xen: check for kernel memory conflicting with memory layout

Checks whether the pre-allocated memory of the loaded kernel is in
conflict with the target memory map. If this is the case, just panic
instead of run into problems later, as there is nothing we can do
to repair this situation.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
(cherry picked from commit 808fdb71936c41d46245f0e3aa6ec889cba70d97)
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 973d29441f965025be794e0f0650940be7422b58..9bd3f358f3d9963195fcde74d3622505b92f3ada 100644 (file)
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -27,6 +27,7 @@
 #include <xen/interface/memory.h>
 #include <xen/interface/physdev.h>
 #include <xen/features.h>
+#include <xen/hvc-console.h>
 #include "xen-ops.h"
 #include "vdso.h"
 #include "p2m.h"
@@ -790,6 +791,17 @@ char * __init xen_memory_setup(void)
 
        sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
 
+       /*
+        * Check whether the kernel itself conflicts with the target E820 map.
+        * Failing now is better than running into weird problems later due
+        * to relocating (and even reusing) pages with kernel text or data.
+        */
+       if (xen_is_e820_reserved(__pa_symbol(_text),
+                       __pa_symbol(__bss_stop) - __pa_symbol(_text))) {
+               xen_raw_console_write("Xen hypervisor allocated kernel memory conflicts with E820 map\n");
+               BUG();
+       }
+
        xen_reserve_xen_mfnlist();
 
        /*