[Xen-devel] [PATCH] x86/setup: do not relocate below the end of current Xen image placement

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

If it is possible we would like to have the Xen image higher than the
booloader put it and certainly do not overwrite the Xen code and data
during copy/relocation. Otherwise the Xen may crash silently at boot.

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
 xen/arch/x86/setup.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 32bb02e..be91d34 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -960,7 +960,13 @@ void __init noreturn __start_xen(unsigned long mbi_p)
         }
         else
             end = 0;
-        if ( end > s )
+
+        /*
+         * Is the region size greater than zero?
+         * Does the region begins above or at the
+         * end of current Xen image placement?
+         */
+        if ( end > s && (end - reloc_size >= _end - _start) )
         {
             l4_pgentry_t *pl4e;
             l3_pgentry_t *pl3e;
-- 
1.7.10.4


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