[Xen-devel] [PATCH 09/12] xen/arm: guest_walk: Avoid theoritical unitialized value in get_top_bit

[Julien Grall <julien.grall@xxxxxxx>]

Clang 8.0 throws an error in the get_top_bit function:

guest_walk.c:328:15: error: variable 'topbit' is used uninitialized
whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
    else if ( is_64bit_domain(d) )
              ^~~~~~~~~~~~~~~~~~

This is happening because clang thinks that is_32bit_domain(d) is not
the exact inverse of is_64bit_domain(d). So it expects a else case to
handle the case where the latter call is false.

In other part of the code, dealing with difference between 32-bit and
64-bit domain, we usually use if ( is_XXbit_domain ) ... else ...

So use the same pattern here.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/arm/guest_walk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/arm/guest_walk.c b/xen/arch/arm/guest_walk.c
index 7db7a7321b..1bee198777 100644
--- a/xen/arch/arm/guest_walk.c
+++ b/xen/arch/arm/guest_walk.c
@@ -325,7 +325,7 @@ static unsigned int get_top_bit(struct domain *d, vaddr_t 
gva, register_t tcr)
      */
     if ( is_32bit_domain(d) )
         topbit = 31;
-    else if ( is_64bit_domain(d) )
+    else
     {
         if ( ((gva & BIT_ULL(55)) && (tcr & TCR_EL1_TBI1)) ||
              (!(gva & BIT_ULL(55)) && (tcr & TCR_EL1_TBI0)) )
-- 
2.11.0


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