[PATCH bpf-next v7 23/24] HID: bpf: add Surface Dial example

Benjamin Tissoires
2022-07-21T15:41:07Z

Add a more complete HID-BPF example.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

---

changes in v7:
- remove unnecessary __must_check definition

new in v6

fix surface dial
---
samples/bpf/.gitignore | 1 +
samples/bpf/Makefile | 6 +-
samples/bpf/hid_surface_dial.bpf.c | 161 ++++++++++++++++++++++
samples/bpf/hid_surface_dial.c | 212 +++++++++++++++++++++++++++++
4 files changed, 379 insertions(+), 1 deletion(-)
create mode 100644 samples/bpf/hid_surface_dial.bpf.c
create mode 100644 samples/bpf/hid_surface_dial.c

diff --git a/samples/bpf/.gitignore b/samples/bpf/.gitignore
index 65440bd618b2..6a1079d3d064 100644
--- a/samples/bpf/.gitignore
+++ b/samples/bpf/.gitignore
@@ -3,6 +3,7 @@ cpustat
fds_example
hbm
hid_mouse
+hid_surface_dial
ibumad
lathist
lwt_len_hist
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index a965bbfaca47..5f5aa7b32565 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -58,6 +58,7 @@ tprogs-y += xdp_redirect
tprogs-y += xdp_monitor

tprogs-y += hid_mouse
+tprogs-y += hid_surface_dial

# Libbpf dependencies
LIBBPF_SRC = $(TOOLS_PATH)/lib/bpf
@@ -122,6 +123,7 @@ xdp_monitor-objs := xdp_monitor_user.o $(XDP_SAMPLE)
xdp_router_ipv4-objs := xdp_router_ipv4_user.o $(XDP_SAMPLE)

hid_mouse-objs := hid_mouse.o
+hid_surface_dial-objs := hid_surface_dial.o

# Tell kbuild to always build the programs
always-y := $(tprogs-y)
@@ -343,6 +345,7 @@ $(obj)/hbm.o: $(src)/hbm.h
$(obj)/hbm_edt_kern.o: $(src)/hbm.h $(src)/hbm_kern.h

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

# Override includes for xdp_sample_user.o because $(srctree)/usr/include in
# TPROGS_CFLAGS causes conflicts
@@ -429,9 +432,10 @@ $(BPF_SKELS_LINKED): $(BPF_OBJS_LINKED) $(BPFTOOL)
$(Q)$(BPFTOOL) gen skeleton $(@:.skel.h=.lbpf.o) name $(notdir $(@:.skel.h=)) > $@

# Generate BPF skeletons for non XDP progs
-OTHER_BPF_SKELS := hid_mouse.skel.h
+OTHER_BPF_SKELS := hid_mouse.skel.h hid_surface_dial.skel.h

hid_mouse.skel.h-deps := hid_mouse.bpf.o
+hid_surface_dial.skel.h-deps := hid_surface_dial.bpf.o

OTHER_BPF_SRCS_LINKED := $(patsubst %.skel.h,%.bpf.c, $(OTHER_BPF_SKELS))
OTHER_BPF_OBJS_LINKED := $(patsubst %.bpf.c,$(obj)/%.bpf.o, $(OTHER_BPF_SRCS_LINKED))
diff --git a/samples/bpf/hid_surface_dial.bpf.c b/samples/bpf/hid_surface_dial.bpf.c
new file mode 100644
index 000000000000..16c821d3decf
--- /dev/null
+++ b/samples/bpf/hid_surface_dial.bpf.c
@@ -0,0 +1,161 @@
+// 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>
+
+#define HID_UP_BUTTON 0x0009
+#define HID_GD_WHEEL 0x0038
+
+/* following are kfuncs exported by HID for HID-BPF */
+extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx,
+ unsigned int offset,
+ const size_t __sz) __ksym;
+extern int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, u32 flags) __ksym;
+extern struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id) __ksym;
+extern void hid_bpf_release_context(struct hid_bpf_ctx *ctx) __ksym;
+extern int hid_bpf_hw_request(struct hid_bpf_ctx *ctx,
+ __u8 *data,
+ size_t buf__sz,
+ enum hid_report_type type,
+ enum hid_class_request reqtype) __ksym;
+
+struct attach_prog_args {
+ int prog_fd;
+ unsigned int hid;
+ int retval;
+};
+
+SEC("syscall")
+int attach_prog(struct attach_prog_args *ctx)
+{
+ ctx->retval = hid_bpf_attach_prog(ctx->hid,
+ ctx->prog_fd,
+ 0);
+ return 0;
+}
+
+SEC("fmod_ret/hid_bpf_device_event")
+int BPF_PROG(hid_event, struct hid_bpf_ctx *hctx)
+{
+ __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
+
+ if (!data)
+ return 0; /* EPERM check */
+
+ /* Touch */
+ data[1] &= 0xfd;
+
+ /* X */
+ data[4] = 0;
+ data[5] = 0;
+
+ /* Y */
+ data[6] = 0;
+ data[7] = 0;
+
+ return 0;
+}
+
+/* 72 == 360 / 5 -> 1 report every 5 degrees */
+int resolution = 72;
+int physical = 5;
+
+struct haptic_syscall_args {
+ unsigned int hid;
+ int retval;
+};
+
+static __u8 haptic_data[8];
+
+SEC("syscall")
+int set_haptic(struct haptic_syscall_args *args)
+{
+ struct hid_bpf_ctx *ctx;
+ const size_t size = sizeof(haptic_data);
+ u16 *res;
+ int ret;
+
+ if (size > sizeof(haptic_data))
+ return -7; /* -E2BIG */
+
+ ctx = hid_bpf_allocate_context(args->hid);
+ if (!ctx)
+ return -1; /* EPERM check */
+
+ haptic_data[0] = 1; /* report ID */
+
+ ret = hid_bpf_hw_request(ctx, haptic_data, size, HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
+
+ bpf_printk("probed/remove event ret value: %d", ret);
+ bpf_printk("buf: %02x %02x %02x",
+ haptic_data[0],
+ haptic_data[1],
+ haptic_data[2]);
+ bpf_printk(" %02x %02x %02x",
+ haptic_data[3],
+ haptic_data[4],
+ haptic_data[5]);
+ bpf_printk(" %02x %02x",
+ haptic_data[6],
+ haptic_data[7]);
+
+ /* whenever resolution multiplier is not 3600, we have the fixed report descriptor */
+ res = (u16 *)&haptic_data[1];
+ if (*res != 3600) {
+// haptic_data[1] = 72; /* resolution multiplier */
+// haptic_data[2] = 0; /* resolution multiplier */
+// haptic_data[3] = 0; /* Repeat Count */
+ haptic_data[4] = 3; /* haptic Auto Trigger */
+// haptic_data[5] = 5; /* Waveform Cutoff Time */
+// haptic_data[6] = 80; /* Retrigger Period */
+// haptic_data[7] = 0; /* Retrigger Period */
+ } else {
+ haptic_data[4] = 0;
+ }
+
+ ret = hid_bpf_hw_request(ctx, haptic_data, size, HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
+
+ bpf_printk("set haptic ret value: %d -> %d", ret, haptic_data[4]);
+
+ args->retval = ret;
+
+ hid_bpf_release_context(ctx);
+
+ return 0;
+}
+
+/* Convert REL_DIAL into REL_WHEEL */
+SEC("fmod_ret/hid_bpf_rdesc_fixup")
+int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
+{
+ __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
+ __u16 *res, *phys;
+
+ if (!data)
+ return 0; /* EPERM check */
+
+ /* Convert TOUCH into a button */
+ data[31] = HID_UP_BUTTON;
+ data[33] = 2;
+
+ /* Convert REL_DIAL into REL_WHEEL */
+ data[45] = HID_GD_WHEEL;
+
+ /* Change Resolution Multiplier */
+ phys = (__u16 *)&data[61];
+ *phys = physical;
+ res = (__u16 *)&data[66];
+ *res = resolution;
+
+ /* Convert X,Y from Abs to Rel */
+ data[88] = 0x06;
+ data[98] = 0x06;
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = 1;
diff --git a/samples/bpf/hid_surface_dial.c b/samples/bpf/hid_surface_dial.c
new file mode 100644
index 000000000000..5a67c4cd9433
--- /dev/null
+++ b/samples/bpf/hid_surface_dial.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2022 Benjamin Tissoires
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <unistd.h>
+
+#include <linux/bpf.h>
+#include <linux/errno.h>
+
+#include "bpf_util.h"
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "hid_surface_dial.skel.h"
+
+static bool running = true;
+
+struct attach_prog_args {
+ int prog_fd;
+ unsigned int hid;
+ int retval;
+};
+
+struct haptic_syscall_args {
+ unsigned int hid;
+ int retval;
+};
+
+static void int_exit(int sig)
+{
+ running = false;
+ exit(0);
+}
+
+static void usage(const char *prog)
+{
+ fprintf(stderr,
+ "%s: %s [OPTIONS] /sys/bus/hid/devices/0BUS:0VID:0PID:00ID\n\n"
+ " OPTIONS:\n"
+ " -r N\t set the given resolution to the device (number of ticks per 360°)\n\n",
+ __func__, prog);
+}
+
+static int get_hid_id(const char *path)
+{
+ const char *str_id, *dir;
+ char uevent[1024];
+ int fd;
+
+ memset(uevent, 0, sizeof(uevent));
+ snprintf(uevent, sizeof(uevent) - 1, "%s/uevent", path);
+
+ fd = open(uevent, O_RDONLY | O_NONBLOCK);
+ if (fd < 0)
+ return -ENOENT;
+
+ close(fd);
+
+ dir = basename((char *)path);
+
+ str_id = dir + sizeof("0003:0001:0A37.");
+ return (int)strtol(str_id, NULL, 16);
+}
+
+static int attach_prog(struct hid_surface_dial_lskel *skel, struct bpf_program *prog, int hid_id)
+{
+ struct attach_prog_args args = {
+ .hid = hid_id,
+ .retval = -1,
+ };
+ int attach_fd, err;
+ DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
+ .ctx_in = &args,
+ .ctx_size_in = sizeof(args),
+ );
+
+ attach_fd = bpf_program__fd(skel->progs.attach_prog);
+ if (attach_fd < 0) {
+ fprintf(stderr, "can't locate attach prog: %m\n");
+ return 1;
+ }
+
+ args.prog_fd = bpf_program__fd(prog);
+ err = bpf_prog_test_run_opts(attach_fd, &tattr);
+ if (err) {
+ fprintf(stderr, "can't attach prog to hid device %d: %m (err: %d)\n",
+ hid_id, err);
+ return 1;
+ }
+ return 0;
+}
+
+static int set_haptic(struct hid_surface_dial_lskel *skel, int hid_id)
+{
+ struct haptic_syscall_args args = {
+ .hid = hid_id,
+ .retval = -1,
+ };
+ int haptic_fd, err;
+ DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
+ .ctx_in = &args,
+ .ctx_size_in = sizeof(args),
+ );
+
+ haptic_fd = bpf_program__fd(skel->progs.set_haptic);
+ if (haptic_fd < 0) {
+ fprintf(stderr, "can't locate haptic prog: %m\n");
+ return 1;
+ }
+
+ err = bpf_prog_test_run_opts(haptic_fd, &tattr);
+ if (err) {
+ fprintf(stderr, "can't set haptic configuration to hid device %d: %m (err: %d)\n",
+ hid_id, err);
+ return 1;
+ }
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ struct hid_surface_dial_lskel *skel;
+ struct bpf_program *prog;
+ const char *optstr = "r:";
+ const char *sysfs_path;
+ int opt, hid_id, resolution = 72;
+
+ while ((opt = getopt(argc, argv, optstr)) != -1) {
+ switch (opt) {
+ case 'r':
+ {
+ char *endp = NULL;
+ long l = -1;
+
+ if (optarg) {
+ l = strtol(optarg, &endp, 10);
+ if (endp && *endp)
+ l = -1;
+ }
+
+ if (l < 0) {
+ fprintf(stderr,
+ "invalid r option %s - expecting a number\n",
+ optarg ? optarg : "");
+ exit(EXIT_FAILURE);
+ };
+
+ resolution = (int) l;
+ break;
+ }
+ default:
+ usage(basename(argv[0]));
+ return 1;
+ }
+ }
+
+ if (optind == argc) {
+ usage(basename(argv[0]));
+ return 1;
+ }
+
+ sysfs_path = argv[optind];
+ if (!sysfs_path) {
+ perror("sysfs");
+ return 1;
+ }
+
+ skel = hid_surface_dial_lskel__open_and_load();
+ if (!skel) {
+ fprintf(stderr, "%s %s:%d", __func__, __FILE__, __LINE__);
+ return -1;
+ }
+
+ hid_id = get_hid_id(sysfs_path);
+ if (hid_id < 0) {
+ fprintf(stderr, "can not open HID device: %m\n");
+ return 1;
+ }
+
+ skel->data->resolution = resolution;
+ skel->data->physical = (int)(resolution / 72);
+
+ bpf_object__for_each_program(prog, *skel->skeleton->obj) {
+ /* ignore syscalls */
+ if (bpf_program__get_type(prog) != BPF_PROG_TYPE_TRACING)
+ continue;
+
+ attach_prog(skel, prog, hid_id);
+ }
+
+ signal(SIGINT, int_exit);
+ signal(SIGTERM, int_exit);
+
+ set_haptic(skel, hid_id);
+
+ while (running)
+ ;
+
+ hid_surface_dial_lskel__destroy(skel);
+
+ return 0;
+}
--
2.36.1