[Xen-devel] [PATCH 25/27] xen/arm: mm: Embed permission in the flags

[Julien Grall <julien.grall@xxxxxxx>]

Currently, it is not possible to specify the permission of a new
mapping. It would be necessary to use the function modify_xen_mappings
with a different set of flags.

Add introduce a couple of new flags for the permissions (Non-eXecutable,
Read-Only) and also provides define that combine the memory attribute
and permission for common combination.

A follow-up patch will change modify_xen_mappings to use the new flags.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/include/asm-arm/page.h | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index 1bf8e9d012..047220f86b 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -67,12 +67,28 @@
  * Layout of the flags used for updating the hypervisor page tables
  *
  * [0:2] Memory Attribute Index
+ * [3:4] Permission flags
  */
 #define PAGE_AI_MASK(x) ((x) & 0x7U)
 
-#define PAGE_HYPERVISOR         (MT_NORMAL)
-#define PAGE_HYPERVISOR_NOCACHE (MT_DEVICE_nGnRE)
-#define PAGE_HYPERVISOR_WC      (MT_NORMAL_NC)
+#define _PAGE_XN_BIT    3
+#define _PAGE_RO_BIT    4
+#define _PAGE_XN    (1U << _PAGE_XN_BIT)
+#define _PAGE_RO    (1U << _PAGE_RO_BIT)
+#define PAGE_XN_MASK(x) (((x) >> _PAGE_XN_BIT) & 0x1U)
+#define PAGE_RO_MASK(x) (((x) >> _PAGE_RO_BIT) & 0x1U)
+
+/* Device memory will always be mapped read-write non-executable. */
+#define _PAGE_DEVICE    _PAGE_XN
+#define _PAGE_NORMAL    MT_NORMAL
+
+#define PAGE_HYPERVISOR_RO      (_PAGE_NORMAL|_PAGE_RO|_PAGE_XN)
+#define PAGE_HYPERVISOR_RX      (_PAGE_NORMAL|_PAGE_RO)
+#define PAGE_HYPERVISOR_RW      (_PAGE_NORMAL|_PAGE_XN)
+
+#define PAGE_HYPERVISOR         PAGE_HYPERVISOR_RW
+#define PAGE_HYPERVISOR_NOCACHE (_PAGE_DEVICE|MT_DEVICE_nGnRE)
+#define PAGE_HYPERVISOR_WC      (_PAGE_DEVICE|MT_NORMAL_NC)
 
 /*
  * Defines for changing the hypervisor PTE .ro and .nx bits. This is only to be
-- 
2.11.0


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