Re: [PATCH 5/8] powerpc/64: enable MSR[EE] in irq replay pt_regs

[Sachin Sant <sachinp@linux.vnet.ibm.com>]

> On 28-Jun-2021, at 1:19 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
> 
> Similar to 2b48e96be2f9f ("powerpc/64: fix irq replay pt_regs->softe
> value"), enable MSR_EE in pt_regs->msr, which makes the regs look a
> bit more normal and allows the extra debug checks to be added to
> interrupt handler entry.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> arch/powerpc/include/asm/interrupt.h | 4 ++++
> arch/powerpc/kernel/irq.c            | 1 +
> 2 files changed, 5 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
> index 789311d1e283..d4bdf7d274ac 100644
> --- a/arch/powerpc/include/asm/interrupt.h
> +++ b/arch/powerpc/include/asm/interrupt.h
> @@ -173,6 +173,8 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
> 			BUG_ON(search_kernel_restart_table(regs->nip));
> #endif
> 	}
> +	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
> +		BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));
> #endif

I think this BUG_ON was triggered while running selftests (powerpc/mm/pkey_exec_prot)

[ 9741.254969] ------------[ cut here ]------------
[ 9741.254978] kernel BUG at arch/powerpc/include/asm/interrupt.h:177!
[ 9741.254985] Oops: Exception in kernel mode, sig: 5 [#1]
[ 9741.254990] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
[ 9741.254995] Modules linked in: rpadlpar_io rpaphp uinput sha512_generic vmac n_gsm pps_ldisc pps_core ppp_synctty ppp_async ppp_generic slcan slip slhc snd_hrtimer snd_seq snd_seq_device snd_timer snd soundcore authenc pcrypt crypto_user n_hdlc dummy veth nfsv3 nfs_acl nfs lockd grace fscache netfs tun brd overlay vfat fat btrfs blake2b_generic xor zstd_compress raid6_pq xfs loop sctp ip6_udp_tunnel udp_tunnel dm_mod bonding nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set rfkill nf_tables libcrc32c nfnetlink sunrpc pseries_rng xts vmx_crypto uio_pdrv_genirq uio sch_fq_codel ip_tables ext4 mbcache jbd2 sr_mod sd_mod cdrom t10_pi sg ibmvscsi ibmveth scsi_transport_srp fuse [last unloaded: test_cpuidle_latency]
[ 9741.255097] CPU: 17 PID: 3278920 Comm: pkey_exec_prot Tainted: G        W  OE     5.13.0-rc7-next-20210625-dirty #4
[ 9741.255106] NIP:  c0000000000300d8 LR: c000000000009604 CTR: c000000000009330
[ 9741.255111] REGS: c0000000347536f0 TRAP: 0700   Tainted: G        W  OE      (5.13.0-rc7-next-20210625-dirty)
[ 9741.255117] MSR:  8000000000021033 <SF,ME,IR,DR,RI,LE>  CR: 22004282  XER: 20040000
[ 9741.255130] CFAR: c00000000003007c IRQMASK: 3 
[ 9741.255130] GPR00: c000000000093cd0 c000000034753990 c0000000029bbe00 c000000034753a30 
[ 9741.255130] GPR04: 00007fff9ebb0000 0000000000200000 000000000000000a 000000000000002d 
[ 9741.255130] GPR08: 0000000000000000 0000000000000001 0000000000000000 7265677368657265 
[ 9741.255130] GPR12: 8000000000021033 c00000001ec27280 0000000000000000 0000000000000000 
[ 9741.255130] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
[ 9741.255130] GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000010003c40 
[ 9741.255130] GPR24: 0000000000000000 0000000000000000 0000000000200000 c00000005e89d200 
[ 9741.255130] GPR28: 0000000000000300 00007fff9ebb0000 c000000034753e80 c000000034753a30 
[ 9741.255191] NIP [c0000000000300d8] program_check_exception+0xe8/0x1c0
[ 9741.255202] LR [c000000000009604] program_check_common_virt+0x2d4/0x320
[ 9741.255209] Call Trace:
[ 9741.255212] [c000000034753990] [0000000000000008] 0x8 (unreliable)
[ 9741.255219] [c0000000347539c0] [c000000034753a80] 0xc000000034753a80
[ 9741.255225] --- interrupt: 700 at arch_local_irq_restore+0x1d0/0x200
[ 9741.255231] NIP:  c000000000016790 LR: c000000000093388 CTR: c000000000008780
[ 9741.255236] REGS: c000000034753a30 TRAP: 0700   Tainted: G        W  OE      (5.13.0-rc7-next-20210625-dirty)
[ 9741.255242] MSR:  8000000000021033 <SF,ME,IR,DR,RI,LE>  CR: 24004288  XER: 20040000
[ 9741.255253] CFAR: c0000000000165ec IRQMASK: 0 
[ 9741.255253] GPR00: c000000000093cd0 c000000034753cd0 c0000000029bbe00 0000000000000000 
[ 9741.255253] GPR04: 00007fff9ebb0000 0000000000200000 000000000000000a 000000000000002d 
[ 9741.255253] GPR08: 0000000000000000 0000000000000000 c0000000bd77d400 7265677368657265 
[ 9741.255253] GPR12: 0000000044000282 c00000001ec27280 0000000000000000 0000000000000000 
[ 9741.255253] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
[ 9741.255253] GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000010003c40 
[ 9741.255253] GPR24: 0000000000000000 0000000000000000 0000000000200000 c00000005e89d200 
[ 9741.255253] GPR28: 0000000000000300 00007fff9ebb0000 c000000034753e80 0000000000000001 
[ 9741.255313] NIP [c000000000016790] arch_local_irq_restore+0x1d0/0x200
[ 9741.255319] LR [c000000000093388] ___do_page_fault+0x438/0xb80
[ 9741.255325] --- interrupt: 700
[ 9741.255328] [c000000034753cd0] [c00000000009be74] hash_page_mm+0x5e4/0x800 (unreliable)
[ 9741.255335] [c000000034753d00] [000000000000002d] 0x2d
[ 9741.255340] [c000000034753db0] [c000000000093cd0] hash__do_page_fault+0x30/0x70
[ 9741.255348] [c000000034753de0] [c00000000009c438] do_hash_fault+0x78/0xb0
[ 9741.255354] [c000000034753e10] [c00000000000891c] data_access_common_virt+0x19c/0x1f0
[ 9741.255361] --- interrupt: 300 at 0x10001e8c
[ 9741.255365] NIP:  0000000010001e8c LR: 0000000010001e84 CTR: 00007fff9ea4eb60
[ 9741.255370] REGS: c000000034753e80 TRAP: 0300   Tainted: G        W  OE      (5.13.0-rc7-next-20210625-dirty)
[ 9741.255376] MSR:  800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 28000282  XER: 20040000
[ 9741.255391] CFAR: c00000000000ca44 DAR: 00007fff9ebb0000 DSISR: 00200000 IRQMASK: 0 
[ 9741.255391] GPR00: 0000000010001e84 00007fffd11fa7b0 0000000010027f00 0000000000000033 
[ 9741.255391] GPR04: 0000000010003c3d 0000000000000001 000000000000000a 000000000000002d 
[ 9741.255391] GPR08: 0000000000000000 00007fff9ebb0000 0000000000000000 000001002ab20337 
[ 9741.255391] GPR12: 0000000000000000 00007fff9ec4a270 0000000000000000 0000000000000000 
[ 9741.255391] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
[ 9741.255391] GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000010003c40 
[ 9741.255391] GPR24: 0000000000000001 0000000010003c18 000000000000002d 0000000010020160 
[ 9741.255391] GPR28: 00c0000000000000 0000000010020230 0000000000000002 0000000000000004 
[ 9741.255455] NIP [0000000010001e8c] 0x10001e8c
[ 9741.255459] LR [0000000010001e84] 0x10001e84
[ 9741.255463] --- interrupt: 300
[ 9741.255466] Instruction dump:
[ 9741.255470] 60000000 e8010040 7c6a1b78 7c0803a6 0b0a0000 e93f0138 71290001 4082004c 
[ 9741.255481] e95f0108 39200001 714a8000 4082ff68 <0b090000> 38210030 7fe3fb78 ebe1fff8 
[ 9741.255494] ---[ end trace c668c70ea0d5061f ]—

Thanks
-Sachin

> 
> 	booke_restore_dbcr0();
> @@ -268,6 +270,8 @@ static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct inte
> 		// arch_irq_disabled_regs(regs) behaves as expected.
> 		regs->softe = IRQS_ALL_DISABLED;
> 	}
> +	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
> +		BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));
> 
> 	/* Don't do any per-CPU operations until interrupt state is fixed */
> 
> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> index 8428caf3194e..91e63eac4e8f 100644
> --- a/arch/powerpc/kernel/irq.c
> +++ b/arch/powerpc/kernel/irq.c
> @@ -121,6 +121,7 @@ void replay_soft_interrupts(void)
> 
> 	ppc_save_regs(&regs);
> 	regs.softe = IRQS_ENABLED;
> +	regs.msr |= MSR_EE;
> 
> again:
> 	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
> -- 
> 2.23.0
>