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SubjectRe: [PATCH V7 04/10] arm64: exception: handle Synchronous External Abort
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On 1/17/2017 3:23 AM, James Morse wrote:
> Hi Tyler,
>
> On 16/01/17 11:53, 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.
>>> 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
>>> @@ -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.
>
> The 'SEA' in this user-string doesn't add anything. Now that these use do_sea()
> instead of do_bad(), when they are printed won't it be:
>> Synchronous External Abort: level 3 SEA (translation table walk) (...) at ....

Good point, yes they will:

+ pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
+ fault_name(esr), esr, addr);

I can just remove SEA here then.

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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