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, 127 insertions, 0 deletions

diff --git a/arch/m68k/mm/cache.c b/arch/m68k/mm/cache.c
new file mode 100644
index 000000000..dde978e66
--- /dev/null
+++ b/arch/m68k/mm/cache.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/arch/m68k/mm/cache.c
+ *
+ *  Instruction cache handling
+ *
+ *  Copyright (C) 1995  Hamish Macdonald
+ */
+
+#include <linux/module.h>
+#include <asm/cacheflush.h>
+#include <asm/traps.h>
+
+
+static unsigned long virt_to_phys_slow(unsigned long vaddr)
+{
+	if (CPU_IS_060) {
+		unsigned long paddr;
+
+		/* The PLPAR instruction causes an access error if the translation
+		 * is not possible. To catch this we use the same exception mechanism
+		 * as for user space accesses in <asm/uaccess.h>. */
+		asm volatile (".chip 68060\n"
+			      "1: plpar (%0)\n"
+			      ".chip 68k\n"
+			      "2:\n"
+			      ".section .fixup,\"ax\"\n"
+			      "   .even\n"
+			      "3: sub.l %0,%0\n"
+			      "   jra 2b\n"
+			      ".previous\n"
+			      ".section __ex_table,\"a\"\n"
+			      "   .align 4\n"
+			      "   .long 1b,3b\n"
+			      ".previous"
+			      : "=a" (paddr)
+			      : "0" (vaddr));
+		return paddr;
+	} else if (CPU_IS_040) {
+		unsigned long mmusr;
+
+		asm volatile (".chip 68040\n\t"
+			      "ptestr (%1)\n\t"
+			      "movec %%mmusr, %0\n\t"
+			      ".chip 68k"
+			      : "=r" (mmusr)
+			      : "a" (vaddr));
+
+		if (mmusr & MMU_R_040)
+			return (mmusr & PAGE_MASK) | (vaddr & ~PAGE_MASK);
+	} else {
+		WARN_ON_ONCE(!CPU_IS_040_OR_060);
+	}
+	return 0;
+}
+
+/* Push n pages at kernel virtual address and clear the icache */
+/* RZ: use cpush %bc instead of cpush %dc, cinv %ic */
+void flush_icache_user_range(unsigned long address, unsigned long endaddr)
+{
+	if (CPU_IS_COLDFIRE) {
+		unsigned long start, end;
+		start = address & ICACHE_SET_MASK;
+		end = endaddr & ICACHE_SET_MASK;
+		if (start > end) {
+			flush_cf_icache(0, end);
+			end = ICACHE_MAX_ADDR;
+		}
+		flush_cf_icache(start, end);
+	} else if (CPU_IS_040_OR_060) {
+		address &= PAGE_MASK;
+
+		do {
+			asm volatile ("nop\n\t"
+				      ".chip 68040\n\t"
+				      "cpushp %%bc,(%0)\n\t"
+				      ".chip 68k"
+				      : : "a" (virt_to_phys_slow(address)));
+			address += PAGE_SIZE;
+		} while (address < endaddr);
+	} else {
+		unsigned long tmp;
+		asm volatile ("movec %%cacr,%0\n\t"
+			      "orw %1,%0\n\t"
+			      "movec %0,%%cacr"
+			      : "=&d" (tmp)
+			      : "di" (FLUSH_I));
+	}
+}
+
+void flush_icache_range(unsigned long address, unsigned long endaddr)
+{
+	set_fc(SUPER_DATA);
+	flush_icache_user_range(address, endaddr);
+	set_fc(USER_DATA);
+}
+EXPORT_SYMBOL(flush_icache_range);
+
+void flush_icache_user_page(struct vm_area_struct *vma, struct page *page,
+			     unsigned long addr, int len)
+{
+	if (CPU_IS_COLDFIRE) {
+		unsigned long start, end;
+		start = addr & ICACHE_SET_MASK;
+		end = (addr + len) & ICACHE_SET_MASK;
+		if (start > end) {
+			flush_cf_icache(0, end);
+			end = ICACHE_MAX_ADDR;
+		}
+		flush_cf_icache(start, end);
+
+	} else if (CPU_IS_040_OR_060) {
+		asm volatile ("nop\n\t"
+			      ".chip 68040\n\t"
+			      "cpushp %%bc,(%0)\n\t"
+			      ".chip 68k"
+			      : : "a" (page_to_phys(page)));
+	} else {
+		unsigned long tmp;
+		asm volatile ("movec %%cacr,%0\n\t"
+			      "orw %1,%0\n\t"
+			      "movec %0,%%cacr"
+			      : "=&d" (tmp)
+			      : "di" (FLUSH_I));
+	}
+}
+