Excerpts from Paul Menzel's message of July 6, 2020 3:20 pm:
> Dear Nicholas,
>
>
> Thank you for the quick response.
>
>
> Am 06.07.20 um 02:41 schrieb Nicholas Piggin:
>> Excerpts from Paul Menzel's message of July 5, 2020 8:30 pm:
>
>>> Am 05.07.20 um 11:22 schrieb Paul Menzel:
>>>> [ 572.253008] Oops: Exception in kernel mode, sig: 5 [#1]
>>>> [ 572.253198] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
>>>> [ 572.253232] Modules linked in: tcp_diag inet_diag unix_diag xt_CHECKSUM
>>>> xt_MASQUERADE xt_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp
>>>> ip6table_mangle ip6table_nat iptable_mangle iptable_nat nf_nat
>>>> nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables nfnetlink
>>>> ip6table_filter ip6_tables iptable_filter bridge stp llc overlay xfs
>>>> kvm_hv kvm binfmt_misc joydev uas usb_storage vmx_crypto bnx2x
>>>> crct10dif_vpmsum ofpart cmdlinepart powernv_flash mtd mdio ibmpowernv at24
>>>> ipmi_powernv ipmi_devintf ipmi_msghandler opal_prd powernv_rng
>>>> sch_fq_codel parport_pc ppdev lp nfsd parport auth_rpcgss nfs_acl lockd
>>>> grace sunrpc ip_tables x_tables autofs4 btrfs blake2b_generic libcrc32c
>>>> xor zstd_compress raid6_pq input_leds mac_hid hid_generic ast
>>>> drm_vram_helper drm_ttm_helper i2c_algo_bit ttm drm_kms_helper syscopyarea
>>>> sysfillrect sysimgblt fb_sys_fops drm ahci drm_panel_orientation_quirks
>>>> libahci usbhid hid crc32c_vpmsum uio_pdrv_genirq uio
>>>> [ 572.253639] CPU: 4 PID: 6728 Comm: Web Content Not tainted 5.8.0-rc3+ #1
>>>> [ 572.253659] NIP: c00000000000ff5c LR: c00000000001a8f8 CTR:
>>>> c0000000001d5f00
>>>> [ 572.253835] REGS: c000007f31f0f420 TRAP: 1500 Not tainted
>>>> (5.8.0-rc3+)
>>>> [ 572.253854] MSR: 900000000290b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>
>>>> CR: 28c48482 XER: 20000000
>>>> [ 572.253888] CFAR: c00000000000fecc IRQMASK: 1
>>>> [ 572.253888] GPR00: c00000000001b228 c000007f31f0f6b0 c000000001f9a900
>>>> c000007f351544d0
>>>> [ 572.253888] GPR04: 0000000000000000 c000007f31f0fe90 c000007f351544f0
>>>> c000007f32e522b0
>>>> [ 572.253888] GPR08: 0000000000000000 0000000000002000 9000000000009033
>>>> c000007fbcd85800
>>>> [ 572.253888] GPR12: 0000000000008800 c000007fffffb680 0000000000000005
>>>> 0000000000000004
>>>> [ 572.253888] GPR16: c000007f35153800 c000007f35154130 0000000000000005
>>>> 0000000000000001
>>>> [ 572.253888] GPR20: 0000000000000024 c000007f32e51e68 c000007f35154028
>>>> 0000007fd8da0000
>>>> [ 572.253888] GPR24: 0000007fd8da0000 c000007f351544d0 c000007e9a4024d0
>>>> c000000001665f18
>>>> [ 572.253888] GPR28: c000007f351544d0 c000007f35153800 900000000290f033
>>>> c000007f35153800
>>>> [ 572.254079] NIP [c00000000000ff5c] save_fpu+0xa8/0x2ac
>>>> [ 572.254098] LR [c00000000001a8f8] __giveup_fpu+0x28/0x80
>>>> [ 572.254114] Call Trace:
>>>> [ 572.254128] [c000007f31f0f6b0] [c000007f35153980] 0xc000007f35153980
>>>> (unreliable)
>>>> [ 572.254156] [c000007f31f0f6e0] [c00000000001b228] giveup_all+0x128/0x150
>>>> [ 572.254327] [c000007f31f0f710] [c00000000001c124]
>>>> __switch_to+0x104/0x490
>>>> [ 572.254352] [c000007f31f0f770] [c0000000010d2e34] __schedule+0x2e4/0xa10
>>>> [ 572.254374] [c000007f31f0f840] [c0000000010d35d4] schedule+0x74/0x140
>>>> [ 572.254397] [c000007f31f0f870] [c0000000010d9478]
>>>> schedule_timeout+0x358/0x5d0
>>>> [ 572.254424] [c000007f31f0f980] [c0000000010d5638]
>>>> wait_for_completion+0xc8/0x210
>>>> [ 572.254451] [c000007f31f0fa00] [c000000000608ed4]
>>>> do_coredump+0x3a4/0xd60
>>>> [ 572.254625] [c000007f31f0fba0] [c00000000018d1cc] get_signal+0x1dc/0xd00
>>>> [ 572.254648] [c000007f31f0fcc0] [c00000000001f088]
>>>> do_notify_resume+0x158/0x450
>>>> [ 572.254672] [c000007f31f0fda0] [c000000000037d04]
>>>> interrupt_exit_user_prepare+0x1c4/0x230
>>>> [ 572.254699] [c000007f31f0fe20] [c00000000000f2b4]
>>>> interrupt_return+0x14/0x1c0
>>>> [ 572.254720] Instruction dump:
>>>> [ 572.254882] dae60170 db060180 db260190 db4601a0 db6601b0 db8601c0
>>>> dba601d0 dbc601e0
>>>> [ 572.254912] dbe601f0 48000204 38800000 f0000250 <7c062798> f0000250
>>>> 38800010 f0210a50
>>>> [ 572.254946] ---[ end trace ba4452ee5c77d58e ]---
>>>
>>> Please find all the messages attached.
>>
>> "Oops: Exception in kernel mode, sig: 5 [#1]"
>>
>> Unfortunately it's a very poor error message. I think it is a 0x1500
>> exception triggering in the kernel FP register saving. Do you have the
>> CONFIG_PPC_DENORMALISATION config option set?
>
> Yes, as it’s set in the Ubuntu Linux kernel configuration, I have it set
> too.
>
> $ grep DENORMALI /boot/config-*
> /boot/config-4.15.0-23-generic:CONFIG_PPC_DENORMALISATION=y
> /boot/config-5.4.0-40-generic:CONFIG_PPC_DENORMALISATION=y
> /boot/config-5.7.0-rc5+:CONFIG_PPC_DENORMALISATION=y
> /boot/config-5.8.0-rc3+:CONFIG_PPC_DENORMALISATION=y
Ah thanks I was able to reproduce with a little denorm test case.
The denorm interrupt handler got broken by some careless person.
This patch should hopefully fix it for you?
Thanks,
Nick
---
arch/powerpc/kernel/exceptions-64s.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index fa080694e581..0fc8bad878b2 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -2551,7 +2551,7 @@ EXC_VIRT_NONE(0x5400, 0x100)
INT_DEFINE_BEGIN(denorm_exception)
IVEC=0x1500
IHSRR=1
- IBRANCH_COMMON=0
+ IBRANCH_TO_COMMON=0
IKVM_REAL=1
INT_DEFINE_END(denorm_exception)
--
2.23.0
