linux.git/arch/powerpc/kernel/smp.c, branch v5.4.211

powerpc: handle kdump appropriately with crash_kexec_post_notifiers option

2022-01-27T08:19:48+00:00

[ Upstream commit 219572d2fc4135b5ce65c735d881787d48b10e71 ]

Kdump can be triggered after panic_notifers since commit f06e5153f4ae2
("kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump
after panic_notifers") introduced crash_kexec_post_notifiers option.
But using this option would mean smp_send_stop(), that marks all other
CPUs as offline, gets called before kdump is triggered. As a result,
kdump routines fail to save other CPUs' registers. To fix this, kdump
friendly crash_smp_send_stop() function was introduced with kernel
commit 0ee59413c967 ("x86/panic: replace smp_send_stop() with kdump
friendly version in panic path"). Override this kdump friendly weak
function to handle crash_kexec_post_notifiers option appropriately
on powerpc.

Reported-by: kernel test robot 
Signed-off-by: Hari Bathini 
[Fixed signature of crash_stop_this_cpu() - reported by lkp@intel.com]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211207103719.91117-1-hbathini@linux.ibm.com
Signed-off-by: Sasha Levin

powerpc/smp: Move setup_profiling_timer() under CONFIG_PROFILING

2022-01-27T08:19:47+00:00

[ Upstream commit a4ac0d249a5db80e79d573db9e4ad29354b643a8 ]

setup_profiling_timer() is only needed when CONFIG_PROFILING is enabled.

Fixes the following W=1 warning when CONFIG_PROFILING=n:
  linux/arch/powerpc/kernel/smp.c:1638:5: error: no previous prototype for ‘setup_profiling_timer’

Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211124093254.1054750-5-mpe@ellerman.id.au
Signed-off-by: Sasha Levin

powerpc: Offline CPU in stop_this_cpu()

2021-07-14T14:53:47+00:00

[ Upstream commit bab26238bbd44d5a4687c0a64fd2c7f2755ea937 ]

printk_safe_flush_on_panic() has special lock breaking code for the case
where we panic()ed with the console lock held. It relies on panic IPI
causing other CPUs to mark themselves offline.

Do as most other architectures do.

This effectively reverts commit de6e5d38417e ("powerpc: smp_send_stop do
not offline stopped CPUs"), unfortunately it may result in some false
positive warnings, but the alternative is more situations where we can
crash without getting messages out.

Fixes: de6e5d38417e ("powerpc: smp_send_stop do not offline stopped CPUs")
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210623041245.865134-1-npiggin@gmail.com
Signed-off-by: Sasha Levin

powerpc/smp: Set numa node before updating mask

2021-05-19T08:08:23+00:00

[ Upstream commit 6980d13f0dd189846887bbbfa43793d9a41768d3 ]

Geethika reported a trace when doing a dlpar CPU add.

------------[ cut here ]------------
WARNING: CPU: 152 PID: 1134 at kernel/sched/topology.c:2057
CPU: 152 PID: 1134 Comm: kworker/152:1 Not tainted 5.12.0-rc5-master #5
Workqueue: events cpuset_hotplug_workfn
NIP:  c0000000001cfc14 LR: c0000000001cfc10 CTR: c0000000007e3420
REGS: c0000034a08eb260 TRAP: 0700   Not tainted  (5.12.0-rc5-master+)
MSR:  8000000000029033   CR: 28828422  XER: 00000020
CFAR: c0000000001fd888 IRQMASK: 0 #012GPR00: c0000000001cfc10
c0000034a08eb500 c000000001f35400 0000000000000027 #012GPR04:
c0000035abaa8010 c0000035abb30a00 0000000000000027 c0000035abaa8018
#012GPR08: 0000000000000023 c0000035abaaef48 00000035aa540000
c0000035a49dffe8 #012GPR12: 0000000028828424 c0000035bf1a1c80
0000000000000497 0000000000000004 #012GPR16: c00000000347a258
0000000000000140 c00000000203d468 c000000001a1a490 #012GPR20:
c000000001f9c160 c0000034adf70920 c0000034aec9fd20 0000000100087bd3
#012GPR24: 0000000100087bd3 c0000035b3de09f8 0000000000000030
c0000035b3de09f8 #012GPR28: 0000000000000028 c00000000347a280
c0000034aefe0b00 c0000000010a2a68
NIP [c0000000001cfc14] build_sched_domains+0x6a4/0x1500
LR [c0000000001cfc10] build_sched_domains+0x6a0/0x1500
Call Trace:
[c0000034a08eb500] [c0000000001cfc10] build_sched_domains+0x6a0/0x1500 (unreliable)
[c0000034a08eb640] [c0000000001d1e6c] partition_sched_domains_locked+0x3ec/0x530
[c0000034a08eb6e0] [c0000000002936d4] rebuild_sched_domains_locked+0x524/0xbf0
[c0000034a08eb7e0] [c000000000296bb0] rebuild_sched_domains+0x40/0x70
[c0000034a08eb810] [c000000000296e74] cpuset_hotplug_workfn+0x294/0xe20
[c0000034a08ebc30] [c000000000178dd0] process_one_work+0x300/0x670
[c0000034a08ebd10] [c0000000001791b8] worker_thread+0x78/0x520
[c0000034a08ebda0] [c000000000185090] kthread+0x1a0/0x1b0
[c0000034a08ebe10] [c00000000000ccec] ret_from_kernel_thread+0x5c/0x70
Instruction dump:
7d2903a6 4e800421 e8410018 7f67db78 7fe6fb78 7f45d378 7f84e378 7c681b78
3c62ff1a 3863c6f8 4802dc35 60000000 <0fe00000> 3920fff4 f9210070 e86100a0
---[ end trace 532d9066d3d4d7ec ]---

Some of the per-CPU masks use cpu_cpu_mask as a filter to limit the search
for related CPUs. On a dlpar add of a CPU, update cpu_cpu_mask before
updating the per-CPU masks. This will ensure the cpu_cpu_mask is updated
correctly before its used in setting the masks. Setting the numa_node will
ensure that when cpu_cpu_mask() gets called, the correct node number is
used. This code movement helped fix the above call trace.

Reported-by: Geetika Moolchandani 
Signed-off-by: Srikar Dronamraju 
Reviewed-by: Nathan Lynch 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210401154200.150077-1-srikar@linux.vnet.ibm.com
Signed-off-by: Sasha Levin

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

powerpc: 'current_set' is now a table of task_struct pointers

2019-02-23T11:31:40+00:00

The table of pointers 'current_set' has been used for retrieving
the stack and current. They used to be thread_info pointers as
they were pointing to the stack and current was taken from the
'task' field of the thread_info.

Now, the pointers of 'current_set' table are now both pointers
to task_struct and pointers to thread_info.

As they are used to get current, and the stack pointer is
retrieved from current's stack field, this patch changes
their type to task_struct, and renames secondary_ti to
secondary_current.

Reviewed-by: Nicholas Piggin 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman

powerpc: Activate CONFIG_THREAD_INFO_IN_TASK

2019-02-23T11:31:40+00:00

This patch activates CONFIG_THREAD_INFO_IN_TASK which
moves the thread_info into task_struct.

Moving thread_info into task_struct has the following advantages:
  - It protects thread_info from corruption in the case of stack
    overflows.
  - Its address is harder to determine if stack addresses are leaked,
    making a number of attacks more difficult.

This has the following consequences:
  - thread_info is now located at the beginning of task_struct.
  - The 'cpu' field is now in task_struct, and only exists when
    CONFIG_SMP is active.
  - thread_info doesn't have anymore the 'task' field.

This patch:
  - Removes all recopy of thread_info struct when the stack changes.
  - Changes the CURRENT_THREAD_INFO() macro to point to current.
  - Selects CONFIG_THREAD_INFO_IN_TASK.
  - Modifies raw_smp_processor_id() to get ->cpu from current without
    including linux/sched.h to avoid circular inclusion and without
    including asm/asm-offsets.h to avoid symbol names duplication
    between ASM constants and C constants.
  - Modifies klp_init_thread_info() to take a task_struct pointer
    argument.

Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
[mpe: Add task_stack.h to livepatch.h to fix build fails]
Signed-off-by: Michael Ellerman

powerpc/64: Use task_stack_page() to initialise paca->kstack

2019-02-23T11:31:40+00:00

Rather than using the thread info use task_stack_page() to initialise
paca->kstack, that way it will work with THREAD_INFO_IN_TASK.

Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman

powerpc/smp: Make __smp_send_nmi_ipi() static

2019-02-21T13:10:15+00:00

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman

powerpc/smp: Fix NMI IPI xmon timeout

2019-02-21T13:10:15+00:00

The xmon debugger IPI handler waits in the callback function while
xmon is still active. This means they don't complete the IPI, and the
initiator always times out waiting for them.

Things manage to work after the timeout because there is some fallback
logic to keep NMI IPI state sane in case of the timeout, but this is a
bit ugly.

This patch changes NMI IPI back to half-asynchronous (i.e., wait for
everyone to call in, do not wait for IPI function to complete), but
the complexity is avoided by going one step further and allowing new
IPIs to be issued before the IPI functions to all complete.

If synchronization against that is required, it is left up to the
caller, but current callers don't require that. In fact with the
timeout handling, callers must be able to cope with this already.

Fixes: 5b73151fff63 ("powerpc: NMI IPI make NMI IPIs fully sychronous")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman