include/linker_lists.h - uboot-imx - Git at Google

 /*
  * include/linker_lists.h
  *
  * Implementation of linker-generated arrays
  *
  * Copyright (C) 2012 Marek Vasut <marex@denx.de>
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */

 #ifndef __LINKER_LISTS_H__
 #define __LINKER_LISTS_H__

 #include <linux/compiler.h>

 /*
  * There is no use in including this from ASM files, but that happens
  * anyway, e.g. PPC kgdb.S includes command.h which incluse us.
  * So just don't define anything when included from ASM.
  */

 #if !defined(__ASSEMBLY__)

 /**
  * A linker list is constructed by grouping together linker input
  * sections, each containing one entry of the list. Each input section
  * contains a constant initialized variable which holds the entry's
  * content. Linker list input sections are constructed from the list
  * and entry names, plus a prefix which allows grouping all lists
  * together. Assuming _list and _entry are the list and entry names,
  * then the corresponding input section name is
  *
  *   .u_boot_list_ + 2_ + @_list + _2_ + @_entry
  *
  * and the C variable name is
  *
  *   _u_boot_list + _2_ + @_list + _2_ + @_entry
  *
  * This ensures uniqueness for both input section and C variable name.
  *
  * Note that the names differ only in the first character, "." for the
  * section and "_" for the variable, so that the linker cannot confuse
  * section and symbol names. From now on, both names will be referred
  * to as
  *
  *   %u_boot_list_ + 2_ + @_list + _2_ + @_entry
  *
  * Entry variables need never be referred to directly.
  *
  * The naming scheme for input sections allows grouping all linker lists
  * into a single linker output section and grouping all entries for a
  * single list.
  *
  * Note the two '_2_' constant components in the names: their presence
  * allows putting a start and end symbols around a list, by mapping
  * these symbols to sections names with components "1" (before) and
  * "3" (after) instead of "2" (within).
  * Start and end symbols for a list can generally be defined as
  *
  *   %u_boot_list_2_ + @_list + _1_...
  *   %u_boot_list_2_ + @_list + _3_...
  *
  * Start and end symbols for the whole of the linker lists area can be
  * defined as
  *
  *   %u_boot_list_1_...
  *   %u_boot_list_3_...
  *
  * Here is an example of the sorted sections which result from a list
  * "array" made up of three entries : "first", "second" and "third",
  * iterated at least once.
  *
  *   .u_boot_list_2_array_1
  *   .u_boot_list_2_array_2_first
  *   .u_boot_list_2_array_2_second
  *   .u_boot_list_2_array_2_third
  *   .u_boot_list_2_array_3
  *
  * If lists must be divided into sublists (e.g. for iterating only on
  * part of a list), one can simply give the list a name of the form
  * 'outer_2_inner', where 'outer' is the global list name and 'inner'
  * is the sub-list name. Iterators for the whole list should use the
  * global list name ("outer"); iterators for only a sub-list should use
  * the full sub-list name ("outer_2_inner").
  *
  * Here is an example of the sections generated from a global list
  * named "drivers", two sub-lists named "i2c" and "pci", and iterators
  * defined for the whole list and each sub-list:
  *
  *   %u_boot_list_2_drivers_1
  *   %u_boot_list_2_drivers_2_i2c_1
  *   %u_boot_list_2_drivers_2_i2c_2_first
  *   %u_boot_list_2_drivers_2_i2c_2_first
  *   %u_boot_list_2_drivers_2_i2c_2_second
  *   %u_boot_list_2_drivers_2_i2c_2_third
  *   %u_boot_list_2_drivers_2_i2c_3
  *   %u_boot_list_2_drivers_2_pci_1
  *   %u_boot_list_2_drivers_2_pci_2_first
  *   %u_boot_list_2_drivers_2_pci_2_second
  *   %u_boot_list_2_drivers_2_pci_2_third
  *   %u_boot_list_2_drivers_2_pci_3
  *   %u_boot_list_2_drivers_3
  */

 /**
  * llsym() - Access a linker-generated array entry
  * @_type:	Data type of the entry
  * @_name:	Name of the entry
  * @_list:	name of the list. Should contain only characters allowed
  *		in a C variable name!
  */
 #define llsym(_type, _name, _list) \
 		((_type *)&_u_boot_list_2_##_list##_2_##_name)

 /**
  * ll_entry_declare() - Declare linker-generated array entry
  * @_type:	Data type of the entry
  * @_name:	Name of the entry
  * @_list:	name of the list. Should contain only characters allowed
  *		in a C variable name!
  *
  * This macro declares a variable that is placed into a linker-generated
  * array. This is a basic building block for more advanced use of linker-
  * generated arrays. The user is expected to build their own macro wrapper
  * around this one.
  *
  * A variable declared using this macro must be compile-time initialized.
  *
  * Special precaution must be made when using this macro:
  *
  * 1) The _type must not contain the "static" keyword, otherwise the
  *    entry is generated and can be iterated but is listed in the map
  *    file and cannot be retrieved by name.
  *
  * 2) In case a section is declared that contains some array elements AND
  *    a subsection of this section is declared and contains some elements,
  *    it is imperative that the elements are of the same type.
  *
  * 4) In case an outer section is declared that contains some array elements
  *    AND an inner subsection of this section is declared and contains some
  *    elements, then when traversing the outer section, even the elements of
  *    the inner sections are present in the array.
  *
  * Example:
  * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
  *         .x = 3,
  *         .y = 4,
  * };
  */
 #define ll_entry_declare(_type, _name, _list)				\
 	_type _u_boot_list_2_##_list##_2_##_name __aligned(4)		\
 			__attribute__((unused,				\
 			section(".u_boot_list_2_"#_list"_2_"#_name)))

 /**
  * ll_entry_declare_list() - Declare a list of link-generated array entries
  * @_type:	Data type of each entry
  * @_name:	Name of the entry
  * @_list:	name of the list. Should contain only characters allowed
  *		in a C variable name!
  *
  * This is like ll_entry_declare() but creates multiple entries. It should
  * be assigned to an array.
  *
  * ll_entry_declare_list(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
  *	{ .x = 3, .y = 4 },
  *	{ .x = 8, .y = 2 },
  *	{ .x = 1, .y = 7 }
  * };
  */
 #define ll_entry_declare_list(_type, _name, _list)			\
 	_type _u_boot_list_2_##_list##_2_##_name[] __aligned(4)		\
 			__attribute__((unused,				\
 			section(".u_boot_list_2_"#_list"_2_"#_name)))

 /**
  * We need a 0-byte-size type for iterator symbols, and the compiler
  * does not allow defining objects of C type 'void'. Using an empty
  * struct is allowed by the compiler, but causes gcc versions 4.4 and
  * below to complain about aliasing. Therefore we use the next best
  * thing: zero-sized arrays, which are both 0-byte-size and exempt from
  * aliasing warnings.
  */

 /**
  * ll_entry_start() - Point to first entry of linker-generated array
  * @_type:	Data type of the entry
  * @_list:	Name of the list in which this entry is placed
  *
  * This function returns (_type *) pointer to the very first entry of a
  * linker-generated array placed into subsection of .u_boot_list section
  * specified by _list argument.
  *
  * Since this macro defines an array start symbol, its leftmost index
  * must be 2 and its rightmost index must be 1.
  *
  * Example:
  * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
  */
 #define ll_entry_start(_type, _list)					\
 ({									\
 	static char start[0] __aligned(4) __attribute__((unused,	\
 		section(".u_boot_list_2_"#_list"_1")));			\
 	(_type *)&start;						\
 })

 /**
  * ll_entry_end() - Point after last entry of linker-generated array
  * @_type:	Data type of the entry
  * @_list:	Name of the list in which this entry is placed
  *		(with underscores instead of dots)
  *
  * This function returns (_type *) pointer after the very last entry of
  * a linker-generated array placed into subsection of .u_boot_list
  * section specified by _list argument.
  *
  * Since this macro defines an array end symbol, its leftmost index
  * must be 2 and its rightmost index must be 3.
  *
  * Example:
  * struct my_sub_cmd *msc = ll_entry_end(struct my_sub_cmd, cmd_sub);
  */
 #define ll_entry_end(_type, _list)					\
 ({									\
 	static char end[0] __aligned(4) __attribute__((unused,		\
 		section(".u_boot_list_2_"#_list"_3")));			\
 	(_type *)&end;							\
 })
 /**
  * ll_entry_count() - Return the number of elements in linker-generated array
  * @_type:	Data type of the entry
  * @_list:	Name of the list of which the number of elements is computed
  *
  * This function returns the number of elements of a linker-generated array
  * placed into subsection of .u_boot_list section specified by _list
  * argument. The result is of an unsigned int type.
  *
  * Example:
  * int i;
  * const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub);
  * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
  * for (i = 0; i < count; i++, msc++)
  *         printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y);
  */
 #define ll_entry_count(_type, _list)					\
 	({								\
 		_type *start = ll_entry_start(_type, _list);		\
 		_type *end = ll_entry_end(_type, _list);		\
 		unsigned int _ll_result = end - start;			\
 		_ll_result;						\
 	})

 /**
  * ll_entry_get() - Retrieve entry from linker-generated array by name
  * @_type:	Data type of the entry
  * @_name:	Name of the entry
  * @_list:	Name of the list in which this entry is placed
  *
  * This function returns a pointer to a particular entry in linker-generated
  * array identified by the subsection of u_boot_list where the entry resides
  * and it's name.
  *
  * Example:
  * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
  *         .x = 3,
  *         .y = 4,
  * };
  * ...
  * struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub);
  */
 #define ll_entry_get(_type, _name, _list)				\
 	({								\
 		extern _type _u_boot_list_2_##_list##_2_##_name;	\
 		_type *_ll_result =					\
 			&_u_boot_list_2_##_list##_2_##_name;		\
 		_ll_result;						\
 	})

 /**
  * ll_start() - Point to first entry of first linker-generated array
  * @_type:	Data type of the entry
  *
  * This function returns (_type *) pointer to the very first entry of
  * the very first linker-generated array.
  *
  * Since this macro defines the start of the linker-generated arrays,
  * its leftmost index must be 1.
  *
  * Example:
  * struct my_sub_cmd *msc = ll_start(struct my_sub_cmd);
  */
 #define ll_start(_type)							\
 ({									\
 	static char start[0] __aligned(4) __attribute__((unused,	\
 		section(".u_boot_list_1")));				\
 	(_type *)&start;						\
 })

 /**
  * ll_end() - Point after last entry of last linker-generated array
  * @_type:	Data type of the entry
  *
  * This function returns (_type *) pointer after the very last entry of
  * the very last linker-generated array.
  *
  * Since this macro defines the end of the linker-generated arrays,
  * its leftmost index must be 3.
  *
  * Example:
  * struct my_sub_cmd *msc = ll_end(struct my_sub_cmd);
  */
 #define ll_end(_type)							\
 ({									\
 	static char end[0] __aligned(4) __attribute__((unused,		\
 		section(".u_boot_list_3")));				\
 	(_type *)&end;							\
 })

 #endif /* __ASSEMBLY__ */

 #endif	/* __LINKER_LISTS_H__ */
	/*
	* include/linker_lists.h
	*
	* Implementation of linker-generated arrays
	*
	* Copyright (C) 2012 Marek Vasut <marex@denx.de>
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#ifndef __LINKER_LISTS_H__
	#define __LINKER_LISTS_H__

	#include <linux/compiler.h>

	/*
	* There is no use in including this from ASM files, but that happens
	* anyway, e.g. PPC kgdb.S includes command.h which incluse us.
	* So just don't define anything when included from ASM.
	*/

	#if !defined(__ASSEMBLY__)

	/**
	* A linker list is constructed by grouping together linker input
	* sections, each containing one entry of the list. Each input section
	* contains a constant initialized variable which holds the entry's
	* content. Linker list input sections are constructed from the list
	* and entry names, plus a prefix which allows grouping all lists
	* together. Assuming _list and _entry are the list and entry names,
	* then the corresponding input section name is
	*
	* .u_boot_list_ + 2_ + @_list + _2_ + @_entry
	*
	* and the C variable name is
	*
	* _u_boot_list + _2_ + @_list + _2_ + @_entry
	*
	* This ensures uniqueness for both input section and C variable name.
	*
	* Note that the names differ only in the first character, "." for the
	* section and "_" for the variable, so that the linker cannot confuse
	* section and symbol names. From now on, both names will be referred
	* to as
	*
	* %u_boot_list_ + 2_ + @_list + _2_ + @_entry
	*
	* Entry variables need never be referred to directly.
	*
	* The naming scheme for input sections allows grouping all linker lists
	* into a single linker output section and grouping all entries for a
	* single list.
	*
	* Note the two '_2_' constant components in the names: their presence
	* allows putting a start and end symbols around a list, by mapping
	* these symbols to sections names with components "1" (before) and
	* "3" (after) instead of "2" (within).
	* Start and end symbols for a list can generally be defined as
	*
	* %u_boot_list_2_ + @_list + _1_...
	* %u_boot_list_2_ + @_list + _3_...
	*
	* Start and end symbols for the whole of the linker lists area can be
	* defined as
	*
	* %u_boot_list_1_...
	* %u_boot_list_3_...
	*
	* Here is an example of the sorted sections which result from a list
	* "array" made up of three entries : "first", "second" and "third",
	* iterated at least once.
	*
	* .u_boot_list_2_array_1
	* .u_boot_list_2_array_2_first
	* .u_boot_list_2_array_2_second
	* .u_boot_list_2_array_2_third
	* .u_boot_list_2_array_3
	*
	* If lists must be divided into sublists (e.g. for iterating only on
	* part of a list), one can simply give the list a name of the form
	* 'outer_2_inner', where 'outer' is the global list name and 'inner'
	* is the sub-list name. Iterators for the whole list should use the
	* global list name ("outer"); iterators for only a sub-list should use
	* the full sub-list name ("outer_2_inner").
	*
	* Here is an example of the sections generated from a global list
	* named "drivers", two sub-lists named "i2c" and "pci", and iterators
	* defined for the whole list and each sub-list:
	*
	* %u_boot_list_2_drivers_1
	* %u_boot_list_2_drivers_2_i2c_1
	* %u_boot_list_2_drivers_2_i2c_2_first
	* %u_boot_list_2_drivers_2_i2c_2_first
	* %u_boot_list_2_drivers_2_i2c_2_second
	* %u_boot_list_2_drivers_2_i2c_2_third
	* %u_boot_list_2_drivers_2_i2c_3
	* %u_boot_list_2_drivers_2_pci_1
	* %u_boot_list_2_drivers_2_pci_2_first
	* %u_boot_list_2_drivers_2_pci_2_second
	* %u_boot_list_2_drivers_2_pci_2_third
	* %u_boot_list_2_drivers_2_pci_3
	* %u_boot_list_2_drivers_3
	*/

	/**
	* llsym() - Access a linker-generated array entry
	* @_type: Data type of the entry
	* @_name: Name of the entry
	* @_list: name of the list. Should contain only characters allowed
	* in a C variable name!
	*/
	#define llsym(_type, _name, _list) \
	((_type *)&_u_boot_list_2_##_list##_2_##_name)

	/**
	* ll_entry_declare() - Declare linker-generated array entry
	* @_type: Data type of the entry
	* @_name: Name of the entry
	* @_list: name of the list. Should contain only characters allowed
	* in a C variable name!
	*
	* This macro declares a variable that is placed into a linker-generated
	* array. This is a basic building block for more advanced use of linker-
	* generated arrays. The user is expected to build their own macro wrapper
	* around this one.
	*
	* A variable declared using this macro must be compile-time initialized.
	*
	* Special precaution must be made when using this macro:
	*
	* 1) The _type must not contain the "static" keyword, otherwise the
	* entry is generated and can be iterated but is listed in the map
	* file and cannot be retrieved by name.
	*
	* 2) In case a section is declared that contains some array elements AND
	* a subsection of this section is declared and contains some elements,
	* it is imperative that the elements are of the same type.
	*
	* 4) In case an outer section is declared that contains some array elements
	* AND an inner subsection of this section is declared and contains some
	* elements, then when traversing the outer section, even the elements of
	* the inner sections are present in the array.
	*
	* Example:
	* ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
	* .x = 3,
	* .y = 4,
	* };
	*/
	#define ll_entry_declare(_type, _name, _list) \
	_type _u_boot_list_2_##_list##_2_##_name __aligned(4) \
	__attribute__((unused, \
	section(".u_boot_list_2_"#_list"_2_"#_name)))

	/**
	* ll_entry_declare_list() - Declare a list of link-generated array entries
	* @_type: Data type of each entry
	* @_name: Name of the entry
	* @_list: name of the list. Should contain only characters allowed
	* in a C variable name!
	*
	* This is like ll_entry_declare() but creates multiple entries. It should
	* be assigned to an array.
	*
	* ll_entry_declare_list(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
	* { .x = 3, .y = 4 },
	* { .x = 8, .y = 2 },
	* { .x = 1, .y = 7 }
	* };
	*/
	#define ll_entry_declare_list(_type, _name, _list) \
	_type _u_boot_list_2_##_list##_2_##_name[] __aligned(4) \
	__attribute__((unused, \
	section(".u_boot_list_2_"#_list"_2_"#_name)))

	/**
	* We need a 0-byte-size type for iterator symbols, and the compiler
	* does not allow defining objects of C type 'void'. Using an empty
	* struct is allowed by the compiler, but causes gcc versions 4.4 and
	* below to complain about aliasing. Therefore we use the next best
	* thing: zero-sized arrays, which are both 0-byte-size and exempt from
	* aliasing warnings.
	*/

	/**
	* ll_entry_start() - Point to first entry of linker-generated array
	* @_type: Data type of the entry
	* @_list: Name of the list in which this entry is placed
	*
	* This function returns (_type *) pointer to the very first entry of a
	* linker-generated array placed into subsection of .u_boot_list section
	* specified by _list argument.
	*
	* Since this macro defines an array start symbol, its leftmost index
	* must be 2 and its rightmost index must be 1.
	*
	* Example:
	* struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
	*/
	#define ll_entry_start(_type, _list) \
	({ \
	static char start[0] __aligned(4) __attribute__((unused, \
	section(".u_boot_list_2_"#_list"_1"))); \
	(_type *)&start; \
	})

	/**
	* ll_entry_end() - Point after last entry of linker-generated array
	* @_type: Data type of the entry
	* @_list: Name of the list in which this entry is placed
	* (with underscores instead of dots)
	*
	* This function returns (_type *) pointer after the very last entry of
	* a linker-generated array placed into subsection of .u_boot_list
	* section specified by _list argument.
	*
	* Since this macro defines an array end symbol, its leftmost index
	* must be 2 and its rightmost index must be 3.
	*
	* Example:
	* struct my_sub_cmd *msc = ll_entry_end(struct my_sub_cmd, cmd_sub);
	*/
	#define ll_entry_end(_type, _list) \
	({ \
	static char end[0] __aligned(4) __attribute__((unused, \
	section(".u_boot_list_2_"#_list"_3"))); \
	(_type *)&end; \
	})
	/**
	* ll_entry_count() - Return the number of elements in linker-generated array
	* @_type: Data type of the entry
	* @_list: Name of the list of which the number of elements is computed
	*
	* This function returns the number of elements of a linker-generated array
	* placed into subsection of .u_boot_list section specified by _list
	* argument. The result is of an unsigned int type.
	*
	* Example:
	* int i;
	* const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub);
	* struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
	* for (i = 0; i < count; i++, msc++)
	* printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y);
	*/
	#define ll_entry_count(_type, _list) \
	({ \
	_type *start = ll_entry_start(_type, _list); \
	_type *end = ll_entry_end(_type, _list); \
	unsigned int _ll_result = end - start; \
	_ll_result; \
	})

	/**
	* ll_entry_get() - Retrieve entry from linker-generated array by name
	* @_type: Data type of the entry
	* @_name: Name of the entry
	* @_list: Name of the list in which this entry is placed
	*
	* This function returns a pointer to a particular entry in linker-generated
	* array identified by the subsection of u_boot_list where the entry resides
	* and it's name.
	*
	* Example:
	* ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
	* .x = 3,
	* .y = 4,
	* };
	* ...
	* struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub);
	*/
	#define ll_entry_get(_type, _name, _list) \
	({ \
	extern _type _u_boot_list_2_##_list##_2_##_name; \
	_type *_ll_result = \
	&_u_boot_list_2_##_list##_2_##_name; \
	_ll_result; \
	})

	/**
	* ll_start() - Point to first entry of first linker-generated array
	* @_type: Data type of the entry
	*
	* This function returns (_type *) pointer to the very first entry of
	* the very first linker-generated array.
	*
	* Since this macro defines the start of the linker-generated arrays,
	* its leftmost index must be 1.
	*
	* Example:
	* struct my_sub_cmd *msc = ll_start(struct my_sub_cmd);
	*/
	#define ll_start(_type) \
	({ \
	static char start[0] __aligned(4) __attribute__((unused, \
	section(".u_boot_list_1"))); \
	(_type *)&start; \
	})

	/**
	* ll_end() - Point after last entry of last linker-generated array
	* @_type: Data type of the entry
	*
	* This function returns (_type *) pointer after the very last entry of
	* the very last linker-generated array.
	*
	* Since this macro defines the end of the linker-generated arrays,
	* its leftmost index must be 3.
	*
	* Example:
	* struct my_sub_cmd *msc = ll_end(struct my_sub_cmd);
	*/
	#define ll_end(_type) \
	({ \
	static char end[0] __aligned(4) __attribute__((unused, \
	section(".u_boot_list_3"))); \
	(_type *)&end; \
	})

	#endif /* __ASSEMBLY__ */

	#endif /* __LINKER_LISTS_H__ */