[PATCH bpf-next v3 13/17] HID: bpf: implement hid_bpf_get|set_bits

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

Export implement() outside of hid-core.c and use this and
hid_field_extract() to implement the helprs for hid-bpf.

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

---

changes in v3:
- renamed hid_{get|set}_data into hid_{get|set}_bits

changes in v2:
- split the series by bpf/libbpf/hid/selftests and samples
- allow for n > 32, by relying on memcpy
---
 drivers/hid/hid-bpf.c  | 29 +++++++++++++++++++++++++++++
 drivers/hid/hid-core.c |  4 ++--
 include/linux/hid.h    |  2 ++
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-bpf.c b/drivers/hid/hid-bpf.c
index 45c87ff47324..650dd5e54919 100644
--- a/drivers/hid/hid-bpf.c
+++ b/drivers/hid/hid-bpf.c
@@ -122,6 +122,33 @@ static void hid_bpf_array_detach(struct hid_device *hdev, enum bpf_hid_attach_ty
 	}
 }
 
+static int hid_bpf_get_bits(struct hid_device *hdev, u8 *buf, size_t buf_size, u64 offset, u32 n,
+			    u32 *data)
+{
+	if (n > 32)
+		return -EINVAL;
+
+	if (((offset + n) >> 3) >= buf_size)
+		return -E2BIG;
+
+	*data = hid_field_extract(hdev, buf, offset, n);
+	return n;
+}
+
+static int hid_bpf_set_bits(struct hid_device *hdev, u8 *buf, size_t buf_size, u64 offset, u32 n,
+			    u32 data)
+{
+	if (n > 32)
+		return -EINVAL;
+
+	if (((offset + n) >> 3) >= buf_size)
+		return -E2BIG;
+
+	/* data must be a pointer to a u32 */
+	implement(hdev, buf, offset, n, data);
+	return n;
+}
+
 static int hid_bpf_run_progs(struct hid_device *hdev, struct hid_bpf_ctx_kern *ctx)
 {
 	enum bpf_hid_attach_type type;
@@ -223,6 +250,8 @@ int __init hid_bpf_module_init(void)
 		.pre_link_attach = hid_bpf_pre_link_attach,
 		.post_link_attach = hid_bpf_post_link_attach,
 		.array_detach = hid_bpf_array_detach,
+		.hid_get_bits = hid_bpf_get_bits,
+		.hid_set_bits = hid_bpf_set_bits,
 	};
 
 	bpf_hid_set_hooks(&hooks);
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 3182c39db006..4f669dcddc08 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1416,8 +1416,8 @@ static void __implement(u8 *report, unsigned offset, int n, u32 value)
 	}
 }
 
-static void implement(const struct hid_device *hid, u8 *report,
-		      unsigned offset, unsigned n, u32 value)
+void implement(const struct hid_device *hid, u8 *report, unsigned int offset, unsigned int n,
+	       u32 value)
 {
 	if (unlikely(n > 32)) {
 		hid_warn(hid, "%s() called with n (%d) > 32! (%s)\n",
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 66d949d10b78..7454e844324c 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -944,6 +944,8 @@ bool hid_compare_device_paths(struct hid_device *hdev_a,
 s32 hid_snto32(__u32 value, unsigned n);
 __u32 hid_field_extract(const struct hid_device *hid, __u8 *report,
 		     unsigned offset, unsigned n);
+void implement(const struct hid_device *hid, u8 *report, unsigned int offset, unsigned int n,
+	       u32 value);
 
 #ifdef CONFIG_PM
 int hid_driver_suspend(struct hid_device *hdev, pm_message_t state);
-- 
2.35.1