hw/hppa: Move software power button address back into PDC

The various operating systems (e.g. Linux, NetBSD) have issues
mapping the power button when it's stored in page zero.
NetBSD even crashes, because it fails to map that page and then
accesses unmapped memory.

Since we now have a consistent memory mapping of PDC in 32-bit
and 64-bit address space (the lower 32-bits of the address are in
sync) the power button can be moved back to PDC space.

This patch fixes the power button on Linux, NetBSD and HP-UX.

Signed-off-by: Helge Deller <deller@gmx.de>

hw/hppa/machine.c

@@ -36,16 +36,15 @@
 
 #define MIN_SEABIOS_HPPA_VERSION 12 /* require at least this fw version */
 
-/* Power button address at &PAGE0->pad[4] */
-#define HPA_POWER_BUTTON (0x40 + 4 * sizeof(uint32_t))
+#define HPA_POWER_BUTTON        (FIRMWARE_END - 0x10)
+static hwaddr soft_power_reg;
 
 #define enable_lasi_lan()       0
 
 static DeviceState *lasi_dev;
 
 static void hppa_powerdown_req(Notifier *n, void *opaque)
 {
-    hwaddr soft_power_reg = HPA_POWER_BUTTON;
     uint32_t val;
 
     val = ldl_be_phys(&address_space_memory, soft_power_reg);
@@ -221,7 +220,7 @@ static FWCfgState *create_fw_cfg(MachineState *ms, PCIBus *pci_bus,
     fw_cfg_add_file(fw_cfg, "/etc/hppa/machine",
                     g_memdup(mc->name, len), len);
 
-    val = cpu_to_le64(HPA_POWER_BUTTON);
+    val = cpu_to_le64(soft_power_reg);
     fw_cfg_add_file(fw_cfg, "/etc/hppa/power-button-addr",
                     g_memdup(&val, sizeof(val)), sizeof(val));
 
@@ -295,6 +294,8 @@ static TranslateFn *machine_HP_common_init_cpus(MachineState *machine)
         ram_max = 0xf0000000;      /* 3.75 GB (32-bit CPU) */
     }
 
+    soft_power_reg = translate(NULL, HPA_POWER_BUTTON);
+
     for (unsigned int i = 0; i < smp_cpus; i++) {
         g_autofree char *name = g_strdup_printf("cpu%u-io-eir", i);