powerpc: Check return value of instance-to-package OF call

On PA-Semi firmware, the instance-to-package callback doesn't seem
to be implemented. We didn't check for error, however, thus
subsequently passed the -1 value returned into stdout_node to
thins like prom_getprop etc...

Thus caused the firmware to load values around 0 (physical) internally
as node structures. It somewhat "worked" as long as we had a NULL in the
right place (address 8) at the beginning of the kernel, we didn't "see"
the bug. But commit 5c0484e25ec03243d4c2f2d4416d4a13efc77f6a
"powerpc: Endian safe trampoline" changed the kernel entry point causing
that old bug to now cause a crash early during boot.

This fixes booting on PA-Semi board by properly checking the return
value from instance-to-package.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Olof Johansson <olof@lixom.net>
---

1 files changed, 13 insertions, 9 deletions

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index cb64a6e1dc51..078145acf7fb 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -1986,19 +1986,23 @@ static void __init prom_init_stdout(void)
         /* Get the full OF pathname of the stdout device */
         memset(path, 0, 256);
         call_prom("instance-to-path", 3, 1, prom.stdout, path, 255);
-        stdout_node = call_prom("instance-to-package", 1, 1, prom.stdout);
-        val = cpu_to_be32(stdout_node);
-        prom_setprop(prom.chosen, "/chosen", "linux,stdout-package",
-                     &val, sizeof(val));
         prom_printf("OF stdout device is: %s\n", of_stdout_device);
         prom_setprop(prom.chosen, "/chosen", "linux,stdout-path",
                      path, strlen(path) + 1);
 
-        /* If it's a display, note it */
-        memset(type, 0, sizeof(type));
-        prom_getprop(stdout_node, "device_type", type, sizeof(type));
-        if (strcmp(type, "display") == 0)
-                prom_setprop(stdout_node, path, "linux,boot-display", NULL, 0);
+        /* instance-to-package fails on PA-Semi */
+        stdout_node = call_prom("instance-to-package", 1, 1, prom.stdout);
+        if (stdout_node != PROM_ERROR) {
+                val = cpu_to_be32(stdout_node);
+                prom_setprop(prom.chosen, "/chosen", "linux,stdout-package",
+                             &val, sizeof(val));
+
+                /* If it's a display, note it */
+                memset(type, 0, sizeof(type));
+                prom_getprop(stdout_node, "device_type", type, sizeof(type));
+                if (strcmp(type, "display") == 0)
+                        prom_setprop(stdout_node, path, "linux,boot-display", NULL, 0);
+        }
 }
 
 static int __init prom_find_machine_type(void)