[Xen-devel] [PATCH] xen/arm: add warning if memory modules overlap

[Brian Woods <brian.woods@xxxxxxxxxx>]

It's possible for a misconfigured device tree to cause Xen to crash when
there are overlapping addresses in the memory modules.  Add a warning
when printing the addresses to let the user know there's a possible
issue when DEBUG is enabled.

Signed-off-by: Brian Woods <brian.woods@xxxxxxxxxx>
---
sample output:
...
(XEN) MODULE[0]: 0000000001400000 - 000000000153b8f1 Xen         
(XEN) MODULE[1]: 00000000076d2000 - 00000000076dc080 Device Tree 
(XEN) MODULE[2]: 00000000076df000 - 0000000007fff364 Ramdisk     
(XEN) MODULE[3]: 0000000000080000 - 0000000003180000 Kernel      
(XEN)  RESVD[0]: 00000000076d2000 - 00000000076dc000
(XEN)  RESVD[1]: 00000000076df000 - 0000000007fff364
(XEN) 
(XEN) WARNING: modules Xen          and Kernel       overlap
(XEN) 
(XEN) Command line: console=dtuart dtuart=serial0 dom0_mem=1G bootscrub=0 
maxcpus=1 timer_slop=0
...

 xen/arch/arm/bootfdt.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
index 08fb59f..3cb0c43 100644
--- a/xen/arch/arm/bootfdt.c
+++ b/xen/arch/arm/bootfdt.c
@@ -387,6 +387,23 @@ static void __init early_print_info(void)
                mem_resv->bank[j].start + mem_resv->bank[j].size - 1);
     }
     printk("\n");
+
+#ifndef NDEBUG
+    /*
+     * Assuming all combinations are checked, only the starting address
+     * has to be checked if it's in another memory module's range.
+     */
+    for ( i = 0 ; i < mods->nr_mods; i++ )
+        for ( j = 0 ; j < mods->nr_mods; j++ )
+            if ( (i != j) &&
+                 (mods->module[i].start >= mods->module[j].start) &&
+                 (mods->module[i].start <
+                  mods->module[j].start + mods->module[j].size) )
+                printk("WARNING: modules %-12s and %-12s overlap\n",
+                       boot_module_kind_as_string(mods->module[i].kind),
+                       boot_module_kind_as_string(mods->module[j].kind));
+#endif
+
     for ( i = 0 ; i < cmds->nr_mods; i++ )
         printk("CMDLINE[%"PRIpaddr"]:%s %s\n", cmds->cmdline[i].start,
                cmds->cmdline[i].dt_name,
-- 
2.7.4


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