1/* 2 * Copyright 2022 The Pigweed Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not 5 * use this file except in compliance with the License. You may obtain a copy of 6 * the License at 7 * 8 * https://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 13 * License for the specific language governing permissions and limitations under 14 * the License. 15 */ 16 17/* This relatively simplified linker script will work with many ARMv7-M and 18 * ARMv8-M cores that have on-board memory-mapped RAM and FLASH. For more 19 * complex projects and devices, it's possible this linker script will not be 20 * sufficient as-is. 21 * 22 * This linker script is likely not suitable for a project with a bootloader. 23 */ 24 25/* Provide useful error messages when required configurations are not set. */ 26#ifndef PW_BOOT_VECTOR_TABLE_BEGIN 27#error "PW_BOOT_VECTOR_TABLE_BEGIN is not defined, and is required to use pw_boot_cortex_m" 28#endif // PW_BOOT_VECTOR_TABLE_BEGIN 29 30#ifndef PW_BOOT_VECTOR_TABLE_SIZE 31#error "PW_BOOT_VECTOR_TABLE_SIZE is not defined, and is required to use pw_boot_cortex_m" 32#endif // PW_BOOT_VECTOR_TABLE_SIZE 33 34#ifndef PW_BOOT_CODE_BEGIN 35#error "PW_BOOT_CODE_BEGIN is not defined, and is required to use pw_boot_cortex_m" 36#endif // PW_BOOT_CODE_BEGIN 37 38#ifndef PW_BOOT_CODE_SIZE 39#error "PW_BOOT_CODE_SIZE is not defined, and is required to use pw_boot_cortex_m" 40#endif // PW_BOOT_CODE_SIZE 41 42#ifndef PW_BOOT_RAM_BEGIN 43#error "PW_BOOT_RAM_BEGIN is not defined, and is required to use pw_boot_cortex_m" 44#endif // PW_BOOT_RAM_BEGIN 45 46#ifndef PW_BOOT_RAM_SIZE 47#error "PW_BOOT_RAM_SIZE is not defined, and is required to use pw_boot_cortex_m" 48#endif // PW_BOOT_RAM_SIZE 49 50#ifndef PW_BOOT_HEAP_SIZE 51#error "PW_BOOT_HEAP_SIZE is not defined, and is required to use pw_boot_cortex_m" 52#endif // PW_BOOT_HEAP_SIZE 53 54#ifndef PW_BOOT_MIN_STACK_SIZE 55#error "PW_BOOT_MIN_STACK_SIZE is not defined, and is required to use pw_boot_cortex_m" 56#endif // PW_BOOT_MIN_STACK_SIZE 57 58 59/* Note: This technically doesn't set the firmware's entry point. Setting the 60 * firmware entry point is done by setting vector_table[1] 61 * (Reset_Handler). However, this DOES tell the compiler how to optimize 62 * when --gc-sections is enabled. 63 */ 64ENTRY(pw_boot_Entry) 65 66MEMORY 67{ 68 /* TODO(b/234892223): Make it possible for projects to freely customize 69 * memory regions. 70 */ 71 72 /* Vector Table */ 73 VECTOR_TABLE(rx) : \ 74 ORIGIN = PW_BOOT_VECTOR_TABLE_BEGIN, \ 75 LENGTH = PW_BOOT_VECTOR_TABLE_SIZE 76 /* External RAM being used for code. */ 77 TEXT_EXTERNAL_RAM(rx) : \ 78 ORIGIN = PW_BOOT_CODE_BEGIN, \ 79 LENGTH = PW_BOOT_CODE_SIZE 80 /* External DDR RAM */ 81 EXTERNAL_RAM(rwx) : \ 82 ORIGIN = PW_BOOT_RAM_BEGIN, \ 83 LENGTH = PW_BOOT_RAM_SIZE 84 85 /* Each memory region above has an associated .*.unused_space section that 86 * overlays the unused space at the end of the memory segment. These segments 87 * are used by pw_bloat.bloaty_config to create the utilization data source 88 * for bloaty size reports. 89 * 90 * These sections MUST be located immediately after the last section that is 91 * placed in the respective memory region or lld will issue a warning like: 92 * 93 * warning: ignoring memory region assignment for non-allocatable section 94 * '.VECTOR_TABLE.unused_space' 95 * 96 * If this warning occurs, it's also likely that LLD will have created quite 97 * large padded regions in the ELF file due to bad cursor operations. This 98 * can cause ELF files to balloon from hundreds of kilobytes to hundreds of 99 * megabytes. 100 * 101 * Attempting to add sections to the memory region AFTER the unused_space 102 * section will cause the region to overflow. 103 */ 104} 105 106SECTIONS 107{ 108 /* This is the link-time vector table. If used, the VTOR (Vector Table Offset 109 * Register) MUST point to this memory location in order to be used. This can 110 * be done by ensuring this section exists at the default location of the VTOR 111 * so it's used on reset, or by explicitly setting the VTOR in a bootloader 112 * manually to point to &pw_boot_vector_table_addr before interrupts are 113 * enabled. 114 * 115 * The ARMv7-M architecture requires this is at least aligned to 128 bytes, 116 * and aligned to a power of two that is greater than 4 times the number of 117 * supported exceptions. 512 has been selected as it accommodates this 118 * device's vector table. 119 */ 120 .vector_table : ALIGN(512) 121 { 122 pw_boot_vector_table_addr = .; 123 KEEP(*(.vector_table)) 124 } >VECTOR_TABLE 125 126 /* Represents unused space in the VECTOR_TABLE segment. This MUST be the last 127 * section assigned to the VECTOR_TABLE region. 128 */ 129 .VECTOR_TABLE.unused_space (NOLOAD) : ALIGN(4) 130 { 131 . = ABSOLUTE(ORIGIN(VECTOR_TABLE) + LENGTH(VECTOR_TABLE)); 132 } >VECTOR_TABLE 133 134 /* Main executable code. */ 135 .code : ALIGN(4) 136 { 137 CREATE_OBJECT_SYMBOLS 138 __text_load = LOADADDR(.code); 139 /* Application code. */ 140 *(.text) 141 *(.text*) 142 KEEP(*(.init)) 143 KEEP(*(.fini)) 144 145 . = ALIGN(4); 146 /* Constants.*/ 147 *(.rodata) 148 *(.rodata*) 149 150 /* .preinit_array, .init_array, .fini_array are used by libc. 151 * Each section is a list of function pointers that are called pre-main and 152 * post-exit for object initialization and tear-down. 153 * Since the region isn't explicitly referenced, specify KEEP to prevent 154 * link-time garbage collection. SORT is used for sections that have strict 155 * init/de-init ordering requirements. */ 156 . = ALIGN(4); 157 PROVIDE_HIDDEN(__preinit_array_start = .); 158 KEEP(*(.preinit_array*)) 159 PROVIDE_HIDDEN(__preinit_array_end = .); 160 161 PROVIDE_HIDDEN(__init_array_start = .); 162 KEEP(*(SORT(.init_array.*))) 163 KEEP(*(.init_array*)) 164 PROVIDE_HIDDEN(__init_array_end = .); 165 166 PROVIDE_HIDDEN(__fini_array_start = .); 167 KEEP(*(SORT(.fini_array.*))) 168 KEEP(*(.fini_array*)) 169 PROVIDE_HIDDEN(__fini_array_end = .); 170 } >TEXT_EXTERNAL_RAM 171 172 /* Used by unwind-arm/ */ 173 .ARM : ALIGN(4) { 174 __exidx_start = .; 175 *(.ARM.exidx*) 176 __exidx_end = .; 177 } >TEXT_EXTERNAL_RAM 178 179 /* Explicitly initialized global and static data. (.data)*/ 180 .static_init_ram : ALIGN(4) 181 { 182 *(.data) 183 *(.data*) 184 . = ALIGN(4); 185 } >EXTERNAL_RAM AT> TEXT_EXTERNAL_RAM 186 187 /* Represents unused space in the TEXT_EXTERNAL_RAM segment. This MUST be the 188 * last section assigned to the TEXT_EXTERNAL_RAM region. 189 */ 190 .TEXT_EXTERNAL_RAM.unused_space (NOLOAD) : ALIGN(4) 191 { 192 . = ABSOLUTE(ORIGIN(TEXT_EXTERNAL_RAM) + LENGTH(TEXT_EXTERNAL_RAM)); 193 } >TEXT_EXTERNAL_RAM 194 195 /* The .zero_init_ram, .heap, and .stack sections below require (NOLOAD) 196 * annotations for LLVM lld, but not GNU ld, because LLVM's lld intentionally 197 * interprets the linker file differently from ld: 198 * 199 * https://discourse.llvm.org/t/lld-vs-ld-section-type-progbits-vs-nobits/5999/3 200 * 201 * Zero initialized global/static data (.bss) is initialized in 202 * pw_boot_Entry() via memset(), so the section doesn't need to be loaded from 203 * flash. The .heap and .stack sections don't require any initialization, 204 * as they only represent allocated memory regions, so they also do not need 205 * to be loaded. 206 */ 207 .zero_init_ram (NOLOAD) : ALIGN(4) 208 { 209 *(.bss) 210 *(.bss*) 211 *(COMMON) 212 . = ALIGN(4); 213 } >EXTERNAL_RAM 214 215 .heap (NOLOAD) : ALIGN(4) 216 { 217 pw_boot_heap_low_addr = .; 218 . = . + PW_BOOT_HEAP_SIZE; 219 . = ALIGN(4); 220 pw_boot_heap_high_addr = .; 221 } >EXTERNAL_RAM 222 223 /* Link-time check for stack overlaps. 224 * 225 * The ARMv7-M architecture may require 8-byte alignment of the stack pointer 226 * rather than 4 in some contexts and implementations, so this region is 227 * 8-byte aligned (see ARMv7-M Architecture Reference Manual DDI0403E 228 * section B1.5.7). 229 */ 230 .stack (NOLOAD) : ALIGN(8) 231 { 232 /* Set the address that the main stack pointer should be initialized to. */ 233 pw_boot_stack_low_addr = .; 234 HIDDEN(_stack_size = ORIGIN(EXTERNAL_RAM) + LENGTH(EXTERNAL_RAM) - .); 235 /* Align the stack to a lower address to ensure it isn't out of range. */ 236 HIDDEN(_stack_high = (. + _stack_size) & ~0x7); 237 ASSERT(_stack_high - . >= PW_BOOT_MIN_STACK_SIZE, 238 "Error: Not enough RAM for desired minimum stack size."); 239 . = _stack_high; 240 pw_boot_stack_high_addr = .; 241 } >EXTERNAL_RAM 242 243 /* Represents unused space in the EXTERNAL_RAM segment. This MUST be the last 244 * section assigned to the EXTERNAL_RAM region. 245 */ 246 .EXTERNAL_RAM.unused_space (NOLOAD) : ALIGN(4) 247 { 248 . = ABSOLUTE(ORIGIN(EXTERNAL_RAM) + LENGTH(EXTERNAL_RAM)); 249 } >EXTERNAL_RAM 250 251 /* Discard unwind info. */ 252 .ARM.extab 0x0 (INFO) : 253 { 254 KEEP(*(.ARM.extab*)) 255 } 256} 257 258/* Symbols used by core_init.c: */ 259/* Start of .static_init_ram in TEXT_EXTERNAL_RAM. */ 260_pw_static_init_flash_start = LOADADDR(.static_init_ram); 261 262/* Region of .static_init_ram in RAM. */ 263_pw_static_init_ram_start = ADDR(.static_init_ram); 264_pw_static_init_ram_end = _pw_static_init_ram_start + SIZEOF(.static_init_ram); 265 266/* Region of .zero_init_ram. */ 267_pw_zero_init_ram_start = ADDR(.zero_init_ram); 268_pw_zero_init_ram_end = _pw_zero_init_ram_start + SIZEOF(.zero_init_ram); 269 270/* arm-none-eabi expects `end` symbol to point to start of heap for sbrk. */ 271PROVIDE(end = _pw_zero_init_ram_end); 272 273/* These symbols are used by pw_bloat.bloaty_config to create the memoryregions 274 * data source for bloaty in this format (where the optional _N defaults to 0): 275 * pw_bloat_config_memory_region_NAME_{start,end}{_N,} */ 276pw_bloat_config_memory_region_VECTOR_TABLE_start = ORIGIN(VECTOR_TABLE); 277pw_bloat_config_memory_region_VECTOR_TABLE_end = 278 ORIGIN(VECTOR_TABLE) + LENGTH(VECTOR_TABLE); 279pw_bloat_config_memory_region_FLASH_start = ORIGIN(TEXT_EXTERNAL_RAM); 280pw_bloat_config_memory_region_FLASH_end = ORIGIN(TEXT_EXTERNAL_RAM) + LENGTH(TEXT_EXTERNAL_RAM); 281pw_bloat_config_memory_region_RAM_start = ORIGIN(EXTERNAL_RAM); 282pw_bloat_config_memory_region_RAM_end = ORIGIN(EXTERNAL_RAM) + LENGTH(EXTERNAL_RAM); 283 284/* Symbol mapping used by MSS Startup and Debugger. */ 285PROVIDE (__smartfusion2_memory_remap = 2); /* Remap according to LMA (this script) */ 286PROVIDE (__mirrored_nvm = 1); /* GDB will load to LMA directly no need to load again. */ 287PROVIDE (_estack = pw_boot_stack_high_addr); 288PROVIDE (__stack_start__ = pw_boot_stack_low_addr); 289PROVIDE (__vector_table_load = LOADADDR(.vector_table)); 290PROVIDE (__vector_table_start = pw_boot_vector_table_addr); 291PROVIDE (__vector_table_vma_base_address = __vector_table_start); /* required by debugger for start address */ 292PROVIDE (__text_end = __exidx_end); 293PROVIDE (__heap_start__ = pw_boot_heap_low_addr); 294PROVIDE (_eheap = pw_boot_heap_high_addr); 295PROVIDE (_etext = __exidx_end); 296PROVIDE (_evector_table = pw_boot_vector_table_addr); 297PROVIDE (__data_start = _pw_static_init_ram_start); 298PROVIDE (_edata = _pw_static_init_ram_end); 299PROVIDE (__text_start = __text_load); 300PROVIDE (__bss_start__ = _pw_zero_init_ram_start); 301PROVIDE (__bss_end__ = _pw_static_init_ram_end); 302PROVIDE (__data_load = _pw_static_init_flash_start); 303