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, 201 insertions, 0 deletions

diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
new file mode 100644
index 000000000..8325046a1
--- /dev/null
+++ b/block/partitions/amiga.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  fs/partitions/amiga.c
+ *
+ *  Code extracted from drivers/block/genhd.c
+ *
+ *  Copyright (C) 1991-1998  Linus Torvalds
+ *  Re-organised Feb 1998 Russell King
+ */
+
+#define pr_fmt(fmt) fmt
+
+#include <linux/types.h>
+#include <linux/mm_types.h>
+#include <linux/overflow.h>
+#include <linux/affs_hardblocks.h>
+
+#include "check.h"
+
+/* magic offsets in partition DosEnvVec */
+#define NR_HD	3
+#define NR_SECT	5
+#define LO_CYL	9
+#define HI_CYL	10
+
+static __inline__ u32
+checksum_block(__be32 *m, int size)
+{
+	u32 sum = 0;
+
+	while (size--)
+		sum += be32_to_cpu(*m++);
+	return sum;
+}
+
+int amiga_partition(struct parsed_partitions *state)
+{
+	Sector sect;
+	unsigned char *data;
+	struct RigidDiskBlock *rdb;
+	struct PartitionBlock *pb;
+	u64 start_sect, nr_sects;
+	sector_t blk, end_sect;
+	u32 cylblk;		/* rdb_CylBlocks = nr_heads*sect_per_track */
+	u32 nr_hd, nr_sect, lo_cyl, hi_cyl;
+	int part, res = 0;
+	unsigned int blksize = 1;	/* Multiplier for disk block size */
+	int slot = 1;
+
+	for (blk = 0; ; blk++, put_dev_sector(sect)) {
+		if (blk == RDB_ALLOCATION_LIMIT)
+			goto rdb_done;
+		data = read_part_sector(state, blk, &sect);
+		if (!data) {
+			pr_err("Dev %s: unable to read RDB block %llu\n",
+			       state->disk->disk_name, blk);
+			res = -1;
+			goto rdb_done;
+		}
+		if (*(__be32 *)data != cpu_to_be32(IDNAME_RIGIDDISK))
+			continue;
+
+		rdb = (struct RigidDiskBlock *)data;
+		if (checksum_block((__be32 *)data, be32_to_cpu(rdb->rdb_SummedLongs) & 0x7F) == 0)
+			break;
+		/* Try again with 0xdc..0xdf zeroed, Windows might have
+		 * trashed it.
+		 */
+		*(__be32 *)(data+0xdc) = 0;
+		if (checksum_block((__be32 *)data,
+				be32_to_cpu(rdb->rdb_SummedLongs) & 0x7F)==0) {
+			pr_err("Trashed word at 0xd0 in block %llu ignored in checksum calculation\n",
+			       blk);
+			break;
+		}
+
+		pr_err("Dev %s: RDB in block %llu has bad checksum\n",
+		       state->disk->disk_name, blk);
+	}
+
+	/* blksize is blocks per 512 byte standard block */
+	blksize = be32_to_cpu( rdb->rdb_BlockBytes ) / 512;
+
+	/* Be more informative */
+	seq_buf_printf(&state->pp_buf, " RDSK (%d)", blksize * 512);
+	blk = be32_to_cpu(rdb->rdb_PartitionList);
+	put_dev_sector(sect);
+	for (part = 1; (s32) blk>0 && part<=16; part++, put_dev_sector(sect)) {
+		/* Read in terms partition table understands */
+		if (check_mul_overflow(blk, (sector_t) blksize, &blk)) {
+			pr_err("Dev %s: overflow calculating partition block %llu! Skipping partitions %u and beyond\n",
+				state->disk->disk_name, blk, part);
+			break;
+		}
+		data = read_part_sector(state, blk, &sect);
+		if (!data) {
+			pr_err("Dev %s: unable to read partition block %llu\n",
+			       state->disk->disk_name, blk);
+			res = -1;
+			goto rdb_done;
+		}
+		pb  = (struct PartitionBlock *)data;
+		blk = be32_to_cpu(pb->pb_Next);
+		if (pb->pb_ID != cpu_to_be32(IDNAME_PARTITION))
+			continue;
+		if (checksum_block((__be32 *)pb, be32_to_cpu(pb->pb_SummedLongs) & 0x7F) != 0 )
+			continue;
+
+		/* RDB gives us more than enough rope to hang ourselves with,
+		 * many times over (2^128 bytes if all fields max out).
+		 * Some careful checks are in order, so check for potential
+		 * overflows.
+		 * We are multiplying four 32 bit numbers to one sector_t!
+		 */
+
+		nr_hd   = be32_to_cpu(pb->pb_Environment[NR_HD]);
+		nr_sect = be32_to_cpu(pb->pb_Environment[NR_SECT]);
+
+		/* CylBlocks is total number of blocks per cylinder */
+		if (check_mul_overflow(nr_hd, nr_sect, &cylblk)) {
+			pr_err("Dev %s: heads*sects %u overflows u32, skipping partition!\n",
+				state->disk->disk_name, cylblk);
+			continue;
+		}
+
+		/* check for consistency with RDB defined CylBlocks */
+		if (cylblk > be32_to_cpu(rdb->rdb_CylBlocks)) {
+			pr_warn("Dev %s: cylblk %u > rdb_CylBlocks %u!\n",
+				state->disk->disk_name, cylblk,
+				be32_to_cpu(rdb->rdb_CylBlocks));
+		}
+
+		/* RDB allows for variable logical block size -
+		 * normalize to 512 byte blocks and check result.
+		 */
+
+		if (check_mul_overflow(cylblk, blksize, &cylblk)) {
+			pr_err("Dev %s: partition %u bytes per cyl. overflows u32, skipping partition!\n",
+				state->disk->disk_name, part);
+			continue;
+		}
+
+		/* Calculate partition start and end. Limit of 32 bit on cylblk
+		 * guarantees no overflow occurs if LBD support is enabled.
+		 */
+
+		lo_cyl = be32_to_cpu(pb->pb_Environment[LO_CYL]);
+		start_sect = ((u64) lo_cyl * cylblk);
+
+		hi_cyl = be32_to_cpu(pb->pb_Environment[HI_CYL]);
+		nr_sects = (((u64) hi_cyl - lo_cyl + 1) * cylblk);
+
+		if (!nr_sects)
+			continue;
+
+		/* Warn user if partition end overflows u32 (AmigaDOS limit) */
+
+		if ((start_sect + nr_sects) > UINT_MAX) {
+			pr_warn("Dev %s: partition %u (%llu-%llu) needs 64 bit device support!\n",
+				state->disk->disk_name, part,
+				start_sect, start_sect + nr_sects);
+		}
+
+		if (check_add_overflow(start_sect, nr_sects, &end_sect)) {
+			pr_err("Dev %s: partition %u (%llu-%llu) needs LBD device support, skipping partition!\n",
+				state->disk->disk_name, part,
+				start_sect, end_sect);
+			continue;
+		}
+
+		/* Tell Kernel about it */
+
+		put_partition(state,slot++,start_sect,nr_sects);
+		{
+			/* Be even more informative to aid mounting */
+			char dostype[4];
+
+			__be32 *dt = (__be32 *)dostype;
+			*dt = pb->pb_Environment[16];
+			if (dostype[3] < ' ')
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c^%c)",
+					       dostype[0], dostype[1],
+					       dostype[2],
+					       dostype[3] + '@');
+			else
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c%c)",
+					       dostype[0], dostype[1],
+					       dostype[2], dostype[3]);
+			seq_buf_printf(&state->pp_buf, "(res %d spb %d)",
+				       be32_to_cpu(pb->pb_Environment[6]),
+				       be32_to_cpu(pb->pb_Environment[4]));
+		}
+		res = 1;
+	}
+	seq_buf_puts(&state->pp_buf, "\n");
+
+rdb_done:
+	return res;
+}