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linux/arch/powerpc/kernel
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Shreyas B. Prabhu b32aadc1a8 powerpc/powernv: Fix race in updating core_idle_state 
core_idle_state is maintained for each core. It uses 0-7 bits to track
whether a thread in the core has entered fastsleep or winkle. 8th bit is
used as a lock bit.
The lock bit is set in these 2 scenarios-
 - The thread is first in subcore to wakeup from sleep/winkle.
 - If its the last thread in the core about to enter sleep/winkle

While the lock bit is set, if any other thread in the core wakes up, it
loops until the lock bit is cleared before proceeding in the wakeup
path. This helps prevent race conditions w.r.t fastsleep workaround and
prevents threads from switching to process context before core/subcore
resources are restored.

But, in the path to sleep/winkle entry, we currently don't check for
lock-bit. This exposes us to following race when running with subcore
on-

First thread in the subcorea		Another thread in the same
waking up		   		core entering sleep/winkle

lwarx   r15,0,r14
ori     r15,r15,PNV_CORE_IDLE_LOCK_BIT
stwcx.  r15,0,r14
[Code to restore subcore state]

						lwarx   r15,0,r14
						[clear thread bit]
						stwcx.  r15,0,r14

andi.   r15,r15,PNV_CORE_IDLE_THREAD_BITS
stw     r15,0(r14)

Here, after the thread entering sleep clears its thread bit in
core_idle_state, the value is overwritten by the thread waking up.
In such cases when the core enters fastsleep, code mistakes an idle
thread as running. Because of this, the first thread waking up from
fastsleep which is supposed to resync timebase skips it. So we can
end up having a core with stale timebase value.

This patch fixes the above race by looping on the lock bit even while
entering the idle states.

Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Fixes: 7b54e9f213f76 'powernv/powerpc: Add winkle support for offline cpus'
Cc: stable@vger.kernel.org # 3.19+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2015-07-07 10:16:52 +10:00
..
vdso32 powerpc: 32 bit getcpu VDSO function uses 64 bit instructions 2014-11-27 09:42:12 +11:00
vdso64
.gitignore
align.c powerpc: Remove double braces in alignment code. 2014-11-10 09:59:32 +11:00
asm-offsets.c powerpc/kernel: Rename PACA_DSCR to PACA_DSCR_DEFAULT 2015-06-07 19:29:00 +10:00
audit.c
btext.c
cacheinfo.c powerpc: Fix missing L2 cache size in /sys/devices/system/cpu 2015-04-11 20:49:28 +10:00
cacheinfo.h
compat_audit.c
cpu_setup_6xx.S
cpu_setup_44x.S
cpu_setup_fsl_booke.S powerpc/booke: Restrict SPE exception handlers to e200/e500 cores 2014-09-22 10:11:31 +02:00
cpu_setup_pa6t.S
cpu_setup_power.S powerpc/book3s: Fix flush_tlb cpu_spec hook to take a generic argument. 2015-03-17 07:52:48 +11:00
cpu_setup_ppc970.S
cputable.c powerpc/tm: Abort syscalls in active transactions 2015-06-19 17:10:28 +10:00
crash_dump.c powerpc: Remove superfluous bootmem includes 2014-11-10 09:59:26 +11:00
crash.c
dbell.c powerpc/powernv: Fixes for hypervisor doorbell handling 2015-03-20 14:51:53 +11:00
dma-iommu.c powerpc/iommu: Rename iommu_[un]map_sg functions 2014-11-18 11:30:01 +01:00
dma-swiotlb.c powerpc: fsl_pci, swiotlb: Move controller ops from ppc_md to controller_ops 2015-04-11 20:49:17 +10:00
dma.c powerpc/pci: add dma_set_mask to pci_controller_ops 2015-06-02 13:18:49 +10:00
eeh_cache.c powerpc/eeh: fix start/end/flags type in struct pci_io_addr_range{} 2015-05-13 14:00:07 +10:00
eeh_dev.c powerpc/eeh: Create eeh_dev from pci_dn instead of device_node 2015-03-24 13:15:51 +11:00
eeh_driver.c powerpc/eeh: fix comment for wait_state() 2015-05-13 14:00:07 +10:00
eeh_event.c powerpc/powernv: Fix killed EEH event 2014-06-11 17:04:33 +10:00
eeh_pe.c powerpc/eeh: Fix PE#0 check in eeh_add_to_parent_pe() 2015-03-31 13:10:39 +11:00
eeh_sysfs.c powerpc/eeh: Fix PE state format 2014-11-27 09:32:58 +11:00
eeh.c powerpc/eeh/ioda2: Use device::iommu_group to check IOMMU group 2015-06-11 15:14:54 +10:00
entry_32.S powerpc: Remove old compile time disabled syscall tracing code 2015-02-02 14:51:32 +11:00
entry_64.S powerpc/tm: Abort syscalls in active transactions 2015-06-19 17:10:28 +10:00
epapr_hcalls.S
epapr_paravirt.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-06-10 18:54:22 -07:00
exceptions-64e.S powerpc/booke: Revert SPE/AltiVec common defines for interrupt numbers 2014-09-22 10:11:31 +02:00
exceptions-64s.S powerpc: Non relocatable system call doesn't need a trampoline 2015-06-02 13:26:47 +10:00
fadump.c powerpc/fadump: Fix endianess issues in firmware assisted dump handling 2014-10-30 16:52:46 +11:00
firmware.c
fpu.S
fsl_booke_entry_mapping.S
ftrace.c powerpc updates for 3.19 2014-12-11 17:48:14 -08:00
head_8xx.S powerpc/8xx: Implementation of PAGE_EXEC 2015-06-02 21:37:28 -05:00
head_32.S
head_40x.S powerpc: Remove check for CONFIG_SERIAL_TEXT_DEBUG 2014-06-11 16:31:21 +10:00
head_44x.S powerpc/ppc476: Disable BTAC 2014-08-13 15:13:42 +10:00
head_64.S Merge remote-tracking branch 'scott/next' into next 2014-08-05 14:13:41 +10:00
head_booke.h
head_fsl_booke.S powerpc/booke: Revert SPE/AltiVec common defines for interrupt numbers 2014-09-22 10:11:31 +02:00
hw_breakpoint.c powerpc: Replace __get_cpu_var uses 2014-11-03 12:12:32 +11:00
ibmebus.c powerpc: make of_device_ids const 2014-09-25 23:14:46 +10:00
idle_6xx.S
idle_book3e.S
idle_e500.S powerpc/e500mc: Remove dead L2 flushing code in idle_e500.S 2015-06-02 21:37:19 -05:00
idle_power4.S
idle_power7.S powerpc/powernv: Fix race in updating core_idle_state 2015-07-07 10:16:52 +10:00
idle.c
io-workarounds.c powerpc/mm/thp: Make page table walk safe against thp split/collapse 2015-04-17 11:23:39 +10:00
io.c
iomap.c powerpc/kerenl: Enable EEH for IO accessors 2014-06-24 12:43:13 +10:00
iommu.c powerpc/iommu/powernv: Release replaced TCE 2015-06-11 15:16:49 +10:00
irq.c powerpc: Remove superfluous bootmem includes 2014-11-10 09:59:26 +11:00
isa-bridge.c
jump_label.c
kgdb.c powerpc: Replace __get_cpu_var uses 2014-11-03 12:12:32 +11:00
kprobes.c powerpc: Replace __get_cpu_var uses 2014-11-03 12:12:32 +11:00
kvm_emul.S
kvm.c At over 200 commits, covering almost all supported architectures, this 2014-06-04 08:47:12 -07:00
l2cr_6xx.S
legacy_serial.c powerpc: make of_device_ids const 2014-09-25 23:14:46 +10:00
machine_kexec_32.c
machine_kexec_64.c kexec: add IND_FLAGS macro 2015-02-17 14:34:51 -08:00
machine_kexec.c
Makefile Devicetree changes for v4.2 2015-07-01 19:40:18 -07:00
mce_power.c powerpc/book3s: Fix flush_tlb cpu_spec hook to take a generic argument. 2015-03-17 07:52:48 +11:00
mce.c powerpc/mce: fix off by one errors in mce event handling 2015-05-12 19:44:01 +10:00
misc_32.S
misc_64.S
misc.S powerpc: Rename __get_SP() to current_stack_pointer() 2014-10-15 11:23:20 +11:00
module_32.c powerpc: Use pr_fmt in module loader code 2014-10-02 17:33:54 +10:00
module_64.c powerpc: Use pr_fmt in module loader code 2014-10-02 17:33:54 +10:00
module.c
msi.c powerpc: Remove MSI-related PCI controller ops from ppc_md 2015-06-02 11:47:45 +10:00
nvram_64.c powerpc/rtas: Make timestamp related code y2038-safe 2015-03-23 14:06:11 +11:00
of_platform.c powerpc/eeh: Do probe on pci_dn 2015-03-24 13:15:52 +11:00
paca.c powerpc/kernel: Avoid memory corruption at early stage 2015-01-23 14:02:52 +11:00
pci_32.c powerpc: Remove more traces of bootmem 2014-11-19 21:41:51 +11:00
pci_64.c powerpc updates for 3.19 2014-12-11 17:48:14 -08:00
pci_dn.c powerpc/powernv: Shift VF resource with an offset 2015-03-31 13:02:38 +11:00
pci_of_scan.c powerpc: Remove shims for pci_controller_ops operations 2015-04-11 20:49:18 +10:00
pci-common.c powerpc/pci: Add pcibios_disable_device() hook 2015-06-03 13:27:16 +10:00
pci-hotplug.c powerpc/pci: Add release_device() hook to phb ops 2015-06-03 13:27:15 +10:00
pmc.c
ppc32.h
ppc_ksyms_32.c powerpc: Separate ppc32 symbol exports into ppc_ksyms_32.c 2014-09-25 23:14:40 +10:00
ppc_ksyms.c powerpc: Rename __get_SP() to current_stack_pointer() 2014-10-15 11:23:20 +11:00
ppc_save_regs.S
proc_powerpc.c
process.c powerpc/kernel: Remove the unused extern dscr_default 2015-06-07 19:27:26 +10:00
prom_init_check.sh powerpc: Simplify symbol check in prom_init_check.sh 2014-09-25 23:14:46 +10:00
prom_init.c PCI: Remove unnecessary #includes of <asm/pci.h> 2015-06-08 07:56:09 -05:00
prom_parse.c
prom.c arm64 updates for 4.2, mostly refactoring/clean-up: 2015-06-24 10:02:15 -07:00
ptrace32.c
ptrace.c Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
reloc_32.S
reloc_64.S
rtas_flash.c powerpc: Fix endianness of flash_block_list in rtas_flash 2014-07-28 11:30:54 +10:00
rtas_pci.c powerpc: move find_and_init_phbs() to pSeries specific code 2015-04-11 20:49:09 +10:00
rtas-proc.c powerpc: LLVM complains about forward declaration of struct rtas_sensors 2014-11-10 09:59:32 +11:00
rtas-rtc.c
rtas.c powerpc: Replace mem_init_done with slab_is_available() 2015-04-10 20:02:48 +10:00
rtasd.c powerpc: Make a bunch of things static 2014-09-25 23:14:41 +10:00
setup_32.c powerpc: Remove unused vgacon_remap_base & fix build break 2014-11-10 09:59:31 +11:00
setup_64.c powerpc/mmu: Add userspace-to-physical addresses translation cache 2015-06-11 15:16:54 +10:00
setup-common.c powerpc: Convert power off logic to pm_power_off 2014-11-03 12:12:51 +11:00
signal_32.c all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
signal_64.c all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
signal.c powerpc: Use sigsp() 2014-08-06 13:04:32 +02:00
signal.h powerpc: Use get_signal() signal_setup_done() 2014-08-06 13:03:09 +02:00
smp-tbsync.c
smp.c powerpc/smp: Wait until secondaries are active & online 2015-03-04 13:19:33 +11:00
stacktrace.c powerpc: Rename __get_SP() to current_stack_pointer() 2014-10-15 11:23:20 +11:00
suspend.c nosave: consolidate __nosave_{begin,end} in <asm/sections.h> 2014-10-09 22:26:04 -04:00
swsusp_32.S
swsusp_64.c
swsusp_asm64.S
swsusp_booke.S
swsusp.c
sys_ppc32.c
syscalls.c powerpc: Add a proper syscall for switching endianness 2015-03-28 22:03:40 +11:00
sysfs.c powerpc/dscr: Add some in-code documentation 2015-06-07 19:29:15 +10:00
systbl_chk.c powerpc: Add a proper syscall for switching endianness 2015-03-28 22:03:40 +11:00
systbl_chk.sh
systbl.S powerpc: Add a proper syscall for switching endianness 2015-03-28 22:03:40 +11:00
tau_6xx.c
time.c powerpc: use device_initcall for registering rtc devices 2015-06-16 14:12:29 -04:00
tm.S powerpc/kernel: Rename PACA_DSCR to PACA_DSCR_DEFAULT 2015-06-07 19:29:00 +10:00
traps.c powerpc: Set the correct kernel taint on machine check errors. 2015-07-06 20:24:35 +10:00
udbg_16550.c powerpc: Fix bad NULL pointer check in udbg_uart_getc_poll() 2014-11-12 13:47:20 +11:00
udbg.c powerpc: Remove the celleb support 2015-04-07 17:15:13 +10:00
uprobes.c
vdso.c powerpc/vdso: Disable building the 32-bit VDSO on little endian 2015-05-11 20:01:02 +10:00
vecemu.c
vector.S powerpc: Change vrX register defines to vX to match gcc and glibc 2015-03-16 18:32:11 +11:00
vio.c powerpc: use for_each_sg() 2015-06-24 17:49:38 -07:00
vmlinux.lds.S powerpc: Align TOC to 256 bytes 2015-05-14 16:59:21 +10:00