linux-stable.git/arch/powerpc, branch master

powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()

2026-05-14T05:45:26+00:00

A kernel panic is observed when handling machine check exceptions from
real mode.

  BUG: Unable to handle kernel data access on read at 0xc00000006be21300
  Oops: Kernel access of bad area, sig: 11 [#1]
  MSR:  8000000000001003   CR: 88222248  XER: 00000005
  CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0
  NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70
  LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150
  Call Trace:
  [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150
  [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0

The crash occurs because arch_irq_work_raise() calls preempt_disable()
from machine check exception (MCE) handlers running in real mode. In
this context, accessing the preempt_count can fault, leading to the panic.

The preempt_disable()/preempt_enable() pair in arch_irq_work_raise()
was originally added by commit 0fe1ac48bef0 ("powerpc/perf_event: Fix
oops due to perf_event_do_pending call") to avoid races while raising
irq work from exception context.

Later, commit 471ba0e686cb ("irq_work: Do not raise an IPI when
queueing work on the local CPU") added preemption protection in
irq_work_queue() path, while commit 20b876918c06 ("irq_work: Use per
cpu atomics instead of regular atomics") added equivalent
protection in irq_work_queue_on() before reaching arch_irq_work_raise():

  irq_work_queue() / irq_work_queue_on()
    -> preempt_disable()
      -> __irq_work_queue_local()
        -> irq_work_raise()
          -> arch_irq_work_raise()

As a result, callers other than mce_irq_work_raise() already execute
with preemption disabled, making the additional
preempt_disable()/preempt_enable() pair in arch_irq_work_raise()
redundant.

The arch_irq_work_raise() function executes in NMI context when called
from MCE handler. Hence we will not be preempted or scheduled out since
we are in NMI context with MSR[EE]=0. Therefore, it is safe to remove
the preempt_disable()/preempt_enable() calls from here.

Remove it to avoid accessing preempt_count from real mode context.

Fixes: cc15ff327569 ("powerpc/mce: Avoid using irq_work_queue() in realmode")
Suggested-by: Mahesh Salgaonkar 
Acked-by: Shrikanth Hegde 
Reviewed-by: Ritesh Harjani (IBM) 
Signed-off-by: Sayali Patil 
[Maddy: Fixed the commit title]
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260513081413.222490-1-sayalip@linux.ibm.com

powerpc/hv-gpci: fix preempt count leak in sysfs show paths

2026-05-12T06:21:17+00:00

Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)
(which calls preempt_disable()) but only call the matching put_cpu_var()
on the error path under the 'out:' label. Every successful read leaks
one preempt_disable():

  processor_bus_topology_show()
  processor_config_show()
  affinity_domain_via_virtual_processor_show()
  affinity_domain_via_domain_show()

(affinity_domain_via_partition_show() was already correct.)

On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and
eventually return to userspace with preemption still disabled. The
next user-mode page fault then hits faulthandler_disabled() == 1,
gets forced to SIGSEGV, and the resulting coredump trips
'BUG: scheduling while atomic' in call_usermodehelper_exec ->
wait_for_completion_state -> schedule:

  BUG: scheduling while atomic: //0x00000004
  ...
  __schedule_bug+0x6c/0x90
  __schedule+0x58c/0x13a0
  schedule+0x48/0x1a0
  schedule_timeout+0x104/0x170
  wait_for_completion_state+0x16c/0x330
  call_usermodehelper_exec+0x254/0x2d0
  vfs_coredump+0x1050/0x2590
  get_signal+0xb9c/0xc80
  do_notify_resume+0xf8/0x470

Add an out_success label that calls put_cpu_var() before returning
the byte count, mirroring affinity_domain_via_partition_show().

Fixes: 71f1c39647d8 ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor bus topology information")
Fixes: 1a160c2a13c6 ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor config information")
Fixes: 71a7ccb478fc ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via virtual processor information")
Fixes: a69a57cac1ec ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via domain information")
Signed-off-by: Aboorva Devarajan 
Reviewed-by: Ritesh Harjani (IBM) 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260508041256.3447113-1-aboorvad@linux.ibm.com

powerpc: fix dead default for GUEST_STATE_BUFFER_TEST

2026-05-12T06:20:52+00:00

The GUEST_STATE_BUFFER_TEST config option should default
to KUNIT_ALL_TESTS so that if all tests are enabled then
it is included, but currently the 'default KUNIT_ALL_TESTS'
statement is shadowed by 'def_tristate n',
meaning that this second default statement is currently dead code.

It looks to me like the commit
6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
intended to set the default to KUNIT_ALL_TESTS, but mistakenly
missed the def_tristate.

This dead code was found by kconfirm, a static analysis tool for Kconfig.

Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers")
Signed-off-by: Julian Braha 
Tested-by: Gautam Menghani 
Reviewed-by: Amit Machhiwal 
Reviewed-by: Harsh Prateek Bora 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260405161545.161006-1-julianbraha@gmail.com

powerpc/powermac: Remove pmac_low_i2c_{lock,unlock}()

2026-05-12T06:20:09+00:00

Commit a28d3af2a26c ("[PATCH] 2/5 powerpc: Rework PowerMac i2c part 2")
removed the last calls to the pmac_low_i2c_{lock,unlock}() functions.
Hence, remove these two functions.

Reviewed-by: Christophe Leroy (CS GROUP) 
Signed-off-by: Bart Van Assche 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260316174747.3871924-1-bvanassche@acm.org

powerpc/warp: Fix error handling in pika_dtm_thread

2026-05-12T06:19:30+00:00

pika_dtm_thread() acquires client through of_find_i2c_device_by_node()
but fails to release it in error handling path. This could result in a
reference count leak, preventing proper cleanup and potentially
leading to resource exhaustion. Add put_device() to release the
reference in the error handling path.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 3984114f0562 ("powerpc/warp: Platform fix for i2c change")
Signed-off-by: Ma Ke 
Reviewed-by: Christophe Leroy 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20251116024411.21968-1-make24@iscas.ac.cn

powerpc: 82xx: fix uninitialized pointers with free attribute

2026-05-12T06:18:47+00:00

Uninitialized pointers with `__free` attribute can cause undefined
behavior as the memory allocated to the pointer is freed automatically
when the pointer goes out of scope.

powerpc/km82xx doesn't have any bugs related to this as of now, but,
it is better to initialize and assign pointers with `__free` attribute
in one statement to ensure proper scope-based cleanup

Reported-by: Dan Carpenter 
Closes: https://lore.kernel.org/all/aPiG_F5EBQUjZqsl@stanley.mountain/
Signed-off-by: Ally Heev 
Fixes: 4aa5cc1e0012 ("powerpc-km82xx.c: replace of_node_put() with __free")
Reviewed-by: Christophe Leroy (CS GROUP) 
Reviewed-by: Krzysztof Kozlowski 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20251116-aheev-uninitialized-free-attr-km82xx-v2-1-4307e2b5300d@gmail.com

powerpc/g5: Enable all windfarms by default

2026-05-12T06:18:01+00:00

The G5 defconfig is clearly intended for the G5 Powermac
series, and that should enable all the available
windfarm drivers, or the machine will overheat a short
while after booting and shut itself down, which is
annoying.

Signed-off-by: Linus Walleij 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260505-powermac-g5-config-v3-1-7747bf72f874@kernel.org

powerpc/pasemi: Drop redundant res assignment

2026-05-06T02:19:19+00:00

Return value of pas_add_bridge() is not used, so code can be simplified
to fix W=1 clang warnings:

  arch/powerpc/platforms/pasemi/pci.c:275:6: error: variable 'res' set but not used [-Werror,-Wunused-but-set-variable]

Signed-off-by: Krzysztof Kozlowski 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260317130823.240279-4-krzysztof.kozlowski@oss.qualcomm.com

powerpc/ps3: Drop redundant result assignment

2026-05-06T02:19:19+00:00

Return value of ps3_start_probe_thread() is not used, so code can be
simplified to fix W=1 clang warnings:

  arch/powerpc/platforms/ps3/device-init.c:953:6: error: variable 'result' set but not used [-Werror,-Wunused-but-set-variable]

Signed-off-by: Krzysztof Kozlowski 
Reviewed-by: Geert Uytterhoeven 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260317130823.240279-3-krzysztof.kozlowski@oss.qualcomm.com

powerpc/vdso: Drop -DCC_USING_PATCHABLE_FUNCTION_ENTRY from 32-bit flags with clang

2026-05-06T02:15:59+00:00

After commit 73cdf24e81e4 ("powerpc64: make clang cross-build
friendly"), building 64-bit little endian + CONFIG_COMPAT=y with clang
results in many warnings along the lines of:

  $ cat arch/powerpc/configs/compat.config
  CONFIG_COMPAT=y

  $ make -skj"$(nproc)" ARCH=powerpc LLVM=1 ppc64le_defconfig compat.config arch/powerpc/kernel/vdso/
  ...
  In file included from :4:
  In file included from lib/vdso/gettimeofday.c:6:
  In file included from include/vdso/datapage.h:15:
  In file included from include/vdso/cache.h:5:
  arch/powerpc/include/asm/cache.h:77:8: warning: unknown attribute 'patchable_function_entry' ignored [-Wunknown-attributes]
     77 | static inline u32 l1_icache_bytes(void)
        |        ^~~~~~
  include/linux/compiler_types.h:235:58: note: expanded from macro 'inline'
    235 | #define inline inline __gnu_inline __inline_maybe_unused notrace
        |                                                          ^~~~~~~
  include/linux/compiler_types.h:215:34: note: expanded from macro 'notrace'
    215 | #define notrace                 __attribute__((patchable_function_entry(0, 0)))
        |                                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ...

arch/powerpc/Makefile adds -DCC_USING_PATCHABLE_FUNCTION_ENTRY to
KBUILD_CPPFLAGS, which is inherited by the 32-bit vDSO. However, the
32-bit little endian target does not support
'-fpatchable-function-entry', resulting in the warnings above.

Remove -DCC_USING_PATCHABLE_FUNCTION_ENTRY from the 32-bit vDSO flags
when building with clang to avoid the warnings.

Fixes: 73cdf24e81e4 ("powerpc64: make clang cross-build friendly")
Signed-off-by: Nathan Chancellor 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260311-ppc-vdso-drop-cc-using-pfe-define-clang-v1-1-66c790e22650@kernel.org