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75395690e5
linux/arch/powerpc/kernel
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Michael Ellerman 75395690e5 powerpc/stacktrace: Fix spurious "stale" traces in raise_backtrace_ipi() 
commit 7c6986ade6 upstream.

In raise_backtrace_ipi() we iterate through the cpumask of CPUs, sending
each an IPI asking them to do a backtrace, but we don't wait for the
backtrace to happen.

We then iterate through the CPU mask again, and if any CPU hasn't done
the backtrace and cleared itself from the mask, we print a trace on its
behalf, noting that the trace may be "stale".

This works well enough when a CPU is not responding, because in that
case it doesn't receive the IPI and the sending CPU is left to print the
trace. But when all CPUs are responding we are left with a race between
the sending and receiving CPUs, if the sending CPU wins the race then it
will erroneously print a trace.

This leads to spurious "stale" traces from the sending CPU, which can
then be interleaved messily with the receiving CPU, note the CPU
numbers, eg:

  [ 1658.929157][    C7] rcu: Stack dump where RCU GP kthread last ran:
  [ 1658.929223][    C7] Sending NMI from CPU 7 to CPUs 1:
  [ 1658.929303][    C1] NMI backtrace for cpu 1
  [ 1658.929303][    C7] CPU 1 didn't respond to backtrace IPI, inspecting paca.
  [ 1658.929362][    C1] CPU: 1 PID: 325 Comm: kworker/1:1H Tainted: G        W   E     5.13.0-rc2+ #46
  [ 1658.929405][    C7] irq_soft_mask: 0x01 in_mce: 0 in_nmi: 0 current: 325 (kworker/1:1H)
  [ 1658.929465][    C1] Workqueue: events_highpri test_work_fn [test_lockup]
  [ 1658.929549][    C7] Back trace of paca->saved_r1 (0xc0000000057fb400) (possibly stale):
  [ 1658.929592][    C1] NIP:  c00000000002cf50 LR: c008000000820178 CTR: c00000000002cfa0

To fix it, change the logic so that the sending CPU waits 5s for the
receiving CPU to print its trace. If the receiving CPU prints its trace
successfully then the sending CPU just continues, avoiding any spurious
"stale" trace.

This has the added benefit of allowing all CPUs to print their traces in
order and avoids any interleaving of their output.

Fixes: 5cc05910f2 ("powerpc/64s: Wire up arch_trigger_cpumask_backtrace()")
Cc: stable@vger.kernel.org # v4.18+
Reported-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210625140408.3351173-1-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-14 16:55:46 +02:00
..
ptrace powerpc/watchpoint/ptrace: Introduce PPC_DEBUG_FEATURE_DATA_BP_ARCH_31 2020-09-15 22:13:20 +10:00
syscalls mm/madvise: introduce process_madvise() syscall: an external memory hinting API 2020-10-18 09:27:10 -07:00
trace powerpc: Add a ppc_inst_as_str() helper 2020-07-23 17:41:36 +10:00
vdso32 Kbuild updates for v5.10 2020-10-22 13:13:57 -07:00
vdso64 powerpc/64/signal: Fix regression in __kernel_sigtramp_rt64() semantics 2021-02-13 13:55:02 +01:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
align.c powerpc: Use fallthrough pseudo-keyword 2020-07-29 21:09:37 +10:00
asm-offsets.c powerpc/64: Fix stack trace not displaying final frame 2021-03-17 17:06:24 +01:00
audit.c
btext.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
cacheinfo.c powerpc/cacheinfo: Warn if cache object chain becomes unordered 2020-07-30 22:53:48 +10:00
cacheinfo.h powerpc/cacheinfo: add cacheinfo_teardown, cacheinfo_rebuild 2019-06-15 16:52:06 +10:00
compat_audit.c
cpu_setup_6xx.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
cpu_setup_44x.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
cpu_setup_fsl_booke.S powerpc/booke: Spelling s/date/data/ 2019-11-17 01:56:31 -06:00
cpu_setup_pa6t.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
cpu_setup_power.S powerpc/perf: Initialize power10 PMU registers in cpu setup routine 2020-07-26 23:34:23 +10:00
cpu_setup_ppc970.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
cputable.c powerpc/64s: Remove TM from Power10 features 2020-10-20 23:33:51 +11:00
crash_dump.c powerpc: Add prefixed instructions to instruction data type 2020-05-19 00:10:39 +10:00
dawr.c powerpc/watchpoint: Guest support for 2nd DAWR hcall 2020-07-26 23:34:19 +10:00
dbell.c powerpc: Inline doorbell sending functions 2020-07-29 21:02:09 +10:00
dma-iommu.c dma-mapping: add a new dma_alloc_pages API 2020-09-25 06:20:47 +02:00
dma-mask.c dma-mapping, powerpc: simplify the arch dma_set_mask override 2019-02-18 22:41:03 +11:00
dma-swiotlb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
dt_cpu_ftrs.c powerpc: untangle cputable mce include 2020-10-06 23:22:22 +11:00
early_32.c powerpc/fsl_booke/32: implement KASLR infrastructure 2019-11-13 19:27:40 +11:00
eeh_cache.c powerpc/eeh_cache: Fix a possible debugfs deadlock 2020-11-02 12:54:20 +11:00
eeh_driver.c pci-v5.9-changes 2020-08-07 18:48:15 -07:00
eeh_event.c powerpc/eeh: Fix build with STACKTRACE=n 2019-09-14 00:01:14 +10:00
eeh_pe.c powerpc/eeh: Delete eeh_pe->config_addr 2020-10-07 22:34:47 +11:00
eeh_sysfs.c powerpc/eeh: Pass eeh_dev to eeh_ops->resume_notify() 2020-07-26 23:34:20 +10:00
eeh.c powerpc/eeh: Fix EEH handling for hugepages in ioremap space. 2021-05-11 14:47:35 +02:00
entry_32.S powerpc/32s: Add missing call to kuep_lock on syscall entry 2021-03-04 11:38:40 +01:00
entry_64.S powerpc/64s: fix scv entry fallback flush vs interrupt 2021-01-27 11:55:12 +01:00
epapr_hcalls.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
epapr_paravirt.c powerpc: Use a datatype for instructions 2020-05-19 00:10:37 +10:00
exceptions-64e.S powerpc/64e: remove 64s specific interrupt soft-mask code 2020-10-06 23:22:23 +11:00
exceptions-64s.S powerpc/64s/exception: Clean up a missed SRR specifier 2021-03-17 17:06:34 +01:00
fadump.c powerpc/fadump: Mark fadump_calculate_reserve_size as __init 2021-05-14 09:50:30 +02:00
firmware.c powerpc/pseries: Add KVM guest doorbell restrictions 2020-07-29 21:02:10 +10:00
fpu.S powerpc: Drop SYNC_601() ISYNC_601() and SYNC() 2020-10-08 21:17:13 +11:00
fsl_booke_entry_mapping.S powerpc/fsl_booke/32: implement KASLR infrastructure 2019-11-13 19:27:40 +11:00
head_8xx.S powerpc/8xx: Fix software emulation interrupt 2021-03-04 11:38:05 +01:00
head_32.h powerpc/32: Statically initialise first emergency context 2021-05-19 10:12:54 +02:00
head_40x.S powerpc/40x: Always fault when _PAGE_ACCESSED is not set 2020-11-05 23:34:16 +11:00
head_44x.S mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
head_64.S powerpc/64: Fix an EMIT_BUG_ENTRY in head_64.S 2020-12-30 11:53:32 +01:00
head_book3s_32.S powerpc/603: Fix protection of user pages mapped with PROT_NONE 2021-03-17 17:06:13 +01:00
head_booke.h powerpc: Remove SYNC on non 6xx 2020-10-08 21:17:12 +11:00
head_fsl_booke.S mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
hw_breakpoint_constraints.c powerpc/watchpoint: Move DAWR detection logic outside of hw_breakpoint.c 2020-09-15 22:13:19 +10:00
hw_breakpoint.c powerpc/watchpoint: Move DAWR detection logic outside of hw_breakpoint.c 2020-09-15 22:13:19 +10:00
idle_6xx.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
idle_book3e.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
idle_book3s.S powerpc/64s: Reimplement power4_idle code in C 2020-01-16 14:59:37 +10:00
idle_e500.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
idle.c sched/idle: Fix arch_cpu_idle() vs tracing 2020-11-24 16:47:35 +01:00
ima_arch.c powerpc/ima: Fix secure boot rules in ima arch policy 2020-05-07 17:25:54 +10:00
io-workarounds.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
io.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
iomap.c iomap: constify ioreadX() iomem argument (as in generic implementation) 2020-08-14 19:56:57 -07:00
iommu.c powerpc/iommu: Annotate nested lock for lockdep 2021-05-19 10:12:58 +02:00
irq.c powerpc/kuap: Restore AMR after replaying soft interrupts 2021-03-04 11:38:06 +01:00
isa-bridge.c powerpc: remove __ioremap_at and __iounmap_at 2020-06-02 10:59:10 -07:00
jump_label.c powerpc: Use a datatype for instructions 2020-05-19 00:10:37 +10:00
kgdb.c maccess: make get_kernel_nofault() check for minimal type compatibility 2020-06-18 12:10:37 -07:00
kprobes-ftrace.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
kprobes.c powerpc/kprobes: Fix validation of prefixed instructions across page boundary 2021-06-10 13:39:27 +02:00
kvm_emul.S powerpc/kvm: Add ifdefs around template code 2019-09-14 00:04:40 +10:00
kvm.c powerpc/kvm: Explicitly mark kvm guest code as __init 2019-09-14 00:04:40 +10:00
l2cr_6xx.S powerpc: Drop SYNC_601() ISYNC_601() and SYNC() 2020-10-08 21:17:13 +11:00
legacy_serial.c tty/serial: Migrate 8250_fsl to use has_sysrq 2019-12-18 15:04:42 +01:00
Makefile powerpc: Avoid broken GCC __attribute__((optimize)) 2020-12-30 11:53:15 +01:00
mce_power.c powerpc/powernv: Machine check handler for POWER10 2020-07-23 17:43:30 +10:00
mce.c powerpc/mce: Avoid nmi_enter/exit in real mode on pseries hash 2020-10-16 20:13:55 +11:00
misc_32.S powerpc: Rewrite FSL_BOOKE flush_cache_instruction() in C 2020-09-02 11:00:21 +10:00
misc_64.S powerpc: Remove SYNC on non 6xx 2020-10-08 21:17:12 +11:00
misc.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
module_32.c powerpc: module_[32|64].c: replace swap function with built-in one 2020-05-11 23:15:14 +10:00
module_64.c maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17 10:57:41 -07:00
module.c powerpc: Use MODULES_VADDR if defined 2020-07-27 00:01:30 +10:00
msi.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
note.S powerpc: Add PowerPC Capabilities ELF note 2019-08-30 09:40:15 +10:00
nvram_64.c powerpc updates for 5.8 2020-06-05 12:39:30 -07:00
of_platform.c powerpc/eeh: Remove eeh_dev_phb_init_dynamic() 2020-07-26 23:34:19 +10:00
optprobes_head.S powerpc: Add prefixed instructions to instruction data type 2020-05-19 00:10:39 +10:00
optprobes.c powerpc: Add ppc_inst_as_u64() 2020-05-26 23:36:57 +10:00
paca.c powerpc: Avoid broken GCC __attribute__((optimize)) 2020-12-30 11:53:15 +01:00
pci_32.c powerpc/64: Adjust order in pcibios_init() 2019-08-22 23:11:48 +10:00
pci_64.c powerpc updates for 5.8 2020-06-05 12:39:30 -07:00
pci_dn.c powerpc/eeh: Rename eeh_{add_to|remove_from}_parent_pe() 2020-07-26 23:34:21 +10:00
pci_of_scan.c powerpc/pci: Remove pcibios_setup_bus_devices() 2020-01-06 16:25:29 +11:00
pci-common.c powerpc/pci: Add ppc_md.discover_phbs() 2021-03-17 17:06:23 +01:00
pci-hotplug.c powerpc/eeh: Release EEH device state synchronously 2020-05-18 21:58:44 +10:00
pmc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ppc_save_regs.S powerpc: Improve ppc_save_regs() 2020-04-04 21:40:57 +11:00
ppc32.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
proc_powerpc.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
process.c powerpc/64: Fix stack trace not displaying final frame 2021-03-17 17:06:24 +01:00
prom_init_check.sh powerpc/prom_init: Undo relocation before entering secure mode 2019-10-29 15:12:17 +11:00
prom_init.c powerpc/prom: Fix "ibm,arch-vec-5-platform-support" scan 2021-03-04 11:38:35 +01:00
prom_parse.c
prom.c powerpc/prom: Mark identical_pvr_fixup as __init 2021-05-14 09:50:30 +02:00
reloc_32.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
reloc_64.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
rtas_flash.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
rtas_pci.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
rtas-proc.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
rtas-rtc.c
rtas.c powerpc/rtas: Fix typo of ibm,open-errinjct in RTAS filter 2020-12-30 11:54:15 +01:00
rtasd.c powerpc/rtasd: simplify handle_rtas_event(), emit message on events 2020-07-16 13:12:38 +10:00
secure_boot.c powerpc/pseries: Detect secure and trusted boot state of the system. 2020-07-16 14:49:53 +10:00
security.c powerpc/security: Fix link stack flush instruction 2020-10-08 12:50:52 +11:00
secvar-ops.c powerpc/powernv: Add OPAL API interface to access secure variable 2019-11-13 00:33:22 +11:00
secvar-sysfs.c powerpc: expose secure variables to userspace via sysfs 2019-11-13 00:33:22 +11:00
setup_32.c powerpc/32: Statically initialise first emergency context 2021-05-19 10:12:54 +02:00
setup_64.c powerpc: Fix early setup to make early_ioremap() work 2021-05-26 12:06:50 +02:00
setup-common.c powerpc/64: Set up a kernel stack for secondaries before cpu_restore() 2020-12-30 11:53:01 +01:00
setup.h powerpc: Avoid broken GCC __attribute__((optimize)) 2020-12-30 11:53:15 +01:00
signal_32.c powerpc/signal_32: Simplify loop in PPC64 save_general_regs() 2020-07-15 12:04:40 +10:00
signal_64.c powerpc/signal64: Don't opencode page prefaulting 2020-07-15 12:04:40 +10:00
signal.c arch-cleanup-2020-10-22 2020-10-23 10:06:38 -07:00
signal.h powerpc/64/sycall: Implement syscall entry/exit logic in C 2020-04-01 13:42:13 +11:00
smp-tbsync.c
smp.c powerpc/smp: Set numa node before updating mask 2021-05-19 10:12:57 +02:00
stacktrace.c powerpc/stacktrace: Fix spurious "stale" traces in raise_backtrace_ipi() 2021-07-14 16:55:46 +02:00
suspend.c PM: hibernate: powerpc: Expose pfn_is_nosave() prototype 2019-06-14 10:48:56 +02:00
swsusp_32.S powerpc/32: Blacklist functions running with MMU disabled for kprobe 2020-06-02 20:59:11 +10:00
swsusp_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 505 2019-06-19 17:11:22 +02:00
swsusp_asm64.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 505 2019-06-19 17:11:22 +02:00
swsusp_booke.S
swsusp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sys_ppc32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
syscall_64.c powerpc: Only include kup-radix.h for 64-bit Book3S 2020-11-19 23:47:20 +11:00
syscalls.c y2038: syscalls: change remaining timeval to __kernel_old_timeval 2019-11-15 14:38:29 +01:00
sysfs.c powerpc/sysfs: Remove unused 'err' variable in sysfs_create_dscr_default() 2020-09-18 20:05:24 +10:00
systbl_chk.sh treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
systbl.S powerpc/64/sycall: Implement syscall entry/exit logic in C 2020-04-01 13:42:13 +11:00
tau_6xx.c powerpc/tau: Disable TAU between measurements 2020-09-15 22:13:30 +10:00
time.c powerpc/time: Enable sched clock for irqtime 2021-03-04 11:38:01 +01:00
tm.S powerpc/tm: Save and restore AMR on treclaim and trechkpt 2020-10-06 23:22:25 +11:00
traps.c powerpc: improve handling of unrecoverable system reset 2021-03-17 17:06:23 +01:00
ucall.S powerpc/kernel: Add ucall_norets() ultravisor call handler 2019-08-30 09:40:15 +10:00
udbg_16550.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
udbg.c powerpc/udbg: Make it safe to call udbg_printf() always 2019-10-11 19:33:25 +11:00
uprobes.c powerpc: Add ppc_inst_next() 2020-05-26 23:36:51 +10:00
vdso.c powerpc/64/signal: Fix regression in __kernel_sigtramp_rt64() semantics 2021-02-13 13:55:02 +01:00
vecemu.c powerpc: Define and use get_user_instr() et. al. 2020-05-19 00:10:37 +10:00
vector.S powerpc: re-initialise lazy FPU/VEC counters on every fault 2020-07-16 13:00:24 +10:00
vmlinux.lds.S powerpc/64s: fix scv entry fallback flush vs interrupt 2021-01-27 11:55:12 +01:00
watchdog.c powerpc/watchdog: Use hrtimers for per-CPU heartbeat 2019-04-30 11:31:02 +10:00