struct vdso_per_cpu_data {
__u64 ectg_timer_base;
__u64 ectg_user_time;
- __u32 cpu_nr;
- __u32 node_id;
+ /*
+ * Note: node_id and cpu_nr must be at adjacent memory locations.
+ * VDSO userspace must read both values with a single instruction.
+ */
+ union {
+ __u64 getcpu_val;
+ struct {
+ __u32 node_id;
+ __u32 cpu_nr;
+ };
+ };
};
extern struct vdso_data *vdso_data;
OFFSET(__VDSO_TS_END, vdso_data, ts_end);
OFFSET(__VDSO_ECTG_BASE, vdso_per_cpu_data, ectg_timer_base);
OFFSET(__VDSO_ECTG_USER, vdso_per_cpu_data, ectg_user_time);
- OFFSET(__VDSO_CPU_NR, vdso_per_cpu_data, cpu_nr);
- OFFSET(__VDSO_NODE_ID, vdso_per_cpu_data, node_id);
+ OFFSET(__VDSO_GETCPU_VAL, vdso_per_cpu_data, getcpu_val);
BLANK();
/* constants used by the vdso */
DEFINE(__CLOCK_REALTIME, CLOCK_REALTIME);
.type __kernel_getcpu,@function
__kernel_getcpu:
CFI_STARTPROC
- la %r4,0
sacf 256
- l %r5,__VDSO_CPU_NR(%r4)
- l %r4,__VDSO_NODE_ID(%r4)
+ lm %r4,%r5,__VDSO_GETCPU_VAL(%r0)
sacf 0
ltr %r2,%r2
jz 2f
.type __kernel_getcpu,@function
__kernel_getcpu:
CFI_STARTPROC
- la %r4,0
sacf 256
- l %r5,__VDSO_CPU_NR(%r4)
- l %r4,__VDSO_NODE_ID(%r4)
+ lm %r4,%r5,__VDSO_GETCPU_VAL(%r0)
sacf 0
ltgr %r2,%r2
jz 2f