diff options
| author | Benjamin Tissoires <bentiss@kernel.org> | 2024-10-01 16:30:05 +0200 |
|---|---|---|
| committer | Benjamin Tissoires <bentiss@kernel.org> | 2024-10-04 16:10:27 +0200 |
| commit | 8b7fd6a15f8c32760c2026a62dcf55219b4da15b (patch) | |
| tree | 529362110a1ff8ee137907448f9ee1a98486a4d3 /include/linux/hid.h | |
| parent | f23aa4c0761a70bfd046dd5755281667f0769a94 (diff) | |
HID: bpf: move HID-BPF report descriptor fixup earlier
Currently, hid_bpf_rdesc_fixup() is called once the match between the
HID device and the driver is done. This can be problematic in case
the driver selected by the kernel would change the report descriptor
after the fact.
To give a chance for hid_bpf_rdesc_fixup() to provide hints on to how
to select a dedicated driver or not, move the call to that BPF hook
earlier in the .probe() process, when we get the first match.
However, this means that we might get called more than once (typically
once for hid-generic, and once for hid-vendor-specific). So we store the
result of HID-BPF fixup in struct hid_device. Basically, this means that
->bpf_rdesc can replace ->dev_rdesc when it was used in the code.
In order to not grow struct hid_device, some fields are re-ordered. This
was the output of pahole for the first 128 bytes:
struct hid_device {
__u8 * dev_rdesc; /* 0 8 */
unsigned int dev_rsize; /* 8 4 */
/* XXX 4 bytes hole, try to pack */
__u8 * rdesc; /* 16 8 */
unsigned int rsize; /* 24 4 */
/* XXX 4 bytes hole, try to pack */
struct hid_collection * collection; /* 32 8 */
unsigned int collection_size; /* 40 4 */
unsigned int maxcollection; /* 44 4 */
unsigned int maxapplication; /* 48 4 */
__u16 bus; /* 52 2 */
__u16 group; /* 54 2 */
__u32 vendor; /* 56 4 */
__u32 product; /* 60 4 */
/* --- cacheline 1 boundary (64 bytes) --- */
__u32 version; /* 64 4 */
enum hid_type type; /* 68 4 */
unsigned int country; /* 72 4 */
/* XXX 4 bytes hole, try to pack */
struct hid_report_enum report_enum[3]; /* 80 6216 */
Basically, we got three holes of 4 bytes. We can reorder things a little
and makes those 3 holes a continuous 12 bytes hole, which can be replaced
by the new pointer and the new unsigned int we need.
In terms of code allocation, when not using HID-BPF, we are back to kernel
v6.2 in hid_open_report(). These multiple kmemdup() calls will be fixed
in a later commit.
Link: https://patch.msgid.link/20241001-hid-bpf-hid-generic-v3-1-2ef1019468df@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Diffstat (limited to 'include/linux/hid.h')
| -rw-r--r-- | include/linux/hid.h | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/include/linux/hid.h b/include/linux/hid.h index 121d5b8bc867..ff58b5ceb62e 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -599,15 +599,17 @@ enum hid_battery_status { struct hid_driver; struct hid_ll_driver; -struct hid_device { /* device report descriptor */ - const __u8 *dev_rdesc; - unsigned dev_rsize; - const __u8 *rdesc; - unsigned rsize; +struct hid_device { + const __u8 *dev_rdesc; /* device report descriptor */ + const __u8 *bpf_rdesc; /* bpf modified report descriptor, if any */ + const __u8 *rdesc; /* currently used report descriptor */ + unsigned int dev_rsize; + unsigned int bpf_rsize; + unsigned int rsize; + unsigned int collection_size; /* Number of allocated hid_collections */ struct hid_collection *collection; /* List of HID collections */ - unsigned collection_size; /* Number of allocated hid_collections */ - unsigned maxcollection; /* Number of parsed collections */ - unsigned maxapplication; /* Number of applications */ + unsigned int maxcollection; /* Number of parsed collections */ + unsigned int maxapplication; /* Number of applications */ __u16 bus; /* BUS ID */ __u16 group; /* Report group */ __u32 vendor; /* Vendor ID */ |