sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 521 insertions, 0 deletions

diff --git a/drivers/input/mouse/trackpoint.c b/drivers/input/mouse/trackpoint.c
new file mode 100644
index 000000000..3bd8fdf56
--- /dev/null
+++ b/drivers/input/mouse/trackpoint.c
@@ -0,0 +1,521 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Stephen Evanchik <evanchsa@gmail.com>
+ *
+ * Trademarks are the property of their respective owners.
+ */
+
+#include <linux/array_size.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/serio.h>
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/libps2.h>
+#include <linux/proc_fs.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include "psmouse.h"
+#include "trackpoint.h"
+
+static const char * const trackpoint_variants[] = {
+	[TP_VARIANT_IBM]		= "IBM",
+	[TP_VARIANT_ALPS]		= "ALPS",
+	[TP_VARIANT_ELAN]		= "Elan",
+	[TP_VARIANT_NXP]		= "NXP",
+	[TP_VARIANT_JYT_SYNAPTICS]	= "JYT_Synaptics",
+	[TP_VARIANT_SYNAPTICS]		= "Synaptics",
+};
+
+/*
+ * Power-on Reset: Resets all trackpoint parameters, including RAM values,
+ * to defaults.
+ * Returns zero on success, non-zero on failure.
+ */
+static int trackpoint_power_on_reset(struct ps2dev *ps2dev)
+{
+	u8 param[2] = { TP_POR };
+	int err;
+
+	err = ps2_command(ps2dev, param, MAKE_PS2_CMD(1, 2, TP_COMMAND));
+	if (err)
+		return err;
+
+	/* Check for success response -- 0xAA00 */
+	if (param[0] != 0xAA || param[1] != 0x00)
+		return -ENODEV;
+
+	return 0;
+}
+
+/*
+ * Device IO: read, write and toggle bit
+ */
+static int trackpoint_read(struct ps2dev *ps2dev, u8 loc, u8 *results)
+{
+	results[0] = loc;
+
+	return ps2_command(ps2dev, results, MAKE_PS2_CMD(1, 1, TP_COMMAND));
+}
+
+static int trackpoint_write(struct ps2dev *ps2dev, u8 loc, u8 val)
+{
+	u8 param[3] = { TP_WRITE_MEM, loc, val };
+
+	return ps2_command(ps2dev, param, MAKE_PS2_CMD(3, 0, TP_COMMAND));
+}
+
+static int trackpoint_toggle_bit(struct ps2dev *ps2dev, u8 loc, u8 mask)
+{
+	u8 param[3] = { TP_TOGGLE, loc, mask };
+
+	/* Bad things will happen if the loc param isn't in this range */
+	if (loc < 0x20 || loc >= 0x2F)
+		return -EINVAL;
+
+	return ps2_command(ps2dev, param, MAKE_PS2_CMD(3, 0, TP_COMMAND));
+}
+
+static int trackpoint_update_bit(struct ps2dev *ps2dev,
+				 u8 loc, u8 mask, u8 value)
+{
+	int retval;
+	u8 data;
+
+	retval = trackpoint_read(ps2dev, loc, &data);
+	if (retval)
+		return retval;
+
+	if (((data & mask) == mask) != !!value)
+		retval = trackpoint_toggle_bit(ps2dev, loc, mask);
+
+	return retval;
+}
+
+/*
+ * Trackpoint-specific attributes
+ */
+struct trackpoint_attr_data {
+	size_t field_offset;
+	u8 command;
+	u8 mask;
+	bool inverted;
+	u8 power_on_default;
+};
+
+static ssize_t trackpoint_show_int_attr(struct psmouse *psmouse,
+					void *data, char *buf)
+{
+	struct trackpoint_data *tp = psmouse->private;
+	struct trackpoint_attr_data *attr = data;
+	u8 value = *(u8 *)((void *)tp + attr->field_offset);
+
+	if (attr->inverted)
+		value = !value;
+
+	return sprintf(buf, "%u\n", value);
+}
+
+static ssize_t trackpoint_set_int_attr(struct psmouse *psmouse, void *data,
+					const char *buf, size_t count)
+{
+	struct trackpoint_data *tp = psmouse->private;
+	struct trackpoint_attr_data *attr = data;
+	u8 *field = (void *)tp + attr->field_offset;
+	u8 value;
+	int err;
+
+	err = kstrtou8(buf, 10, &value);
+	if (err)
+		return err;
+
+	*field = value;
+	err = trackpoint_write(&psmouse->ps2dev, attr->command, value);
+
+	return err ?: count;
+}
+
+#define TRACKPOINT_INT_ATTR(_name, _command, _default)				\
+	static struct trackpoint_attr_data trackpoint_attr_##_name = {		\
+		.field_offset = offsetof(struct trackpoint_data, _name),	\
+		.command = _command,						\
+		.power_on_default = _default,					\
+	};									\
+	PSMOUSE_DEFINE_ATTR(_name, S_IWUSR | S_IRUGO,				\
+			    &trackpoint_attr_##_name,				\
+			    trackpoint_show_int_attr, trackpoint_set_int_attr)
+
+static ssize_t trackpoint_set_bit_attr(struct psmouse *psmouse, void *data,
+					const char *buf, size_t count)
+{
+	struct trackpoint_data *tp = psmouse->private;
+	struct trackpoint_attr_data *attr = data;
+	bool *field = (void *)tp + attr->field_offset;
+	bool value;
+	int err;
+
+	err = kstrtobool(buf, &value);
+	if (err)
+		return err;
+
+	if (attr->inverted)
+		value = !value;
+
+	if (*field != value) {
+		*field = value;
+		err = trackpoint_toggle_bit(&psmouse->ps2dev,
+					    attr->command, attr->mask);
+	}
+
+	return err ?: count;
+}
+
+
+#define TRACKPOINT_BIT_ATTR(_name, _command, _mask, _inv, _default)	\
+static struct trackpoint_attr_data trackpoint_attr_##_name = {		\
+	.field_offset		= offsetof(struct trackpoint_data,	\
+					   _name),			\
+	.command		= _command,				\
+	.mask			= _mask,				\
+	.inverted		= _inv,					\
+	.power_on_default	= _default,				\
+	};								\
+PSMOUSE_DEFINE_ATTR(_name, S_IWUSR | S_IRUGO,				\
+		    &trackpoint_attr_##_name,				\
+		    trackpoint_show_int_attr, trackpoint_set_bit_attr)
+
+TRACKPOINT_INT_ATTR(sensitivity, TP_SENS, TP_DEF_SENS);
+TRACKPOINT_INT_ATTR(speed, TP_SPEED, TP_DEF_SPEED);
+TRACKPOINT_INT_ATTR(inertia, TP_INERTIA, TP_DEF_INERTIA);
+TRACKPOINT_INT_ATTR(reach, TP_REACH, TP_DEF_REACH);
+TRACKPOINT_INT_ATTR(draghys, TP_DRAGHYS, TP_DEF_DRAGHYS);
+TRACKPOINT_INT_ATTR(mindrag, TP_MINDRAG, TP_DEF_MINDRAG);
+TRACKPOINT_INT_ATTR(thresh, TP_THRESH, TP_DEF_THRESH);
+TRACKPOINT_INT_ATTR(upthresh, TP_UP_THRESH, TP_DEF_UP_THRESH);
+TRACKPOINT_INT_ATTR(ztime, TP_Z_TIME, TP_DEF_Z_TIME);
+TRACKPOINT_INT_ATTR(jenks, TP_JENKS_CURV, TP_DEF_JENKS_CURV);
+TRACKPOINT_INT_ATTR(drift_time, TP_DRIFT_TIME, TP_DEF_DRIFT_TIME);
+
+TRACKPOINT_BIT_ATTR(press_to_select, TP_TOGGLE_PTSON, TP_MASK_PTSON, false,
+		    TP_DEF_PTSON);
+TRACKPOINT_BIT_ATTR(skipback, TP_TOGGLE_SKIPBACK, TP_MASK_SKIPBACK, false,
+		    TP_DEF_SKIPBACK);
+TRACKPOINT_BIT_ATTR(ext_dev, TP_TOGGLE_EXT_DEV, TP_MASK_EXT_DEV, true,
+		    TP_DEF_EXT_DEV);
+
+static bool trackpoint_is_attr_available(struct psmouse *psmouse,
+					 struct attribute *attr)
+{
+	struct trackpoint_data *tp = psmouse->private;
+
+	return tp->variant_id == TP_VARIANT_IBM ||
+		attr == &psmouse_attr_sensitivity.dattr.attr ||
+		attr == &psmouse_attr_press_to_select.dattr.attr;
+}
+
+static umode_t trackpoint_is_attr_visible(struct kobject *kobj,
+					  struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct serio *serio = to_serio_port(dev);
+	struct psmouse *psmouse = psmouse_from_serio(serio);
+
+	return trackpoint_is_attr_available(psmouse, attr) ? attr->mode : 0;
+}
+
+static struct attribute *trackpoint_attrs[] = {
+	&psmouse_attr_sensitivity.dattr.attr,
+	&psmouse_attr_speed.dattr.attr,
+	&psmouse_attr_inertia.dattr.attr,
+	&psmouse_attr_reach.dattr.attr,
+	&psmouse_attr_draghys.dattr.attr,
+	&psmouse_attr_mindrag.dattr.attr,
+	&psmouse_attr_thresh.dattr.attr,
+	&psmouse_attr_upthresh.dattr.attr,
+	&psmouse_attr_ztime.dattr.attr,
+	&psmouse_attr_jenks.dattr.attr,
+	&psmouse_attr_drift_time.dattr.attr,
+	&psmouse_attr_press_to_select.dattr.attr,
+	&psmouse_attr_skipback.dattr.attr,
+	&psmouse_attr_ext_dev.dattr.attr,
+	NULL
+};
+
+static struct attribute_group trackpoint_attr_group = {
+	.is_visible	= trackpoint_is_attr_visible,
+	.attrs		= trackpoint_attrs,
+};
+
+#define TRACKPOINT_UPDATE(_power_on, _psmouse, _tp, _name)		\
+do {									\
+	struct trackpoint_attr_data *_attr = &trackpoint_attr_##_name;	\
+									\
+	if ((!_power_on || _tp->_name != _attr->power_on_default) &&	\
+	    trackpoint_is_attr_available(_psmouse,			\
+				&psmouse_attr_##_name.dattr.attr)) {	\
+		if (!_attr->mask)					\
+			trackpoint_write(&_psmouse->ps2dev,		\
+					 _attr->command, _tp->_name);	\
+		else							\
+			trackpoint_update_bit(&_psmouse->ps2dev,	\
+					_attr->command, _attr->mask,	\
+					_tp->_name);			\
+	}								\
+} while (0)
+
+#define TRACKPOINT_SET_POWER_ON_DEFAULT(_tp, _name)			\
+do {									\
+	_tp->_name = trackpoint_attr_##_name.power_on_default;		\
+} while (0)
+
+static int trackpoint_start_protocol(struct psmouse *psmouse,
+				     u8 *variant_id, u8 *firmware_id)
+{
+	u8 param[2] = { 0 };
+	int error;
+
+	error = ps2_command(&psmouse->ps2dev,
+			    param, MAKE_PS2_CMD(0, 2, TP_READ_ID));
+	if (error)
+		return error;
+
+	switch (param[0]) {
+	case TP_VARIANT_IBM:
+	case TP_VARIANT_ALPS:
+	case TP_VARIANT_ELAN:
+	case TP_VARIANT_NXP:
+	case TP_VARIANT_JYT_SYNAPTICS:
+	case TP_VARIANT_SYNAPTICS:
+		if (variant_id)
+			*variant_id = param[0];
+		if (firmware_id)
+			*firmware_id = param[1];
+		return 0;
+	}
+
+	return -ENODEV;
+}
+
+/*
+ * Write parameters to trackpad.
+ * in_power_on_state: Set to true if TP is in default / power-on state (ex. if
+ *		      power-on reset was run). If so, values will only be
+ *		      written to TP if they differ from power-on default.
+ */
+static int trackpoint_sync(struct psmouse *psmouse, bool in_power_on_state)
+{
+	struct trackpoint_data *tp = psmouse->private;
+
+	if (!in_power_on_state && tp->variant_id == TP_VARIANT_IBM) {
+		/*
+		 * Disable features that may make device unusable
+		 * with this driver.
+		 */
+		trackpoint_update_bit(&psmouse->ps2dev, TP_TOGGLE_TWOHAND,
+				      TP_MASK_TWOHAND, TP_DEF_TWOHAND);
+
+		trackpoint_update_bit(&psmouse->ps2dev, TP_TOGGLE_SOURCE_TAG,
+				      TP_MASK_SOURCE_TAG, TP_DEF_SOURCE_TAG);
+
+		trackpoint_update_bit(&psmouse->ps2dev, TP_TOGGLE_MB,
+				      TP_MASK_MB, TP_DEF_MB);
+	}
+
+	/*
+	 * These properties can be changed in this driver. Only
+	 * configure them if the values are non-default or if the TP is in
+	 * an unknown state.
+	 */
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, sensitivity);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, inertia);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, speed);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, reach);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, draghys);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, mindrag);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, thresh);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, upthresh);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, ztime);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, jenks);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, drift_time);
+
+	/* toggles */
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, press_to_select);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, skipback);
+	TRACKPOINT_UPDATE(in_power_on_state, psmouse, tp, ext_dev);
+
+	return 0;
+}
+
+static void trackpoint_defaults(struct trackpoint_data *tp)
+{
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, sensitivity);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, speed);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, reach);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, draghys);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, mindrag);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, thresh);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, upthresh);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, ztime);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, jenks);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, drift_time);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, inertia);
+
+	/* toggles */
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, press_to_select);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, skipback);
+	TRACKPOINT_SET_POWER_ON_DEFAULT(tp, ext_dev);
+}
+
+static void trackpoint_disconnect(struct psmouse *psmouse)
+{
+	device_remove_group(&psmouse->ps2dev.serio->dev,
+			    &trackpoint_attr_group);
+
+	kfree(psmouse->private);
+	psmouse->private = NULL;
+}
+
+static int trackpoint_reconnect(struct psmouse *psmouse)
+{
+	struct trackpoint_data *tp = psmouse->private;
+	int error;
+	bool was_reset;
+
+	error = trackpoint_start_protocol(psmouse, NULL, NULL);
+	if (error)
+		return error;
+
+	was_reset = tp->variant_id == TP_VARIANT_IBM &&
+		    trackpoint_power_on_reset(&psmouse->ps2dev) == 0;
+
+	error = trackpoint_sync(psmouse, was_reset);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+/* List of known incapable device PNP IDs */
+static const char * const dt_incompatible_devices[] = {
+	"LEN0304",
+	"LEN0306",
+	"LEN0317",
+	"LEN031A",
+	"LEN031B",
+	"LEN031C",
+	"LEN031D",
+};
+
+/*
+ * Checks if it's a doubletap capable device.
+ * The PNP ID format is "PNP: LEN030d PNP0f13".
+ */
+static bool trackpoint_is_dt_capable(const char *pnp_id)
+{
+	size_t i;
+
+	if (!pnp_id)
+		return false;
+
+	/* Must start with "PNP: LEN03" */
+	if (!strstarts(pnp_id, "PNP: LEN03"))
+		return false;
+
+	/* Ensure enough length before comparing */
+	if (strlen(pnp_id) < 12)
+		return false;
+
+	/* Check deny-list */
+	for (i = 0; i < ARRAY_SIZE(dt_incompatible_devices); i++) {
+		if (!strncmp(pnp_id + 5, dt_incompatible_devices[i], 7))
+			return false;
+	}
+	return true;
+}
+
+int trackpoint_detect(struct psmouse *psmouse, bool set_properties)
+{
+	struct ps2dev *ps2dev = &psmouse->ps2dev;
+	struct trackpoint_data *tp;
+	u8 variant_id;
+	u8 firmware_id;
+	u8 button_info;
+	int error;
+
+	error = trackpoint_start_protocol(psmouse, &variant_id, &firmware_id);
+	if (error)
+		return error;
+
+	if (!set_properties)
+		return 0;
+
+	tp = kzalloc_obj(*tp);
+	if (!tp)
+		return -ENOMEM;
+
+	trackpoint_defaults(tp);
+	tp->variant_id = variant_id;
+	tp->firmware_id = firmware_id;
+
+	psmouse->private = tp;
+
+	psmouse->vendor = trackpoint_variants[variant_id];
+	psmouse->name = "TrackPoint";
+
+	psmouse->reconnect = trackpoint_reconnect;
+	psmouse->disconnect = trackpoint_disconnect;
+
+	if (variant_id != TP_VARIANT_IBM) {
+		/* Newer variants do not support extended button query. */
+		button_info = 0x33;
+	} else {
+		error = trackpoint_read(ps2dev, TP_EXT_BTN, &button_info);
+		if (error) {
+			psmouse_warn(psmouse,
+				     "failed to get extended button data, assuming 3 buttons\n");
+			button_info = 0x33;
+		} else if (!button_info) {
+			psmouse_warn(psmouse,
+				     "got 0 in extended button data, assuming 3 buttons\n");
+			button_info = 0x33;
+		}
+	}
+
+	if ((button_info & 0x0f) >= 3)
+		input_set_capability(psmouse->dev, EV_KEY, BTN_MIDDLE);
+
+	__set_bit(INPUT_PROP_POINTER, psmouse->dev->propbit);
+	__set_bit(INPUT_PROP_POINTING_STICK, psmouse->dev->propbit);
+
+	if (variant_id != TP_VARIANT_IBM ||
+	    trackpoint_power_on_reset(ps2dev) != 0) {
+		/*
+		 * Write defaults to TP if we did not reset the trackpoint.
+		 */
+		trackpoint_sync(psmouse, false);
+	}
+
+	error = device_add_group(&ps2dev->serio->dev, &trackpoint_attr_group);
+	if (error) {
+		psmouse_err(psmouse,
+			    "failed to create sysfs attributes, error: %d\n",
+			    error);
+		kfree(psmouse->private);
+		psmouse->private = NULL;
+		return -1;
+	}
+
+	psmouse_info(psmouse,
+		     "%s TrackPoint firmware: 0x%02x, buttons: %d/%d\n",
+		     psmouse->vendor, firmware_id,
+		     (button_info & 0xf0) >> 4, button_info & 0x0f);
+
+	if (trackpoint_is_dt_capable(ps2dev->serio->firmware_id)) {
+		error = trackpoint_write(ps2dev, TP_DOUBLETAP, TP_DOUBLETAP_ENABLE);
+		if (error)
+			psmouse_warn(psmouse, "Failed to enable doubletap: %d\n", error);
+	}
+
+	return 0;
+}
+