimer_interrupt() -> tick_program_event() -> clockevents_program_event() -> decrementer_set_next_event(). However with CONFIG_HIGH_RES_TIMERS=n or booting with highres=off, we see a stall/lockup, because tick_nohz_handler() does not cause a reprogram of the decrementer, leading to endless timer interrupts. Example trace: [ 1.898617][ T7] Freeing initrd memory: 2624K^M [ 22.680919][ C1] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:^M [ 22.682281][ C1] rcu: 0-....: (25 ticks this GP) idle=073/0/0x1 softirq=10/16 fqs=1050 ^M [ 22.682851][ C1] (detected by 1, t=2102 jiffies, g=-1179, q=476)^M [ 22.683649][ C1] Sending NMI from CPU 1 to CPUs 0:^M [ 22.685252][ C0] NMI backtrace for cpu 0^M [ 22.685649][ C0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.16.0-rc2-00185-g0faf20a1ad16 #145^M [ 22.686393][ C0] NIP: c000000000016d64 LR: c000000000f6cca4 CTR: c00000000019c6e0^M [ 22.686774][ C0] REGS: c000000002833590 TRAP: 0500 Not tainted (5.16.0-rc2-00185-g0faf20a1ad16)^M [ 22.687222][ C0] MSR: 8000000000009033 CR: 24000222 XER: 00000000^M [ 22.688297][ C0] CFAR: c00000000000c854 IRQMASK: 0 ^M ... [ 22.692637][ C0] NIP [c000000000016d64] arch_local_irq_restore+0x174/0x250^M [ 22.694443][ C0] LR [c000000000f6cca4] __do_softirq+0xe4/0x3dc^M [ 22.695762][ C0] Call Trace:^M [ 22.696050][ C0] [c000000002833830] [c000000000f6cc80] __do_softirq+0xc0/0x3dc (unreliable)^M [ 22.697377][ C0] [c000000002833920] [c000000000151508] __irq_exit_rcu+0xd8/0x130^M [ 22.698739][ C0] [c000000002833950] [c000000000151730] irq_exit+0x20/0x40^M [ 22.699938][ C0] [c000000002833970] [c000000000027f40] timer_interrupt+0x270/0x460^M [ 22.701119][ C0] [c0000000028339d0] [c0000000000099a8] decrementer_common_virt+0x208/0x210^M Possibly this should be fixed in the lowres timing code, but that would be a generic change and could take some time and may not backport easily, so for now make the programming of the decrementer unconditional again in timer_interrupt() to avoid the stall/lockup. Fixes: 0faf20a1ad16 ("powerpc/64s/interrupt: Don't enable MSR[EE] in irq handlers unless perf is in use") Reported-by: Miguel Ojeda Signed-off-by: Michael Ellerman Reviewed-by: Nicholas Piggin Link: https://lore.kernel.org/r/20220420141657.771442-1-mpe@ellerman.id.au

powerpc/time: improve decrementer clockevent processing

2022-03-16T05:55:23Z

The stop/shutdown op should not use decrementer_set_next_event because that sets decrementers_next_tb to now + decrementer_max, which means a decrementer interrupt that occurs after that time will call the clockevent event handler unexpectedly. Set next_tb to ~0 here to prevent any clock event call. Init all clockevents to stopped. Then the decrementer clockevent device always has event_handler set and applicable because we know the clock event device was not stopped. So make this call unconditional to show that it is always called. next_tb need not be set to ~0 before the event handler is called because it will stop the clockevent device if there is no other timer. Finally, the timer broadcast interrupt should not modify next_tb because it is not involved with the local decrementer clockevent on this CPU. This doesn't fix a known bug, just tidies the code. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220124143930.3923442-3-npiggin@gmail.com

powerpc/time: Fix KVM host re-arming a timer beyond decrementer range

2022-03-16T05:55:23Z

If the next host timer is beyond decrementer range, timer_rearm_host_dec will leave decrementer not programmed. This will not cause a problem for the host it will just set the decrementer correctly when the decrementer interrupt hits, it seems safer not to leave the next host decrementer interrupt timing able to be influenced by a guest. This code is only used in the P9 KVM paths so it's unlikely to be hit practically unless large decrementer is force disabled in the host. Fixes: 25aa145856cd ("powerpc/time: add API for KVM to re-arm the host timer/decrementer") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220124143930.3923442-2-npiggin@gmail.com

powerpc: Move C prototypes out of asm-prototypes.h

2022-03-08T11:06:25Z

We originally added asm-prototypes.h in commit 42f5b4cacd78 ("powerpc: Introduce asm-prototypes.h"). It's purpose was for prototypes of C functions that are only called from asm, in order to fix sparse warnings about missing prototypes. A few months later Nick added a different use case in commit 4efca4ed05cb ("kbuild: modversions for EXPORT_SYMBOL() for asm") for C prototypes for exported asm functions. This is basically the inverse of our original usage. Since then we've added various prototypes to asm-prototypes.h for both reasons, meaning we now need to unstitch it all. Dispatch prototypes of C functions into relevant headers and keep only the prototypes for functions defined in assembly. For the time being, leave prom_init() there because moving it into asm/prom.h or asm/setup.h conflicts with drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowrom.o This will be fixed later by untaggling asm/pci.h and asm/prom.h or by renaming the function in shadowrom.c Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/62d46904eca74042097acf4cb12c175e3067f3d1.1646413435.git.christophe.leroy@csgroup.eu

powerpc/mce: Avoid using irq_work_queue() in realmode

2022-03-07T13:05:00Z

In realmode mce handler we use irq_work_queue() to defer the processing of mce events, irq_work_queue() can only be called when translation is enabled because it touches memory outside RMA, hence we enable translation before calling irq_work_queue and disable on return, though it is not safe to do in realmode. To avoid this, program the decrementer and call the event processing functions from timer handler. Signed-off-by: Ganesh Goudar Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220120121931.517974-1-ganeshgr@linux.ibm.com

powerpc/64s/interrupt: Fix decrementer storm

2022-01-25T05:50:10Z

The decrementer exception can fail to be cleared when the interrupt returns in the case where the decrementer wraps with the next timer still beyond decrementer_max. This results in a decrementer interrupt storm. This is triggerable with small decrementer system with hard and soft watchdogs disabled. Fix this by always programming the decrementer if there was no timer. Fixes: 0faf20a1ad16 ("powerpc/64s/interrupt: Don't enable MSR[EE] in irq handlers unless perf is in use") Reported-by: Alexey Kardashevskiy Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220124143930.3923442-1-npiggin@gmail.com