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, 162 insertions, 0 deletions

diff --git a/lib/crc/mips/crc32.h b/lib/crc/mips/crc32.h
new file mode 100644
index 000000000..3100354a0
--- /dev/null
+++ b/lib/crc/mips/crc32.h
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * crc32-mips.c - CRC32 and CRC32C using optional MIPSr6 instructions
+ *
+ * Module based on arm64/crypto/crc32-arm.c
+ *
+ * Copyright (C) 2014 Linaro Ltd <yazen.ghannam@linaro.org>
+ * Copyright (C) 2018 MIPS Tech, LLC
+ */
+
+#include <linux/cpufeature.h>
+#include <asm/mipsregs.h>
+#include <linux/unaligned.h>
+
+#ifndef TOOLCHAIN_SUPPORTS_CRC
+#define _ASM_SET_CRC(OP, SZ, TYPE)					  \
+_ASM_MACRO_3R(OP, rt, rs, rt2,						  \
+	".ifnc	\\rt, \\rt2\n\t"					  \
+	".error	\"invalid operands \\\"" #OP " \\rt,\\rs,\\rt2\\\"\"\n\t" \
+	".endif\n\t"							  \
+	_ASM_INSN_IF_MIPS(0x7c00000f | (__rt << 16) | (__rs << 21) |	  \
+			  ((SZ) <<  6) | ((TYPE) << 8))			  \
+	_ASM_INSN32_IF_MM(0x00000030 | (__rs << 16) | (__rt << 21) |	  \
+			  ((SZ) << 14) | ((TYPE) << 3)))
+#define _ASM_UNSET_CRC(op, SZ, TYPE) ".purgem " #op "\n\t"
+#else /* !TOOLCHAIN_SUPPORTS_CRC */
+#define _ASM_SET_CRC(op, SZ, TYPE) ".set\tcrc\n\t"
+#define _ASM_UNSET_CRC(op, SZ, TYPE)
+#endif
+
+#define __CRC32(crc, value, op, SZ, TYPE)		\
+do {							\
+	__asm__ __volatile__(				\
+		".set	push\n\t"			\
+		_ASM_SET_CRC(op, SZ, TYPE)		\
+		#op "	%0, %1, %0\n\t"			\
+		_ASM_UNSET_CRC(op, SZ, TYPE)		\
+		".set	pop"				\
+		: "+r" (crc)				\
+		: "r" (value));				\
+} while (0)
+
+#define _CRC32_crc32b(crc, value)	__CRC32(crc, value, crc32b, 0, 0)
+#define _CRC32_crc32h(crc, value)	__CRC32(crc, value, crc32h, 1, 0)
+#define _CRC32_crc32w(crc, value)	__CRC32(crc, value, crc32w, 2, 0)
+#define _CRC32_crc32d(crc, value)	__CRC32(crc, value, crc32d, 3, 0)
+#define _CRC32_crc32cb(crc, value)	__CRC32(crc, value, crc32cb, 0, 1)
+#define _CRC32_crc32ch(crc, value)	__CRC32(crc, value, crc32ch, 1, 1)
+#define _CRC32_crc32cw(crc, value)	__CRC32(crc, value, crc32cw, 2, 1)
+#define _CRC32_crc32cd(crc, value)	__CRC32(crc, value, crc32cd, 3, 1)
+
+#define _CRC32(crc, value, size, op) \
+	_CRC32_##op##size(crc, value)
+
+#define CRC32(crc, value, size) \
+	_CRC32(crc, value, size, crc32)
+
+#define CRC32C(crc, value, size) \
+	_CRC32(crc, value, size, crc32c)
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_crc32);
+
+static inline u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)
+{
+	if (!static_branch_likely(&have_crc32))
+		return crc32_le_base(crc, p, len);
+
+	if (IS_ENABLED(CONFIG_64BIT)) {
+		for (; len >= sizeof(u64); p += sizeof(u64), len -= sizeof(u64)) {
+			u64 value = get_unaligned_le64(p);
+
+			CRC32(crc, value, d);
+		}
+
+		if (len & sizeof(u32)) {
+			u32 value = get_unaligned_le32(p);
+
+			CRC32(crc, value, w);
+			p += sizeof(u32);
+		}
+	} else {
+		for (; len >= sizeof(u32); len -= sizeof(u32)) {
+			u32 value = get_unaligned_le32(p);
+
+			CRC32(crc, value, w);
+			p += sizeof(u32);
+		}
+	}
+
+	if (len & sizeof(u16)) {
+		u16 value = get_unaligned_le16(p);
+
+		CRC32(crc, value, h);
+		p += sizeof(u16);
+	}
+
+	if (len & sizeof(u8)) {
+		u8 value = *p++;
+
+		CRC32(crc, value, b);
+	}
+
+	return crc;
+}
+
+static inline u32 crc32c_arch(u32 crc, const u8 *p, size_t len)
+{
+	if (!static_branch_likely(&have_crc32))
+		return crc32c_base(crc, p, len);
+
+	if (IS_ENABLED(CONFIG_64BIT)) {
+		for (; len >= sizeof(u64); p += sizeof(u64), len -= sizeof(u64)) {
+			u64 value = get_unaligned_le64(p);
+
+			CRC32C(crc, value, d);
+		}
+
+		if (len & sizeof(u32)) {
+			u32 value = get_unaligned_le32(p);
+
+			CRC32C(crc, value, w);
+			p += sizeof(u32);
+		}
+	} else {
+		for (; len >= sizeof(u32); len -= sizeof(u32)) {
+			u32 value = get_unaligned_le32(p);
+
+			CRC32C(crc, value, w);
+			p += sizeof(u32);
+		}
+	}
+
+	if (len & sizeof(u16)) {
+		u16 value = get_unaligned_le16(p);
+
+		CRC32C(crc, value, h);
+		p += sizeof(u16);
+	}
+
+	if (len & sizeof(u8)) {
+		u8 value = *p++;
+
+		CRC32C(crc, value, b);
+	}
+	return crc;
+}
+
+#define crc32_be_arch crc32_be_base /* not implemented on this arch */
+
+#define crc32_mod_init_arch crc32_mod_init_arch
+static void crc32_mod_init_arch(void)
+{
+	if (cpu_have_feature(cpu_feature(MIPS_CRC32)))
+		static_branch_enable(&have_crc32);
+}
+
+static inline u32 crc32_optimizations_arch(void)
+{
+	if (static_key_enabled(&have_crc32))
+		return CRC32_LE_OPTIMIZATION | CRC32C_OPTIMIZATION;
+	return 0;
+}