diff options
Diffstat (limited to 'hw/intc/armv7m_nvic.c')
| -rw-r--r-- | hw/intc/armv7m_nvic.c | 68 |
1 files changed, 66 insertions, 2 deletions
diff --git a/hw/intc/armv7m_nvic.c b/hw/intc/armv7m_nvic.c index 8ca6ceeb9b..b4a6e7c62e 100644 --- a/hw/intc/armv7m_nvic.c +++ b/hw/intc/armv7m_nvic.c @@ -503,8 +503,25 @@ static void armv7m_nvic_clear_pending(void *opaque, int irq, bool secure) } } -void armv7m_nvic_set_pending(void *opaque, int irq, bool secure) +static void do_armv7m_nvic_set_pending(void *opaque, int irq, bool secure, + bool derived) { + /* Pend an exception, including possibly escalating it to HardFault. + * + * This function handles both "normal" pending of interrupts and + * exceptions, and also derived exceptions (ones which occur as + * a result of trying to take some other exception). + * + * If derived == true, the caller guarantees that we are part way through + * trying to take an exception (but have not yet called + * armv7m_nvic_acknowledge_irq() to make it active), and so: + * - s->vectpending is the "original exception" we were trying to take + * - irq is the "derived exception" + * - nvic_exec_prio(s) gives the priority before exception entry + * Here we handle the prioritization logic which the pseudocode puts + * in the DerivedLateArrival() function. + */ + NVICState *s = (NVICState *)opaque; bool banked = exc_is_banked(irq); VecInfo *vec; @@ -514,7 +531,44 @@ void armv7m_nvic_set_pending(void *opaque, int irq, bool secure) vec = (banked && secure) ? &s->sec_vectors[irq] : &s->vectors[irq]; - trace_nvic_set_pending(irq, secure, vec->enabled, vec->prio); + trace_nvic_set_pending(irq, secure, derived, vec->enabled, vec->prio); + + if (derived) { + /* Derived exceptions are always synchronous. */ + assert(irq >= ARMV7M_EXCP_HARD && irq < ARMV7M_EXCP_PENDSV); + + if (irq == ARMV7M_EXCP_DEBUG && + exc_group_prio(s, vec->prio, secure) >= nvic_exec_prio(s)) { + /* DebugMonitorFault, but its priority is lower than the + * preempted exception priority: just ignore it. + */ + return; + } + + if (irq == ARMV7M_EXCP_HARD && vec->prio >= s->vectpending_prio) { + /* If this is a terminal exception (one which means we cannot + * take the original exception, like a failure to read its + * vector table entry), then we must take the derived exception. + * If the derived exception can't take priority over the + * original exception, then we go into Lockup. + * + * For QEMU, we rely on the fact that a derived exception is + * terminal if and only if it's reported to us as HardFault, + * which saves having to have an extra argument is_terminal + * that we'd only use in one place. + */ + cpu_abort(&s->cpu->parent_obj, + "Lockup: can't take terminal derived exception " + "(original exception priority %d)\n", + s->vectpending_prio); + } + /* We now continue with the same code as for a normal pending + * exception, which will cause us to pend the derived exception. + * We'll then take either the original or the derived exception + * based on which is higher priority by the usual mechanism + * for selecting the highest priority pending interrupt. + */ + } if (irq >= ARMV7M_EXCP_HARD && irq < ARMV7M_EXCP_PENDSV) { /* If a synchronous exception is pending then it may be @@ -585,6 +639,16 @@ void armv7m_nvic_set_pending(void *opaque, int irq, bool secure) } } +void armv7m_nvic_set_pending(void *opaque, int irq, bool secure) +{ + do_armv7m_nvic_set_pending(opaque, irq, secure, false); +} + +void armv7m_nvic_set_pending_derived(void *opaque, int irq, bool secure) +{ + do_armv7m_nvic_set_pending(opaque, irq, secure, true); +} + /* Make pending IRQ active. */ bool armv7m_nvic_acknowledge_irq(void *opaque) { |