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, 275 insertions, 0 deletions

diff --git a/lib/fonts/font_rotate.c b/lib/fonts/font_rotate.c
new file mode 100644
index 000000000..275406008
--- /dev/null
+++ b/lib/fonts/font_rotate.c
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Font rotation
+ *
+ *    Copyright (C) 2005 Antonino Daplas <adaplas @pol.net>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive for
+ * more details.
+ */
+
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/math.h>
+#include <linux/overflow.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include "font.h"
+
+/* number of bits per line */
+static unsigned int font_glyph_bit_pitch(unsigned int width)
+{
+	return round_up(width, 8);
+}
+
+static unsigned int __font_glyph_pos(unsigned int x, unsigned int y, unsigned int bit_pitch,
+				     unsigned int *bit)
+{
+	unsigned int off = y * bit_pitch + x;
+	unsigned int bit_shift = off % 8;
+
+	*bit = 0x80 >> bit_shift; /* MSB has position 0, LSB has position 7 */
+
+	return off / 8;
+}
+
+static bool font_glyph_test_bit(const unsigned char *glyph, unsigned int x, unsigned int y,
+				unsigned int bit_pitch)
+{
+	unsigned int bit;
+	unsigned int i = __font_glyph_pos(x, y, bit_pitch, &bit);
+
+	return glyph[i] & bit;
+}
+
+static void font_glyph_set_bit(unsigned char *glyph, unsigned int x, unsigned int y,
+			       unsigned int bit_pitch)
+{
+	unsigned int bit;
+	unsigned int i = __font_glyph_pos(x, y, bit_pitch, &bit);
+
+	glyph[i] |= bit;
+}
+
+static void __font_glyph_rotate_90(const unsigned char *glyph,
+				   unsigned int width, unsigned int height,
+				   unsigned char *out)
+{
+	unsigned int x, y;
+	unsigned int shift = (8 - (height % 8)) & 7;
+	unsigned int bit_pitch = font_glyph_bit_pitch(width);
+	unsigned int out_bit_pitch = font_glyph_bit_pitch(height);
+
+	for (y = 0; y < height; y++) {
+		for (x = 0; x < width; x++) {
+			if (font_glyph_test_bit(glyph, x, y, bit_pitch)) {
+				font_glyph_set_bit(out, out_bit_pitch - 1 - y - shift, x,
+						   out_bit_pitch);
+			}
+		}
+	}
+}
+
+/**
+ * font_glyph_rotate_90 - Rotate a glyph pattern by 90° in clockwise direction
+ * @glyph: The glyph to rotate
+ * @width: The glyph width in bits per scanline
+ * @height: The number of scanlines in the glyph
+ * @out: The rotated glyph bitmap
+ *
+ * The parameters @width and @height refer to the input glyph given in @glyph.
+ * The caller has to provide the output buffer @out of sufficient size to hold
+ * the rotated glyph. Rotating by 90° flips the width and height for the output
+ * glyph. Depending on the glyph pitch, the size of the output glyph can be
+ * different than the size of the input. Callers have to take this into account
+ * when allocating the output memory.
+ */
+void font_glyph_rotate_90(const unsigned char *glyph, unsigned int width, unsigned int height,
+			  unsigned char *out)
+{
+	memset(out, 0, font_glyph_size(height, width)); /* flip width/height */
+
+	__font_glyph_rotate_90(glyph, width, height, out);
+}
+EXPORT_SYMBOL_GPL(font_glyph_rotate_90);
+
+static void __font_glyph_rotate_180(const unsigned char *glyph,
+				    unsigned int width, unsigned int height,
+				    unsigned char *out)
+{
+	unsigned int x, y;
+	unsigned int shift = (8 - (width % 8)) & 7;
+	unsigned int bit_pitch = font_glyph_bit_pitch(width);
+
+	for (y = 0; y < height; y++) {
+		for (x = 0; x < width; x++) {
+			if (font_glyph_test_bit(glyph, x, y, bit_pitch)) {
+				font_glyph_set_bit(out, bit_pitch - 1 - x - shift, height - 1 - y,
+						   bit_pitch);
+			}
+		}
+	}
+}
+
+/**
+ * font_glyph_rotate_180 - Rotate a glyph pattern by 180°
+ * @glyph: The glyph to rotate
+ * @width: The glyph width in bits per scanline
+ * @height: The number of scanlines in the glyph
+ * @out: The rotated glyph bitmap
+ *
+ * The parameters @width and @height refer to the input glyph given in @glyph.
+ * The caller has to provide the output buffer @out of sufficient size to hold
+ * the rotated glyph.
+ */
+void font_glyph_rotate_180(const unsigned char *glyph, unsigned int width, unsigned int height,
+			   unsigned char *out)
+{
+	memset(out, 0, font_glyph_size(width, height));
+
+	__font_glyph_rotate_180(glyph, width, height, out);
+}
+EXPORT_SYMBOL_GPL(font_glyph_rotate_180);
+
+static void __font_glyph_rotate_270(const unsigned char *glyph,
+				    unsigned int width, unsigned int height,
+				    unsigned char *out)
+{
+	unsigned int x, y;
+	unsigned int shift = (8 - (width % 8)) & 7;
+	unsigned int bit_pitch = font_glyph_bit_pitch(width);
+	unsigned int out_bit_pitch = font_glyph_bit_pitch(height);
+
+	for (y = 0; y < height; y++) {
+		for (x = 0; x < width; x++) {
+			if (font_glyph_test_bit(glyph, x, y, bit_pitch))
+				font_glyph_set_bit(out, y, bit_pitch - 1 - x - shift,
+						   out_bit_pitch);
+		}
+	}
+}
+
+/**
+ * font_glyph_rotate_270 - Rotate a glyph pattern by 270° in clockwise direction
+ * @glyph: The glyph to rotate
+ * @width: The glyph width in bits per scanline
+ * @height: The number of scanlines in the glyph
+ * @out: The rotated glyph bitmap
+ *
+ * The parameters @width and @height refer to the input glyph given in @glyph.
+ * The caller has to provide the output buffer @out of sufficient size to hold
+ * the rotated glyph. Rotating by 270° flips the width and height for the output
+ * glyph. Depending on the glyph pitch, the size of the output glyph can be
+ * different than the size of the input. Callers have to take this into account
+ * when allocating the output memory.
+ */
+void font_glyph_rotate_270(const unsigned char *glyph, unsigned int width, unsigned int height,
+			   unsigned char *out)
+{
+	memset(out, 0, font_glyph_size(height, width)); /* flip width/height */
+
+	__font_glyph_rotate_270(glyph, width, height, out);
+}
+EXPORT_SYMBOL_GPL(font_glyph_rotate_270);
+
+/**
+ * font_data_rotate - Rotate font data by multiples of 90°
+ * @fd: The font data to rotate
+ * @width: The glyph width in bits per scanline
+ * @height: The number of scanlines in the glyph
+ * @charcount: The number of glyphs in the font
+ * @steps: Number of rotation steps of 90°
+ * @buf: Preallocated output buffer; can be NULL
+ * @bufsize: The size of @buf in bytes; can be NULL
+ *
+ * The parameters @width and @height refer to the visible number of pixels
+ * and scanlines in a single glyph. The number of glyphs is given in @charcount.
+ * Rotation happens in steps of 90°. The @steps parameter can have any value,
+ * but only 0 to 3 produce distinct results. With 4 or higher, a full rotation
+ * has been performed. You can pass any value for @steps and the helper will
+ * perform the appropriate rotation. Note that the returned buffer is not
+ * compatible with font_data_t. It only contains glyph data in the same format
+ * as returned by font_data_buf(). Callers are responsible to free the returned
+ * buffer with kfree(). Font rotation typically happens when displays get
+ * re-oriented. To avoid unnecessary re-allocation of the memory buffer, the
+ * caller can pass in an earlier result buffer in @buf for reuse. The old and
+ * new buffer sizes are given and retrieved by the caller in @bufsize. The
+ * allocation semantics are compatible with krealloc().
+ *
+ * Returns:
+ * A buffer with rotated glyphs on success, or an error pointer otherwise
+ */
+unsigned char *font_data_rotate(font_data_t *fd, unsigned int width, unsigned int height,
+				unsigned int charcount, unsigned int steps,
+				unsigned char *buf, size_t *bufsize)
+{
+	const unsigned char *src = font_data_buf(fd);
+	unsigned int s_cellsize = font_glyph_size(width, height);
+	unsigned int d_cellsize, i;
+	unsigned char *dst;
+	size_t size;
+
+	steps %= 4;
+
+	switch (steps) {
+	case 0:
+	case 2:
+		d_cellsize = s_cellsize;
+		break;
+	case 1:
+	case 3:
+		d_cellsize = font_glyph_size(height, width); /* flip width/height */
+		break;
+	}
+
+	if (check_mul_overflow(charcount, d_cellsize, &size))
+		return ERR_PTR(-EINVAL);
+
+	if (!buf || !bufsize || size > *bufsize) {
+		dst = kmalloc_array(charcount, d_cellsize, GFP_KERNEL);
+		if (!dst)
+			return ERR_PTR(-ENOMEM);
+
+		kfree(buf);
+		buf = dst;
+		if (bufsize)
+			*bufsize = size;
+	} else {
+		dst = buf;
+	}
+
+	switch (steps) {
+	case 0:
+		memcpy(dst, src, size);
+		break;
+	case 1:
+		memset(dst, 0, size);
+		for (i = 0; i < charcount; ++i) {
+			__font_glyph_rotate_90(src, width, height, dst);
+			src += s_cellsize;
+			dst += d_cellsize;
+		}
+		break;
+	case 2:
+		memset(dst, 0, size);
+		for (i = 0; i < charcount; ++i) {
+			__font_glyph_rotate_180(src, width, height, dst);
+			src += s_cellsize;
+			dst += d_cellsize;
+		}
+		break;
+	case 3:
+		memset(dst, 0, size);
+		for (i = 0; i < charcount; ++i) {
+			__font_glyph_rotate_270(src, width, height, dst);
+			src += s_cellsize;
+			dst += d_cellsize;
+		}
+		break;
+	}
+
+	return buf;
+}
+EXPORT_SYMBOL_GPL(font_data_rotate);