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linux-stable/arch/powerpc
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Nathan Lynch fda0eb2200 powerpc/paravirt: correct preempt debug splat in vcpu_is_preempted() 
vcpu_is_preempted() can be used outside of preempt-disabled critical
sections, yielding warnings such as:

BUG: using smp_processor_id() in preemptible [00000000] code: systemd-udevd/185
caller is rwsem_spin_on_owner+0x1cc/0x2d0
CPU: 1 PID: 185 Comm: systemd-udevd Not tainted 5.15.0-rc2+ #33
Call Trace:
[c000000012907ac0] [c000000000aa30a8] dump_stack_lvl+0xac/0x108 (unreliable)
[c000000012907b00] [c000000001371f70] check_preemption_disabled+0x150/0x160
[c000000012907b90] [c0000000001e0e8c] rwsem_spin_on_owner+0x1cc/0x2d0
[c000000012907be0] [c0000000001e1408] rwsem_down_write_slowpath+0x478/0x9a0
[c000000012907ca0] [c000000000576cf4] filename_create+0x94/0x1e0
[c000000012907d10] [c00000000057ac08] do_symlinkat+0x68/0x1a0
[c000000012907d70] [c00000000057ae18] sys_symlink+0x58/0x70
[c000000012907da0] [c00000000002e448] system_call_exception+0x198/0x3c0
[c000000012907e10] [c00000000000c54c] system_call_common+0xec/0x250

The result of vcpu_is_preempted() is always used speculatively, and the
function does not access per-cpu resources in a (Linux) preempt-unsafe way.
Use raw_smp_processor_id() to avoid such warnings, adding explanatory
comments.

Fixes: ca3f969dcb ("powerpc/paravirt: Use is_kvm_guest() in vcpu_is_preempted()")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210928214147.312412-3-nathanl@linux.ibm.com
2021-10-09 00:15:59 +11:00
..
boot powerpc/boot: Fix build failure since GCC 4.9 removal 2021-09-14 08:33:32 -07:00
configs powerpc/configs/microwatt: Enable options for systemd 2021-08-27 00:56:53 +10:00
crypto
include powerpc/paravirt: correct preempt debug splat in vcpu_is_preempted() 2021-10-09 00:15:59 +11:00
kernel powerpc: fix unbalanced node refcount in check_kvm_guest() 2021-10-09 00:15:59 +11:00
kexec powerpc updates for 5.15 2021-09-03 11:22:50 -07:00
kvm powerpc/asm: Remove UPD_CONSTR after GCC 4.9 removal 2021-10-09 00:15:59 +11:00
lib powerpc: Only build restart_table.c for 64s 2021-07-01 22:50:54 +10:00
math-emu powerpc/64s: avoid reloading (H)SRR registers if they are still valid 2021-06-25 00:06:55 +10:00
mm powerpc/mem: Fix arch/powerpc/mm/mem.c:53:12: error: no previous prototype for 'create_section_mapping' 2021-10-09 00:15:59 +11:00
net bpf: Introduce BPF nospec instruction for mitigating Spectre v4 2021-07-29 00:20:56 +02:00
perf powerpc/perf: Fix the check for SIAR value 2021-08-25 22:38:19 +10:00
platforms powerpc/powernv/dump: Fix typo in comment 2021-10-09 00:15:59 +11:00
purgatory powerpc/kexec: Don't use .machine ppc64 in trampoline_64.S 2021-04-08 21:17:43 +10:00
sysdev powerpc/xics: Set the IRQ chip data for the ICS native backend 2021-09-15 22:05:53 +10:00
tools powerpc/head_check: Fix shellcheck errors 2021-08-17 22:52:02 +10:00
xmon powerpc: Refactor verification of MSR_RI 2021-08-26 21:21:07 +10:00
Kbuild
Kconfig Tracing updates for 5.15: 2021-09-05 11:50:41 -07:00
Kconfig.debug powerpc/ptdump: Convert powerpc to GENERIC_PTDUMP 2021-08-25 13:35:48 +10:00
Makefile powerpc: Add "-z notext" flag to disable diagnostic 2021-08-15 13:49:39 +10:00
Makefile.postlink