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

["Baicar, Tyler" <tbaicar@xxxxxxxxxxxxxx>]

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@xxxxxxx>
Great, thanks!

Tyler

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