Refactor linker-generated arrays

Refactor linker-generated array code so that symbols
which were previously linker-generated are now compiler-
generated. This causes relocation records of type
R_ARM_ABS32 to become R_ARM_RELATIVE, which makes
code which uses LGA able to run before relocation as
well as after.

Note: this affects more than ARM targets, as linker-
lists span possibly all target architectures, notably
PowerPC.

Conflicts:
	arch/arm/cpu/arm926ejs/mxs/u-boot-spl.lds
	arch/arm/cpu/arm926ejs/spear/u-boot-spl.lds
	arch/arm/cpu/armv7/omap-common/u-boot-spl.lds
	board/ait/cam_enc_4xx/u-boot-spl.lds
	board/davinci/da8xxevm/u-boot-spl-da850evm.lds
	board/davinci/da8xxevm/u-boot-spl-hawk.lds
	board/vpac270/u-boot-spl.lds

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>

3 files changed, 201 insertions, 55 deletions

diff --git a/include/command.h b/include/command.h
index 3785eb9..65692fd 100644
--- a/include/command.h
+++ b/include/command.h
@@ -175,7 +175,7 @@ int cmd_process(int flag, int argc, char * const argv[],
 					_usage, _help, NULL)
 
 #define U_BOOT_CMD_COMPLETE(_name, _maxargs, _rep, _cmd, _usage, _help, _comp) \
-	ll_entry_declare(cmd_tbl_t, _name, cmd, cmd) =			\
+	ll_entry_declare(cmd_tbl_t, _name, cmd) =			\
 		U_BOOT_CMD_MKENT_COMPLETE(_name, _maxargs, _rep, _cmd,	\
 						_usage, _help, _comp);
 
diff --git a/include/env_callback.h b/include/env_callback.h
index 62428d1..e89b6da 100644
--- a/include/env_callback.h
+++ b/include/env_callback.h
@@ -83,7 +83,7 @@ void env_callback_init(ENTRY *var_entry);
 	}
 #else
 #define U_BOOT_ENV_CALLBACK(name, callback) \
-	ll_entry_declare(struct env_clbk_tbl, name, env_clbk, env_clbk) = \
+	ll_entry_declare(struct env_clbk_tbl, name, env_clbk) = \
 	{#name, callback}
 #endif
 
diff --git a/include/linker_lists.h b/include/linker_lists.h
index 0b405d7..6c28bf9 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__ */