Re: [Linaro-uefi] [Xen-devel] [PATCH v4] xen/arm64: check XSM Magic from the second unknown module.

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On 05.04.16 at 15:38, fu.wei@linaro.org wrote:

--- a/xen/xsm/xsm_core.c +++ b/xen/xsm/xsm_core.c @@ -19,6 +19,8 @@ #ifdef CONFIG_XSM +#include <asm/setup.h>

This is not a good idea. Note how xsm_policy.c limits this inclusion to the CONFIG_HAS_DEVICE_TREE case only, which is the least that should be done here too.

@@ -109,6 +111,25 @@ int __init xsm_dt_init(void) return ret; }

+/**

• • has_xsm_magic - Check XSM Magic of the module header by phy address
• • A XSM module has a special header

• • ---

• • uint magic | uint target_len | uchar target[8] |
• • 0xf97cff8c | 8 | "XenFlask" |

• • ---

• • 0xf97cff8c is policy magic number (XSM_MAGIC).
• • Here we only check the "magic" of the module.
• */

+bool __init has_xsm_magic(paddr_t start) +{

• xsm_magic_t magic;
• copy_from_paddr(&magic, start, sizeof(magic) );
• return ( XSM_MAGIC && magic == XSM_MAGIC );

Is XSM_MAGIC == 0 possible here at all? And if it is, wouldn't it be better to avoid the copy_from_paddr() in that case?

Jan