[PATCH V7 04/10] arm64: exception: handle Synchronous External Abort
From: james.morse@arm.com (James Morse)
Date: 2017-01-17 10:34:37
Also in:
kvm, kvmarm, linux-acpi, linux-efi, lkml
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.
quoted hunk ↗ jump to hunk
@@ -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.
+ 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