[XEN v4 09/11] xen/arm: Restrict zeroeth_table_offset for ARM_64

[Ayan Kumar Halder <ayan.kumar.halder@amd.com>]

When 32 bit physical addresses are used (ie ARM_PA_32=y),
"va >> ZEROETH_SHIFT" causes an overflow.
Also, there is no zeroeth level page table on Arm 32-bit.

Also took the opportunity to clean up dump_pt_walk(). One could use
DECLARE_OFFSETS() macro instead of declaring the declaring an array
of page table offsets.

Acked-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
---
Changes from -

v1 - Removed the duplicate declaration for DECLARE_OFFSETS.

v2 - 1. Reworded the commit message. 
2. Use CONFIG_ARM_PA_32 to restrict zeroeth_table_offset.

v3 - 1. Added R-b and Ack.

 xen/arch/arm/include/asm/lpae.h | 4 ++++
 xen/arch/arm/mm.c               | 7 +------
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/include/asm/lpae.h b/xen/arch/arm/include/asm/lpae.h
index 3fdd5d0de2..0d40388f93 100644
--- a/xen/arch/arm/include/asm/lpae.h
+++ b/xen/arch/arm/include/asm/lpae.h
@@ -259,7 +259,11 @@ lpae_t mfn_to_xen_entry(mfn_t mfn, unsigned int attr);
 #define first_table_offset(va)  TABLE_OFFSET(first_linear_offset(va))
 #define second_table_offset(va) TABLE_OFFSET(second_linear_offset(va))
 #define third_table_offset(va)  TABLE_OFFSET(third_linear_offset(va))
+#ifdef CONFIG_ARM_PA_BITS_32
+#define zeroeth_table_offset(va)  0
+#else
 #define zeroeth_table_offset(va)  TABLE_OFFSET(zeroeth_linear_offset(va))
+#endif
 
 /*
  * Macros to define page-tables:
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index d8b43ef38c..41e0896b0f 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -221,12 +221,7 @@ void dump_pt_walk(paddr_t ttbr, paddr_t addr,
 {
     static const char *level_strs[4] = { "0TH", "1ST", "2ND", "3RD" };
     const mfn_t root_mfn = maddr_to_mfn(ttbr);
-    const unsigned int offsets[4] = {
-        zeroeth_table_offset(addr),
-        first_table_offset(addr),
-        second_table_offset(addr),
-        third_table_offset(addr)
-    };
+    DECLARE_OFFSETS(offsets, addr);
     lpae_t pte, *mapping;
     unsigned int level, root_table;
 
-- 
2.17.1