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, 353 insertions, 0 deletions

diff --git a/drivers/input/mouse/lifebook.c b/drivers/input/mouse/lifebook.c
new file mode 100644
index 000000000..ef11b7b19
--- /dev/null
+++ b/drivers/input/mouse/lifebook.c
@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Fujitsu B-series Lifebook PS/2 TouchScreen driver
+ *
+ * Copyright (c) 2005 Vojtech Pavlik <vojtech@suse.cz>
+ * Copyright (c) 2005 Kenan Esau <kenan.esau@conan.de>
+ *
+ * TouchScreen detection, absolute mode setting and packet layout is taken from
+ * Harald Hoyer's description of the device.
+ */
+
+#include <linux/input.h>
+#include <linux/serio.h>
+#include <linux/libps2.h>
+#include <linux/dmi.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "psmouse.h"
+#include "lifebook.h"
+
+struct lifebook_data {
+	struct input_dev *dev2;		/* Relative device */
+	char phys[32];
+};
+
+static bool lifebook_present;
+
+static const char *desired_serio_phys;
+
+static int lifebook_limit_serio3(const struct dmi_system_id *d)
+{
+	desired_serio_phys = "isa0060/serio3";
+	return 1;
+}
+
+static bool lifebook_use_6byte_proto;
+
+static int lifebook_set_6byte_proto(const struct dmi_system_id *d)
+{
+	lifebook_use_6byte_proto = true;
+	return 1;
+}
+
+static const struct dmi_system_id lifebook_dmi_table[] __initconst = {
+	{
+		/* FLORA-ie 55mi */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "FLORA-ie 55mi"),
+		},
+	},
+	{
+		/* LifeBook B */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "Lifebook B Series"),
+		},
+	},
+	{
+		/* LifeBook B */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "LifeBook B Series"),
+		},
+	},
+	{
+		/* Lifebook B */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "LIFEBOOK B Series"),
+		},
+	},
+	{
+		/* Lifebook B-2130 */
+		.matches = {
+			DMI_MATCH(DMI_BOARD_NAME, "ZEPHYR"),
+		},
+	},
+	{
+		/* Lifebook B213x/B2150 */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "LifeBook B2131/B2133/B2150"),
+		},
+	},
+	{
+		/* Zephyr */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "ZEPHYR"),
+		},
+	},
+	{
+		/* Panasonic CF-18 */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "CF-18"),
+		},
+		.callback = lifebook_limit_serio3,
+	},
+	{
+		/* Panasonic CF-28 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Matsushita"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CF-28"),
+		},
+		.callback = lifebook_set_6byte_proto,
+	},
+	{
+		/* Panasonic CF-29 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Matsushita"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CF-29"),
+		},
+		.callback = lifebook_set_6byte_proto,
+	},
+	{
+		/* Panasonic CF-72 */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "CF-72"),
+		},
+		.callback = lifebook_set_6byte_proto,
+	},
+	{
+		/* Lifebook B142 */
+		.matches = {
+			DMI_MATCH(DMI_PRODUCT_NAME, "LifeBook B142"),
+		},
+	},
+	{ }
+};
+
+void __init lifebook_module_init(void)
+{
+	lifebook_present = dmi_check_system(lifebook_dmi_table);
+}
+
+static psmouse_ret_t lifebook_process_byte(struct psmouse *psmouse)
+{
+	struct lifebook_data *priv = psmouse->private;
+	struct input_dev *dev1 = psmouse->dev;
+	struct input_dev *dev2 = priv ? priv->dev2 : NULL;
+	u8 *packet = psmouse->packet;
+	bool relative_packet = packet[0] & 0x08;
+
+	if (relative_packet || !lifebook_use_6byte_proto) {
+		if (psmouse->pktcnt != 3)
+			return PSMOUSE_GOOD_DATA;
+	} else {
+		switch (psmouse->pktcnt) {
+		case 1:
+			return (packet[0] & 0xf8) == 0x00 ?
+				PSMOUSE_GOOD_DATA : PSMOUSE_BAD_DATA;
+		case 2:
+			return PSMOUSE_GOOD_DATA;
+		case 3:
+			return ((packet[2] & 0x30) << 2) == (packet[2] & 0xc0) ?
+				PSMOUSE_GOOD_DATA : PSMOUSE_BAD_DATA;
+		case 4:
+			return (packet[3] & 0xf8) == 0xc0 ?
+				PSMOUSE_GOOD_DATA : PSMOUSE_BAD_DATA;
+		case 5:
+			return (packet[4] & 0xc0) == (packet[2] & 0xc0) ?
+				PSMOUSE_GOOD_DATA : PSMOUSE_BAD_DATA;
+		case 6:
+			if (((packet[5] & 0x30) << 2) != (packet[5] & 0xc0))
+				return PSMOUSE_BAD_DATA;
+			if ((packet[5] & 0xc0) != (packet[1] & 0xc0))
+				return PSMOUSE_BAD_DATA;
+			break; /* report data */
+		}
+	}
+
+	if (relative_packet) {
+		if (!dev2)
+			psmouse_warn(psmouse,
+				     "got relative packet but no relative device set up\n");
+	} else {
+		if (lifebook_use_6byte_proto) {
+			input_report_abs(dev1, ABS_X,
+				((packet[1] & 0x3f) << 6) | (packet[2] & 0x3f));
+			input_report_abs(dev1, ABS_Y,
+				4096 - (((packet[4] & 0x3f) << 6) | (packet[5] & 0x3f)));
+		} else {
+			input_report_abs(dev1, ABS_X,
+				(packet[1] | ((packet[0] & 0x30) << 4)));
+			input_report_abs(dev1, ABS_Y,
+				1024 - (packet[2] | ((packet[0] & 0xC0) << 2)));
+		}
+		input_report_key(dev1, BTN_TOUCH, packet[0] & 0x04);
+		input_sync(dev1);
+	}
+
+	if (dev2) {
+		if (relative_packet)
+			psmouse_report_standard_motion(dev2, packet);
+
+		psmouse_report_standard_buttons(dev2, packet[0]);
+		input_sync(dev2);
+	}
+
+	return PSMOUSE_FULL_PACKET;
+}
+
+static int lifebook_absolute_mode(struct psmouse *psmouse)
+{
+	struct ps2dev *ps2dev = &psmouse->ps2dev;
+	u8 param;
+	int error;
+
+	error = psmouse_reset(psmouse);
+	if (error)
+		return error;
+
+	/*
+	 * Enable absolute output -- ps2_command fails always but if
+	 * you leave this call out the touchscreen will never send
+	 * absolute coordinates
+	 */
+	param = lifebook_use_6byte_proto ? 0x08 : 0x07;
+	ps2_command(ps2dev, &param, PSMOUSE_CMD_SETRES);
+
+	return 0;
+}
+
+static void lifebook_relative_mode(struct psmouse *psmouse)
+{
+	struct ps2dev *ps2dev = &psmouse->ps2dev;
+	u8 param = 0x06;
+
+	ps2_command(ps2dev, &param, PSMOUSE_CMD_SETRES);
+}
+
+static void lifebook_set_resolution(struct psmouse *psmouse, unsigned int resolution)
+{
+	static const u8 params[] = { 0, 1, 2, 2, 3 };
+	u8 p;
+
+	if (resolution == 0 || resolution > 400)
+		resolution = 400;
+
+	p = params[resolution / 100];
+	ps2_command(&psmouse->ps2dev, &p, PSMOUSE_CMD_SETRES);
+	psmouse->resolution = 50 << p;
+}
+
+static void lifebook_disconnect(struct psmouse *psmouse)
+{
+	struct lifebook_data *priv = psmouse->private;
+
+	psmouse_reset(psmouse);
+	if (priv) {
+		input_unregister_device(priv->dev2);
+		kfree(priv);
+	}
+	psmouse->private = NULL;
+}
+
+int lifebook_detect(struct psmouse *psmouse, bool set_properties)
+{
+	if (!lifebook_present)
+		return -ENXIO;
+
+	if (desired_serio_phys &&
+	    strcmp(psmouse->ps2dev.serio->phys, desired_serio_phys))
+		return -ENXIO;
+
+	if (set_properties) {
+		psmouse->vendor = "Fujitsu";
+		psmouse->name = "Lifebook TouchScreen";
+	}
+
+	return 0;
+}
+
+static int lifebook_create_relative_device(struct psmouse *psmouse)
+{
+	struct input_dev *dev2;
+	struct lifebook_data *priv;
+	int error = -ENOMEM;
+
+	priv = kzalloc_obj(*priv);
+	dev2 = input_allocate_device();
+	if (!priv || !dev2)
+		goto err_out;
+
+	priv->dev2 = dev2;
+	scnprintf(priv->phys, sizeof(priv->phys),
+		  "%s/input1", psmouse->ps2dev.serio->phys);
+
+	dev2->phys = priv->phys;
+	dev2->name = "LBPS/2 Fujitsu Lifebook Touchpad";
+	dev2->id.bustype = BUS_I8042;
+	dev2->id.vendor  = 0x0002;
+	dev2->id.product = PSMOUSE_LIFEBOOK;
+	dev2->id.version = 0x0000;
+	dev2->dev.parent = &psmouse->ps2dev.serio->dev;
+
+	input_set_capability(dev2, EV_REL, REL_X);
+	input_set_capability(dev2, EV_REL, REL_Y);
+	input_set_capability(dev2, EV_KEY, BTN_LEFT);
+	input_set_capability(dev2, EV_KEY, BTN_RIGHT);
+
+	error = input_register_device(priv->dev2);
+	if (error)
+		goto err_out;
+
+	psmouse->private = priv;
+	return 0;
+
+ err_out:
+	input_free_device(dev2);
+	kfree(priv);
+	return error;
+}
+
+int lifebook_init(struct psmouse *psmouse)
+{
+	struct input_dev *dev1 = psmouse->dev;
+	int max_coord = lifebook_use_6byte_proto ? 4096 : 1024;
+	int error;
+
+	error = lifebook_absolute_mode(psmouse);
+	if (error)
+		return error;
+
+	/* Clear default capabilities */
+	bitmap_zero(dev1->evbit, EV_CNT);
+	bitmap_zero(dev1->relbit, REL_CNT);
+	bitmap_zero(dev1->keybit, KEY_CNT);
+
+	input_set_capability(dev1, EV_KEY, BTN_TOUCH);
+	input_set_abs_params(dev1, ABS_X, 0, max_coord, 0, 0);
+	input_set_abs_params(dev1, ABS_Y, 0, max_coord, 0, 0);
+
+	if (!desired_serio_phys) {
+		error = lifebook_create_relative_device(psmouse);
+		if (error) {
+			lifebook_relative_mode(psmouse);
+			return error;
+		}
+	}
+
+	psmouse->protocol_handler = lifebook_process_byte;
+	psmouse->set_resolution = lifebook_set_resolution;
+	psmouse->disconnect = lifebook_disconnect;
+	psmouse->reconnect  = lifebook_absolute_mode;
+
+	psmouse->model = lifebook_use_6byte_proto ? 6 : 3;
+
+	/*
+	 * Use packet size = 3 even when using 6-byte protocol because
+	 * that's what POLL will return on Lifebooks (according to spec).
+	 */
+	psmouse->pktsize = 3;
+
+	return 0;
+}
+