path: root/target/arm/cpu.c
diff options
authorPeter Maydell <peter.maydell@linaro.org>2017-02-20 14:04:41 +0000
committerPeter Maydell <peter.maydell@linaro.org>2017-02-20 14:04:41 +0000
commit6cbf97bf937743974938464d11f5dcd0366d0709 (patch)
tree2cec3986628a27a8f39962a00334be0fc84a1e19 /target/arm/cpu.c
parentb6a915dec8706e427f75231c8fc1ee728a1cef02 (diff)
armv7m: Fix condition check for taking exceptions
The M profile condition for when we can take a pending exception or interrupt is not the same as that for A/R profile. The code originally copied from the A/R profile version of the cpu_exec_interrupt function only worked by chance for the very simple case of exceptions being masked by PRIMASK. Replace it with a call to a function in the NVIC code that correctly compares the priority of the pending exception against the current execution priority of the CPU. [Michael Davidsaver's patchset had a patch to do something similar but the implementation ended up being a rewrite.] Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Diffstat (limited to 'target/arm/cpu.c')
1 files changed, 8 insertions, 8 deletions
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 4a069f6985..edbc87b889 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -338,13 +338,6 @@ static bool arm_v7m_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
CPUARMState *env = &cpu->env;
bool ret = false;
- if (interrupt_request & CPU_INTERRUPT_FIQ
- && !(env->daif & PSTATE_F)) {
- cs->exception_index = EXCP_FIQ;
- cc->do_interrupt(cs);
- ret = true;
- }
/* ARMv7-M interrupt return works by loading a magic value
* into the PC. On real hardware the load causes the
* return to occur. The qemu implementation performs the
@@ -354,9 +347,16 @@ static bool arm_v7m_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
* the stack if an interrupt occurred at the wrong time.
* We avoid this by disabling interrupts when
* pc contains a magic address.
+ *
+ * ARMv7-M interrupt masking works differently than -A or -R.
+ * There is no FIQ/IRQ distinction. Instead of I and F bits
+ * masking FIQ and IRQ interrupts, an exception is taken only
+ * if it is higher priority than the current execution priority
+ * (which depends on state like BASEPRI, FAULTMASK and the
+ * currently active exception).
if (interrupt_request & CPU_INTERRUPT_HARD
- && !(env->daif & PSTATE_I)
+ && (armv7m_nvic_can_take_pending_exception(env->nvic))
&& (env->regs[15] < 0xfffffff0)) {
cs->exception_index = EXCP_IRQ;