1/* 2 * U-Boot - x86 Startup Code 3 * 4 * (C) Copyright 2008-2011 5 * Graeme Russ, <graeme.russ@gmail.com> 6 * 7 * (C) Copyright 2002 8 * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> 9 * 10 * SPDX-License-Identifier: GPL-2.0+ 11 */ 12 13#include <config.h> 14#include <asm/global_data.h> 15#include <asm/post.h> 16#include <asm/processor.h> 17#include <asm/processor-flags.h> 18#include <generated/generic-asm-offsets.h> 19#include <generated/asm-offsets.h> 20 21.section .text 22.code32 23.globl _start 24.type _start, @function 25.globl _x86boot_start 26_x86boot_start: 27 /* 28 * This is the fail-safe 32-bit bootstrap entry point. 29 * 30 * This code is used when booting from another boot loader like 31 * coreboot or EFI. So we repeat some of the same init found in 32 * start16. 33 */ 34 cli 35 cld 36 37 /* Turn off cache (this might require a 486-class CPU) */ 38 movl %cr0, %eax 39 orl $(X86_CR0_NW | X86_CR0_CD), %eax 40 movl %eax, %cr0 41 wbinvd 42 43 /* Tell 32-bit code it is being entered from an in-RAM copy */ 44 movl $GD_FLG_WARM_BOOT, %ebx 45 46 /* 47 * Zero the BIST (Built-In Self Test) value since we don't have it. 48 * It must be 0 or the previous loader would have reported an error. 49 */ 50 movl $0, %ebp 51 52 jmp 1f 53 54 /* Add a way for tools to discover the _start entry point */ 55 .align 4 56 .long 0x12345678 57_start: 58 /* 59 * This is the 32-bit cold-reset entry point, coming from start16. 60 * Set %ebx to GD_FLG_COLD_BOOT to indicate this. 61 */ 62 movl $GD_FLG_COLD_BOOT, %ebx 63 64 /* Save BIST */ 65 movl %eax, %ebp 661: 67 68 /* Save table pointer */ 69 movl %ecx, %esi 70 71 /* Load the segement registers to match the GDT loaded in start16.S */ 72 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 73 movw %ax, %fs 74 movw %ax, %ds 75 movw %ax, %gs 76 movw %ax, %es 77 movw %ax, %ss 78 79 /* Clear the interrupt vectors */ 80 lidt blank_idt_ptr 81 82 /* 83 * Critical early platform init - generally not used, we prefer init 84 * to happen later when we have a console, in case something goes 85 * wrong. 86 */ 87 jmp early_board_init 88.globl early_board_init_ret 89early_board_init_ret: 90 post_code(POST_START) 91 92 /* Initialise Cache-As-RAM */ 93 jmp car_init 94.globl car_init_ret 95car_init_ret: 96#ifndef CONFIG_HAVE_FSP 97 /* 98 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 99 * or fully initialised SDRAM - we really don't care which) 100 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 101 * and early malloc() area. The MRC requires some space at the top. 102 * 103 * Stack grows down from top of CAR. We have: 104 * 105 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 106 * MRC area 107 * global_data 108 * x86 global descriptor table 109 * early malloc area 110 * stack 111 * bottom-> CONFIG_SYS_CAR_ADDR 112 */ 113 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 114#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 115 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 116#endif 117#else 118 /* 119 * When we get here after car_init(), esp points to a temporary stack 120 * and esi holds the HOB list address returned by the FSP. 121 */ 122#endif 123 124 /* Reserve space on stack for global data */ 125 subl $GENERATED_GBL_DATA_SIZE, %esp 126 127 /* Align global data to 16-byte boundary */ 128 andl $0xfffffff0, %esp 129 post_code(POST_START_STACK) 130 131 /* Zero the global data since it won't happen later */ 132 xorl %eax, %eax 133 movl $GENERATED_GBL_DATA_SIZE, %ecx 134 movl %esp, %edi 135 rep stosb 136 137#ifdef CONFIG_HAVE_FSP 138 test %esi, %esi 139 jz skip_hob 140 141 /* Store HOB list */ 142 movl %esp, %edx 143 addl $GD_HOB_LIST, %edx 144 movl %esi, (%edx) 145 146skip_hob: 147#else 148 /* Store table pointer */ 149 movl %esp, %edx 150 addl $GD_TABLE, %edx 151 movl %esi, (%edx) 152#endif 153 154 /* Setup first parameter to setup_gdt, pointer to global_data */ 155 movl %esp, %eax 156 157 /* Reserve space for global descriptor table */ 158 subl $X86_GDT_SIZE, %esp 159 160 /* Align temporary global descriptor table to 16-byte boundary */ 161 andl $0xfffffff0, %esp 162 movl %esp, %ecx 163 164#if defined(CONFIG_SYS_MALLOC_F_LEN) 165 /* Set up the pre-relocation malloc pool */ 166 subl $CONFIG_SYS_MALLOC_F_LEN, %esp 167 movl %eax, %edx 168 addl $GD_MALLOC_BASE, %edx 169 movl %esp, (%edx) 170#endif 171 /* Store BIST into global_data */ 172 movl %eax, %edx 173 addl $GD_BIST, %edx 174 movl %ebp, (%edx) 175 176 /* Set second parameter to setup_gdt() */ 177 movl %ecx, %edx 178 179 /* Setup global descriptor table so gd->xyz works */ 180 call setup_gdt 181 182 /* Set parameter to board_init_f() to boot flags */ 183 post_code(POST_START_DONE) 184 xorl %eax, %eax 185 186 /* Enter, U-Boot! */ 187 call board_init_f 188 189 /* indicate (lack of) progress */ 190 movw $0x85, %ax 191 jmp die 192 193.globl board_init_f_r_trampoline 194.type board_init_f_r_trampoline, @function 195board_init_f_r_trampoline: 196 /* 197 * SDRAM has been initialised, U-Boot code has been copied into 198 * RAM, BSS has been cleared and relocation adjustments have been 199 * made. It is now time to jump into the in-RAM copy of U-Boot 200 * 201 * %eax = Address of top of new stack 202 */ 203 204 /* Stack grows down from top of SDRAM */ 205 movl %eax, %esp 206 207 /* Reserve space on stack for global data */ 208 subl $GENERATED_GBL_DATA_SIZE, %esp 209 210 /* Align global data to 16-byte boundary */ 211 andl $0xfffffff0, %esp 212 213 /* Setup first parameter to memcpy() and setup_gdt() */ 214 movl %esp, %eax 215 216 /* Setup second parameter to memcpy() */ 217 fs movl 0, %edx 218 219 /* Set third parameter to memcpy() */ 220 movl $GENERATED_GBL_DATA_SIZE, %ecx 221 222 /* Copy global data from CAR to SDRAM stack */ 223 call memcpy 224 225 /* Reserve space for global descriptor table */ 226 subl $X86_GDT_SIZE, %esp 227 228 /* Align global descriptor table to 16-byte boundary */ 229 andl $0xfffffff0, %esp 230 231 /* Set second parameter to setup_gdt() */ 232 movl %esp, %edx 233 234 /* Setup global descriptor table so gd->xyz works */ 235 call setup_gdt 236 237 /* Set if we need to disable CAR */ 238.weak car_uninit 239 movl $car_uninit, %eax 240 cmpl $0, %eax 241 jz 1f 242 243 call car_uninit 2441: 245 /* Re-enter U-Boot by calling board_init_f_r() */ 246 call board_init_f_r 247 248die: 249 hlt 250 jmp die 251 hlt 252 253blank_idt_ptr: 254 .word 0 /* limit */ 255 .long 0 /* base */ 256 257 .p2align 2 /* force 4-byte alignment */ 258 259 /* Add a multiboot header so U-Boot can be loaded by GRUB2 */ 260multiboot_header: 261 /* magic */ 262 .long 0x1badb002 263 /* flags */ 264 .long (1 << 16) 265 /* checksum */ 266 .long -0x1BADB002 - (1 << 16) 267 /* header addr */ 268 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 269 /* load addr */ 270 .long CONFIG_SYS_TEXT_BASE 271 /* load end addr */ 272 .long 0 273 /* bss end addr */ 274 .long 0 275 /* entry addr */ 276 .long CONFIG_SYS_TEXT_BASE 277