ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 579 insertions, 0 deletions

diff --git a/drivers/hid/hid-picolcd_fb.c b/drivers/hid/hid-picolcd_fb.c
new file mode 100644
index 000000000..8c28e982e
--- /dev/null
+++ b/drivers/hid/hid-picolcd_fb.c
@@ -0,0 +1,579 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/***************************************************************************
+ *   Copyright (C) 2010-2012 by Bruno Prémont <bonbons@linux-vserver.org>  *
+ *                                                                         *
+ *   Based on Logitech G13 driver (v0.4)                                   *
+ *     Copyright (C) 2009 by Rick L. Vinyard, Jr. <rvinyard@cs.nmsu.edu>   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include <linux/hid.h>
+#include <linux/vmalloc.h>
+
+#include <linux/fb.h>
+#include <linux/module.h>
+
+#include "hid-picolcd.h"
+
+/* Framebuffer
+ *
+ * The PicoLCD use a Topway LCD module of 256x64 pixel
+ * This display area is tiled over 4 controllers with 8 tiles
+ * each. Each tile has 8x64 pixel, each data byte representing
+ * a 1-bit wide vertical line of the tile.
+ *
+ * The display can be updated at a tile granularity.
+ *
+ *       Chip 1           Chip 2           Chip 3           Chip 4
+ * +----------------+----------------+----------------+----------------+
+ * |     Tile 1     |     Tile 1     |     Tile 1     |     Tile 1     |
+ * +----------------+----------------+----------------+----------------+
+ * |     Tile 2     |     Tile 2     |     Tile 2     |     Tile 2     |
+ * +----------------+----------------+----------------+----------------+
+ *                                  ...
+ * +----------------+----------------+----------------+----------------+
+ * |     Tile 8     |     Tile 8     |     Tile 8     |     Tile 8     |
+ * +----------------+----------------+----------------+----------------+
+ */
+#define PICOLCDFB_NAME "picolcdfb"
+#define PICOLCDFB_WIDTH (256)
+#define PICOLCDFB_HEIGHT (64)
+#define PICOLCDFB_SIZE (PICOLCDFB_WIDTH * PICOLCDFB_HEIGHT / 8)
+
+#define PICOLCDFB_UPDATE_RATE_LIMIT   10
+#define PICOLCDFB_UPDATE_RATE_DEFAULT  2
+
+/* Framebuffer visual structures */
+static const struct fb_fix_screeninfo picolcdfb_fix = {
+	.id          = PICOLCDFB_NAME,
+	.type        = FB_TYPE_PACKED_PIXELS,
+	.visual      = FB_VISUAL_MONO01,
+	.xpanstep    = 0,
+	.ypanstep    = 0,
+	.ywrapstep   = 0,
+	.line_length = PICOLCDFB_WIDTH / 8,
+	.accel       = FB_ACCEL_NONE,
+};
+
+static const struct fb_var_screeninfo picolcdfb_var = {
+	.xres           = PICOLCDFB_WIDTH,
+	.yres           = PICOLCDFB_HEIGHT,
+	.xres_virtual   = PICOLCDFB_WIDTH,
+	.yres_virtual   = PICOLCDFB_HEIGHT,
+	.width          = 103,
+	.height         = 26,
+	.bits_per_pixel = 1,
+	.grayscale      = 1,
+	.red            = {
+		.offset = 0,
+		.length = 1,
+		.msb_right = 0,
+	},
+	.green          = {
+		.offset = 0,
+		.length = 1,
+		.msb_right = 0,
+	},
+	.blue           = {
+		.offset = 0,
+		.length = 1,
+		.msb_right = 0,
+	},
+	.transp         = {
+		.offset = 0,
+		.length = 0,
+		.msb_right = 0,
+	},
+};
+
+/* Send a given tile to PicoLCD */
+static int picolcd_fb_send_tile(struct picolcd_data *data, u8 *vbitmap,
+		int chip, int tile)
+{
+	struct hid_report *report1, *report2;
+	unsigned long flags;
+	u8 *tdata;
+	int i;
+
+	report1 = picolcd_out_report(REPORT_LCD_CMD_DATA, data->hdev);
+	if (!report1 || report1->maxfield != 1)
+		return -ENODEV;
+	report2 = picolcd_out_report(REPORT_LCD_DATA, data->hdev);
+	if (!report2 || report2->maxfield != 1)
+		return -ENODEV;
+
+	spin_lock_irqsave(&data->lock, flags);
+	if ((data->status & PICOLCD_FAILED)) {
+		spin_unlock_irqrestore(&data->lock, flags);
+		return -ENODEV;
+	}
+	hid_set_field(report1->field[0],  0, chip << 2);
+	hid_set_field(report1->field[0],  1, 0x02);
+	hid_set_field(report1->field[0],  2, 0x00);
+	hid_set_field(report1->field[0],  3, 0x00);
+	hid_set_field(report1->field[0],  4, 0xb8 | tile);
+	hid_set_field(report1->field[0],  5, 0x00);
+	hid_set_field(report1->field[0],  6, 0x00);
+	hid_set_field(report1->field[0],  7, 0x40);
+	hid_set_field(report1->field[0],  8, 0x00);
+	hid_set_field(report1->field[0],  9, 0x00);
+	hid_set_field(report1->field[0], 10,   32);
+
+	hid_set_field(report2->field[0],  0, (chip << 2) | 0x01);
+	hid_set_field(report2->field[0],  1, 0x00);
+	hid_set_field(report2->field[0],  2, 0x00);
+	hid_set_field(report2->field[0],  3,   32);
+
+	tdata = vbitmap + (tile * 4 + chip) * 64;
+	for (i = 0; i < 64; i++)
+		if (i < 32)
+			hid_set_field(report1->field[0], 11 + i, tdata[i]);
+		else
+			hid_set_field(report2->field[0], 4 + i - 32, tdata[i]);
+
+	hid_hw_request(data->hdev, report1, HID_REQ_SET_REPORT);
+	hid_hw_request(data->hdev, report2, HID_REQ_SET_REPORT);
+	spin_unlock_irqrestore(&data->lock, flags);
+	return 0;
+}
+
+/* Translate a single tile*/
+static int picolcd_fb_update_tile(u8 *vbitmap, const u8 *bitmap, int bpp,
+		int chip, int tile)
+{
+	int i, b, changed = 0;
+	u8 tdata[64];
+	u8 *vdata = vbitmap + (tile * 4 + chip) * 64;
+
+	if (bpp == 1) {
+		for (b = 7; b >= 0; b--) {
+			const u8 *bdata = bitmap + tile * 256 + chip * 8 + b * 32;
+			for (i = 0; i < 64; i++) {
+				tdata[i] <<= 1;
+				tdata[i] |= (bdata[i/8] >> (i % 8)) & 0x01;
+			}
+		}
+	} else if (bpp == 8) {
+		for (b = 7; b >= 0; b--) {
+			const u8 *bdata = bitmap + (tile * 256 + chip * 8 + b * 32) * 8;
+			for (i = 0; i < 64; i++) {
+				tdata[i] <<= 1;
+				tdata[i] |= (bdata[i] & 0x80) ? 0x01 : 0x00;
+			}
+		}
+	} else {
+		/* Oops, we should never get here! */
+		WARN_ON(1);
+		return 0;
+	}
+
+	for (i = 0; i < 64; i++)
+		if (tdata[i] != vdata[i]) {
+			changed = 1;
+			vdata[i] = tdata[i];
+		}
+	return changed;
+}
+
+void picolcd_fb_refresh(struct picolcd_data *data)
+{
+	if (data->fb_info)
+		schedule_delayed_work(&data->fb_info->deferred_work, 0);
+}
+
+/* Reconfigure LCD display */
+int picolcd_fb_reset(struct picolcd_data *data, int clear)
+{
+	struct hid_report *report = picolcd_out_report(REPORT_LCD_CMD, data->hdev);
+	struct picolcd_fb_data *fbdata = data->fb_info->par;
+	int i, j;
+	unsigned long flags;
+	static const u8 mapcmd[8] = { 0x00, 0x02, 0x00, 0x64, 0x3f, 0x00, 0x64, 0xc0 };
+
+	if (!report || report->maxfield != 1)
+		return -ENODEV;
+
+	spin_lock_irqsave(&data->lock, flags);
+	for (i = 0; i < 4; i++) {
+		for (j = 0; j < report->field[0]->maxusage; j++)
+			if (j == 0)
+				hid_set_field(report->field[0], j, i << 2);
+			else if (j < sizeof(mapcmd))
+				hid_set_field(report->field[0], j, mapcmd[j]);
+			else
+				hid_set_field(report->field[0], j, 0);
+		hid_hw_request(data->hdev, report, HID_REQ_SET_REPORT);
+	}
+	spin_unlock_irqrestore(&data->lock, flags);
+
+	if (clear) {
+		memset(fbdata->vbitmap, 0, PICOLCDFB_SIZE);
+		memset(fbdata->bitmap, 0, PICOLCDFB_SIZE*fbdata->bpp);
+	}
+	fbdata->force = 1;
+
+	/* schedule first output of framebuffer */
+	if (fbdata->ready)
+		schedule_delayed_work(&data->fb_info->deferred_work, 0);
+	else
+		fbdata->ready = 1;
+
+	return 0;
+}
+
+/* Update fb_vbitmap from the screen_buffer and send changed tiles to device */
+static void picolcd_fb_update(struct fb_info *info)
+{
+	int chip, tile, n;
+	unsigned long flags;
+	struct picolcd_fb_data *fbdata = info->par;
+	struct picolcd_data *data;
+
+	mutex_lock(&info->lock);
+
+	spin_lock_irqsave(&fbdata->lock, flags);
+	if (!fbdata->ready && fbdata->picolcd)
+		picolcd_fb_reset(fbdata->picolcd, 0);
+	spin_unlock_irqrestore(&fbdata->lock, flags);
+
+	/*
+	 * Translate the framebuffer into the format needed by the PicoLCD.
+	 * See display layout above.
+	 * Do this one tile after the other and push those tiles that changed.
+	 *
+	 * Wait for our IO to complete as otherwise we might flood the queue!
+	 */
+	n = 0;
+	for (chip = 0; chip < 4; chip++)
+		for (tile = 0; tile < 8; tile++) {
+			if (!fbdata->force && !picolcd_fb_update_tile(
+					fbdata->vbitmap, fbdata->bitmap,
+					fbdata->bpp, chip, tile))
+				continue;
+			n += 2;
+			if (n >= HID_OUTPUT_FIFO_SIZE / 2) {
+				spin_lock_irqsave(&fbdata->lock, flags);
+				data = fbdata->picolcd;
+				spin_unlock_irqrestore(&fbdata->lock, flags);
+				mutex_unlock(&info->lock);
+				if (!data)
+					return;
+				hid_hw_wait(data->hdev);
+				mutex_lock(&info->lock);
+				n = 0;
+			}
+			spin_lock_irqsave(&fbdata->lock, flags);
+			data = fbdata->picolcd;
+			spin_unlock_irqrestore(&fbdata->lock, flags);
+			if (!data || picolcd_fb_send_tile(data,
+					fbdata->vbitmap, chip, tile))
+				goto out;
+		}
+	fbdata->force = false;
+	if (n) {
+		spin_lock_irqsave(&fbdata->lock, flags);
+		data = fbdata->picolcd;
+		spin_unlock_irqrestore(&fbdata->lock, flags);
+		mutex_unlock(&info->lock);
+		if (data)
+			hid_hw_wait(data->hdev);
+		return;
+	}
+out:
+	mutex_unlock(&info->lock);
+}
+
+static int picolcd_fb_blank(int blank, struct fb_info *info)
+{
+	/* We let fb notification do this for us via lcd/backlight device */
+	return 0;
+}
+
+static void picolcd_fb_destroy(struct fb_info *info)
+{
+	struct picolcd_fb_data *fbdata = info->par;
+
+	/* make sure no work is deferred */
+	fb_deferred_io_cleanup(info);
+
+	/* No thirdparty should ever unregister our framebuffer! */
+	WARN_ON(fbdata->picolcd != NULL);
+
+	vfree((u8 *)info->fix.smem_start);
+	framebuffer_release(info);
+}
+
+static int picolcd_fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
+{
+	__u32 bpp      = var->bits_per_pixel;
+	__u32 activate = var->activate;
+
+	/* only allow 1/8 bit depth (8-bit is grayscale) */
+	*var = picolcdfb_var;
+	var->activate = activate;
+	if (bpp >= 8) {
+		var->bits_per_pixel = 8;
+		var->red.length     = 8;
+		var->green.length   = 8;
+		var->blue.length    = 8;
+	} else {
+		var->bits_per_pixel = 1;
+		var->red.length     = 1;
+		var->green.length   = 1;
+		var->blue.length    = 1;
+	}
+	return 0;
+}
+
+static int picolcd_set_par(struct fb_info *info)
+{
+	struct picolcd_fb_data *fbdata = info->par;
+	u8 *tmp_fb, *o_fb;
+	if (info->var.bits_per_pixel == fbdata->bpp)
+		return 0;
+	/* switch between 1/8 bit depths */
+	if (info->var.bits_per_pixel != 1 && info->var.bits_per_pixel != 8)
+		return -EINVAL;
+
+	o_fb   = fbdata->bitmap;
+	tmp_fb = kmalloc_array(PICOLCDFB_SIZE, info->var.bits_per_pixel,
+			       GFP_KERNEL);
+	if (!tmp_fb)
+		return -ENOMEM;
+
+	/* translate FB content to new bits-per-pixel */
+	if (info->var.bits_per_pixel == 1) {
+		int i, b;
+		for (i = 0; i < PICOLCDFB_SIZE; i++) {
+			u8 p = 0;
+			for (b = 0; b < 8; b++) {
+				p <<= 1;
+				p |= o_fb[i*8+b] ? 0x01 : 0x00;
+			}
+			tmp_fb[i] = p;
+		}
+		memcpy(o_fb, tmp_fb, PICOLCDFB_SIZE);
+		info->fix.visual = FB_VISUAL_MONO01;
+		info->fix.line_length = PICOLCDFB_WIDTH / 8;
+	} else {
+		int i;
+		memcpy(tmp_fb, o_fb, PICOLCDFB_SIZE);
+		for (i = 0; i < PICOLCDFB_SIZE * 8; i++)
+			o_fb[i] = tmp_fb[i/8] & (0x01 << (7 - i % 8)) ? 0xff : 0x00;
+		info->fix.visual = FB_VISUAL_DIRECTCOLOR;
+		info->fix.line_length = PICOLCDFB_WIDTH;
+	}
+
+	kfree(tmp_fb);
+	fbdata->bpp = info->var.bits_per_pixel;
+	return 0;
+}
+
+static void picolcdfb_ops_damage_range(struct fb_info *info, off_t off, size_t len)
+{
+	if (!info->par)
+		return;
+	schedule_delayed_work(&info->deferred_work, 0);
+}
+
+static void picolcdfb_ops_damage_area(struct fb_info *info, u32 x, u32 y, u32 width, u32 height)
+{
+	if (!info->par)
+		return;
+	schedule_delayed_work(&info->deferred_work, 0);
+}
+
+FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(picolcdfb_ops,
+				   picolcdfb_ops_damage_range,
+				   picolcdfb_ops_damage_area)
+
+static const struct fb_ops picolcdfb_ops = {
+	.owner        = THIS_MODULE,
+	FB_DEFAULT_DEFERRED_OPS(picolcdfb_ops),
+	.fb_destroy   = picolcd_fb_destroy,
+	.fb_blank     = picolcd_fb_blank,
+	.fb_check_var = picolcd_fb_check_var,
+	.fb_set_par   = picolcd_set_par,
+};
+
+
+/* Callback from deferred IO workqueue */
+static void picolcd_fb_deferred_io(struct fb_info *info, struct list_head *pagereflist)
+{
+	picolcd_fb_update(info);
+}
+
+static const struct fb_deferred_io picolcd_fb_defio = {
+	.delay = HZ / PICOLCDFB_UPDATE_RATE_DEFAULT,
+	.deferred_io = picolcd_fb_deferred_io,
+};
+
+
+/*
+ * The "fb_update_rate" sysfs attribute
+ */
+static ssize_t picolcd_fb_update_rate_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct picolcd_data *data = dev_get_drvdata(dev);
+	struct picolcd_fb_data *fbdata = data->fb_info->par;
+	unsigned i, fb_update_rate = fbdata->update_rate;
+	size_t ret = 0;
+
+	for (i = 1; i <= PICOLCDFB_UPDATE_RATE_LIMIT; i++)
+		if (i == fb_update_rate)
+			ret += sysfs_emit_at(buf, ret, "[%u] ", i);
+		else
+			ret += sysfs_emit_at(buf, ret, "%u ", i);
+	if (ret > 0)
+		buf[min(ret, (size_t)PAGE_SIZE)-1] = '\n';
+	return ret;
+}
+
+static ssize_t picolcd_fb_update_rate_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct picolcd_data *data = dev_get_drvdata(dev);
+	struct picolcd_fb_data *fbdata = data->fb_info->par;
+	int i;
+	unsigned u;
+
+	if (count < 1 || count > 10)
+		return -EINVAL;
+
+	i = sscanf(buf, "%u", &u);
+	if (i != 1)
+		return -EINVAL;
+
+	if (u > PICOLCDFB_UPDATE_RATE_LIMIT)
+		return -ERANGE;
+	else if (u == 0)
+		u = PICOLCDFB_UPDATE_RATE_DEFAULT;
+
+	fbdata->update_rate = u;
+	data->fb_info->fbdefio->delay = HZ / fbdata->update_rate;
+	return count;
+}
+
+static DEVICE_ATTR(fb_update_rate, 0664, picolcd_fb_update_rate_show,
+		picolcd_fb_update_rate_store);
+
+/* initialize Framebuffer device */
+int picolcd_init_framebuffer(struct picolcd_data *data)
+{
+	struct device *dev = &data->hdev->dev;
+	struct fb_info *info = NULL;
+	struct picolcd_fb_data *fbdata = NULL;
+	int i, error = -ENOMEM;
+	u32 *palette;
+
+	/* The extra memory is:
+	 * - 256*u32 for pseudo_palette
+	 * - struct fb_deferred_io
+	 */
+	info = framebuffer_alloc(256 * sizeof(u32) +
+			sizeof(struct fb_deferred_io) +
+			sizeof(struct picolcd_fb_data) +
+			PICOLCDFB_SIZE, dev);
+	if (!info)
+		goto err_nomem;
+
+	info->fbdefio = info->par;
+	*info->fbdefio = picolcd_fb_defio;
+	info->par += sizeof(struct fb_deferred_io);
+	palette = info->par;
+	info->par += 256 * sizeof(u32);
+	for (i = 0; i < 256; i++)
+		palette[i] = i > 0 && i < 16 ? 0xff : 0;
+	info->pseudo_palette = palette;
+	info->fbops = &picolcdfb_ops;
+	info->var = picolcdfb_var;
+	info->fix = picolcdfb_fix;
+	info->fix.smem_len   = PICOLCDFB_SIZE*8;
+
+#ifdef CONFIG_FB_BACKLIGHT
+#ifdef CONFIG_HID_PICOLCD_BACKLIGHT
+	info->bl_dev = data->backlight;
+#endif
+#endif
+
+#ifdef CONFIG_HID_PICOLCD_LCD
+	info->lcd_dev = data->lcd;
+#endif
+
+	fbdata = info->par;
+	spin_lock_init(&fbdata->lock);
+	fbdata->picolcd = data;
+	fbdata->update_rate = PICOLCDFB_UPDATE_RATE_DEFAULT;
+	fbdata->bpp     = picolcdfb_var.bits_per_pixel;
+	fbdata->force   = 1;
+	fbdata->vbitmap = info->par + sizeof(struct picolcd_fb_data);
+	fbdata->bitmap  = vmalloc(PICOLCDFB_SIZE*8);
+	if (fbdata->bitmap == NULL) {
+		dev_err(dev, "can't get a free page for framebuffer\n");
+		goto err_nomem;
+	}
+	info->flags |= FBINFO_VIRTFB;
+	info->screen_buffer = fbdata->bitmap;
+	info->fix.smem_start = (unsigned long)fbdata->bitmap;
+	memset(fbdata->vbitmap, 0xff, PICOLCDFB_SIZE);
+	data->fb_info = info;
+
+	error = picolcd_fb_reset(data, 1);
+	if (error) {
+		dev_err(dev, "failed to configure display\n");
+		goto err_cleanup;
+	}
+
+	error = device_create_file(dev, &dev_attr_fb_update_rate);
+	if (error) {
+		dev_err(dev, "failed to create sysfs attributes\n");
+		goto err_cleanup;
+	}
+
+	fb_deferred_io_init(info);
+	error = register_framebuffer(info);
+	if (error) {
+		dev_err(dev, "failed to register framebuffer\n");
+		goto err_sysfs;
+	}
+	return 0;
+
+err_sysfs:
+	device_remove_file(dev, &dev_attr_fb_update_rate);
+	fb_deferred_io_cleanup(info);
+err_cleanup:
+	data->fb_info    = NULL;
+
+err_nomem:
+	if (fbdata)
+		vfree(fbdata->bitmap);
+	framebuffer_release(info);
+	return error;
+}
+
+void picolcd_exit_framebuffer(struct picolcd_data *data)
+{
+	struct fb_info *info = data->fb_info;
+	struct picolcd_fb_data *fbdata;
+	unsigned long flags;
+
+	if (!info)
+		return;
+
+	device_remove_file(&data->hdev->dev, &dev_attr_fb_update_rate);
+	fbdata = info->par;
+
+	/* disconnect framebuffer from HID dev */
+	spin_lock_irqsave(&fbdata->lock, flags);
+	fbdata->picolcd = NULL;
+	spin_unlock_irqrestore(&fbdata->lock, flags);
+
+	/* make sure there is no running update - thus that fbdata->picolcd
+	 * once obtained under lock is guaranteed not to get free() under
+	 * the feet of the deferred work */
+	flush_delayed_work(&info->deferred_work);
+
+	data->fb_info = NULL;
+	unregister_framebuffer(info);
+}