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Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External Abort

From "Baicar, Tyler" <tbaicar@codeaurora.org>
Newsgroups linux.kernel
Subject Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External Abort
Date 2017-01-16 21:20 +0100
Message-ID <t0lV0-5Di-23@gated-at.bofh.it> (permalink)
References <sYS8G-7eZ-5@gated-at.bofh.it> <sYS8H-7eZ-31@gated-at.bofh.it> <t0e77-8ky-15@gated-at.bofh.it>
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Hello Will,


On 1/16/2017 4:53 AM, Will Deacon wrote:
> On Thu, Jan 12, 2017 at 11:15:18AM -0700, Tyler Baicar wrote:
>> SEA exceptions are often caused by an uncorrected hardware
>> error, and are handled when data abort and instruction abort
>> exception classes have specific values for their Fault Status
>> Code.
>> When SEA occurs, before killing the process, go through
>> the handlers registered in the notification list.
>> Update fault_info[] with specific SEA faults so that the
>> new SEA handler is used.
>>
>> Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
>> Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
>> Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>
>> ---
>>   arch/arm64/include/asm/system_misc.h | 13 ++++++++
>>   arch/arm64/mm/fault.c                | 58 +++++++++++++++++++++++++++++-------
>>   2 files changed, 61 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h
>> index 57f110b..e7f3440 100644
>> --- a/arch/arm64/include/asm/system_misc.h
>> +++ b/arch/arm64/include/asm/system_misc.h
>> @@ -64,4 +64,17 @@ extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
>>   
>>   #endif	/* __ASSEMBLY__ */
>>   
>> +/*
>> + * The functions below are used to register and unregister callbacks
>> + * that are to be invoked when a Synchronous External Abort (SEA)
>> + * occurs. An SEA is raised by certain fault status codes that have
>> + * either data or instruction abort as the exception class, and
>> + * callbacks may be registered to parse or handle such hardware errors.
>> + *
>> + * Registered callbacks are run in an interrupt/atomic context. They
>> + * are not allowed to block or sleep.
>> + */
>> +int register_sea_notifier(struct notifier_block *nb);
>> +void unregister_sea_notifier(struct notifier_block *nb);
> I still don't understand why you need notifiers for this. You register
> precisely one hook in the series.
I didn't see a response to my last comment on the previous series so I 
just left it in for this series.
The notifier usage is consistent with the GHES code for SCI errors which 
are also only used a single
time in the code. If you think making the call directly is a better 
option I will remove the notifiers.
>>   #endif	/* __ASM_SYSTEM_MISC_H */
>> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
>> index 05d2bd7..81039c7 100644
>> --- a/arch/arm64/mm/fault.c
>> +++ b/arch/arm64/mm/fault.c
>> @@ -39,6 +39,22 @@
>>   #include <asm/pgtable.h>
>>   #include <asm/tlbflush.h>
>>   
>> +/*
>> + * GHES SEA handler code may register a notifier call here to
>> + * handle HW error record passed from platform.
>> + */
>> +static ATOMIC_NOTIFIER_HEAD(sea_handler_chain);
>> +
>> +int register_sea_notifier(struct notifier_block *nb)
>> +{
>> +	return atomic_notifier_chain_register(&sea_handler_chain, nb);
>> +}
>> +
>> +void unregister_sea_notifier(struct notifier_block *nb)
>> +{
>> +	atomic_notifier_chain_unregister(&sea_handler_chain, nb);
>> +}
>> +
>>   static const char *fault_name(unsigned int esr);
>>   
>>   #ifdef CONFIG_KPROBES
>> @@ -480,6 +496,28 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>>   	return 1;
>>   }
>>   
>> +/*
>> + * This abort handler deals with Synchronous External Abort.
>> + * It calls notifiers, and then returns "fault".
>> + */
>> +static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>> +{
>> +	struct siginfo info;
>> +
>> +	atomic_notifier_call_chain(&sea_handler_chain, 0, NULL);
>> +
>> +	pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
>> +		 fault_name(esr), esr, addr);
>> +
>> +	info.si_signo = SIGBUS;
>> +	info.si_errno = 0;
>> +	info.si_code  = 0;
>> +	info.si_addr  = (void __user *)addr;
>> +	arm64_notify_die("", regs, &info, esr);
>> +
>> +	return 0;
>> +}
>> +
>>   static const struct fault_info {
>>   	int	(*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
>>   	int	sig;
>> @@ -502,22 +540,22 @@ static const struct fault_info {
>>   	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 1 permission fault"	},
>>   	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 permission fault"	},
>>   	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 3 permission fault"	},
>> -	{ do_bad,		SIGBUS,  0,		"synchronous external abort"	},
>> +	{ do_sea,		SIGBUS,  0,		"synchronous external abort"	},
>>   	{ do_bad,		SIGBUS,  0,		"unknown 17"			},
>>   	{ do_bad,		SIGBUS,  0,		"unknown 18"			},
>>   	{ do_bad,		SIGBUS,  0,		"unknown 19"			},
>> -	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
>> -	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
>> -	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
>> -	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
>> -	{ do_bad,		SIGBUS,  0,		"synchronous parity error"	},
>> +	{ do_sea,		SIGBUS,  0,		"level 0 SEA (translation table walk)"	},
>> +	{ do_sea,		SIGBUS,  0,		"level 1 SEA (translation table walk)"	},
>> +	{ do_sea,		SIGBUS,  0,		"level 2 SEA (translation table walk)"	},
>> +	{ do_sea,		SIGBUS,  0,		"level 3 SEA (translation table walk)"	},
> Perhaps I wasn't clear enough in my previous review, but please expand the
> acronym for strings and comments.
Sorry, I will expand these.
>> +	{ do_sea,		SIGBUS,  0,		"synchronous parity or ECC err" },
> s/err/error/
>
> Will
Thanks,
Tyler

-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.

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[PATCH V7 00/10] Add UEFI 2.6 and ACPI 6.1 updates for RAS on ARM64 Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:20 +0100
  [PATCH V7 01/10] acpi: apei: read ack upon ghes record consumption Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:20 +0100
  [PATCH V7 04/10] arm64: exception: handle Synchronous External Abort Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:20 +0100
    Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort Will Deacon <will.deacon@arm.com> - 2017-01-16 13:00 +0100
      Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-16 21:20 +0100
        Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort Will Deacon <will.deacon@arm.com> - 2017-01-17 11:30 +0100
          Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-19 00:10 +0100
      Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort James Morse <james.morse@arm.com> - 2017-01-17 11:30 +0100
        Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-19 00:00 +0100
    Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort James Morse <james.morse@arm.com> - 2017-01-17 11:40 +0100
      Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-19 00:30 +0100
        Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort James Morse <james.morse@arm.com> - 2017-01-19 19:20 +0100
          Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-20 21:40 +0100
            Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort James Morse <james.morse@arm.com> - 2017-01-23 11:10 +0100
              Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External  Abort "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-24 19:50 +0100
  [PATCH V7 10/10] arm/arm64: KVM: add guest SEA support Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:30 +0100
    Re: [PATCH V7 10/10] arm/arm64: KVM: add guest SEA support Marc Zyngier <marc.zyngier@arm.com> - 2017-01-16 13:00 +0100
      Re: [PATCH V7 10/10] arm/arm64: KVM: add guest SEA support "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-16 21:20 +0100
  [PATCH V7 08/10] ras: acpi / apei: generate trace event for unrecognized CPER section Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:30 +0100
  [PATCH V7 06/10] acpi: apei: panic OS with fatal error status block Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:30 +0100
  [PATCH V7 07/10] efi: print unrecognized CPER section Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:30 +0100
  [PATCH V7 09/10] trace, ras: add ARM processor error trace event Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:30 +0100
  [PATCH V7 05/10] acpi: apei: handle SEA notification type for ARMv8 Tyler Baicar <tbaicar@codeaurora.org> - 2017-01-12 19:30 +0100
    Re: [PATCH V7 05/10] acpi: apei: handle SEA notification type for  ARMv8 James Morse <james.morse@arm.com> - 2017-01-18 16:10 +0100
      Re: [PATCH V7 05/10] acpi: apei: handle SEA notification type for  ARMv8 "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-19 01:00 +0100
        Re: [PATCH V7 05/10] acpi: apei: handle SEA notification type for  ARMv8 James Morse <james.morse@arm.com> - 2017-01-19 19:10 +0100
          Re: [PATCH V7 05/10] acpi: apei: handle SEA notification type for  ARMv8 "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-20 22:00 +0100
            Re: [PATCH V7 05/10] acpi: apei: handle SEA notification type for  ARMv8 James Morse <james.morse@arm.com> - 2017-01-24 19:00 +0100
              Re: [PATCH V7 05/10] acpi: apei: handle SEA notification type for  ARMv8 "Baicar, Tyler" <tbaicar@codeaurora.org> - 2017-01-24 19:50 +0100

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