diff options
Diffstat (limited to 'os/ports/GCC/ARMCMx/chcore_v6m.c')
| -rw-r--r-- | os/ports/GCC/ARMCMx/chcore_v6m.c | 54 |
1 files changed, 24 insertions, 30 deletions
diff --git a/os/ports/GCC/ARMCMx/chcore_v6m.c b/os/ports/GCC/ARMCMx/chcore_v6m.c index 4e49e6256..5004b2256 100644 --- a/os/ports/GCC/ARMCMx/chcore_v6m.c +++ b/os/ports/GCC/ARMCMx/chcore_v6m.c @@ -28,11 +28,6 @@ #include "ch.h"
/**
- * @brief PC register temporary storage.
- */
-regarm_t _port_saved_pc;
-
-/**
* @brief System Timer vector.
* @details This interrupt is used as system tick.
* @note The timer must be initialized in the startup code.
@@ -49,39 +44,38 @@ CH_IRQ_HANDLER(SysTickVector) { }
/**
+ * @brief NMI vector.
+ * @details The NMI vector is used for exception mode re-entering after a
+ * context switch.
+ */
+void NMIVector(void) {
+ register struct extctx *ctxp;
+
+ /* Discarding the current exception context and positioning the stack to
+ point to the real one.*/
+ asm volatile ("mrs %0, PSP" : "=r" (ctxp) : : "memory");
+ ctxp++;
+ asm volatile ("msr PSP, %0" : : "r" (ctxp) : "memory");
+ port_unlock_from_isr();
+}
+
+/**
* @brief Post-IRQ switch code.
- * @details On entry the stack and the registers are restored by the exception
- * return, the PC value is stored in @p _port_saved_pc, the interrupts
- * are disabled.
+ * @details The switch is performed in thread context then an NMI exception
+ * is enforced in order to return to the exact point before the
+ * preemption.
*/
#if !defined(__DOXYGEN__)
__attribute__((naked))
#endif
void _port_switch_from_isr(void) {
- /* Note, saves r4 to make space for the PC.*/
- asm volatile ("push {r0, r1, r2, r3, r4} \n\t"
- "mrs r0, APSR \n\t"
- "mov r1, r12 \n\t"
- "push {r0, r1, lr} \n\t"
- "ldr r0, =_port_saved_pc \n\t"
- "ldr r0, [r0] \n\t"
- "add r0, r0, #1 \n\t"
- "str r0, [sp, #28]" : : : "memory");
chSchDoRescheduleI();
-
- /* Note, the last register is restored alone after re-enabling the
- interrupts in order to minimize the (very remote and unlikely)
- possibility that the stack is filled by continuous and saturating
- interrupts that would not allow that last words to be pulled out of
- the stack.*/
- asm volatile ("pop {r0, r1, r2} \n\t"
- "mov r12, r1 \n\t"
- "msr APSR, r0 \n\t"
- "mov lr, r2 \n\t"
- "pop {r0, r1, r2, r3} \n\t"
- "cpsie i \n\t"
- "pop {pc}" : : : "memory");
+ SCB_ICSR = ICSR_NMIPENDSET;
+ /* The following loop should never be executed, the NMI will kick in
+ immediately.*/
+ while (TRUE)
+ ;
}
#define PUSH_CONTEXT(sp) { \
|