ppc/vof: Make nextprop behave more like Open Firmware

The FDT does not normally store name properties but reconstructs it
from path but Open Firmware specification says each node should at
least have this property. This is correctly handled in getprop but
nextprop should also return it even if not present as a property.

Explicit name properties are still allowed because they are needed
e.g. on the root node that guests expect to have specific names as
seen on real machines instead of being empty so sometimes the node
name may need to be overriden. For example on pegasos MorphOS checks
the name of "/" and expects to find bplan,Pegasos2 which is how it
identifies the machine.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Link: https://lore.kernel.org/qemu-devel/366f14ce852415cc079727c54ac21a2aa6ff3917.1761176219.git.balaton@eik.bme.hu
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>

diff --git a/hw/ppc/vof.c b/hw/ppc/vof.c
index f14efa3a7c80662070c82abf240613fd17eb4e04..5ecfc6891047eb63f498fe286d57f52a54c0a0db 100644 (file)
--- a/hw/ppc/vof.c
+++ b/hw/ppc/vof.c
@@ -353,34 +353,50 @@ static uint32_t vof_nextprop(const void *fdt, uint32_t phandle,
 {
     int offset, nodeoff = fdt_node_offset_by_phandle(fdt, phandle);
     char prev[OF_PROPNAME_LEN_MAX + 1];
-    const char *tmp;
+    const char *tmp = NULL;
+    bool match = false;
 
     if (readstr(prevaddr, prev, sizeof(prev))) {
         return PROM_ERROR;
     }
-
-    fdt_for_each_property_offset(offset, fdt, nodeoff) {
-        if (!fdt_getprop_by_offset(fdt, offset, &tmp, NULL)) {
-            return 0;
+    /*
+     * "name" may or may not be present in fdt but we should still return it.
+     * Do that first and then skip it if seen later.
+     */
+    if (prev[0] == '\0') {
+        tmp = "name";
+    } else {
+        if (strcmp(prev, "name") == 0) {
+            prev[0] = '\0';
         }
-        if (prev[0] == '\0' || strcmp(prev, tmp) == 0) {
-            if (prev[0] != '\0') {
-                offset = fdt_next_property_offset(fdt, offset);
-                if (offset < 0) {
-                    return 0;
-                }
-            }
+        fdt_for_each_property_offset(offset, fdt, nodeoff) {
             if (!fdt_getprop_by_offset(fdt, offset, &tmp, NULL)) {
                 return 0;
             }
-
-            if (VOF_MEM_WRITE(nameaddr, tmp, strlen(tmp) + 1) != MEMTX_OK) {
-                return PROM_ERROR;
+            if (strcmp(tmp, "name") == 0) {
+                continue;
+            }
+            if (match) {
+                break;
             }
-            return 1;
+            if (strcmp(prev, tmp) == 0) {
+                match = true;
+                continue;
+            }
+            if (prev[0] == '\0') {
+                break;
+            }
+        }
+        if (offset < 0) {
+            return 0;
         }
     }
-
+    if (tmp) {
+        if (VOF_MEM_WRITE(nameaddr, tmp, strlen(tmp) + 1) != MEMTX_OK) {
+            return PROM_ERROR;
+        }
+        return 1;
+    }
     return 0;
 }