linux-toradex.git/drivers/cpuidle, branch v6.7

cpuidle: dt: Replace deprecated strncpy() with strscpy()

2023-09-29T21:48:31+00:00

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer. With this, we can also drop
the now unnecessary `CPUIDLE_(NAME|DESC)_LEN - 1` pieces.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt 
Reviewed-by: Kees Cook 
Link: https://lore.kernel.org/r/20230913-strncpy-drivers-cpuidle-dt_idle_states-c-v1-1-d16a0dbe5658@google.com
Signed-off-by: Kees Cook

Merge tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2023-08-31T19:43:10+00:00

Pull powerpc updates from Michael Ellerman:

 - Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and honour the
   configured SMT state when hotplugging CPUs into the system

 - Combine final TLB flush and lazy TLB mm shootdown IPIs when using the
   Radix MMU to avoid a broadcast TLBIE flush on exit

 - Drop the exclusion between ptrace/perf watchpoints, and drop the now
   unused associated arch hooks

 - Add support for the "nohlt" command line option to disable CPU idle

 - Add support for -fpatchable-function-entry for ftrace, with GCC >=
   13.1

 - Rework memory block size determination, and support 256MB size on
   systems with GPUs that have hotpluggable memory

 - Various other small features and fixes

Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira
Rajeev, Benjamin Gray, Christophe Leroy, Frederic Barrat, Gautam
Menghani, Geoff Levand, Hari Bathini, Immad Mir, Jialin Zhang, Joel
Stanley, Jordan Niethe, Justin Stitt, Kajol Jain, Kees Cook, Krzysztof
Kozlowski, Laurent Dufour, Liang He, Linus Walleij, Mahesh Salgaonkar,
Masahiro Yamada, Michal Suchanek, Nageswara R Sastry, Nathan Chancellor,
Nathan Lynch, Naveen N Rao, Nicholas Piggin, Nick Desaulniers, Omar
Sandoval, Randy Dunlap, Reza Arbab, Rob Herring, Russell Currey, Sourabh
Jain, Thomas Gleixner, Trevor Woerner, Uwe Kleine-König, Vaibhav Jain,
Xiongfeng Wang, Yuan Tan, Zhang Rui, and Zheng Zengkai.

* tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (135 commits)
  macintosh/ams: linux/platform_device.h is needed
  powerpc/xmon: Reapply "Relax frame size for clang"
  powerpc/mm/book3s64: Use 256M as the upper limit with coherent device memory attached
  powerpc/mm/book3s64: Fix build error with SPARSEMEM disabled
  powerpc/iommu: Fix notifiers being shared by PCI and VIO buses
  powerpc/mpc5xxx: Add missing fwnode_handle_put()
  powerpc/config: Disable SLAB_DEBUG_ON in skiroot
  powerpc/pseries: Remove unused hcall tracing instruction
  powerpc/pseries: Fix hcall tracepoints with JUMP_LABEL=n
  powerpc: dts: add missing space before {
  powerpc/eeh: Use pci_dev_id() to simplify the code
  powerpc/64s: Move CPU -mtune options into Kconfig
  powerpc/powermac: Fix unused function warning
  powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT
  powerpc: Don't include lppaca.h in paca.h
  powerpc/pseries: Move hcall_vphn() prototype into vphn.h
  powerpc/pseries: Move VPHN constants into vphn.h
  cxl: Drop unused detach_spa()
  powerpc: Drop zalloc_maybe_bootmem()
  powerpc/powernv: Use struct opal_prd_msg in more places
  ...

Merge branches 'pm-cpuidle' and 'pm-cpufreq'

2023-08-25T19:15:56+00:00

Merge CPU power management updates for 6.6-rc1:

 - Rework the menu and teo cpuidle governors to avoid calling
   tick_nohz_get_sleep_length(), which is likely to become quite
   expensive going forward, too often and improve making decisions
   regarding whether or not to stop the scheduler tick in the teo
   governor (Rafael Wysocki).

 - Improve the performance of cpufreq_stats_create_table() in some
   cases (Liao Chang).

 - Fix two issues in the amd-pstate-ut cpufreq driver (Swapnil Sapkal).

 - Use clamp() helper macro to improve the code readability in
   cpufreq_verify_within_limits() (Liao Chang).

 - Set stale CPU frequency to minimum in intel_pstate (Doug Smythies).

* pm-cpuidle:
  cpuidle: teo: Avoid unnecessary variable assignments
  cpuidle: menu: Skip tick_nohz_get_sleep_length() call in some cases
  cpuidle: teo: Gather statistics regarding whether or not to stop the tick
  cpuidle: teo: Skip tick_nohz_get_sleep_length() call in some cases
  cpuidle: teo: Do not call tick_nohz_get_sleep_length() upfront
  cpuidle: teo: Drop utilized from struct teo_cpu
  cpuidle: teo: Avoid stopping the tick unnecessarily when bailing out
  cpuidle: teo: Update idle duration estimate when choosing shallower state

* pm-cpufreq:
  cpufreq: amd-pstate-ut: Fix kernel panic when loading the driver
  cpufreq: amd-pstate-ut: Remove module parameter access
  cpufreq: Use clamp() helper macro to improve the code readability
  cpufreq: intel_pstate: set stale CPU frequency to minimum
  cpufreq: stats: Improve the performance of cpufreq_stats_create_table()

powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT

2023-08-24T12:33:17+00:00

lppaca_shared_proc() takes a pointer to the lppaca which is typically
accessed through get_lppaca().  With DEBUG_PREEMPT enabled, this leads
to checking if preemption is enabled, for example:

  BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693
  caller is lparcfg_data+0x408/0x19a0
  CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2
  Call Trace:
    dump_stack_lvl+0x154/0x200 (unreliable)
    check_preemption_disabled+0x214/0x220
    lparcfg_data+0x408/0x19a0
    ...

This isn't actually a problem however, as it does not matter which
lppaca is accessed, the shared proc state will be the same.
vcpudispatch_stats_procfs_init() already works around this by disabling
preemption, but the lparcfg code does not, erroring any time
/proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled.

Instead of disabling preemption on the caller side, rework
lppaca_shared_proc() to not take a pointer and instead directly access
the lppaca, bypassing any potential preemption checks.

Fixes: f13c13a00512 ("powerpc: Stop using non-architected shared_proc field in lppaca")
Signed-off-by: Russell Currey 
[mpe: Rework to avoid needing a definition in paca.h and lppaca.h]
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230823055317.751786-4-mpe@ellerman.id.au

cpuidle: teo: Avoid unnecessary variable assignments

2023-08-23T16:25:04+00:00

Notice that it is not necessary to assign tick_intercept_sum in every
iteration of the first loop over idle states in teo_select(), because
the intercept_sum value does not change after the assignment in a
given iteration of the loop, so its value after the last iteration of
the loop can be used for computing the tick_intercept_sum value
directly.

Modify the code accordingly.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki

cpuidle: menu: Skip tick_nohz_get_sleep_length() call in some cases

2023-08-17T09:28:38+00:00

Because the cost of calling tick_nohz_get_sleep_length() may increase
in the future, reorder the code in menu_select() so it first uses the
statistics to determine the expected idle duration.  If that value is
higher than RESIDENCY_THRESHOLD_NS, tick_nohz_get_sleep_length() will
be called to obtain the time till the closest timer and refine the
idle duration prediction if necessary.

This causes the governor to always take the full overhead of
get_typical_interval() with the assumption that the cost will be
amortized by skipping the tick_nohz_get_sleep_length() call in the
cases when the predicted idle duration is relatively very small.

Signed-off-by: Rafael J. Wysocki 
Tested-by: Doug Smythies

cpuidle: teo: Gather statistics regarding whether or not to stop the tick

2023-08-09T17:58:53+00:00

Currently, if the target residency of the deepest idle state is less than
the tick period length, which is quite likely for HZ=100, and the deepest
idle state is about to be selected by the TEO idle governor, the decision
on whether or not to stop the scheduler tick is based entirely on the
time till the closest timer.  This is often insufficient, because timers
may not be in heavy use and there may be a plenty of other CPU wakeup
events between the deepest idle state's target residency and the closest
tick.

Allow the governor to count those events by making the deepest idle
state's bin effectively end at TICK_NSEC and introducing an additional
"bin" for collecting "hit" events (ie. the ones in which the measured
idle duration falls into the same bin as the time till the closest
timer) with idle duration values past TICK_NSEC.

This way the "intercepts" metric for the deepest idle state's bin
becomes nonzero in general, and so it can influence the decision on
whether or not to stop the tick possibly increasing the governor's
accuracy in that respect.

Signed-off-by: Rafael J. Wysocki 
Tested-by: Kajetan Puchalski 
Tested-by: Anna-Maria Behnsen

cpuidle: teo: Skip tick_nohz_get_sleep_length() call in some cases

2023-08-09T17:58:46+00:00

Make teo_select() avoid calling tick_nohz_get_sleep_length() if the
candidate idle state to return is state 0 or if state 0 is a polling
one and the target residency of the current candidate one is below
a certain threshold, in which cases it may be assumed that the CPU will
be woken up immediately by a non-timer wakeup source and the timers
are not likely to matter.

Signed-off-by: Rafael J. Wysocki 
Tested-by: Kajetan Puchalski 
Tested-by: Anna-Maria Behnsen

cpuidle: teo: Do not call tick_nohz_get_sleep_length() upfront

2023-08-09T17:58:05+00:00

Because the cost of calling tick_nohz_get_sleep_length() may increase
in the future, reorder the code in teo_select() so it first uses the
statistics to pick up a candidate idle state and applies the utilization
heuristic to it and only then calls tick_nohz_get_sleep_length() to
obtain the sleep length value and refine the selection if necessary.

This change by itself does not cause tick_nohz_get_sleep_length() to
be called less often, but it prepares the code for subsequent changes
that will do so.

Signed-off-by: Rafael J. Wysocki 
Tested-by: Kajetan Puchalski 
Tested-by: Anna-Maria Behnsen

cpuidle: psci: Move enabling OSI mode after power domains creation

2023-08-08T14:07:01+00:00

A switch from OSI to PC mode is only possible if all CPUs other than the
calling one are OFF, either through a call to CPU_OFF or not yet booted.

Currently OSI mode is enabled before power domains are created. In cases
where CPUidle states are not using hierarchical CPU topology the bail out
path tries to switch back to PC mode which gets denied by firmware since
other CPUs are online at this point and creates inconsistent state as
firmware is in OSI mode and Linux in PC mode.

This change moves enabling OSI mode after power domains are created,
this would makes sure that hierarchical CPU topology is used before
switching firmware to OSI mode.

Cc: stable@vger.kernel.org
Fixes: 70c179b49870 ("cpuidle: psci: Allow PM domain to be initialized even if no OSI mode")
Signed-off-by: Maulik Shah 
Reviewed-by: Ulf Hansson 
Signed-off-by: Ulf Hansson