kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 589 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/dbmethod.c b/drivers/acpi/acpica/dbmethod.c
new file mode 100644
index 000000000..889d13828
--- /dev/null
+++ b/drivers/acpi/acpica/dbmethod.c
@@ -0,0 +1,589 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/*******************************************************************************
+ *
+ * Module Name: dbmethod - Debug commands for control methods
+ *
+ ******************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acdispat.h"
+#include "acnamesp.h"
+#include "acdebug.h"
+#include "acparser.h"
+#include "acpredef.h"
+
+#define _COMPONENT          ACPI_CA_DEBUGGER
+ACPI_MODULE_NAME("dbmethod")
+
+/* Local prototypes */
+static acpi_status
+acpi_db_walk_for_execute(acpi_handle obj_handle,
+			 u32 nesting_level, void *context, void **return_value);
+
+static acpi_status acpi_db_evaluate_object(struct acpi_namespace_node *node);
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_set_method_breakpoint
+ *
+ * PARAMETERS:  location            - AML offset of breakpoint
+ *              walk_state          - Current walk info
+ *              op                  - Current Op (from parse walk)
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Set a breakpoint in a control method at the specified
+ *              AML offset
+ *
+ ******************************************************************************/
+
+void
+acpi_db_set_method_breakpoint(char *location,
+			      struct acpi_walk_state *walk_state,
+			      union acpi_parse_object *op)
+{
+	u32 address;
+	u32 aml_offset;
+
+	if (!op) {
+		acpi_os_printf("There is no method currently executing\n");
+		return;
+	}
+
+	/* Get and verify the breakpoint address */
+
+	address = strtoul(location, NULL, 16);
+	aml_offset = (u32)ACPI_PTR_DIFF(op->common.aml,
+					walk_state->parser_state.aml_start);
+	if (address <= aml_offset) {
+		acpi_os_printf("Breakpoint %X is beyond current address %X\n",
+			       address, aml_offset);
+	}
+
+	/* Save breakpoint in current walk */
+
+	walk_state->user_breakpoint = address;
+	acpi_os_printf("Breakpoint set at AML offset %X\n", address);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_set_method_call_breakpoint
+ *
+ * PARAMETERS:  op                  - Current Op (from parse walk)
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Set a breakpoint in a control method at the specified
+ *              AML offset
+ *
+ ******************************************************************************/
+
+void acpi_db_set_method_call_breakpoint(union acpi_parse_object *op)
+{
+
+	if (!op) {
+		acpi_os_printf("There is no method currently executing\n");
+		return;
+	}
+
+	acpi_gbl_step_to_next_call = TRUE;
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_set_method_data
+ *
+ * PARAMETERS:  type_arg        - L for local, A for argument
+ *              index_arg       - which one
+ *              value_arg       - Value to set.
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Set a local or argument for the running control method.
+ *              NOTE: only object supported is Number.
+ *
+ ******************************************************************************/
+
+void acpi_db_set_method_data(char *type_arg, char *index_arg, char *value_arg)
+{
+	char type;
+	u32 index;
+	u32 value;
+	struct acpi_walk_state *walk_state;
+	union acpi_operand_object *obj_desc;
+	acpi_status status;
+	struct acpi_namespace_node *node;
+
+	/* Validate type_arg */
+
+	acpi_ut_strupr(type_arg);
+	type = type_arg[0];
+	if ((type != 'L') && (type != 'A') && (type != 'N')) {
+		acpi_os_printf("Invalid SET operand: %s\n", type_arg);
+		return;
+	}
+
+	value = strtoul(value_arg, NULL, 16);
+
+	if (type == 'N') {
+		node = acpi_db_convert_to_node(index_arg);
+		if (!node) {
+			return;
+		}
+
+		if (node->type != ACPI_TYPE_INTEGER) {
+			acpi_os_printf("Can only set Integer nodes\n");
+			return;
+		}
+		obj_desc = node->object;
+		obj_desc->integer.value = value;
+		return;
+	}
+
+	/* Get the index and value */
+
+	index = strtoul(index_arg, NULL, 16);
+
+	walk_state = acpi_ds_get_current_walk_state(acpi_gbl_current_walk_list);
+	if (!walk_state) {
+		acpi_os_printf("There is no method currently executing\n");
+		return;
+	}
+
+	/* Create and initialize the new object */
+
+	obj_desc = acpi_ut_create_integer_object((u64)value);
+	if (!obj_desc) {
+		acpi_os_printf("Could not create an internal object\n");
+		return;
+	}
+
+	/* Store the new object into the target */
+
+	switch (type) {
+	case 'A':
+
+		/* Set a method argument */
+
+		if (index > ACPI_METHOD_MAX_ARG) {
+			acpi_os_printf("Arg%u - Invalid argument name\n",
+				       index);
+			goto cleanup;
+		}
+
+		status = acpi_ds_store_object_to_local(ACPI_REFCLASS_ARG,
+						       index, obj_desc,
+						       walk_state);
+		if (ACPI_FAILURE(status)) {
+			goto cleanup;
+		}
+
+		obj_desc = walk_state->arguments[index].object;
+
+		acpi_os_printf("Arg%u: ", index);
+		acpi_db_display_internal_object(obj_desc, walk_state);
+		break;
+
+	case 'L':
+
+		/* Set a method local */
+
+		if (index > ACPI_METHOD_MAX_LOCAL) {
+			acpi_os_printf
+			    ("Local%u - Invalid local variable name\n", index);
+			goto cleanup;
+		}
+
+		status = acpi_ds_store_object_to_local(ACPI_REFCLASS_LOCAL,
+						       index, obj_desc,
+						       walk_state);
+		if (ACPI_FAILURE(status)) {
+			goto cleanup;
+		}
+
+		obj_desc = walk_state->local_variables[index].object;
+
+		acpi_os_printf("Local%u: ", index);
+		acpi_db_display_internal_object(obj_desc, walk_state);
+		break;
+
+	default:
+
+		break;
+	}
+
+cleanup:
+	acpi_ut_remove_reference(obj_desc);
+}
+
+#ifdef ACPI_DISASSEMBLER
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_disassemble_aml
+ *
+ * PARAMETERS:  statements          - Number of statements to disassemble
+ *              op                  - Current Op (from parse walk)
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Display disassembled AML (ASL) starting from Op for the number
+ *              of statements specified.
+ *
+ ******************************************************************************/
+
+void acpi_db_disassemble_aml(char *statements, union acpi_parse_object *op)
+{
+	u32 num_statements = 8;
+
+	if (!op) {
+		acpi_os_printf("There is no method currently executing\n");
+		return;
+	}
+
+	if (statements) {
+		num_statements = strtoul(statements, NULL, 0);
+	}
+
+	acpi_dm_disassemble(NULL, op, num_statements);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_disassemble_method
+ *
+ * PARAMETERS:  name            - Name of control method
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Display disassembled AML (ASL) starting from Op for the number
+ *              of statements specified.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_db_disassemble_method(char *name)
+{
+	acpi_status status;
+	union acpi_parse_object *op;
+	struct acpi_walk_state *walk_state;
+	union acpi_operand_object *obj_desc;
+	struct acpi_namespace_node *method;
+
+	method = acpi_db_convert_to_node(name);
+	if (!method) {
+		return (AE_BAD_PARAMETER);
+	}
+
+	if (method->type != ACPI_TYPE_METHOD) {
+		ACPI_ERROR((AE_INFO, "%s (%s): Object must be a control method",
+			    name, acpi_ut_get_type_name(method->type)));
+		return (AE_BAD_PARAMETER);
+	}
+
+	obj_desc = method->object;
+
+	op = acpi_ps_create_scope_op(obj_desc->method.aml_start);
+	if (!op) {
+		return (AE_NO_MEMORY);
+	}
+
+	/* Create and initialize a new walk state */
+
+	walk_state = acpi_ds_create_walk_state(0, op, NULL, NULL);
+	if (!walk_state) {
+		return (AE_NO_MEMORY);
+	}
+
+	status = acpi_ds_init_aml_walk(walk_state, op, NULL,
+				       obj_desc->method.aml_start,
+				       obj_desc->method.aml_length, NULL,
+				       ACPI_IMODE_LOAD_PASS1);
+	if (ACPI_FAILURE(status)) {
+		return (status);
+	}
+
+	status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
+	if (ACPI_FAILURE(status)) {
+		return (status);
+	}
+
+	walk_state->owner_id = obj_desc->method.owner_id;
+
+	/* Push start scope on scope stack and make it current */
+
+	status = acpi_ds_scope_stack_push(method, method->type, walk_state);
+	if (ACPI_FAILURE(status)) {
+		return (status);
+	}
+
+	/* Parse the entire method AML including deferred operators */
+
+	walk_state->parse_flags &= ~ACPI_PARSE_DELETE_TREE;
+	walk_state->parse_flags |= ACPI_PARSE_DISASSEMBLE;
+
+	status = acpi_ps_parse_aml(walk_state);
+	if (ACPI_FAILURE(status)) {
+		return (status);
+	}
+
+	(void)acpi_dm_parse_deferred_ops(op);
+
+	/* Now we can disassemble the method */
+
+	acpi_gbl_dm_opt_verbose = FALSE;
+	acpi_dm_disassemble(NULL, op, 0);
+	acpi_gbl_dm_opt_verbose = TRUE;
+
+	acpi_ps_delete_parse_tree(op);
+
+	/* Method cleanup */
+
+	acpi_ns_delete_namespace_subtree(method);
+	acpi_ns_delete_namespace_by_owner(obj_desc->method.owner_id);
+	acpi_ut_release_owner_id(&obj_desc->method.owner_id);
+	return (AE_OK);
+}
+#endif
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_evaluate_object
+ *
+ * PARAMETERS:  node                - Namespace node for the object
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Main execution function for the Evaluate/Execute/All debugger
+ *              commands.
+ *
+ ******************************************************************************/
+
+static acpi_status acpi_db_evaluate_object(struct acpi_namespace_node *node)
+{
+	char *pathname;
+	u32 i;
+	struct acpi_device_info *obj_info;
+	struct acpi_object_list param_objects;
+	union acpi_object params[ACPI_METHOD_NUM_ARGS];
+	struct acpi_buffer return_obj;
+	acpi_status status;
+
+	pathname = acpi_ns_get_external_pathname(node);
+	if (!pathname) {
+		return (AE_OK);
+	}
+
+	/* Get the object info for number of method parameters */
+
+	status = acpi_get_object_info(node, &obj_info);
+	if (ACPI_FAILURE(status)) {
+		ACPI_FREE(pathname);
+		return (status);
+	}
+
+	param_objects.pointer = NULL;
+	param_objects.count = 0;
+
+	if (obj_info->type == ACPI_TYPE_METHOD) {
+
+		/* Setup default parameters */
+
+		for (i = 0; i < obj_info->param_count; i++) {
+			params[i].type = ACPI_TYPE_INTEGER;
+			params[i].integer.value = 1;
+		}
+
+		param_objects.pointer = params;
+		param_objects.count = obj_info->param_count;
+	}
+
+	ACPI_FREE(obj_info);
+	return_obj.pointer = NULL;
+	return_obj.length = ACPI_ALLOCATE_BUFFER;
+
+	/* Do the actual method execution */
+
+	acpi_gbl_method_executing = TRUE;
+
+	status = acpi_evaluate_object(node, NULL, &param_objects, &return_obj);
+	acpi_gbl_method_executing = FALSE;
+
+	acpi_os_printf("%-32s returned %s\n", pathname,
+		       acpi_format_exception(status));
+	if (return_obj.length) {
+		acpi_os_printf("Evaluation of %s returned object %p, "
+			       "external buffer length %X\n",
+			       pathname, return_obj.pointer,
+			       (u32)return_obj.length);
+
+		acpi_db_dump_external_object(return_obj.pointer, 1);
+		acpi_os_printf("\n");
+	}
+
+	ACPI_FREE(pathname);
+
+	/* Ignore status from method execution */
+
+	return (AE_OK);
+
+	/* Update count, check if we have executed enough methods */
+
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_walk_for_execute
+ *
+ * PARAMETERS:  Callback from walk_namespace
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Batch execution function. Evaluates all "predefined" objects --
+ *              the nameseg begins with an underscore.
+ *
+ ******************************************************************************/
+
+static acpi_status
+acpi_db_walk_for_execute(acpi_handle obj_handle,
+			 u32 nesting_level, void *context, void **return_value)
+{
+	struct acpi_namespace_node *node =
+	    (struct acpi_namespace_node *)obj_handle;
+	struct acpi_db_execute_walk *info =
+	    (struct acpi_db_execute_walk *)context;
+	acpi_status status;
+	const union acpi_predefined_info *predefined;
+
+	predefined = acpi_ut_match_predefined_method(node->name.ascii);
+	if (!predefined) {
+		return (AE_OK);
+	}
+
+	if (node->type == ACPI_TYPE_LOCAL_SCOPE) {
+		return (AE_OK);
+	}
+
+	acpi_db_evaluate_object(node);
+
+	/* Ignore status from object evaluation */
+
+	status = AE_OK;
+
+	/* Update count, check if we have executed enough methods */
+
+	info->count++;
+	if (info->count >= info->max_count) {
+		status = AE_CTRL_TERMINATE;
+	}
+
+	return (status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_walk_for_execute_all
+ *
+ * PARAMETERS:  Callback from walk_namespace
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Batch execution function. Evaluates all objects whose path ends
+ *              with the nameseg "Info->NameSeg". Used for the "ALL" command.
+ *
+ ******************************************************************************/
+
+static acpi_status
+acpi_db_walk_for_execute_all(acpi_handle obj_handle,
+			     u32 nesting_level,
+			     void *context, void **return_value)
+{
+	struct acpi_namespace_node *node =
+	    (struct acpi_namespace_node *)obj_handle;
+	struct acpi_db_execute_walk *info =
+	    (struct acpi_db_execute_walk *)context;
+	acpi_status status;
+
+	if (!ACPI_COMPARE_NAMESEG(node->name.ascii, info->name_seg)) {
+		return (AE_OK);
+	}
+
+	if (node->type == ACPI_TYPE_LOCAL_SCOPE) {
+		return (AE_OK);
+	}
+
+	/* Now evaluate the input object (node) */
+
+	acpi_db_evaluate_object(node);
+
+	/* Ignore status from method execution */
+
+	status = AE_OK;
+
+	/* Update count of executed methods/objects */
+
+	info->count++;
+	return (status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_evaluate_predefined_names
+ *
+ * PARAMETERS:  None
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Namespace batch execution. Execute predefined names in the
+ *              namespace, up to the max count, if specified.
+ *
+ ******************************************************************************/
+
+void acpi_db_evaluate_predefined_names(void)
+{
+	struct acpi_db_execute_walk info;
+
+	info.count = 0;
+	info.max_count = ACPI_UINT32_MAX;
+
+	/* Search all nodes in namespace */
+
+	(void)acpi_walk_namespace(ACPI_TYPE_ANY, ACPI_ROOT_OBJECT,
+				  ACPI_UINT32_MAX, acpi_db_walk_for_execute,
+				  NULL, (void *)&info, NULL);
+
+	acpi_os_printf("Evaluated %u predefined names in the namespace\n",
+		       info.count);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_db_evaluate_all
+ *
+ * PARAMETERS:  none_acpi_gbl_db_method_info
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Namespace batch execution. Implements the "ALL" command.
+ *              Execute all namepaths whose final nameseg matches the
+ *              input nameseg.
+ *
+ ******************************************************************************/
+
+void acpi_db_evaluate_all(char *name_seg)
+{
+	struct acpi_db_execute_walk info;
+
+	info.count = 0;
+	info.max_count = ACPI_UINT32_MAX;
+	ACPI_COPY_NAMESEG(info.name_seg, name_seg);
+	info.name_seg[ACPI_NAMESEG_SIZE] = 0;
+
+	/* Search all nodes in namespace */
+
+	(void)acpi_walk_namespace(ACPI_TYPE_ANY, ACPI_ROOT_OBJECT,
+				  ACPI_UINT32_MAX, acpi_db_walk_for_execute_all,
+				  NULL, (void *)&info, NULL);
+
+	acpi_os_printf("Evaluated %u names in the namespace\n", info.count);
+}