[Qemu-devel] Fix a bug in debug printing of memory translation tables

[Mikhail Ilin]

Hi,

I've enabled DEBUG_MMAP in linux-user/mmap.c and got debug info of memory
layout.

This is the debug output of guest memory layout from qemu (including
the last mmap call marked with *).

mmap: start=0x0804a000 len=0x00021000 prot=rw- flags=MAP_ANON 
MAP_PRIVATE fd=0 offset=00000000
ret=0x0804a000
  start    end      size     prot
  00048000-00049000 00001000 r-x
* 00049000-0006b000 00022000 rw-
  002f6400-002f7400 00001000 rw-
  002f7400-003ff400 00108000 r-x
  003ff400-003ff400 00000000 r--
  003ff400-003f6400 ffff7000 rw-
  003fe400-003ff400 00001000 rw-
  003ff400-003ff400 00000000 r-x
  003ff400-003fe400 fffff000 r--
  003fe400-003ff400 00001000 rw-
  003ff400-000f6800 ffcf7400 ---
  000f6800-000f7000 00000800 rw-

It looks completely insane with weird records where the start is bigger
than the end, the size is likely negative and in general all addresses are
in wrong boundaries.

Found a bug in the function which textualize memory translation tables. Made
a fix. Now I have the following output:

mmap: start=0x0804a000 len=0x00021000 prot=rw- flags=MAP_ANON 
MAP_PRIVATE fd=0 offset=00000000
ret=0x0804a000
  start    end      size     prot
  08048000-08049000 00001000 r-x
* 08049000-0806b000 00022000 rw-
  f6612000-f6615000 00003000 rw-
  f6615000-f67bb000 001a6000 r-x
  f67bb000-f67bd000 00002000 r--
  f67bd000-f67c2000 00005000 rw-
  f67da000-f67dd000 00003000 rw-
  f67dd000-f67fd000 00020000 r-x
  f67fd000-f67fe000 00001000 r--
  f67fe000-f67ff000 00001000 rw-
  f67ff000-f6800000 00001000 ---

This looks much better.

From 297045c6e7da0089c6ea4ee271000c507c5a8bf8 Mon Sep 17 00:00:00 2001
From: Mikhail Ilyin <address@hidden>
Date: Wed, 23 Jul 2014 13:06:15 +0400
Subject: [PATCH] Fix a bug in debug printing of memory translation tables.

Signed-off-by: Mikhail Ilyin <address@hidden>
---
 translate-all.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/translate-all.c b/translate-all.c
index 8f7e11b..cb7a33d 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -1728,9 +1728,8 @@ int walk_memory_regions(void *priv, 
walk_memory_regions_fn fn)
     data.prot = 0;

     for (i = 0; i < V_L1_SIZE; i++) {
-        int rc = walk_memory_regions_1(&data, (abi_ulong)i << V_L1_SHIFT,
+        int rc = walk_memory_regions_1(&data, (abi_ulong)i << 
(V_L1_SHIFT + TARGET_PAGE_BITS),
                                        V_L1_SHIFT / V_L2_BITS - 1, 
l1_map + i);
-
         if (rc != 0) {
             return rc;
         }
--
1.9.1