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, 490 insertions, 0 deletions

diff --git a/drivers/video/vgastate.c b/drivers/video/vgastate.c
new file mode 100644
index 000000000..6a29d198f
--- /dev/null
+++ b/drivers/video/vgastate.c
@@ -0,0 +1,490 @@
+/*
+ * linux/drivers/video/vgastate.c -- VGA state save/restore
+ *
+ * Copyright 2002 James Simmons
+ *
+ * Copyright history from vga16fb.c:
+ *	Copyright 1999 Ben Pfaff and Petr Vandrovec
+ *	Based on VGA info at http://www.goodnet.com/~tinara/FreeVGA/home.htm
+ *	Based on VESA framebuffer (c) 1998 Gerd Knorr
+ *
+ * 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/module.h>
+#include <linux/slab.h>
+#include <linux/fb.h>
+#include <linux/vmalloc.h>
+#include <video/vga.h>
+
+struct regstate {
+	__u8 *vga_font0;
+	__u8 *vga_font1;
+	__u8 *vga_text;
+	__u8 *vga_cmap;
+	__u8 *attr;
+	__u8 *crtc;
+	__u8 *gfx;
+	__u8 *seq;
+	__u8 misc;
+};
+
+static inline unsigned char vga_rcrtcs(void __iomem *regbase, unsigned short iobase,
+				       unsigned char reg)
+{
+	vga_w(regbase, iobase + 0x4, reg);
+	return vga_r(regbase, iobase + 0x5);
+}
+
+static inline void vga_wcrtcs(void __iomem *regbase, unsigned short iobase,
+			      unsigned char reg, unsigned char val)
+{
+	vga_w(regbase, iobase + 0x4, reg);
+	vga_w(regbase, iobase + 0x5, val);
+}
+
+static void save_vga_text(struct vgastate *state, void __iomem *fbbase)
+{
+	struct regstate *saved = (struct regstate *) state->vidstate;
+	int i;
+	u8 misc, attr10, gr4, gr5, gr6, seq1, seq2, seq4;
+	unsigned short iobase;
+
+	/* if in graphics mode, no need to save */
+	misc = vga_r(state->vgabase, VGA_MIS_R);
+	iobase = (misc & 1) ? 0x3d0 : 0x3b0;
+
+	vga_r(state->vgabase, iobase + 0xa);
+	vga_w(state->vgabase, VGA_ATT_W, 0x00);
+	attr10 = vga_rattr(state->vgabase, 0x10);
+	vga_r(state->vgabase, iobase + 0xa);
+	vga_w(state->vgabase, VGA_ATT_W, 0x20);
+
+	if (attr10 & 1)
+		return;
+
+	/* save regs */
+	gr4 = vga_rgfx(state->vgabase, VGA_GFX_PLANE_READ);
+	gr5 = vga_rgfx(state->vgabase, VGA_GFX_MODE);
+	gr6 = vga_rgfx(state->vgabase, VGA_GFX_MISC);
+	seq2 = vga_rseq(state->vgabase, VGA_SEQ_PLANE_WRITE);
+	seq4 = vga_rseq(state->vgabase, VGA_SEQ_MEMORY_MODE);
+
+	/* blank screen */
+	seq1 = vga_rseq(state->vgabase, VGA_SEQ_CLOCK_MODE);
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 | 1 << 5);
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+	/* save font at plane 2 */
+	if (state->flags & VGA_SAVE_FONT0) {
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x4);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x2);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < 4 * 8192; i++)
+			saved->vga_font0[i] = vga_r(fbbase, i);
+	}
+
+	/* save font at plane 3 */
+	if (state->flags & VGA_SAVE_FONT1) {
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x8);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x3);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < state->memsize; i++)
+			saved->vga_font1[i] = vga_r(fbbase, i);
+	}
+
+	/* save font at plane 0/1 */
+	if (state->flags & VGA_SAVE_TEXT) {
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x1);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < 8192; i++)
+			saved->vga_text[i] = vga_r(fbbase, i);
+
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x2);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x1);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < 8192; i++)
+			saved->vga_text[8192+i] = vga_r(fbbase + 2 * 8192, i);
+	}
+
+	/* restore regs */
+	vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, seq2);
+	vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, seq4);
+
+	vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, gr4);
+	vga_wgfx(state->vgabase, VGA_GFX_MODE, gr5);
+	vga_wgfx(state->vgabase, VGA_GFX_MISC, gr6);
+
+	/* unblank screen */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 & ~(1 << 5));
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1);
+}
+
+static void restore_vga_text(struct vgastate *state, void __iomem *fbbase)
+{
+	struct regstate *saved = (struct regstate *) state->vidstate;
+	int i;
+	u8 gr1, gr3, gr4, gr5, gr6, gr8;
+	u8 seq1, seq2, seq4;
+
+	/* save regs */
+	gr1 = vga_rgfx(state->vgabase, VGA_GFX_SR_ENABLE);
+	gr3 = vga_rgfx(state->vgabase, VGA_GFX_DATA_ROTATE);
+	gr4 = vga_rgfx(state->vgabase, VGA_GFX_PLANE_READ);
+	gr5 = vga_rgfx(state->vgabase, VGA_GFX_MODE);
+	gr6 = vga_rgfx(state->vgabase, VGA_GFX_MISC);
+	gr8 = vga_rgfx(state->vgabase, VGA_GFX_BIT_MASK);
+	seq2 = vga_rseq(state->vgabase, VGA_SEQ_PLANE_WRITE);
+	seq4 = vga_rseq(state->vgabase, VGA_SEQ_MEMORY_MODE);
+
+	/* blank screen */
+	seq1 = vga_rseq(state->vgabase, VGA_SEQ_CLOCK_MODE);
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 | 1 << 5);
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+	if (state->depth == 4) {
+		vga_wgfx(state->vgabase, VGA_GFX_DATA_ROTATE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_BIT_MASK, 0xff);
+		vga_wgfx(state->vgabase, VGA_GFX_SR_ENABLE, 0x00);
+	}
+
+	/* restore font at plane 2 */
+	if (state->flags & VGA_SAVE_FONT0) {
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x4);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x2);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < 4 * 8192; i++)
+			vga_w(fbbase, i, saved->vga_font0[i]);
+	}
+
+	/* restore font at plane 3 */
+	if (state->flags & VGA_SAVE_FONT1) {
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x8);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x3);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < state->memsize; i++)
+			vga_w(fbbase, i, saved->vga_font1[i]);
+	}
+
+	/* restore font at plane 0/1 */
+	if (state->flags & VGA_SAVE_TEXT) {
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x1);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < 8192; i++)
+			vga_w(fbbase, i, saved->vga_text[i]);
+
+		vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x2);
+		vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+		vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x1);
+		vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+		vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+		for (i = 0; i < 8192; i++)
+			vga_w(fbbase, i, saved->vga_text[8192+i]);
+	}
+
+	/* unblank screen */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 & ~(1 << 5));
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+	/* restore regs */
+	vga_wgfx(state->vgabase, VGA_GFX_SR_ENABLE, gr1);
+	vga_wgfx(state->vgabase, VGA_GFX_DATA_ROTATE, gr3);
+	vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, gr4);
+	vga_wgfx(state->vgabase, VGA_GFX_MODE, gr5);
+	vga_wgfx(state->vgabase, VGA_GFX_MISC, gr6);
+	vga_wgfx(state->vgabase, VGA_GFX_BIT_MASK, gr8);
+
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1);
+	vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, seq2);
+	vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, seq4);
+}
+
+static void save_vga_mode(struct vgastate *state)
+{
+	struct regstate *saved = (struct regstate *) state->vidstate;
+	unsigned short iobase;
+	int i;
+
+	saved->misc = vga_r(state->vgabase, VGA_MIS_R);
+	if (saved->misc & 1)
+		iobase = 0x3d0;
+	else
+		iobase = 0x3b0;
+
+	for (i = 0; i < state->num_crtc; i++)
+		saved->crtc[i] = vga_rcrtcs(state->vgabase, iobase, i);
+
+	vga_r(state->vgabase, iobase + 0xa);
+	vga_w(state->vgabase, VGA_ATT_W, 0x00);
+	for (i = 0; i < state->num_attr; i++) {
+		vga_r(state->vgabase, iobase + 0xa);
+		saved->attr[i] = vga_rattr(state->vgabase, i);
+	}
+	vga_r(state->vgabase, iobase + 0xa);
+	vga_w(state->vgabase, VGA_ATT_W, 0x20);
+
+	for (i = 0; i < state->num_gfx; i++)
+		saved->gfx[i] = vga_rgfx(state->vgabase, i);
+
+	for (i = 0; i < state->num_seq; i++)
+		saved->seq[i] = vga_rseq(state->vgabase, i);
+}
+
+static void restore_vga_mode(struct vgastate *state)
+{
+	struct regstate *saved = (struct regstate *) state->vidstate;
+	unsigned short iobase;
+	int i;
+
+	vga_w(state->vgabase, VGA_MIS_W, saved->misc);
+
+	if (saved->misc & 1)
+		iobase = 0x3d0;
+	else
+		iobase = 0x3b0;
+
+	/* turn off display */
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE,
+		 saved->seq[VGA_SEQ_CLOCK_MODE] | 0x20);
+
+	/* disable sequencer */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x01);
+
+	/* enable palette addressing */
+	vga_r(state->vgabase, iobase + 0xa);
+	vga_w(state->vgabase, VGA_ATT_W, 0x00);
+
+	for (i = 2; i < state->num_seq; i++)
+		vga_wseq(state->vgabase, i, saved->seq[i]);
+
+
+	/* unprotect vga regs */
+	vga_wcrtcs(state->vgabase, iobase, 17, saved->crtc[17] & ~0x80);
+	for (i = 0; i < state->num_crtc; i++)
+		vga_wcrtcs(state->vgabase, iobase, i, saved->crtc[i]);
+
+	for (i = 0; i < state->num_gfx; i++)
+		vga_wgfx(state->vgabase, i, saved->gfx[i]);
+
+	for (i = 0; i < state->num_attr; i++) {
+		vga_r(state->vgabase, iobase + 0xa);
+		vga_wattr(state->vgabase, i, saved->attr[i]);
+	}
+
+	/* reenable sequencer */
+	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x03);
+	/* turn display on */
+	vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE,
+		 saved->seq[VGA_SEQ_CLOCK_MODE] & ~(1 << 5));
+
+	/* disable video/palette source */
+	vga_r(state->vgabase, iobase + 0xa);
+	vga_w(state->vgabase, VGA_ATT_W, 0x20);
+}
+
+static void save_vga_cmap(struct vgastate *state)
+{
+	struct regstate *saved = (struct regstate *) state->vidstate;
+	int i;
+
+	vga_w(state->vgabase, VGA_PEL_MSK, 0xff);
+
+	/* assumes DAC is readable and writable */
+	vga_w(state->vgabase, VGA_PEL_IR, 0x00);
+	for (i = 0; i < 768; i++)
+		saved->vga_cmap[i] = vga_r(state->vgabase, VGA_PEL_D);
+}
+
+static void restore_vga_cmap(struct vgastate *state)
+{
+	struct regstate *saved = (struct regstate *) state->vidstate;
+	int i;
+
+	vga_w(state->vgabase, VGA_PEL_MSK, 0xff);
+
+	/* assumes DAC is readable and writable */
+	vga_w(state->vgabase, VGA_PEL_IW, 0x00);
+	for (i = 0; i < 768; i++)
+		vga_w(state->vgabase, VGA_PEL_D, saved->vga_cmap[i]);
+}
+
+static void vga_cleanup(struct vgastate *state)
+{
+	if (state->vidstate != NULL) {
+		struct regstate *saved = (struct regstate *) state->vidstate;
+
+		vfree(saved->vga_font0);
+		vfree(saved->vga_font1);
+		vfree(saved->vga_text);
+		vfree(saved->vga_cmap);
+		vfree(saved->attr);
+		kfree(saved);
+		state->vidstate = NULL;
+	}
+}
+
+int save_vga(struct vgastate *state)
+{
+	struct regstate *saved;
+
+	saved = kzalloc_obj(struct regstate);
+
+	if (saved == NULL)
+		return 1;
+
+	state->vidstate = (void *)saved;
+
+	if (state->flags & VGA_SAVE_CMAP) {
+		saved->vga_cmap = vmalloc(768);
+		if (!saved->vga_cmap) {
+			vga_cleanup(state);
+			return 1;
+		}
+		save_vga_cmap(state);
+	}
+
+	if (state->flags & VGA_SAVE_MODE) {
+		int total;
+
+		if (state->num_attr < 21)
+			state->num_attr = 21;
+		if (state->num_crtc < 25)
+			state->num_crtc = 25;
+		if (state->num_gfx < 9)
+			state->num_gfx = 9;
+		if (state->num_seq < 5)
+			state->num_seq = 5;
+		total = state->num_attr + state->num_crtc +
+			state->num_gfx + state->num_seq;
+
+		saved->attr = vmalloc(total);
+		if (!saved->attr) {
+			vga_cleanup(state);
+			return 1;
+		}
+		saved->crtc = saved->attr + state->num_attr;
+		saved->gfx = saved->crtc + state->num_crtc;
+		saved->seq = saved->gfx + state->num_gfx;
+
+		save_vga_mode(state);
+	}
+
+	if (state->flags & VGA_SAVE_FONTS) {
+		void __iomem *fbbase;
+
+		/* exit if window is less than 32K */
+		if (state->memsize && state->memsize < 4 * 8192) {
+			vga_cleanup(state);
+			return 1;
+		}
+		if (!state->memsize)
+			state->memsize = 8 * 8192;
+
+		if (!state->membase)
+			state->membase = 0xA0000;
+
+		fbbase = ioremap(state->membase, state->memsize);
+
+		if (!fbbase) {
+			vga_cleanup(state);
+			return 1;
+		}
+
+		/*
+		 * save only first 32K used by vgacon
+		 */
+		if (state->flags & VGA_SAVE_FONT0) {
+			saved->vga_font0 = vmalloc(4 * 8192);
+			if (!saved->vga_font0) {
+				iounmap(fbbase);
+				vga_cleanup(state);
+				return 1;
+			}
+		}
+		/*
+		 * largely unused, but if required by the caller
+		 * we'll just save everything.
+		 */
+		if (state->flags & VGA_SAVE_FONT1) {
+			saved->vga_font1 = vmalloc(state->memsize);
+			if (!saved->vga_font1) {
+				iounmap(fbbase);
+				vga_cleanup(state);
+				return 1;
+			}
+		}
+		/*
+		 * Save 8K at plane0[0], and 8K at plane1[16K]
+		 */
+		if (state->flags & VGA_SAVE_TEXT) {
+			saved->vga_text = vmalloc(8192 * 2);
+			if (!saved->vga_text) {
+				iounmap(fbbase);
+				vga_cleanup(state);
+				return 1;
+			}
+		}
+
+		save_vga_text(state, fbbase);
+		iounmap(fbbase);
+	}
+	return 0;
+}
+
+int restore_vga(struct vgastate *state)
+{
+	if (state->vidstate == NULL)
+		return 1;
+
+	if (state->flags & VGA_SAVE_MODE)
+		restore_vga_mode(state);
+
+	if (state->flags & VGA_SAVE_FONTS) {
+		void __iomem *fbbase = ioremap(state->membase, state->memsize);
+
+		if (!fbbase) {
+			vga_cleanup(state);
+			return 1;
+		}
+		restore_vga_text(state, fbbase);
+		iounmap(fbbase);
+	}
+
+	if (state->flags & VGA_SAVE_CMAP)
+		restore_vga_cmap(state);
+
+	vga_cleanup(state);
+	return 0;
+}
+
+EXPORT_SYMBOL(save_vga);
+EXPORT_SYMBOL(restore_vga);
+
+MODULE_AUTHOR("James Simmons <jsimmons@users.sf.net>");
+MODULE_DESCRIPTION("VGA State Save/Restore");
+MODULE_LICENSE("GPL");
+