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, 80 insertions, 0 deletions

diff --git a/arch/powerpc/boot/hack-coff.c b/arch/powerpc/boot/hack-coff.c
new file mode 100644
index 000000000..6bf0c9430
--- /dev/null
+++ b/arch/powerpc/boot/hack-coff.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * hack-coff.c - hack the header of an xcoff file to fill in
+ * a few fields needed by the Open Firmware xcoff loader on
+ * Power Macs but not initialized by objcopy.
+ *
+ * Copyright (C) Paul Mackerras 1997.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include "rs6000.h"
+
+#define AOUT_MAGIC	0x010b
+
+#define get_16be(x)	((((unsigned char *)(x))[0] << 8) \
+			 + ((unsigned char *)(x))[1])
+#define put_16be(x, v)	(((unsigned char *)(x))[0] = (v) >> 8, \
+			 ((unsigned char *)(x))[1] = (v) & 0xff)
+#define get_32be(x)	((((unsigned char *)(x))[0] << 24) \
+			 + (((unsigned char *)(x))[1] << 16) \
+			 + (((unsigned char *)(x))[2] << 8) \
+			 + ((unsigned char *)(x))[3])
+
+int
+main(int ac, char **av)
+{
+    int fd;
+    int i, nsect;
+    int aoutsz;
+    struct external_filehdr fhdr;
+    struct aouthdr aout;
+    struct external_scnhdr shdr;
+
+    if (ac != 2) {
+	fprintf(stderr, "Usage: hack-coff coff-file\n");
+	exit(1);
+    }
+    if ((fd = open(av[1], 2)) == -1) {
+	perror(av[2]);
+	exit(1);
+    }
+    if (read(fd, &fhdr, sizeof(fhdr)) != sizeof(fhdr))
+	goto readerr;
+    i = get_16be(fhdr.f_magic);
+    if (i != U802TOCMAGIC && i != U802WRMAGIC && i != U802ROMAGIC) {
+	fprintf(stderr, "%s: not an xcoff file\n", av[1]);
+	exit(1);
+    }
+    aoutsz = get_16be(fhdr.f_opthdr);
+    if (read(fd, &aout, aoutsz) != aoutsz)
+	goto readerr;
+    nsect = get_16be(fhdr.f_nscns);
+    for (i = 0; i < nsect; ++i) {
+	if (read(fd, &shdr, sizeof(shdr)) != sizeof(shdr))
+	    goto readerr;
+	if (strcmp(shdr.s_name, ".text") == 0) {
+	    put_16be(aout.o_snentry, i+1);
+	    put_16be(aout.o_sntext, i+1);
+	} else if (strcmp(shdr.s_name, ".data") == 0) {
+	    put_16be(aout.o_sndata, i+1);
+	} else if (strcmp(shdr.s_name, ".bss") == 0) {
+	    put_16be(aout.o_snbss, i+1);
+	}
+    }
+    put_16be(aout.magic, AOUT_MAGIC);
+    if (lseek(fd, (long) sizeof(struct external_filehdr), 0) == -1
+	|| write(fd, &aout, aoutsz) != aoutsz) {
+	fprintf(stderr, "%s: write error\n", av[1]);
+	exit(1);
+    }
+    close(fd);
+    exit(0);
+
+readerr:
+    fprintf(stderr, "%s: read error or file too short\n", av[1]);
+    exit(1);
+}