PPC: Fix GDB read on code area for PPC6xx

On PPC 6xx, data and code have separated TLBs. Until now QEMU was only
looking at data TLBs, which is not good when GDB wants to read code.

This patch adds a second call to get_physical_address() with an
ACCESS_CODE type of access when the first call with ACCESS_INT fails.
Signed-off-by: NFabien Chouteau <chouteau@adacore.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-ppc/mmu_helper.c

@@ -1431,8 +1431,16 @@ hwaddr cpu_get_phys_page_debug(CPUPPCState *env, target_ulong addr)
     }
 
     if (unlikely(get_physical_address(env, &ctx, addr, 0, ACCESS_INT) != 0)) {
+
+        /* Some MMUs have separate TLBs for code and data. If we only try an
+         * ACCESS_INT, we may not be able to read instructions mapped by code
+         * TLBs, so we also try a ACCESS_CODE.
+         */
+        if (unlikely(get_physical_address(env, &ctx, addr, 0,
+                                          ACCESS_CODE) != 0)) {
             return -1;
         }
+    }
 
     return ctx.raddr & TARGET_PAGE_MASK;
 }