diff options
Diffstat (limited to 'include/linker_lists.h')
| -rw-r--r-- | include/linker_lists.h | 252 |
1 files changed, 199 insertions, 53 deletions
diff --git a/include/linker_lists.h b/include/linker_lists.h index 0b405d78ea..6c28bf961b 100644 --- a/include/linker_lists.h +++ b/include/linker_lists.h @@ -13,6 +13,96 @@ * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. */ + +/* + * 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 containning 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 + * setion 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 + */ + #ifndef __LINKER_LISTS_H__ #define __LINKER_LISTS_H__ @@ -20,43 +110,28 @@ * ll_entry_declare() - Declare linker-generated array entry * @_type: Data type of the entry * @_name: Name of the entry - * @_section_u: Subsection of u_boot_list in which this entry is placed - * (with underscores instead of dots, for name concatenation) - * @_section_d: Subsection of u_boot_list in which this entry is placed - * (with dots, for section concatenation) + * @_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 - * and is as such placed into subsection of special section, .u_boot_list. - * The subsection is specified by the _section_[u,d] parameter, see below. - * The base name of the variable is _name, yet the actual variable is - * declared as concatenation of - * - * %_u_boot_list_ + @_section_u + _ + @_name - * - * which ensures name uniqueness. This variable shall never be refered - * directly though. + * 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 not generated. * - * 2) The @_section_u and @_section_d variables must match, the only difference - * is that in @_section_u is every dot "." character present in @_section_d - * replaced by a single underscore "_" character in @_section_u. The actual - * purpose of these parameters is to select proper subsection in the global - * .u_boot_list section. + * 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. * - * 3) 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. + * 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 am inner subsection of this section is declared and contains some + * 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. * @@ -66,39 +141,71 @@ * .y = 4, * }; */ -#define ll_entry_declare(_type, _name, _section_u, _section_d) \ - _type _u_boot_list_##_section_u##_##_name __attribute__(( \ - unused, aligned(4), \ - section(".u_boot_list."#_section_d"."#_name))) +#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))) + +/** + * 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 - * @_section_u: Subsection of u_boot_list in which this entry is placed - * (with underscores instead of dots) + * @_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 _section_u argument. + * 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, _section_u) \ - ({ \ - extern _type _u_boot_list_##_section_u##__start; \ - _type *_ll_result = &_u_boot_list_##_section_u##__start;\ - _ll_result; \ - }) +#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_count() - Return the number of elements in linker-generated array + * ll_entry_end() - Point after last entry of linker-generated array * @_type: Data type of the entry - * @_section_u: Subsection of u_boot_list in which this entry is placed + * @_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 _section_u + * placed into subsection of .u_boot_list section specified by _list * argument. The result is of an unsigned int type. * * Example: @@ -108,23 +215,19 @@ * 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, _section_u) \ +#define ll_entry_count(_type, _list) \ ({ \ - extern _type _u_boot_list_##_section_u##__start; \ - extern _type _u_boot_list_##_section_u##__end; \ - unsigned int _ll_result = \ - &_u_boot_list_##_section_u##__end - \ - &_u_boot_list_##_section_u##__start; \ + _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 - * @_section_u: Subsection of u_boot_list in which this entry is placed - * (with underscores instead of dots) + * @_list: Name of the list in which this entry is placed * * This function returns a pointer to a particular entry in LG-array * identified by the subsection of u_boot_list where the entry resides @@ -138,11 +241,54 @@ * ... * struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub); */ -#define ll_entry_get(_type, _name, _section_u) \ +#define ll_entry_get(_type, _name, _list) \ ({ \ - extern _type _u_boot_list_##_section_u##_##_name; \ - _type *_ll_result = &_u_boot_list_##_section_u##_##_name;\ + 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_entry_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__ */ |
