[PATCH] xen/arm64: check XSM Magic and Signature from the second unknown module.

[fu.wei@linaro.org]

From: Fu Wei <fu.wei@linaro.org>

This patch add a check_xsm_signature static function for detecting XSM
from the second unknown module.

If xen can't get the kind of module from compatible, we guess the kind of
these first two unknown respectively:
    (1) The first unknown must be kernel;
    (2) The second unknown is ramdisk, only if we have ramdisk;
    (3) Start from the 2nd unknown, detect the XSM binary signature;
    (4) If we got XSM in the 2nd unknown, that means we don't load initrd.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
---
ChangeLog:
v1: This patch - the first upstream patch to xen-devel mailing lists.

 xen/arch/arm/bootfdt.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
index 8a14015..1a74ecf 100644
--- a/xen/arch/arm/bootfdt.c
+++ b/xen/arch/arm/bootfdt.c
@@ -163,6 +163,36 @@ static void __init process_memory_node(const void *fdt, int node,
     }
 }
 
+static bool __init check_xsm_signature(const void *fdt, int node,
+                                       const char *name,
+                                       u32 address_cells, u32 size_cells)
+{
+    uint32_t selinux_magic = 0xf97cff8c;
+    const struct fdt_property *prop;
+    paddr_t start, size;
+    const __be32 *cell;
+    /* 16 == sizeof(uint32_t) * 2 + sizeof("XenFlask") - 1 */
+    char magic[16];
+    int len;
+
+    prop = fdt_get_property(fdt, node, "reg", &len);
+    if ( !prop )
+        panic("node %s missing `reg' property\n", name);
+
+    if ( len < dt_cells_to_size(address_cells + size_cells) )
+        panic("fdt: node `%s': `reg` property length is too short\n", name);
+
+    cell = (const __be32 *)prop->data;
+    device_tree_get_reg(&cell, address_cells, size_cells, &start, &size);
+
+    copy_from_paddr(magic, start, 16);
+    if (strncmp(magic, (char *) &selinux_magic, sizeof(uint32_t)) ||
+        strncmp(magic + sizeof(uint32_t) * 2, "XenFlask", 8))
+        return 0;
+
+    return 1;
+}
+
 static void __init process_multiboot_node(const void *fdt, int node,
                                           const char *name,
                                           u32 address_cells, u32 size_cells)
@@ -186,7 +216,13 @@ static void __init process_multiboot_node(const void *fdt, int node,
     else
         kind = BOOTMOD_UNKNOWN;
 
-    /* Guess that first two unknown are kernel and ramdisk respectively. */
+    /**
+     * Guess the kind of these first two unknown respectively:
+     * (1) The first unknown must be kernel;
+     * (2) The second unknown is ramdisk, only if we have ramdisk;
+     * (3) Start from the 2nd unknown, detect the XSM binary signature;
+     * (4) If we got XSM in the 2nd unknown, that means we have not initrd.
+     */
     if ( kind == BOOTMOD_UNKNOWN )
     {
         switch ( kind_guess++ )
@@ -195,6 +231,9 @@ static void __init process_multiboot_node(const void *fdt, int node,
         case 1: kind = BOOTMOD_RAMDISK; break;
         default: break;
         }
+        if (kind_guess > 1 && check_xsm_signature(fdt, node, name,
+                                                  address_cells, size_cells))
+            kind = BOOTMOD_XSM;
     }
 
     prop = fdt_get_property(fdt, node, "reg", &len);
-- 
2.5.0


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