+extern void
+perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip);
+
+/*
+ * Take a snapshot of the regs. Skip ip and frame pointer to
+ * the nth caller. We only need a few of the regs:
+ * - ip for PERF_SAMPLE_IP
+ * - cs for user_mode() tests
+ * - bp for callchains
+ * - eflags, for future purposes, just in case
+ */
+static inline void perf_fetch_caller_regs(struct pt_regs *regs, int skip)
+{
+ unsigned long ip;
+
+ memset(regs, 0, sizeof(*regs));
+
+ switch (skip) {
+ case 1 :
+ ip = CALLER_ADDR0;
+ break;
+ case 2 :
+ ip = CALLER_ADDR1;
+ break;
+ case 3 :
+ ip = CALLER_ADDR2;
+ break;
+ case 4:
+ ip = CALLER_ADDR3;
+ break;
+ /* No need to support further for now */
+ default:
+ ip = 0;
+ }
+
+ return perf_arch_fetch_caller_regs(regs, ip, skip);
+}
+