Re: [PATCH V8 04/10] arm64: exception: handle Synchronous External Abort

Baicar, Tyler
2017-02-03T20:24:48Z

Hello James,

On 2/3/2017 8:59 AM, James Morse wrote:
> On 01/02/17 17:16, 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, report the error
>> in the kernel logs.
>> 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 156169c..9ae7e65 100644
>> --- a/arch/arm64/mm/fault.c
>> +++ b/arch/arm64/mm/fault.c
>> @@ -487,6 +487,31 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>> return 1;
>> }
>>
>> +#define SEA_FnV_MASK 0x00000400
> There are a glut of ESR_ELx_ macros in arch/arm64/include/asm/esr.h, could this
> be fitted in there in a similar format?
>
>
> --- a/arch/arm64/include/asm/esr.h
> +++ b/arch/arm64/include/asm/esr.h
> @@ -83,6 +83,7 @@
> #define ESR_ELx_WNR (UL(1) << 6)
>
> /* Shared ISS field definitions for Data/Instruction aborts */
> +#define ESR_ELx_FnV (UL(1) << 10)
> #define ESR_ELx_EA (UL(1) << 9)
> #define ESR_ELx_S1PTW (UL(1) << 7)
I'll make this change in the next version.
>> +
>> +/*
>> + * 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;
>> +
>> + 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;
>> + if (esr & SEA_FnV_MASK)
>> + info.si_addr = 0;
>> + else
>> + 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;
>> @@ -509,22 +534,22 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
>> { 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" },
> This will print:
>> Synchronous External Abort: synchronous external abort
> It looks odd, but I can't think of anything better to put there.
>
>
>> { do_bad, SIGBUS, 0, "unknown 17" },
>> { do_bad, SIGBUS, 0, "unknown 18" },
>> { do_bad, SIGBUS, 0, "unknown 19" },
>> - { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" },
>> - { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" },
>> - { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" },
>> - { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" },
>> - { do_bad, SIGBUS, 0, "synchronous parity error" },
>> + { do_sea, SIGBUS, 0, "level 0 (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "level 1 (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "level 2 (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "level 3 (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "synchronous parity or ECC error" },
>> { do_bad, SIGBUS, 0, "unknown 25" },
>> { do_bad, SIGBUS, 0, "unknown 26" },
>> { do_bad, SIGBUS, 0, "unknown 27" },
>> - { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" },
>> - { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" },
>> - { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" },
>> - { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "level 0 synchronous parity error (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "level 1 synchronous parity error (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "level 2 synchronous parity error (translation table walk)" },
>> + { do_sea, SIGBUS, 0, "level 3 synchronous parity error (translation table walk)" },
>> { do_bad, SIGBUS, 0, "unknown 32" },
>> { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" },
>> { do_bad, SIGBUS, 0, "unknown 34" },
>>
>
> With the ESR_ELx_FnV change above,
> Reviewed-by: James Morse <james.morse@arm.com>
>
Great, thanks!

Tyler