Update kretprobe example

Signed-off-by: sanfern <[email protected]>

examples/probes/kprobe/kprobe-payload.json

@@ -13,8 +13,8 @@
         "monitor_maps": [
           { "name": "counting_map", "key": 0, "aggregator": "scalar"}
         ],
-        "object_file": "tracepoint.bpf.o",
-        "entry_function_name": "tcp_bad_csum"
+        "object_file": "kprobe.bpf.o",
+        "entry_function_name": "do_unlinkat"
       }
       ]
     }

examples/probes/kretprobe/Makefile

@@ -0,0 +1,212 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+
+LINUX_SRC_PATH ?= /usr/src/linux
+BPF_SAMPLES_PATH := $(LINUX_SRC_PATH)/samples/bpf
+TOOLS_PATH := $(BPF_SAMPLES_PATH)/../../tools
+L3AF_SRC_PATH := $(CURDIR)
+
+# Libbpf dependencies
+LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a
+
+# Tell kbuild to always build the programs
+always-y := $(tprogs-y)
+always-y += kretprobe.bpf.o
+
+
+ifeq ($(ARCH), arm)
+# Strip all except -D__LINUX_ARM_ARCH__ option needed to handle linux
+# headers when arm instruction set identification is requested.
+ARM_ARCH_SELECTOR := $(filter -D__LINUX_ARM_ARCH__%, $(KBUILD_CFLAGS))
+BPF_EXTRA_CFLAGS := $(ARM_ARCH_SELECTOR)
+TPROGS_CFLAGS += $(ARM_ARCH_SELECTOR)
+endif
+
+ifeq ($(ARCH), mips)
+TPROGS_CFLAGS += -D__SANE_USERSPACE_TYPES__
+ifdef CONFIG_MACH_LOONGSON64
+BPF_EXTRA_CFLAGS += -I$(srctree)/arch/mips/include/asm/mach-loongson64
+BPF_EXTRA_CFLAGS += -I$(srctree)/arch/mips/include/asm/mach-generic
+endif
+endif
+
+TPROGS_CFLAGS += -Wall -O2
+TPROGS_CFLAGS += -Wmissing-prototypes
+TPROGS_CFLAGS += -Wstrict-prototypes
+
+TPROGS_CFLAGS += -I$(objtree)/usr/include
+TPROGS_CFLAGS += -I$(srctree)/tools/testing/selftests/bpf/
+TPROGS_CFLAGS += -I$(srctree)/tools/lib/
+TPROGS_CFLAGS += -I$(srctree)/tools/include
+TPROGS_CFLAGS += -I$(srctree)/tools/perf
+TPROGS_CFLAGS += -DHAVE_ATTR_TEST=0
+
+ifdef SYSROOT
+TPROGS_CFLAGS += --sysroot=$(SYSROOT)
+TPROGS_LDFLAGS := -L$(SYSROOT)/usr/lib
+endif
+
+TPROGS_LDLIBS			+= $(LIBBPF) -lelf -lz -lcrypto
+
+# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
+# make M=samples/bpf LLC=~/git/llvm-project/llvm/build/bin/llc CLANG=~/git/llvm-project/llvm/build/bin/clang
+LLC ?= llc
+CLANG ?= clang
+OPT ?= opt
+LLVM_DIS ?= llvm-dis
+LLVM_OBJCOPY ?= llvm-objcopy
+BTF_PAHOLE ?= pahole
+
+# Detect that we're cross compiling and use the cross compiler
+ifdef CROSS_COMPILE
+CLANG_ARCH_ARGS = --target=$(notdir $(CROSS_COMPILE:%-=%))
+endif
+
+# Don't evaluate probes and warnings if we need to run make recursively
+ifneq ($(src),)
+HDR_PROBE := $(shell printf "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
+	$(CC) $(TPROGS_CFLAGS) $(TPROGS_LDFLAGS) -x c - \
+	-o /dev/null 2>/dev/null && echo okay)
+
+ifeq ($(HDR_PROBE),)
+$(warning WARNING: Detected possible issues with include path.)
+$(warning WARNING: Please install kernel headers locally (make headers_install).)
+endif
+
+BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help 2>&1 | grep dwarfris)
+BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help 2>&1 | grep BTF)
+BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --help 2>&1 | grep -i 'usage.*llvm')
+BTF_LLVM_PROBE := $(shell echo "int main() { return 0; }" | \
+			  $(CLANG) -target bpf -O2 -g -c -x c - -o ./llvm_btf_verify.o; \
+			  readelf -S ./llvm_btf_verify.o | grep BTF; \
+			  /bin/rm -f ./llvm_btf_verify.o)
+
+BPF_EXTRA_CFLAGS += -fno-stack-protector
+ifneq ($(BTF_LLVM_PROBE),)
+	BPF_EXTRA_CFLAGS += -g
+else
+ifneq ($(and $(BTF_LLC_PROBE),$(BTF_PAHOLE_PROBE),$(BTF_OBJCOPY_PROBE)),)
+	BPF_EXTRA_CFLAGS += -g
+	LLC_FLAGS += -mattr=dwarfris
+	DWARF2BTF = y
+endif
+endif
+endif
+
+# Trick to allow make to be run from this directory
+all:build tar.zip
+build:
+	if [ ! -f $(L3AF_SRC_PATH)/vmlinux.h ]; then \
+		bpftool btf dump file /sys/kernel/btf/vmlinux format c > $(L3AF_SRC_PATH)/vmlinux.h; \
+    fi
+	$(MAKE) -C $(LINUX_SRC_PATH) M=$(L3AF_SRC_PATH)
+
+tar.zip:
+	@rm -rf l3af_kretprobe
+	@rm -f l3af_kretprobe.tar.gz
+	@mkdir l3af_kretprobe
+	@cp $(L3AF_SRC_PATH)/kretprobe.bpf.o ./l3af_kretprobe
+	@tar -cvf l3af_kretprobe.tar ./l3af_kretprobe
+	@gzip l3af_kretprobe.tar
+
+clean:
+	$(MAKE) -C $(LINUX_SRC_PATH) M=$(L3AF_SRC_PATH) clean
+	@find $(CURDIR) -type f -name '*~' -delete
+	@rm -f ./*.o
+	@rm -f *~
+
+$(LIBBPF): FORCE
+# Fix up variables inherited from Kbuild that tools/ build system won't like
+	$(MAKE) -C $(dir $@) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \
+		LDFLAGS=$(TPROGS_LDFLAGS) srctree=$(BPF_SAMPLES_PATH)/../../ O=
+
+BPFTOOLDIR := $(TOOLS_PATH)/bpf/bpftool
+BPFTOOL := $(BPFTOOLDIR)/bpftool
+$(BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)
+	    $(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../
+
+$(obj)/syscall_nrs.h:	$(obj)/syscall_nrs.s FORCE
+	$(call filechk,offsets,__SYSCALL_NRS_H__)
+
+targets += syscall_nrs.s
+clean-files += syscall_nrs.h
+
+FORCE:
+
+
+# Verify LLVM compiler tools are available and bpf target is supported by llc
+.PHONY: verify_cmds verify_target_bpf $(CLANG) $(LLC)
+
+verify_cmds: $(CLANG) $(LLC)
+	@for TOOL in $^ ; do \
+		if ! (which -- "$${TOOL}" > /dev/null 2>&1); then \
+			echo "*** ERROR: Cannot find LLVM tool $${TOOL}" ;\
+			exit 1; \
+		else true; fi; \
+	done
+
+verify_target_bpf: verify_cmds
+	@if ! (${LLC} -march=bpf -mattr=help > /dev/null 2>&1); then \
+		echo "*** ERROR: LLVM (${LLC}) does not support 'bpf' target" ;\
+		echo "   NOTICE: LLVM version >= 3.7.1 required" ;\
+		exit 2; \
+	else true; fi
+
+$(BPF_SAMPLES_PATH)/*.c: verify_target_bpf $(LIBBPF)
+$(src)/*.c: verify_target_bpf $(LIBBPF)
+
+
+-include $(BPF_SAMPLES_PATH)/Makefile.target
+
+VMLINUX_BTF_PATHS ?= $(abspath $(if $(O),$(O)/vmlinux))				\
+		     $(abspath $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux))	\
+		     $(abspath ./vmlinux)
+VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
+
+clean-files += vmlinux.h
+
+# Get Clang's default includes on this system, as opposed to those seen by
+# '-target bpf'. This fixes "missing" files on some architectures/distros,
+# such as asm/byteorder.h, asm/socket.h, asm/sockios.h, sys/cdefs.h etc.
+#
+# Use '-idirafter': Don't interfere with include mechanics except where the
+# build would have failed anyways.
+define get_sys_includes
+$(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)/%.bpf.o: $(src)/%.bpf.c $(BPF_SAMPLES_PATH)/xdp_sample.bpf.h $(BPF_SAMPLES_PATH)/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$(srctree)/tools/lib -I$(srctree)/tools/lib/bpf $(CLANG_SYS_INCLUDES) \
+		-c $(filter %.bpf.c,$^) -o $@
+
+# asm/sysreg.h - inline assembly used by it is incompatible with llvm.
+# But, there is no easy way to fix it, so just exclude it since it is
+# useless for BPF samples.
+# below we use long chain of commands, clang | opt | llvm-dis | llc,
+# to generate final object file. 'clang' compiles the source into IR
+# with native target, e.g., x64, arm64, etc. 'opt' does bpf CORE IR builtin
+# processing (llvm12) and IR optimizations. 'llvm-dis' converts
+# 'opt' output to IR, and finally 'llc' generates bpf byte code.
+$(obj)/%.o: $(src)/%.c
+	@echo "  CLANG-bpf " $@
+	$(Q)$(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(BPF_EXTRA_CFLAGS) \
+		-I$(obj) -I$(srctree)/tools/testing/selftests/bpf/ \
+		-I$(srctree)/tools/lib/  -I$(srctree)/tools/lib/bpf \
+		-D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign \
+		-D__TARGET_ARCH_$(SRCARCH) -Wno-compare-distinct-pointer-types \
+		-Wno-gnu-variable-sized-type-not-at-end \
+		-Wno-address-of-packed-member -Wno-tautological-compare \
+                -Wno-unknown-warning-option $(CLANG_ARCH_ARGS) \
+                -fno-asynchronous-unwind-tables \
+                -I$(srctree)/samples/bpf/ -include asm_goto_workaround.h \
+                -O2 -emit-llvm -Xclang -disable-llvm-passes -c $< -o - | \
+                $(OPT) -O2 -mtriple=bpf-pc-linux | $(LLVM_DIS) | \
+                $(LLC) -march=bpf $(LLC_FLAGS) -filetype=obj -o $@

examples/probes/kretprobe/kretprobe-payload.json

@@ -0,0 +1,22 @@
+[
+  {
+    "host_name" : "lima-ubuntu-lts",
+    "iface" : "enp0s3",
+    "bpf_programs" : {
+      "probes" : [{
+        "name": "file-unlink",
+        "artifact": "l3af_kretprobe.tar.gz",
+        "version": "latest",
+        "admin_status": "enabled",
+        "prog_type": "kprobe",
+        "cfg_version": 1,
+        "monitor_maps": [
+          { "name": "counting_map", "key": 0, "aggregator": "scalar"}
+        ],
+        "object_file": "kretprobe.bpf.o",
+        "entry_function_name": "do_unlinkat_exit"
+      }
+      ]
+    }
+  }
+]

examples/probes/kretprobe/kretprobe.bpf.c

@@ -0,0 +1,35 @@
+// Copyright Contributors to the L3AF Project.
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+
+#include "vmlinux.h"
+#include "bpf_helpers.h"
+#include "bpf_tracing.h"
+#include "bpf_core_read.h"
+
+struct {
+    __uint(type, BPF_MAP_TYPE_ARRAY);
+    __type(key, u32);
+    __type(value, u64);
+    __uint(max_entries, 1);
+} counting_map SEC(".maps");
+
+SEC("kretprobe/do_unlinkat")
+int BPF_KRETPROBE(do_unlinkat_exit, long ret)
+{
+    pid_t pid;
+    u32 key     = 0;
+    u64 initval = 1, *valp;
+
+    pid = bpf_get_current_pid_tgid() >> 32;
+    bpf_printk("KRETPROBE ENTRY pid = %d, ret = %ld\n", pid, ret);
+
+    valp = bpf_map_lookup_elem(&counting_map, &key);
+    if (!valp) {
+        bpf_map_update_elem(&counting_map, &key, &initval, BPF_ANY);
+        return 0;
+    }
+    __sync_fetch_and_add(valp, 1);
+    return 0;
+}
+
+char _license[] SEC("license") = "Dual BSD/GPL";