[Xen-devel] [PATCH v3 5/6] xen: arm: ensure that the boot code is <4K in size

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

This avoids having to deal with the 1:1 boot mapping crossing a
section or page boundary.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
v3: Use GLOBAL()
v2: New patch #5/4
---
 xen/arch/arm/arm32/head.S |    2 ++
 xen/arch/arm/arm64/head.S |    2 ++
 xen/arch/arm/xen.lds.S    |    6 ++++++
 3 files changed, 10 insertions(+)

diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
index afb4c6d..14b172f 100644
--- a/xen/arch/arm/arm32/head.S
+++ b/xen/arch/arm/arm32/head.S
@@ -457,6 +457,8 @@ fail:   PRINT("- Boot failed -\r\n")
 1:      wfe
         b     1b
 
+GLOBAL(_end_boot)
+
 /* Copy Xen to new location and switch TTBR
  * r1:r0       ttbr
  * r2          source address
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index 4e22374..9497ca1 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -487,6 +487,8 @@ fail:   PRINT("- Boot failed -\r\n")
 1:      wfe
         b     1b
 
+GLOBAL(_end_boot)
+
 /* Copy Xen to new location and switch TTBR
  * x0    ttbr
  * x1    source address
diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
index be55dad..079e085 100644
--- a/xen/arch/arm/xen.lds.S
+++ b/xen/arch/arm/xen.lds.S
@@ -178,3 +178,9 @@ SECTIONS
   .stab.indexstr 0 : { *(.stab.indexstr) }
   .comment 0 : { *(.comment) }
 }
+
+/*
+ * We require that Xen is loaded at a 4K boundary, so this ensures that any
+ * code running on the boot time identity map cannot cross a section boundary.
+ */
+ASSERT( _end_boot - start <= PAGE_SIZE, "Boot code is larger than 4K")
-- 
1.7.10.4


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