[Xen-devel] [PATCH] xen/arm64: Avoid trying to map of paddr(start) as a block entry in boot_pgtable

[Chen Baozi <baozich@xxxxxxxxx>]

Block entries are only supported after first-level table. Since the physical
address of 'start' is usally less than 512GB, this section of codes wouldn't
be executed and therefore useless. Remove this part of codes to avoid
potiential bug if it tries to map paddr(start) as a level-0 block entry by
accident.

Thus, we need to specified that xen image should be loaded at the address less
than 512GB.

Signed-off-by: Chen Baozi <baozich@xxxxxxxxx>
---
 xen/arch/arm/arm64/head.S | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index 31afdd0..bebddf0 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -266,18 +266,7 @@ skip_bss:
         orr   x2, x1, x3             /*       + rights for linear PT */
         str   x2, [x4, #0]           /* Map it in slot 0 */
 
-        /* ... map of paddr(start) in boot_pgtable */
-        lsr   x1, x19, #39           /* Offset of base paddr in boot_pgtable */
-        cbz   x1, 1f                 /* It's in slot 0, map in boot_first
-                                      * or boot_second later on */
-
-        lsl   x2, x1, #39            /* Base address for 512GB mapping */
-        mov   x3, #PT_MEM            /* x2 := Section mapping */
-        orr   x2, x2, x3
-        lsl   x1, x1, #3             /* x1 := Slot offset */
-        str   x2, [x4, x1]           /* Mapping of paddr(start)*/
-
-1:      /* Setup boot_first: */
+        /* Setup boot_first: */
         ldr   x4, =boot_first        /* Next level into boot_first */
         add   x4, x4, x20            /* x4 := paddr(boot_first) */
 
-- 
1.8.4.3


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