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Diffstat (limited to 'arch/x86/cpu/start.S')
| -rw-r--r-- | arch/x86/cpu/start.S | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S new file mode 100644 index 00000000000..0ef27cc5a00 --- /dev/null +++ b/arch/x86/cpu/start.S @@ -0,0 +1,316 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * U-Boot - x86 Startup Code + * + * This is always the first code to run from the U-Boot source. To spell it out: + * + * 1. When TPL (Tertiary Program Loader) is enabled, the boot flow is + * TPL->SPL->U-Boot and this file is used for TPL. Then start_from_tpl.S is used + * for SPL and start_from_spl.S is used for U-Boot proper. + * + * 2. When SPL (Secondary Program Loader) is enabled, but not TPL, the boot + * flow is SPL->U-Boot and this file is used for SPL. Then start_from_spl.S is + * used for U-Boot proper. + * + * 3. When neither TPL nor SPL is used, this file is used for U-Boot proper. + * + * (C) Copyright 2008-2011 + * Graeme Russ, <graeme.russ@gmail.com> + * + * (C) Copyright 2002 + * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> + */ + +#include <config.h> +#include <asm/post.h> +#include <asm/processor.h> +#include <asm/processor-flags.h> +#include <generated/generic-asm-offsets.h> +#include <generated/asm-offsets.h> +#include <linux/linkage.h> + +.section .text.start +.code32 +.globl _start +.type _start, @function +.globl _x86boot_start +_x86boot_start: + /* + * This is the fail-safe 32-bit bootstrap entry point. + * + * This code is used when booting from another boot loader like + * coreboot or EFI. So we repeat some of the same init found in + * start16. + */ + cli + cld + + /* Turn off cache (this might require a 486-class CPU) */ + movl %cr0, %eax + orl $(X86_CR0_NW | X86_CR0_CD), %eax + movl %eax, %cr0 + wbinvd + + /* + * Zero the BIST (Built-In Self Test) value since we don't have it. + * It must be 0 or the previous loader would have reported an error. + */ + movl $0, %ebp + + jmp 1f + + /* Add a way for tools to discover the _start entry point */ + .align 4 + .long 0x12345678 +_start: + /* This is the 32-bit cold-reset entry point, coming from start16 */ + + /* Save BIST */ + movl %eax, %ebp +1: + + /* Save table pointer */ + movl %ecx, %esi + +#ifdef CONFIG_X86_LOAD_FROM_32_BIT + lgdt gdt_ptr2 +#endif + + /* Load the segment registers to match the GDT loaded in start16.S */ + movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax + movw %ax, %fs + movw %ax, %ds + movw %ax, %gs + movw %ax, %es + movw %ax, %ss + + /* Clear the interrupt vectors */ + lidt blank_idt_ptr + +#ifdef CONFIG_USE_EARLY_BOARD_INIT + /* + * Critical early platform init - generally not used, we prefer init + * to happen later when we have a console, in case something goes + * wrong. + */ + jmp early_board_init +.globl early_board_init_ret +early_board_init_ret: +#endif + + post_code(POST_START) + + /* Initialise Cache-As-RAM */ + jmp car_init +.globl car_init_ret +car_init_ret: +#ifdef CONFIG_USE_CAR + /* + * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, + * or fully initialised SDRAM - we really don't care which) + * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack + * and early malloc() area. The MRC requires some space at the top. + * + * Stack grows down from top of CAR. We have: + * + * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE + * MRC area + * global_data with x86 global descriptor table + * early malloc area + * stack + * bottom-> CONFIG_SYS_CAR_ADDR + */ + movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp +#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE + subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp +#endif +#else + /* + * Instructions for FSP1, but not FSP2: + * U-Boot enters here twice. For the first time it comes from + * car_init_done() with esp points to a temporary stack and esi + * set to zero. For the second time it comes from fsp_init_done() + * with esi holding the HOB list address returned by the FSP. + */ +#endif + /* Set up global data */ + mov %esp, %eax + call board_init_f_alloc_reserve + mov %eax, %esp + call board_init_f_init_reserve + +#ifdef CONFIG_DEBUG_UART + call debug_uart_init +#endif + + /* Get address of global_data */ + mov %fs:0, %edx +#if defined(CONFIG_USE_HOB) && !defined(CONFIG_USE_CAR) + /* Store the HOB list if we have one */ + test %esi, %esi + jz skip_hob + movl %esi, GD_HOB_LIST(%edx) + +#ifdef CONFIG_HAVE_FSP + /* + * After fsp_init() returns, the stack has already been switched to a + * place within system memory as defined by CONFIG_FSP_TEMP_RAM_ADDR. + * Enlarge the size of malloc() pool before relocation since we have + * plenty of memory now. + */ + subl $CONFIG_FSP_SYS_MALLOC_F_LEN, %esp + movl %esp, GD_MALLOC_BASE(%edx) +#endif +skip_hob: +#else + /* Store table pointer */ + movl %esi, GD_TABLE(%edx) +#endif + /* Store BIST */ + movl %ebp, GD_BIST(%edx) + + /* Set parameter to board_init_f() to boot flags */ + post_code(POST_START_DONE) + xorl %eax, %eax + + /* Enter, U-Boot! */ + call board_init_f + + /* indicate (lack of) progress */ + movw $0x85, %ax + jmp die + +.globl board_init_f_r_trampoline +.type board_init_f_r_trampoline, @function +board_init_f_r_trampoline: + /* + * SDRAM has been initialised, U-Boot code has been copied into + * RAM, BSS has been cleared and relocation adjustments have been + * made. It is now time to jump into the in-RAM copy of U-Boot + * + * %eax = Address of top of new stack + */ + + /* Stack grows down from top of SDRAM */ + movl %eax, %esp + + /* See if we need to disable CAR */ + call car_uninit + + /* Re-enter U-Boot by calling board_init_f_r() */ + call board_init_f_r + +#ifdef CONFIG_TPL +.globl jump_to_spl +.type jump_to_spl, @function +jump_to_spl: + /* Reset stack to the top of CAR space */ + movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp +#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE + subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp +#endif + + jmp *%eax +#endif + +die: + hlt + jmp die + hlt + +WEAK(car_uninit) + ret +ENDPROC(car_uninit) + +blank_idt_ptr: + .word 0 /* limit */ + .long 0 /* base */ + + .p2align 2 /* force 4-byte alignment */ + + /* Add a multiboot header so U-Boot can be loaded by GRUB2 */ +multiboot_header: + /* magic */ + .long 0x1badb002 + /* flags */ + .long (1 << 16) + /* checksum */ + .long -0x1BADB002 - (1 << 16) + /* header addr */ + .long multiboot_header - _x86boot_start + CONFIG_TEXT_BASE + /* load addr */ + .long CONFIG_TEXT_BASE + /* load end addr */ + .long 0 + /* bss end addr */ + .long 0 + /* entry addr */ + .long CONFIG_TEXT_BASE + +#ifdef CONFIG_X86_LOAD_FROM_32_BIT + /* + * The following Global Descriptor Table is just enough to get us into + * 'Flat Protected Mode' - It will be discarded as soon as the final + * GDT is setup in a safe location in RAM + */ +gdt_ptr2: + .word 0x1f /* limit (31 bytes = 4 GDT entries - 1) */ + .long gdt_rom2 /* base */ + + /* Some CPUs are picky about GDT alignment... */ + .align 16 +.globl gdt_rom2 +gdt_rom2: + /* + * The GDT table ... + * + * Selector Type + * 0x00 NULL + * 0x08 Unused + * 0x10 32bit code + * 0x18 32bit data/stack + */ + /* The NULL Desciptor - Mandatory */ + .word 0x0000 /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x00 /* access */ + .byte 0x00 /* flags + limit_high */ + .byte 0x00 /* base_high */ + + /* Unused Desciptor - (matches Linux) */ + .word 0x0000 /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x00 /* access */ + .byte 0x00 /* flags + limit_high */ + .byte 0x00 /* base_high */ + + /* + * The Code Segment Descriptor: + * - Base = 0x00000000 + * - Size = 4GB + * - Access = Present, Ring 0, Exec (Code), Readable + * - Flags = 4kB Granularity, 32-bit + */ + .word 0xffff /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x9b /* access */ + .byte 0xcf /* flags + limit_high */ + .byte 0x00 /* base_high */ + + /* + * The Data Segment Descriptor: + * - Base = 0x00000000 + * - Size = 4GB + * - Access = Present, Ring 0, Non-Exec (Data), Writable + * - Flags = 4kB Granularity, 32-bit + */ + .word 0xffff /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x93 /* access */ + .byte 0xcf /* flags + limit_high */ + .byte 0x00 /* base_high */ +#endif |