linux/arch/s390
David Hildenbrand 60f1bf29c0 s390/smp: Fix calling smp_call_ipl_cpu() from ipl CPU
When calling smp_call_ipl_cpu() from the IPL CPU, we will try to read
from pcpu_devices->lowcore. However, due to prefixing, that will result
in reading from absolute address 0 on that CPU. We have to go via the
actual lowcore instead.

This means that right now, we will read lc->nodat_stack == 0 and
therfore work on a very wrong stack.

This BUG essentially broke rebooting under QEMU TCG (which will report
a low address protection exception). And checking under KVM, it is
also broken under KVM. With 1 VCPU it can be easily triggered.

:/# echo 1 > /proc/sys/kernel/sysrq
:/# echo b > /proc/sysrq-trigger
[   28.476745] sysrq: SysRq : Resetting
[   28.476793] Kernel stack overflow.
[   28.476817] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13
[   28.476820] Hardware name: IBM 2964 NE1 716 (KVM/Linux)
[   28.476826] Krnl PSW : 0400c00180000000 0000000000115c0c (pcpu_delegate+0x12c/0x140)
[   28.476861]            R:0 T:1 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
[   28.476863] Krnl GPRS: ffffffffffffffff 0000000000000000 000000000010dff8 0000000000000000
[   28.476864]            0000000000000000 0000000000000000 0000000000ab7090 000003e0006efbf0
[   28.476864]            000000000010dff8 0000000000000000 0000000000000000 0000000000000000
[   28.476865]            000000007fffc000 0000000000730408 000003e0006efc58 0000000000000000
[   28.476887] Krnl Code: 0000000000115bfe: 4170f000            la      %r7,0(%r15)
[   28.476887]            0000000000115c02: 41f0a000            la      %r15,0(%r10)
[   28.476887]           #0000000000115c06: e370f0980024        stg     %r7,152(%r15)
[   28.476887]           >0000000000115c0c: c0e5fffff86e        brasl   %r14,114ce8
[   28.476887]            0000000000115c12: 41f07000            la      %r15,0(%r7)
[   28.476887]            0000000000115c16: a7f4ffa8            brc     15,115b66
[   28.476887]            0000000000115c1a: 0707                bcr     0,%r7
[   28.476887]            0000000000115c1c: 0707                bcr     0,%r7
[   28.476901] Call Trace:
[   28.476902] Last Breaking-Event-Address:
[   28.476920]  [<0000000000a01c4a>] arch_call_rest_init+0x22/0x80
[   28.476927] Kernel panic - not syncing: Corrupt kernel stack, can't continue.
[   28.476930] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13
[   28.476932] Hardware name: IBM 2964 NE1 716 (KVM/Linux)
[   28.476932] Call Trace:

Fixes: 2f859d0dad ("s390/smp: reduce size of struct pcpu")
Cc: stable@vger.kernel.org # 4.0+
Reported-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-01-11 17:12:03 +01:00
..
appldata sched: loadavg: consolidate LOAD_INT, LOAD_FRAC, CALC_LOAD 2018-10-26 16:26:32 -07:00
boot s390: avoid vmlinux segments overlap 2018-10-26 10:19:40 +02:00
configs s390: update defconfigs 2018-11-05 15:10:27 +01:00
crypto crypto: drop mask=CRYPTO_ALG_ASYNC from 'cipher' tfm allocations 2018-11-20 14:26:55 +08:00
hypfs s390/hypfs: do not use stack buffers for hardware data 2018-10-09 11:20:53 +02:00
include s390/vdso: correct vdso mapping for compat tasks 2019-01-11 17:12:02 +01:00
kernel s390/smp: Fix calling smp_call_ipl_cpu() from ipl CPU 2019-01-11 17:12:03 +01:00
kvm Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
lib s390/kasan: avoid user access code instrumentation 2018-10-09 11:21:21 +02:00
mm s390 updates for the 4.21 merge window 2019-01-02 18:37:01 -08:00
net s390: bpf: implement jitting of BPF_ALU | BPF_ARSH | BPF_* 2018-12-07 13:30:48 -08:00
numa s390 updates for 4.20-rc2 2018-11-09 06:30:44 -06:00
oprofile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci pci-v4.21-changes 2019-01-05 17:57:34 -08:00
purgatory s390: clean up stacks setup 2018-09-20 13:20:29 +02:00
scripts s390/build: add *.o.chkbss files to targets list 2018-07-02 12:32:23 +02:00
tools kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
defconfig s390: update defconfigs 2018-11-05 15:10:27 +01:00
Kbuild s390/kexec_file: Add purgatory 2018-04-16 09:10:22 +02:00
Kconfig Kconfig file consolidation for v4.21 2018-12-29 13:40:29 -08:00
Kconfig.debug Kconfig: consolidate the "Kernel hacking" menu 2018-08-02 08:06:48 +09:00
Makefile s390/kasan: increase instrumented stack size to 64k 2018-11-02 08:31:57 +01:00