@@ -490,7 +490,7 @@ el0_inv:
mov x0, sp
mov x1, #BAD_SYNC
mrs x2, esr_el1
- b bad_mode
+ b bad_el0_sync
ENDPROC(el0_sync)
.align 6
@@ -307,16 +307,33 @@ asmlinkage long do_ni_syscall(struct pt_regs *regs)
}
/*
- * bad_mode handles the impossible case in the exception vector.
+ * bad_mode handles the impossible case in the exception vector. This is always
+ * fatal.
*/
asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
{
- siginfo_t info;
- void __user *pc = (void __user *)instruction_pointer(regs);
console_verbose();
pr_crit("Bad mode in %s handler detected, code 0x%08x\n",
handler[reason], esr);
+
+ die("Oops - bad mode", regs, 0);
+ local_irq_disable();
+ panic("bad mode");
+}
+
+/*
+ * bad_el0_sync handles unexpected, but potentially recoverable synchronous
+ * exceptions taken from EL0. Unlike bad_mode, this returns.
+ */
+asmlinkage void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr)
+{
+ siginfo_t info;
+ void __user *pc = (void __user *)instruction_pointer(regs);
+ console_verbose();
+
+ pr_crit("Bad EL0 synchronous exception detected on CPU%d, code 0x%08x\n",
+ smp_processor_id(), esr);
__show_regs(regs);
info.si_signo = SIGILL;
@@ -324,7 +341,7 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
info.si_code = ILL_ILLOPC;
info.si_addr = pc;
- arm64_notify_die("Oops - bad mode", regs, &info, 0);
+ force_sig_info(info.si_signo, &info, current);
}
void __pte_error(const char *file, int line, unsigned long val)
commit 7d9e8f71b989230bc613d121ca38507d34ada849 upstream. Generally, taking an unexpected exception should be a fatal event, and bad_mode is intended to cater for this. However, it should be possible to contain unexpected synchronous exceptions from EL0 without bringing the kernel down, by sending a SIGILL to the task. We tried to apply this approach in commit 9955ac47f4ba1c95 ("arm64: don't kill the kernel on a bad esr from el0"), by sending a signal for any bad_mode call resulting from an EL0 exception. However, this also applies to other unexpected exceptions, such as SError and FIQ. The entry paths for these exceptions branch to bad_mode without configuring the link register, and have no kernel_exit. Thus, if we take one of these exceptions from EL0, bad_mode will eventually return to the original user link register value. This patch fixes this by introducing a new bad_el0_sync handler to cater for the recoverable case, and restoring bad_mode to its original state, whereby it calls panic() and never returns. The recoverable case branches to bad_el0_sync with a bl, and returns to userspace via the usual ret_to_user mechanism. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Fixes: 9955ac47f4ba1c95 ("arm64: don't kill the kernel on a bad esr from el0") Reported-by: Mark Salter <msalter@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Cc: stable@vger.kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- arch/arm64/kernel/entry.S | 2 +- arch/arm64/kernel/traps.c | 25 +++++++++++++++++++++---- 2 files changed, 22 insertions(+), 5 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html