Messages in this thread | | | Subject | Re: [PATCH V7 04/10] arm64: exception: handle Synchronous External Abort | From | "Baicar, Tyler" <> | Date | Wed, 18 Jan 2017 16:26:10 -0700 |
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Hello James,
On 1/17/2017 3:31 AM, James Morse wrote: > Hi Tyler, > > On 12/01/17 18:15, 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. >> @@ -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; > Half of the other do_*() functions in this file read the signo and code from the > fault_info table. > > >> + info.si_addr = (void __user *)addr; > addr here was read from FAR_EL1, but for some of the classes of exception you > have listed below this register isn't updated with the faulting address. > > The ARM-ARM version 'k' in D1.10.5 "Summary of registers on faults taken to an > Exception level that is using Aarch64" has: >> The architecture permits that the FAR_ELx is UNKNOWN for Synchronous External >> Aborts other than Synchronous External Aborts on Translation Table Walks. In >> this case, the ISS.FnV bit returned in ESR_ELx indicates whether FAR_ELx is >> valid. > This is a problem if we get 'synchronous external abort' or 'synchronous parity > error' while a user space process was running. It looks like this would just cause an incorrect address to be printed in the above pr_err. Unless I'm missing something, I don't see arm64_notify_die or anything that gets called from there using the info.si_addr variable.
What do you suggest I do here? The firmware should be reporting the physical and virtual address information if it is available in the HEST entry that the kernel will parse. So should I just remove the use of the addr parameter in do_sea?
Thanks, Tyler >> + 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; > > Thanks, > > James > >
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