linux.git/arch/powerpc/kernel/time.c, branch v6.12.80

powerpc/4xx: Remove CONFIG_BOOKE_OR_40x

2024-06-28T12:28:48+00:00

Now that 40x is gone, replace CONFIG_BOOKE_OR_40x by CONFIG_BOOKE.

Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20240628121201.130802-5-mpe@ellerman.id.au

sched/vtime: Get rid of generic vtime_task_switch() implementation

2024-04-17T11:37:20+00:00

The generic vtime_task_switch() implementation gets built only
if __ARCH_HAS_VTIME_TASK_SWITCH is not defined, but requires an
architecture to implement arch_vtime_task_switch() callback at
the same time, which is confusing.

Further, arch_vtime_task_switch() is implemented for 32-bit PowerPC
architecture only and vtime_task_switch() generic variant is rather
superfluous.

Simplify the whole vtime_task_switch() wiring by moving the existing
generic implementation to PowerPC.

Signed-off-by: Alexander Gordeev 
Signed-off-by: Ingo Molnar 
Reviewed-by: Frederic Weisbecker 
Reviewed-by: Nicholas Piggin 
Acked-by: Michael Ellerman 
Link: https://lore.kernel.org/r/2cb6e3caada93623f6d4f78ad938ac6cd0e2fda8.1712760275.git.agordeev@linux.ibm.com

powerpc: Make generic_calibrate_decr() the default

2023-03-15T21:56:48+00:00

ppc_md.calibrate_decr() is a mandatory item. Its nullity is never
checked so it must be non null on all platforms.

Most platforms define generic_calibrate_decr() as their
ppc_md.calibrate_decr(). Have time_init() call
generic_calibrate_decr() when ppc_md.calibrate_decr() is NULL,
and remove default assignment from all machines.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/6cb9865d916231c38401ba34ad1a98c249fae135.1676711562.git.christophe.leroy@csgroup.eu

Merge branch 'fixes' into next

2023-02-12T11:11:56+00:00

Merge our fixes branch to bring in some changes that conflict with
upcoming next content.

powerpc/kcsan: Exclude udelay to prevent recursive instrumentation

2023-02-10T11:19:56+00:00

In order for KCSAN to increase its likelihood of observing a data race,
it sets a watchpoint on memory accesses and stalls, allowing for
detection of conflicting accesses by other kernel threads or interrupts.

Stalls are implemented by injecting a call to udelay in instrumented code.
To prevent recursive instrumentation, exclude udelay from being instrumented.

Signed-off-by: Rohan McLure 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20230206021801.105268-3-rmclure@linux.ibm.com

powerpc/64: Fix perf profiling asynchronous interrupt handlers

2023-01-30T09:07:42+00:00

Interrupt entry sets the soft mask to IRQS_ALL_DISABLED to match the
hard irq disabled state. So when should_hard_irq_enable() returns true
because we want PMI interrupts in irq handlers, MSR[EE] is enabled but
PMIs just get soft-masked. Fix this by clearing IRQS_PMI_DISABLED before
enabling MSR[EE].

This also tidies some of the warnings, no need to duplicate them in
both should_hard_irq_enable() and do_hard_irq_enable().

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20230121100156.2824054-1-npiggin@gmail.com

powerpc: remove the last remnants of cputime_t

2022-11-24T12:31:48+00:00

cputime_t was a core kernel type, removed by commits
ed5c8c854f2b..b672592f0221. As explained in commit b672592f0221
("sched/cputime: Remove generic asm headers"), the final cleanup
is for the arch to provide cputime_to_nsec[s](). Commit ade7667a981b
("powerpc: Add cputime_to_nsecs()") did that, but justdidn't remove
the then-unused cputime_to_usecs(), cputime_t type, and associated
remnants.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20221006105653.115829-1-npiggin@gmail.com

powerpc/time: avoid programming DEC at the start of the timer interrupt

2022-09-28T09:22:09+00:00

Setting DEC to maximum at the start of the timer interrupt is not
necessary and can be avoided for performance when MSR[EE] is not
enabled during the handler as explained in commit 0faf20a1ad16
("powerpc/64s/interrupt: Don't enable MSR[EE] in irq handlers unless
perf is in use"), where this change was first attempted.

The idea is that the timer interrupt runs with MSR[EE]=0, and at the end
of the interrupt DEC is programmed to the next timer interval, so there
is no need to clear the decrementer exception before then.

When the above commit was merged, that was not quite true. The low res
timer subsystem had some cases in the oneshot timer code where if the
tick was to be stopped and no timers active, the clock device would not
get the ->set_state_oneshot_stopped() call, so DEC would not get
reprogrammed, and this would hang taking continual timer interrupts.

So this was reverted in commit d2b9be1f4af5 ("powerpc/time: Always set
decrementer in timer_interrupt()"), which was a partial revert of the
above commit.

Commit 62c1256d5447 ("timers/nohz: Switch to ONESHOT_STOPPED in the
low-res handler when the tick is stopped") was later merged to fix this
missing case in the timer subsystem, so now the behaviour can be
restored.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220909142457.278032-1-npiggin@gmail.com

powerpc/pseries: Move dtl scanning and steal time accounting to pseries platform

2022-09-05T04:14:27+00:00

dtl is the PAPR Dispatch Trace Log, which is entirely a pseries feature.
The pseries platform alrady has a file dealing with the dtl, so move
scanning for stolen time accounting there from kernel/time.c.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220902085316.2071519-5-npiggin@gmail.com

powerpc: Add missing headers

2022-05-08T12:15:40+00:00

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