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

Nicholas Piggin npiggin at gmail.com
Tue Jun 29 06:15:25 AEST 2021


Excerpts from Sachin Sant's message of June 29, 2021 12:37 am:
> 
>> On 28-Jun-2021, at 1:19 PM, Nicholas Piggin <npiggin at 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 at 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

This looks like it's probably running un-reconciled due to the first 
call to hash__do_page_fault not calling a real interrupt handler.  
Without this patch, the test must be causing a warning due to the same
thing probably (the bug triggered in the program check interrupt handler).

I think this patch is probably the right fix for it.

Thanks,
Nick

---

diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index 96d9aa164007..ac5720371c0d 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1522,8 +1522,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap,
 }
 EXPORT_SYMBOL_GPL(hash_page);
 
-DECLARE_INTERRUPT_HANDLER_RET(__do_hash_fault);
-DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
+DECLARE_INTERRUPT_HANDLER(__do_hash_fault);
+DEFINE_INTERRUPT_HANDLER(__do_hash_fault)
 {
 	unsigned long ea = regs->dar;
 	unsigned long dsisr = regs->dsisr;
@@ -1533,6 +1533,11 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
 	unsigned int region_id;
 	long err;
 
+	if (unlikely(dsisr & (DSISR_BAD_FAULT_64S | DSISR_KEYFAULT))) {
+		hash__do_page_fault(regs);
+		return;
+	}
+
 	region_id = get_region_id(ea);
 	if ((region_id == VMALLOC_REGION_ID) || (region_id == IO_REGION_ID))
 		mm = &init_mm;
@@ -1571,9 +1576,10 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
 			bad_page_fault(regs, SIGBUS);
 		}
 		err = 0;
-	}
 
-	return err;
+	} else if (err) {
+		hash__do_page_fault(regs);
+	}
 }
 
 /*
@@ -1582,13 +1588,6 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
  */
 DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault)
 {
-	unsigned long dsisr = regs->dsisr;
-
-	if (unlikely(dsisr & (DSISR_BAD_FAULT_64S | DSISR_KEYFAULT))) {
-		hash__do_page_fault(regs);
-		return 0;
-	}
-
 	/*
 	 * If we are in an "NMI" (e.g., an interrupt when soft-disabled), then
 	 * don't call hash_page, just fail the fault. This is required to
@@ -1607,8 +1606,7 @@ DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault)
 		return 0;
 	}
 
-	if (__do_hash_fault(regs))
-		hash__do_page_fault(regs);
+	__do_hash_fault(regs);
 
 	return 0;
 }


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