[PATCH 1/2] perf sample_filter.bpf: Stop using vmlinux.h generated by bpftool, use CO-RE

[Arnaldo Carvalho de Melo]

Including linux/bpf.h and linux/perf_events.h we get the UAPI structs
and then define a subset  'struct perf_sample_data' with the fields we
use in this tool while using __attribute__((preserve_access_index)) so
that at libbpf load time it can fixup the offsets according to the
'struct perf_data_sample' obtained from the running kernel BTF
(/sys/kernel/btf/vmlinux).

Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/bpf_skel/sample_filter.bpf.c | 37 +++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c
index cffe493af1ed5f31..045532c2366d74ef 100644
--- a/tools/perf/util/bpf_skel/sample_filter.bpf.c
+++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c
@@ -1,12 +1,47 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (c) 2023 Google
-#include "vmlinux.h"
+#include <linux/bpf.h>
+#include <linux/perf_event.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include <bpf/bpf_core_read.h>
 
 #include "sample-filter.h"
 
+// non-UAPI kernel data structures, just the fields used in this tool,
+// preserving the access index so that libbpf can fixup offsets with the ones
+// used in the kernel when loading the BPF bytecode, if they differ from what
+// is used here.
+
+struct perf_sample_data {
+	__u64			 addr;
+	__u64			 period;
+	union perf_sample_weight weight;
+	__u64			 txn;
+	union perf_mem_data_src  data_src;
+	__u64			 ip;
+	struct {
+		__u32		 pid;
+		__u32		 tid;
+	} tid_entry;
+	__u64			 time;
+	__u64			 id;
+	struct {
+		__u32		 cpu;
+	} cpu_entry;
+	__u64			 phys_addr;
+	__u64			 data_page_size;
+	__u64			 code_page_size;
+} __attribute__((__aligned__(64))) __attribute__((preserve_access_index));
+
+struct bpf_perf_event_data_kern {
+	struct perf_sample_data *  data;
+	struct perf_event *        event;
+
+	/* size: 24, cachelines: 1, members: 3 */
+	/* last cacheline: 24 bytes */
+} __attribute__((preserve_access_index));
+
 /* BPF map that will be filled by user space */
 struct filters {
 	__uint(type, BPF_MAP_TYPE_ARRAY);
-- 
2.39.2