2014-12-05 06:16:40

by Jürgen Groß

Subject: [PATCH] xen: fix sparse warning in p2m.c

The patch "Speed up set_phys_to_machine() by using read-only mappings"
introduced a sparse warning:

arch/x86/xen/p2m.c:628:13: sparse: incorrect type in argument 1
(different address spaces)

Avoid the warning.

Signed-off-by: Juergen Gross <[email protected]>
---
arch/x86/xen/p2m.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 8b5db51..2defca9 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -615,6 +615,7 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
pte_t *ptep;
unsigned int level;
+ unsigned long __user *addr;

/* don't track P2M changes in autotranslate guests */
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
@@ -625,7 +626,8 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
return true;
}

- if (likely(!__put_user(mfn, xen_p2m_addr + pfn)))
+ addr = (unsigned long __user *)xen_p2m_addr + pfn;
+ if (likely(!__put_user(mfn, addr)))
return true;

ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
--
2.1.2

2014-12-05 10:43:16

by David Vrabel

Subject: Re: [Xen-devel] [PATCH] xen: fix sparse warning in p2m.c

On 05/12/14 06:16, Juergen Gross wrote:
> The patch "Speed up set_phys_to_machine() by using read-only mappings"
> introduced a sparse warning:
>
> arch/x86/xen/p2m.c:628:13: sparse: incorrect type in argument 1
> (different address spaces)
>
> Avoid the warning.

Thanks.

But can you add some helper functions instead? Perhaps:

static inline int xen_safe_write_ulong(unsigned long *addr,
unsigned long val)
{
//...
}

static inline int xen_safe_read_ulong(unsigned long *addr,
unsigned long *val)
{
//...
}

David