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, 214 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/psutils.c b/drivers/acpi/acpica/psutils.c
new file mode 100644
index 000000000..789d75dc4
--- /dev/null
+++ b/drivers/acpi/acpica/psutils.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Module Name: psutils - Parser miscellaneous utilities (Parser only)
+ *
+ * Copyright (C) 2000 - 2026, Intel Corp.
+ *
+ *****************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acparser.h"
+#include "amlcode.h"
+#include "acconvert.h"
+
+#define _COMPONENT          ACPI_PARSER
+ACPI_MODULE_NAME("psutils")
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ps_create_scope_op
+ *
+ * PARAMETERS:  None
+ *
+ * RETURN:      A new Scope object, null on failure
+ *
+ * DESCRIPTION: Create a Scope and associated namepath op with the root name
+ *
+ ******************************************************************************/
+union acpi_parse_object *acpi_ps_create_scope_op(u8 *aml)
+{
+	union acpi_parse_object *scope_op;
+
+	scope_op = acpi_ps_alloc_op(AML_SCOPE_OP, aml);
+	if (!scope_op) {
+		return (NULL);
+	}
+
+	scope_op->named.name = ACPI_ROOT_NAME;
+	return (scope_op);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ps_init_op
+ *
+ * PARAMETERS:  op              - A newly allocated Op object
+ *              opcode          - Opcode to store in the Op
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Initialize a parse (Op) object
+ *
+ ******************************************************************************/
+
+void acpi_ps_init_op(union acpi_parse_object *op, u16 opcode)
+{
+	ACPI_FUNCTION_ENTRY();
+
+	op->common.descriptor_type = ACPI_DESC_TYPE_PARSER;
+	op->common.aml_opcode = opcode;
+
+	ACPI_DISASM_ONLY_MEMBERS(acpi_ut_safe_strncpy(op->common.aml_op_name,
+						      (acpi_ps_get_opcode_info
+						       (opcode))->name,
+						      sizeof(op->common.
+							     aml_op_name)));
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ps_alloc_op
+ *
+ * PARAMETERS:  opcode          - Opcode that will be stored in the new Op
+ *              aml             - Address of the opcode
+ *
+ * RETURN:      Pointer to the new Op, null on failure
+ *
+ * DESCRIPTION: Allocate an acpi_op, choose op type (and thus size) based on
+ *              opcode. A cache of opcodes is available for the pure
+ *              GENERIC_OP, since this is by far the most commonly used.
+ *
+ ******************************************************************************/
+
+union acpi_parse_object *acpi_ps_alloc_op(u16 opcode, u8 *aml)
+{
+	union acpi_parse_object *op;
+	const struct acpi_opcode_info *op_info;
+	u8 flags = ACPI_PARSEOP_GENERIC;
+
+	ACPI_FUNCTION_ENTRY();
+
+	op_info = acpi_ps_get_opcode_info(opcode);
+
+	/* Determine type of parse_op required */
+
+	if (op_info->flags & AML_DEFER) {
+		flags = ACPI_PARSEOP_DEFERRED;
+	} else if (op_info->flags & AML_NAMED) {
+		flags = ACPI_PARSEOP_NAMED_OBJECT;
+	} else if (opcode == AML_INT_BYTELIST_OP) {
+		flags = ACPI_PARSEOP_BYTELIST;
+	}
+
+	/* Allocate the minimum required size object */
+
+	if (flags == ACPI_PARSEOP_GENERIC) {
+
+		/* The generic op (default) is by far the most common (16 to 1) */
+
+		op = acpi_os_acquire_object(acpi_gbl_ps_node_cache);
+	} else {
+		/* Extended parseop */
+
+		op = acpi_os_acquire_object(acpi_gbl_ps_node_ext_cache);
+	}
+
+	/* Initialize the Op */
+
+	if (op) {
+		acpi_ps_init_op(op, opcode);
+		op->common.aml = aml;
+		op->common.flags = flags;
+		ASL_CV_CLEAR_OP_COMMENTS(op);
+
+		if (opcode == AML_SCOPE_OP) {
+			acpi_gbl_current_scope = op;
+		}
+
+		if (acpi_gbl_capture_comments) {
+			ASL_CV_TRANSFER_COMMENTS(op);
+		}
+	}
+
+	return (op);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ps_free_op
+ *
+ * PARAMETERS:  op              - Op to be freed
+ *
+ * RETURN:      None.
+ *
+ * DESCRIPTION: Free an Op object. Either put it on the GENERIC_OP cache list
+ *              or actually free it.
+ *
+ ******************************************************************************/
+
+void acpi_ps_free_op(union acpi_parse_object *op)
+{
+	ACPI_FUNCTION_NAME(ps_free_op);
+
+	ASL_CV_CLEAR_OP_COMMENTS(op);
+	if (op->common.aml_opcode == AML_INT_RETURN_VALUE_OP) {
+		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
+				  "Free retval op: %p\n", op));
+	}
+
+	if (op->common.flags & ACPI_PARSEOP_GENERIC) {
+		(void)acpi_os_release_object(acpi_gbl_ps_node_cache, op);
+	} else {
+		(void)acpi_os_release_object(acpi_gbl_ps_node_ext_cache, op);
+	}
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    Utility functions
+ *
+ * DESCRIPTION: Low level character and object functions
+ *
+ ******************************************************************************/
+
+/*
+ * Is "c" a namestring lead character?
+ */
+u8 acpi_ps_is_leading_char(u32 c)
+{
+	return ((u8) (c == '_' || (c >= 'A' && c <= 'Z')));
+}
+
+/*
+ * Get op's name (4-byte name segment) or 0 if unnamed
+ */
+u32 acpi_ps_get_name(union acpi_parse_object * op)
+{
+
+	/* The "generic" object has no name associated with it */
+
+	if (op->common.flags & ACPI_PARSEOP_GENERIC) {
+		return (0);
+	}
+
+	/* Only the "Extended" parse objects have a name */
+
+	return (op->named.name);
+}
+
+/*
+ * Set op's name
+ */
+void acpi_ps_set_name(union acpi_parse_object *op, u32 name)
+{
+
+	/* The "generic" object has no name associated with it */
+
+	if (op->common.flags & ACPI_PARSEOP_GENERIC) {
+		return;
+	}
+
+	op->named.name = name;
+}