samples/hid: add new hid BPF example

F:	drivers/hid/

F:	include/linux/hid*

F:	include/uapi/linux/hid*

F:	samples/hid/

F:	tools/testing/selftests/hid/

HID LOGITECH DRIVERS

# SPDX-License-Identifier: GPL-2.0-only

hid_mouse

*.out

*.skel.h

/vmlinux.h

/bpftool/

/libbpf/

# SPDX-License-Identifier: GPL-2.0

HID_SAMPLES_PATH ?= $(abspath $(srctree)/$(src))

TOOLS_PATH := $(HID_SAMPLES_PATH)/../../tools

pound := \#

# List of programs to build

tprogs-y += hid_mouse

# Libbpf dependencies

LIBBPF_SRC = $(TOOLS_PATH)/lib/bpf

LIBBPF_OUTPUT = $(abspath $(HID_SAMPLES_PATH))/libbpf

LIBBPF_DESTDIR = $(LIBBPF_OUTPUT)

LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include

LIBBPF = $(LIBBPF_OUTPUT)/libbpf.a

EXTRA_HEADERS := hid_bpf_attach.h

EXTRA_BPF_HEADERS := hid_bpf_helpers.h

hid_mouse-objs := hid_mouse.o

# Tell kbuild to always build the programs

always-y := $(tprogs-y)

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$(LIBBPF_INCLUDE)

TPROGS_CFLAGS += -I$(srctree)/tools/include

ifdef SYSROOT

TPROGS_CFLAGS += --sysroot=$(SYSROOT)

TPROGS_LDFLAGS := -L$(SYSROOT)/usr/lib

endif

TPROGS_LDLIBS			+= $(LIBBPF) -lelf -lz

# 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

LLVM_READELF ?= llvm-readelf

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 := $(shell printf "$(pound)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; \

			  $(LLVM_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:

	$(MAKE) -C ../../ M=$(CURDIR) HID_SAMPLES_PATH=$(CURDIR)

clean:

	$(MAKE) -C ../../ M=$(CURDIR) clean

	@find $(CURDIR) -type f -name '*~' -delete

	@$(RM) -r $(CURDIR)/libbpf $(CURDIR)/bpftool

$(LIBBPF): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUTPUT)

# Fix up variables inherited from Kbuild that tools/ build system won't like

	$(MAKE) -C $(LIBBPF_SRC) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \

		LDFLAGS=$(TPROGS_LDFLAGS) srctree=$(HID_SAMPLES_PATH)/../../ \

		O= OUTPUT=$(LIBBPF_OUTPUT)/ DESTDIR=$(LIBBPF_DESTDIR) prefix= \

		$@ install_headers

BPFTOOLDIR := $(TOOLS_PATH)/bpf/bpftool

BPFTOOL_OUTPUT := $(abspath $(HID_SAMPLES_PATH))/bpftool

BPFTOOL := $(BPFTOOL_OUTPUT)/bootstrap/bpftool

$(BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) | $(BPFTOOL_OUTPUT)

	$(MAKE) -C $(BPFTOOLDIR) srctree=$(HID_SAMPLES_PATH)/../../ 		\

		OUTPUT=$(BPFTOOL_OUTPUT)/ bootstrap

$(LIBBPF_OUTPUT) $(BPFTOOL_OUTPUT):

	$(call msg,MKDIR,$@)

	$(Q)mkdir -p $@

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

$(HID_SAMPLES_PATH)/*.c: verify_target_bpf $(LIBBPF)

$(src)/*.c: verify_target_bpf $(LIBBPF)

libbpf_hdrs: $(LIBBPF)

.PHONY: libbpf_hdrs

$(obj)/hid_mouse.o: $(obj)/hid_mouse.skel.h

-include $(HID_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))))

$(obj)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL)

ifeq ($(VMLINUX_H),)

ifeq ($(VMLINUX_BTF),)

	$(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)",\

		build the kernel or set VMLINUX_BTF or VMLINUX_H variable)

endif

	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@

else

	$(Q)cp "$(VMLINUX_H)" $@

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))

EXTRA_BPF_HEADERS_SRC := $(addprefix $(src)/,$(EXTRA_BPF_HEADERS))

$(obj)/%.bpf.o: $(src)/%.bpf.c $(EXTRA_BPF_HEADERS_SRC) $(obj)/vmlinux.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$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES) \

		-c $(filter %.bpf.c,$^) -o $@

LINKED_SKELS := hid_mouse.skel.h

clean-files += $(LINKED_SKELS)

hid_mouse.skel.h-deps := hid_mouse.bpf.o hid_bpf_attach.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.

# 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$(LIBBPF_INCLUDE) \

		-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/hid/ \

		-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 $@

ifeq ($(DWARF2BTF),y)

	$(BTF_PAHOLE) -J $@

endif

# SPDX-License-Identifier: GPL-2.0

# ==========================================================================

# Building binaries on the host system

# Binaries are not used during the compilation of the kernel, and intended

# to be build for target board, target board can be host of course. Added to

# build binaries to run not on host system.

#

# Sample syntax

# tprogs-y := xsk_example

# Will compile xsk_example.c and create an executable named xsk_example

#

# tprogs-y    := xdpsock

# xdpsock-objs := xdpsock_1.o xdpsock_2.o

# Will compile xdpsock_1.c and xdpsock_2.c, and then link the executable

# xdpsock, based on xdpsock_1.o and xdpsock_2.o

#

# Derived from scripts/Makefile.host

#

__tprogs := $(sort $(tprogs-y))

# C code

# Executables compiled from a single .c file

tprog-csingle	:= $(foreach m,$(__tprogs), \

			$(if $($(m)-objs),,$(m)))

# C executables linked based on several .o files

tprog-cmulti	:= $(foreach m,$(__tprogs),\

			$(if $($(m)-objs),$(m)))

# Object (.o) files compiled from .c files

tprog-cobjs	:= $(sort $(foreach m,$(__tprogs),$($(m)-objs)))

tprog-csingle	:= $(addprefix $(obj)/,$(tprog-csingle))

tprog-cmulti	:= $(addprefix $(obj)/,$(tprog-cmulti))

tprog-cobjs	:= $(addprefix $(obj)/,$(tprog-cobjs))

#####

# Handle options to gcc. Support building with separate output directory

_tprogc_flags   = $(TPROGS_CFLAGS) \

                 $(TPROGCFLAGS_$(basetarget).o)

# $(objtree)/$(obj) for including generated headers from checkin source files

ifeq ($(KBUILD_EXTMOD),)

ifdef building_out_of_srctree

_tprogc_flags   += -I $(objtree)/$(obj)

endif

endif

tprogc_flags    = -Wp,-MD,$(depfile) $(_tprogc_flags)

# Create executable from a single .c file

# tprog-csingle -> Executable

quiet_cmd_tprog-csingle 	= CC  $@

      cmd_tprog-csingle	= $(CC) $(tprogc_flags) $(TPROGS_LDFLAGS) -o $@ $< \

		$(TPROGS_LDLIBS) $(TPROGLDLIBS_$(@F))

$(tprog-csingle): $(obj)/%: $(src)/%.c FORCE

	$(call if_changed_dep,tprog-csingle)

# Link an executable based on list of .o files, all plain c

# tprog-cmulti -> executable

quiet_cmd_tprog-cmulti	= LD  $@

      cmd_tprog-cmulti	= $(CC) $(tprogc_flags) $(TPROGS_LDFLAGS) -o $@ \

			  $(addprefix $(obj)/,$($(@F)-objs)) \

			  $(TPROGS_LDLIBS) $(TPROGLDLIBS_$(@F))

$(tprog-cmulti): $(tprog-cobjs) FORCE

	$(call if_changed,tprog-cmulti)

$(call multi_depend, $(tprog-cmulti), , -objs)

# Create .o file from a single .c file

# tprog-cobjs -> .o

quiet_cmd_tprog-cobjs	= CC  $@

      cmd_tprog-cobjs	= $(CC) $(tprogc_flags) -c -o $@ $<

$(tprog-cobjs): $(obj)/%.o: $(src)/%.c FORCE

	$(call if_changed_dep,tprog-cobjs)

// SPDX-License-Identifier: GPL-2.0-only

/* Copyright (c) 2022 Benjamin Tissoires

 */

#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include "hid_bpf_attach.h"

#include "hid_bpf_helpers.h"

SEC("syscall")

int attach_prog(struct attach_prog_args *ctx)

{

	ctx->retval = hid_bpf_attach_prog(ctx->hid,

					  ctx->prog_fd,

					  0);

	return 0;

}