bpf/samples: Fix PT_REGS_IP on s390x and use it

The files "sampleip_kern.c" and "trace_event_kern.c" directly access
"ctx->regs.ip" which is not available on s390x. Fix this and use the
PT_REGS_IP() macro instead.

Also fix the macro for s390x and use "psw.addr" from "pt_regs".

Reported-by: Zvonko Kosic <zvonko.kosic@de.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Michael Holzheu

samples/bpf/bpf_helpers.h

@@ -113,7 +113,7 @@ static int (*bpf_skb_under_cgroup)(void *ctx, void *map, int index) =
 #define PT_REGS_FP(x) ((x)->gprs[11]) /* Works only with CONFIG_FRAME_POINTER */
 #define PT_REGS_RC(x) ((x)->gprs[2])
 #define PT_REGS_SP(x) ((x)->gprs[15])
-#define PT_REGS_IP(x) ((x)->ip)
+#define PT_REGS_IP(x) ((x)->psw.addr)
 
 #elif defined(__aarch64__)
 

samples/bpf/sampleip_kern.c

@@ -25,7 +25,7 @@ int do_sample(struct bpf_perf_event_data *ctx)
 	u64 ip;
 	u32 *value, init_val = 1;
 
-	ip = ctx->regs.ip;
+	ip = PT_REGS_IP(&ctx->regs);
 	value = bpf_map_lookup_elem(&ip_map, &ip);
 	if (value)
 		*value += 1;

samples/bpf/trace_event_kern.c

@@ -50,7 +50,7 @@ int bpf_prog1(struct bpf_perf_event_data *ctx)
 	key.userstack = bpf_get_stackid(ctx, &stackmap, USER_STACKID_FLAGS);
 	if ((int)key.kernstack < 0 && (int)key.userstack < 0) {
 		bpf_trace_printk(fmt, sizeof(fmt), cpu, ctx->sample_period,
-				 ctx->regs.ip);
+				 PT_REGS_IP(&ctx->regs));
 		return 0;
 	}