samples: bpf: Convert xdp_monitor_kern.o to XDP samples helper

We already moved all the functionality it provided in XDP samples helper
userspace and kernel BPF object, so just delete the unneeded code.

We also add generation of BPF skeleton and compilation using clang
-target bpf for files ending with .bpf.c suffix (to denote that they use
vmlinux.h).
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-14-memxor@gmail.com

samples/bpf/Makefile

@@ -164,7 +164,6 @@ always-y += xdp_redirect_kern.o
 always-y += xdp_redirect_map_kern.o
 always-y += xdp_redirect_map_multi_kern.o
 always-y += xdp_redirect_cpu_kern.o
-always-y += xdp_monitor_kern.o
 always-y += xdp_rxq_info_kern.o
 always-y += xdp2skb_meta_kern.o
 always-y += syscall_tp_kern.o
@@ -338,6 +337,47 @@ endif
 
 clean-files += vmlinux.h
 
+# Get Clang's default includes on this system, as opposed to those seen by
+# '-target bpf'. This fixes "missing" files on some architectures/distros,
+# such as asm/byteorder.h, asm/socket.h, asm/sockios.h, sys/cdefs.h etc.
+#
+# Use '-idirafter': Don't interfere with include mechanics except where the
+# build would have failed anyways.
+define get_sys_includes
+$(shell $(1) -v -E - </dev/null 2>&1 \
+        | sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }') \
+$(shell $(1) -dM -E - </dev/null | grep '#define __riscv_xlen ' | sed 's/#define /-D/' | sed 's/ /=/')
+endef
+
+CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG))
+
+$(obj)/xdp_monitor.bpf.o: $(obj)/xdp_sample.bpf.o
+
+$(obj)/%.bpf.o: $(src)/%.bpf.c $(obj)/vmlinux.h $(src)/xdp_sample.bpf.h $(src)/xdp_sample_shared.h
+	@echo "  CLANG-BPF " $@
+	$(Q)$(CLANG) -g -O2 -target bpf -D__TARGET_ARCH_$(SRCARCH) \
+		-Wno-compare-distinct-pointer-types -I$(srctree)/include \
+		-I$(srctree)/samples/bpf -I$(srctree)/tools/include \
+		-I$(srctree)/tools/lib $(CLANG_SYS_INCLUDES) \
+		-c $(filter %.bpf.c,$^) -o $@
+
+LINKED_SKELS := xdp_monitor.skel.h
+clean-files += $(LINKED_SKELS)
+
+xdp_monitor.skel.h-deps := xdp_monitor.bpf.o xdp_sample.bpf.o
+
+LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.bpf.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
+
+BPF_SRCS_LINKED := $(notdir $(wildcard $(src)/*.bpf.c))
+BPF_OBJS_LINKED := $(patsubst %.bpf.c,$(obj)/%.bpf.o, $(BPF_SRCS_LINKED))
+BPF_SKELS_LINKED := $(addprefix $(obj)/,$(LINKED_SKELS))
+
+$(BPF_SKELS_LINKED): $(BPF_OBJS_LINKED) $(BPFTOOL)
+	@echo "  BPF GEN-OBJ " $(@:.skel.h=)
+	$(Q)$(BPFTOOL) gen object $(@:.skel.h=.lbpf.o) $(addprefix $(obj)/,$($(@F)-deps))
+	@echo "  BPF GEN-SKEL" $(@:.skel.h=)
+	$(Q)$(BPFTOOL) gen skeleton $(@:.skel.h=.lbpf.o) name $(notdir $(@:.skel.h=)) > $@
+
 # asm/sysreg.h - inline assembly used by it is incompatible with llvm.
 # But, there is no easy way to fix it, so just exclude it since it is
 # useless for BPF samples.

samples/bpf/xdp_monitor.bpf.c

+// SPDX-License-Identifier: GPL-2.0
+/*  Copyright(c) 2017-2018 Jesper Dangaard Brouer, Red Hat Inc.
+ *
+ * XDP monitor tool, based on tracepoints
+ */
+#include "xdp_sample.bpf.h"
+
+char _license[] SEC("license") = "GPL";

samples/bpf/xdp_monitor_kern.c

-/* SPDX-License-Identifier: GPL-2.0
- *  Copyright(c) 2017-2018 Jesper Dangaard Brouer, Red Hat Inc.
- *
- * XDP monitor tool, based on tracepoints
- */
-#include <uapi/linux/bpf.h>
-#include <bpf/bpf_helpers.h>
-
-struct {
-	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
-	__type(key, u32);
-	__type(value, u64);
-	__uint(max_entries, 2);
-	/* TODO: have entries for all possible errno's */
-} redirect_err_cnt SEC(".maps");
-
-#define XDP_UNKNOWN	XDP_REDIRECT + 1
-struct {
-	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
-	__type(key, u32);
-	__type(value, u64);
-	__uint(max_entries, XDP_UNKNOWN + 1);
-} exception_cnt SEC(".maps");
-
-/* Tracepoint format: /sys/kernel/debug/tracing/events/xdp/xdp_redirect/format
- * Code in:                kernel/include/trace/events/xdp.h
- */
-struct xdp_redirect_ctx {
-	u64 __pad;		// First 8 bytes are not accessible by bpf code
-	int prog_id;		//	offset:8;  size:4; signed:1;
-	u32 act;		//	offset:12  size:4; signed:0;
-	int ifindex;		//	offset:16  size:4; signed:1;
-	int err;		//	offset:20  size:4; signed:1;
-	int to_ifindex;		//	offset:24  size:4; signed:1;
-	u32 map_id;		//	offset:28  size:4; signed:0;
-	int map_index;		//	offset:32  size:4; signed:1;
-};				//	offset:36
-
-enum {
-	XDP_REDIRECT_SUCCESS = 0,
-	XDP_REDIRECT_ERROR = 1
-};
-
-static __always_inline
-int xdp_redirect_collect_stat(struct xdp_redirect_ctx *ctx)
-{
-	u32 key = XDP_REDIRECT_ERROR;
-	int err = ctx->err;
-	u64 *cnt;
-
-	if (!err)
-		key = XDP_REDIRECT_SUCCESS;
-
-	cnt  = bpf_map_lookup_elem(&redirect_err_cnt, &key);
-	if (!cnt)
-		return 1;
-	*cnt += 1;
-
-	return 0; /* Indicate event was filtered (no further processing)*/
-	/*
-	 * Returning 1 here would allow e.g. a perf-record tracepoint
-	 * to see and record these events, but it doesn't work well
-	 * in-practice as stopping perf-record also unload this
-	 * bpf_prog.  Plus, there is additional overhead of doing so.
-	 */
-}
-
-SEC("tracepoint/xdp/xdp_redirect_err")
-int trace_xdp_redirect_err(struct xdp_redirect_ctx *ctx)
-{
-	return xdp_redirect_collect_stat(ctx);
-}
-
-
-SEC("tracepoint/xdp/xdp_redirect_map_err")
-int trace_xdp_redirect_map_err(struct xdp_redirect_ctx *ctx)
-{
-	return xdp_redirect_collect_stat(ctx);
-}
-
-/* Likely unloaded when prog starts */
-SEC("tracepoint/xdp/xdp_redirect")
-int trace_xdp_redirect(struct xdp_redirect_ctx *ctx)
-{
-	return xdp_redirect_collect_stat(ctx);
-}
-
-/* Likely unloaded when prog starts */
-SEC("tracepoint/xdp/xdp_redirect_map")
-int trace_xdp_redirect_map(struct xdp_redirect_ctx *ctx)
-{
-	return xdp_redirect_collect_stat(ctx);
-}
-
-/* Tracepoint format: /sys/kernel/debug/tracing/events/xdp/xdp_exception/format
- * Code in:                kernel/include/trace/events/xdp.h
- */
-struct xdp_exception_ctx {
-	u64 __pad;	// First 8 bytes are not accessible by bpf code
-	int prog_id;	//	offset:8;  size:4; signed:1;
-	u32 act;	//	offset:12; size:4; signed:0;
-	int ifindex;	//	offset:16; size:4; signed:1;
-};
-
-SEC("tracepoint/xdp/xdp_exception")
-int trace_xdp_exception(struct xdp_exception_ctx *ctx)
-{
-	u64 *cnt;
-	u32 key;
-
-	key = ctx->act;
-	if (key > XDP_REDIRECT)
-		key = XDP_UNKNOWN;
-
-	cnt = bpf_map_lookup_elem(&exception_cnt, &key);
-	if (!cnt)
-		return 1;
-	*cnt += 1;
-
-	return 0;
-}
-
-/* Common stats data record shared with _user.c */
-struct datarec {
-	u64 processed;
-	u64 dropped;
-	u64 info;
-	u64 err;
-};
-#define MAX_CPUS 64
-
-struct {
-	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
-	__type(key, u32);
-	__type(value, struct datarec);
-	__uint(max_entries, MAX_CPUS);
-} cpumap_enqueue_cnt SEC(".maps");
-
-struct {
-	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
-	__type(key, u32);
-	__type(value, struct datarec);
-	__uint(max_entries, 1);
-} cpumap_kthread_cnt SEC(".maps");
-
-/* Tracepoint: /sys/kernel/debug/tracing/events/xdp/xdp_cpumap_enqueue/format
- * Code in:         kernel/include/trace/events/xdp.h
- */
-struct cpumap_enqueue_ctx {
-	u64 __pad;		// First 8 bytes are not accessible by bpf code
-	int map_id;		//	offset:8;  size:4; signed:1;
-	u32 act;		//	offset:12; size:4; signed:0;
-	int cpu;		//	offset:16; size:4; signed:1;
-	unsigned int drops;	//	offset:20; size:4; signed:0;
-	unsigned int processed;	//	offset:24; size:4; signed:0;
-	int to_cpu;		//	offset:28; size:4; signed:1;
-};
-
-SEC("tracepoint/xdp/xdp_cpumap_enqueue")
-int trace_xdp_cpumap_enqueue(struct cpumap_enqueue_ctx *ctx)
-{
-	u32 to_cpu = ctx->to_cpu;
-	struct datarec *rec;
-
-	if (to_cpu >= MAX_CPUS)
-		return 1;
-
-	rec = bpf_map_lookup_elem(&cpumap_enqueue_cnt, &to_cpu);
-	if (!rec)
-		return 0;
-	rec->processed += ctx->processed;
-	rec->dropped   += ctx->drops;
-
-	/* Record bulk events, then userspace can calc average bulk size */
-	if (ctx->processed > 0)
-		rec->info += 1;
-
-	return 0;
-}
-
-/* Tracepoint: /sys/kernel/debug/tracing/events/xdp/xdp_cpumap_kthread/format
- * Code in:         kernel/include/trace/events/xdp.h
- */
-struct cpumap_kthread_ctx {
-	u64 __pad;		// First 8 bytes are not accessible by bpf code
-	int map_id;		//	offset:8;  size:4; signed:1;
-	u32 act;		//	offset:12; size:4; signed:0;
-	int cpu;		//	offset:16; size:4; signed:1;
-	unsigned int drops;	//	offset:20; size:4; signed:0;
-	unsigned int processed;	//	offset:24; size:4; signed:0;
-	int sched;		//	offset:28; size:4; signed:1;
-};
-
-SEC("tracepoint/xdp/xdp_cpumap_kthread")
-int trace_xdp_cpumap_kthread(struct cpumap_kthread_ctx *ctx)
-{
-	struct datarec *rec;
-	u32 key = 0;
-
-	rec = bpf_map_lookup_elem(&cpumap_kthread_cnt, &key);
-	if (!rec)
-		return 0;
-	rec->processed += ctx->processed;
-	rec->dropped   += ctx->drops;
-
-	/* Count times kthread yielded CPU via schedule call */
-	if (ctx->sched)
-		rec->info++;
-
-	return 0;
-}
-
-struct {
-	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
-	__type(key, u32);
-	__type(value, struct datarec);
-	__uint(max_entries, 1);
-} devmap_xmit_cnt SEC(".maps");
-
-/* Tracepoint: /sys/kernel/debug/tracing/events/xdp/xdp_devmap_xmit/format
- * Code in:         kernel/include/trace/events/xdp.h
- */
-struct devmap_xmit_ctx {
-	u64 __pad;		// First 8 bytes are not accessible by bpf code
-	int from_ifindex;	//	offset:8;  size:4; signed:1;
-	u32 act;		//	offset:12; size:4; signed:0;
-	int to_ifindex; 	//	offset:16; size:4; signed:1;
-	int drops;		//	offset:20; size:4; signed:1;
-	int sent;		//	offset:24; size:4; signed:1;
-	int err;		//	offset:28; size:4; signed:1;
-};
-
-SEC("tracepoint/xdp/xdp_devmap_xmit")
-int trace_xdp_devmap_xmit(struct devmap_xmit_ctx *ctx)
-{
-	struct datarec *rec;
-	u32 key = 0;
-
-	rec = bpf_map_lookup_elem(&devmap_xmit_cnt, &key);
-	if (!rec)
-		return 0;
-	rec->processed += ctx->sent;
-	rec->dropped   += ctx->drops;
-
-	/* Record bulk events, then userspace can calc average bulk size */
-	rec->info += 1;
-
-	/* Record error cases, where no frame were sent */
-	if (ctx->err)
-		rec->err++;
-
-	/* Catch API error of drv ndo_xdp_xmit sent more than count */
-	if (ctx->drops < 0)
-		rec->err++;
-
-	return 1;
-}