diff options
Diffstat (limited to 'arch/x86/include/asm/xen/page.h')
| -rw-r--r-- | arch/x86/include/asm/xen/page.h | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index b54a3d20d6b2..5eea09915a15 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -60,6 +60,20 @@ extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn); /* + * Helper functions to write or read unsigned long values to/from + * memory, when the access may fault. + */ +static inline int xen_safe_write_ulong(unsigned long *addr, unsigned long val) +{ + return __put_user(val, (unsigned long __user *)addr); +} + +static inline int xen_safe_read_ulong(unsigned long *addr, unsigned long *val) +{ + return __get_user(*val, (unsigned long __user *)addr); +} + +/* * When to use pfn_to_mfn(), __pfn_to_mfn() or get_phys_to_machine(): * - pfn_to_mfn() returns either INVALID_P2M_ENTRY or the mfn. No indicator * bits (identity or foreign) are set. @@ -125,7 +139,7 @@ static inline unsigned long mfn_to_pfn_no_overrides(unsigned long mfn) * In such cases it doesn't matter what we return (we return garbage), * but we must handle the fault without crashing! */ - ret = __get_user(pfn, &machine_to_phys_mapping[mfn]); + ret = xen_safe_read_ulong(&machine_to_phys_mapping[mfn], &pfn); if (ret < 0) return ~0; |