uint64_t entry;
uint64_t lowaddr;
int big_endian;
- MemoryRegion *hack = g_new(MemoryRegion, 1);
if (cpu_model == NULL) {
cpu_model = "cortex-m3";
}
}
- /* Hack to map an additional page of ram at the top of the address
- space. This stops qemu complaining about executing code outside RAM
- when returning from an exception. */
- memory_region_init_ram(hack, NULL, "armv7m.hack", 0x1000, &error_fatal);
- vmstate_register_ram_global(hack);
- memory_region_add_subregion(system_memory, 0xfffff000, hack);
-
qemu_register_reset(armv7m_reset, cpu);
return nvic;
}
}
#if !defined(CONFIG_USER_ONLY) || !defined(TARGET_AARCH64)
+static void arm_v7m_unassigned_access(CPUState *cpu, hwaddr addr,
+ bool is_write, bool is_exec, int opaque,
+ unsigned size)
+{
+ ARMCPU *arm = ARM_CPU(cpu);
+ CPUARMState *env = &arm->env;
+
+ /* 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 jump normally, then does the exception
+ * return by throwing a special exception when when the CPU tries to
+ * execute code at the magic address.
+ */
+ if (env->v7m.exception != 0 && addr >= 0xfffffff0 && is_exec) {
+ cpu->exception_index = EXCP_EXCEPTION_EXIT;
+ cpu_loop_exit(cpu);
+ }
+
+ /* In real hardware an attempt to access parts of the address space
+ * with nothing there will usually cause an external abort.
+ * However our QEMU board models are often missing device models where
+ * the guest can boot anyway with the default read-as-zero/writes-ignored
+ * behaviour that you get without a QEMU unassigned_access hook.
+ * So just return here to retain that default behaviour.
+ */
+}
+
static bool arm_v7m_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
{
CPUClass *cc = CPU_GET_CLASS(cs);
cc->do_interrupt = arm_v7m_cpu_do_interrupt;
#endif
+ cc->do_unassigned_access = arm_v7m_unassigned_access;
cc->cpu_exec_interrupt = arm_v7m_cpu_exec_interrupt;
}
break;
}
#else
- if (dc->pc >= 0xfffffff0 && arm_dc_feature(dc, ARM_FEATURE_M)) {
- /* We always get here via a jump, so know we are not in a
- conditional execution block. */
- gen_exception_internal(EXCP_EXCEPTION_EXIT);
- dc->is_jmp = DISAS_EXC;
- break;
+ if (arm_dc_feature(dc, ARM_FEATURE_M)) {
+ /* Branches to the magic exception-return addresses should
+ * already have been caught via the arm_v7m_unassigned_access hook,
+ * and never get here.
+ */
+ assert(dc->pc < 0xfffffff0);
}
#endif