diff options
Diffstat (limited to 'include/linker_lists.h')
| -rw-r--r-- | include/linker_lists.h | 75 |
1 files changed, 22 insertions, 53 deletions
diff --git a/include/linker_lists.h b/include/linker_lists.h index 0f4a2d686e2..4425fcb6785 100644 --- a/include/linker_lists.h +++ b/include/linker_lists.h @@ -145,6 +145,20 @@ * Since this macro defines an array end symbol, its leftmost index * must be 2 and its rightmost index must be 3. * + * The end symbol uses __aligned(1) to ensure it is placed immediately after + * the last entry without any padding. This is critical for ll_entry_count() + * to work correctly. + * + * If the end marker had a higher alignment (e.g., 4 or 32 bytes), the linker + * might insert padding between the last entry and the end marker to satisfy + * alignment requirements of the following section. This would cause pointer + * subtraction (end - start) to produce incorrect results because the compiler + * optimizes pointer division using magic-number multiplication, which only + * works correctly when the byte span is an exact multiple of the struct size. + * + * With __aligned(1), the end marker is placed at exactly (start + n * sizeof) + * where n is the number of entries, ensuring correct pointer arithmetic. + * * Example: * * :: @@ -153,7 +167,7 @@ */ #define ll_entry_end(_type, _list) \ ({ \ - static char end[0] __aligned(4) __attribute__((unused)) \ + static char end[0] __aligned(1) __attribute__((unused)) \ __section("__u_boot_list_2_"#_list"_3"); \ _type * tmp = (_type *)&end; \ asm("":"+r"(tmp)); \ @@ -239,8 +253,12 @@ static _type _sym[0] __aligned(CONFIG_LINKER_LIST_ALIGN) \ __maybe_unused __section("__u_boot_list_2_" #_list "_1") +/* + * ll_end_decl uses __aligned(1) to avoid padding before the end marker. + * See the comment for ll_entry_end() for a full explanation. + */ #define ll_end_decl(_sym, _type, _list) \ - static _type _sym[0] __aligned(CONFIG_LINKER_LIST_ALIGN) \ + static _type _sym[0] __aligned(1) \ __maybe_unused __section("__u_boot_list_2_" #_list "_3") /** @@ -266,7 +284,8 @@ */ #define ll_entry_get(_type, _name, _list) \ ({ \ - extern _type _u_boot_list_2_##_list##_2_##_name; \ + extern _type _u_boot_list_2_##_list##_2_##_name \ + __aligned(4); \ _type *_ll_result = \ &_u_boot_list_2_##_list##_2_##_name; \ _ll_result; \ @@ -288,56 +307,6 @@ #define ll_entry_ref(_type, _name, _list) \ ((_type *)&_u_boot_list_2_##_list##_2_##_name) -/** - * 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 * tmp = (_type *)&start; \ - asm("":"+r"(tmp)); \ - tmp; \ -}) - -/** - * 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 * tmp = (_type *)&end; \ - asm("":"+r"(tmp)); \ - tmp; \ -}) - #endif /* __ASSEMBLY__ */ #endif /* __LINKER_LISTS_H__ */ |