[PATCH v2] xen/arm: ioremap_attr: return NULL is __vmap failed

[Julien Grall <julien.grall@linaro.org>]

Most of ioremap_* caller check if ioremap returns NULL. Actually, if the
physical address is non-aligned, Xen will return the pointer given by
__vmap plus the offset in the page. So if ioremap_* fails, the caller
will retrieve an non-NULL address and continue as if there was no error.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

---
    Changes in v2:
        - remove brackets for return
        - don't split declaration and initialisation of ptr
---
 xen/arch/arm/mm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 26c6768..d5b22a4 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -742,8 +742,12 @@ void *ioremap_attr(paddr_t pa, size_t len, unsigned int attributes)
     unsigned long pfn = PFN_DOWN(pa);
     unsigned int offs = pa & (PAGE_SIZE - 1);
     unsigned int nr = PFN_UP(offs + len);
+    void *ptr = __vmap(&pfn, nr, 1, 1, attributes);
 
-    return (__vmap(&pfn, nr, 1, 1, attributes) + offs);
+    if ( ptr == NULL )
+        return NULL;
+
+    return ptr + offs;
 }
 
 void *ioremap(paddr_t pa, size_t len)
-- 
1.8.3.1