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, 145 insertions, 0 deletions

diff --git a/lib/raid/raid6/int.uc b/lib/raid/raid6/int.uc
new file mode 100644
index 000000000..e63bd5a9c
--- /dev/null
+++ b/lib/raid/raid6/int.uc
@@ -0,0 +1,145 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright 2002-2004 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
+ *   Boston MA 02111-1307, USA; either version 2 of the License, or
+ *   (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * int$#.c
+ *
+ * $#-way unrolled portable integer math RAID-6 instruction set
+ *
+ * This file is postprocessed using unroll.awk
+ */
+
+#include "algos.h"
+
+/*
+ * This is the C data type to use
+ */
+
+/* Change this from BITS_PER_LONG if there is something better... */
+#if BITS_PER_LONG == 64
+# define NBYTES(x) ((x) * 0x0101010101010101UL)
+# define NSIZE  8
+# define NSHIFT 3
+# define NSTRING "64"
+typedef u64 unative_t;
+#else
+# define NBYTES(x) ((x) * 0x01010101U)
+# define NSIZE  4
+# define NSHIFT 2
+# define NSTRING "32"
+typedef u32 unative_t;
+#endif
+
+
+
+/*
+ * These sub-operations are separate inlines since they can sometimes be
+ * specially optimized using architecture-specific hacks.
+ */
+
+/*
+ * The SHLBYTE() operation shifts each byte left by 1, *not*
+ * rolling over into the next byte
+ */
+static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
+{
+	unative_t vv;
+
+	vv = (v << 1) & NBYTES(0xfe);
+	return vv;
+}
+
+/*
+ * The MASK() operation returns 0xFF in any byte for which the high
+ * bit is 1, 0x00 for any byte for which the high bit is 0.
+ */
+static inline __attribute_const__ unative_t MASK(unative_t v)
+{
+	unative_t vv;
+
+	vv = v & NBYTES(0x80);
+	vv = (vv << 1) - (vv >> 7); /* Overflow on the top bit is OK */
+	return vv;
+}
+
+
+static void raid6_int$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
+{
+	u8 **dptr = (u8 **)ptrs;
+	u8 *p, *q;
+	int d, z, z0;
+
+	unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
+
+	z0 = disks - 3;		/* Highest data disk */
+	p = dptr[z0+1];		/* XOR parity */
+	q = dptr[z0+2];		/* RS syndrome */
+
+	for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
+		wq$$ = wp$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
+		for ( z = z0-1 ; z >= 0 ; z-- ) {
+			wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
+			wp$$ ^= wd$$;
+			w2$$ = MASK(wq$$);
+			w1$$ = SHLBYTE(wq$$);
+			w2$$ &= NBYTES(0x1d);
+			w1$$ ^= w2$$;
+			wq$$ = w1$$ ^ wd$$;
+		}
+		*(unative_t *)&p[d+NSIZE*$$] = wp$$;
+		*(unative_t *)&q[d+NSIZE*$$] = wq$$;
+	}
+}
+
+static void raid6_int$#_xor_syndrome(int disks, int start, int stop,
+				     size_t bytes, void **ptrs)
+{
+	u8 **dptr = (u8 **)ptrs;
+	u8 *p, *q;
+	int d, z, z0;
+
+	unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
+
+	z0 = stop;		/* P/Q right side optimization */
+	p = dptr[disks-2];	/* XOR parity */
+	q = dptr[disks-1];	/* RS syndrome */
+
+	for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
+		/* P/Q data pages */
+		wq$$ = wp$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
+		for ( z = z0-1 ; z >= start ; z-- ) {
+			wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
+			wp$$ ^= wd$$;
+			w2$$ = MASK(wq$$);
+			w1$$ = SHLBYTE(wq$$);
+			w2$$ &= NBYTES(0x1d);
+			w1$$ ^= w2$$;
+			wq$$ = w1$$ ^ wd$$;
+		}
+		/* P/Q left side optimization */
+		for ( z = start-1 ; z >= 0 ; z-- ) {
+			w2$$ = MASK(wq$$);
+			w1$$ = SHLBYTE(wq$$);
+			w2$$ &= NBYTES(0x1d);
+			wq$$ = w1$$ ^ w2$$;
+		}
+		*(unative_t *)&p[d+NSIZE*$$] ^= wp$$;
+		*(unative_t *)&q[d+NSIZE*$$] ^= wq$$;
+	}
+
+}
+
+const struct raid6_calls raid6_intx$# = {
+	.gen_syndrome	= raid6_int$#_gen_syndrome,
+	.xor_syndrome	= raid6_int$#_xor_syndrome,
+	.name		= "int" NSTRING "x$#",
+};