diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64e.S | 7 | ||||
| -rw-r--r-- | arch/powerpc/kernel/interrupt.c | 12 |
2 files changed, 16 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S index 930e36099015..2f68fb2ee4fc 100644 --- a/arch/powerpc/kernel/exceptions-64e.S +++ b/arch/powerpc/kernel/exceptions-64e.S @@ -813,6 +813,13 @@ kernel_dbg_exc: EXCEPTION_COMMON(0x260) CHECK_NAPPING() addi r3,r1,STACK_FRAME_OVERHEAD + /* + * XXX: Returning from performance_monitor_exception taken as a + * soft-NMI (Linux irqs disabled) may be risky to use interrupt_return + * and could cause bugs in return or elsewhere. That case should just + * restore registers and return. There is a workaround for one known + * problem in interrupt_exit_kernel_prepare(). + */ bl performance_monitor_exception b interrupt_return diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c index f9db0a172401..7bc93367de68 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -374,10 +374,16 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs) if (regs_is_unrecoverable(regs)) unrecoverable_exception(regs); /* - * CT_WARN_ON comes here via program_check_exception, - * so avoid recursion. + * CT_WARN_ON comes here via program_check_exception, so avoid + * recursion. + * + * Skip the assertion on PMIs to work around a problem caused by NMI + * PMIs incorrectly taking this interrupt return path, it's possible + * for this to hit after interrupt exit to user switches context to + * user. See also the comment in the performance monitor handler in + * exceptions-64e/s.S */ - if (TRAP(regs) != INTERRUPT_PROGRAM) + if (TRAP(regs) != INTERRUPT_PROGRAM && TRAP(regs) != INTERRUPT_PERFMON) CT_WARN_ON(ct_state() == CONTEXT_USER); kuap = kuap_get_and_assert_locked(); |