diff options
Diffstat (limited to 'xen/arch/x86/percpu.c')
-rw-r--r-- | xen/arch/x86/percpu.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/xen/arch/x86/percpu.c b/xen/arch/x86/percpu.c index e5450248ad..1c1dad9011 100644 --- a/xen/arch/x86/percpu.c +++ b/xen/arch/x86/percpu.c @@ -6,7 +6,14 @@ #include <xen/rcupdate.h> unsigned long __per_cpu_offset[NR_CPUS]; -#define INVALID_PERCPU_AREA (-(long)__per_cpu_start) + +/* + * Force uses of per_cpu() with an invalid area to attempt to access the + * middle of the non-canonical address space resulting in a #GP, rather than a + * possible #PF at (NULL + a little) which has security implications in the + * context of PV guests. + */ +#define INVALID_PERCPU_AREA (0x8000000000000000L - (long)__per_cpu_start) #define PERCPU_ORDER (get_order_from_bytes(__per_cpu_data_end-__per_cpu_start)) void __init percpu_init_areas(void) |