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Clean up the bootloader code.

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This commit is contained in:
Enrico Fraccaroli
2021-11-09 16:30:35 +01:00
parent 04bf7b9e3b
commit f7297e3ded
2 changed files with 54 additions and 57 deletions
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mentos/inc/boot.h
+18 -21
View File
@@ -4,15 +4,14 @@
/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
/// See LICENSE.md for details.
#ifndef MENTOS_BOOT_H
#define MENTOS_BOOT_H
#pragma once
#include "multiboot.h"
/// @brief Mentos structure to communicate bootloader info to the kernel
typedef struct boot_info_t {
/// Boot magic number.
uint32_t magic;
unsigned int magic;
/*
* Bootloader physical range
@@ -20,9 +19,9 @@ typedef struct boot_info_t {
* */
/// bootloader code start
uint32_t bootloader_phy_start;
unsigned int bootloader_phy_start;
/// bootloader code end
uint32_t bootloader_phy_end;
unsigned int bootloader_phy_end;
/*
* Kernel virtual and physical range
@@ -31,20 +30,20 @@ typedef struct boot_info_t {
* */
/// kernel physical code start
uint32_t kernel_phy_start;
unsigned int kernel_phy_start;
/// kernel physical code end
uint32_t kernel_phy_end;
unsigned int kernel_phy_end;
/// kernel code start
uint32_t kernel_start;
unsigned int kernel_start;
/// kernel code end
uint32_t kernel_end;
unsigned int kernel_end;
/// kernel size.
uint32_t kernel_size;
unsigned int kernel_size;
/// Address after the modules.
uint32_t module_end;
unsigned int module_end;
/*
* Range of addressable lowmemory, is memory that is available
@@ -53,17 +52,17 @@ typedef struct boot_info_t {
* */
/// lowmem physical addressable start
uint32_t lowmem_phy_start;
unsigned int lowmem_phy_start;
/// lowmem physical addressable end
uint32_t lowmem_phy_end;
unsigned int lowmem_phy_end;
/// lowmem addressable start
uint32_t lowmem_start;
unsigned int lowmem_start;
/// lowmem addressable end
uint32_t lowmem_end;
unsigned int lowmem_end;
/// stack end (comes after lowmem_end, and is the end of the low mapped memory)
uint32_t stack_end;
unsigned int stack_end;
/*
* Range of non-addressable highmemory, is memory that can be
@@ -71,15 +70,13 @@ typedef struct boot_info_t {
* */
/// highmem addressable start
uint32_t highmem_phy_start;
unsigned int highmem_phy_start;
/// highmem addressable end
uint32_t highmem_phy_end;
unsigned int highmem_phy_end;
/// multiboot info
multiboot_info_t *multiboot_header;
/// stack suggested start address (also set by the bootloader)
uint32_t stack_base;
unsigned int stack_base;
} boot_info_t;
#endif //MENTOS_BOOT_H
mentos/src/boot.c
+36 -36
View File
@@ -4,11 +4,11 @@
/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
/// See LICENSE.md for details.
#include "boot.h"
#include "link_access.h"
#include "multiboot.h"
#include "mem/paging.h"
#include "sys/module.h"
#include "stdint.h"
#include "mem/paging.h"
#include "elf/elf.h"
/// @defgroup bootloader Bootloader
@@ -42,18 +42,25 @@ static page_directory_t boot_pgdir;
/// @brief Boot page tables.
static page_table_t boot_pgtables[1024];
/// @brief Use this to write to I/O ports to send bytes to devices.
/// @param port The output port.
/// @param data The data to write.
static inline void __outportb(uint16_t port, uint8_t data)
{
__asm__ __volatile__("outb %%al, %%dx" ::"a"(data), "d"(port));
}
/// @brief Writes the given character on the debug port.
/// @param c the character to send to the debug port.
static inline void __debug_putchar(char c)
{
#if (defined(DEBUG_STDIO) || defined(DEBUG_LOG))
__outportb(SERIAL_COM1, c);
outportb(SERIAL_COM1, c);
#endif
}
/// @brief Writes the given string on the debug port.
/// @param s the string to send to the debug port.
static inline void __debug_puts(char *s)
{
#if (defined(DEBUG_STDIO) || defined(DEBUG_LOG))
@@ -62,19 +69,29 @@ static inline void __debug_puts(char *s)
#endif
}
/// @brief Align memory to the specified value (round up).
/// @brief Align memory address to the specified value (round up).
/// @param addr the address to align
/// @param value the value used to align.
/// @return the aligned address.
static inline uint32_t __align_rup(uint32_t addr, uint32_t value)
{
uint32_t reminder = (addr % value);
return addr + (reminder ? (value - reminder) : 0);
}
/// @brief Align memory to the specified value (round down).
/// @brief Align memory address to the specified value (round down).
/// @param addr the address to align
/// @param value the value used to align.
/// @return the aligned address.
static inline uint32_t __align_rdown(uint32_t addr, uint32_t value)
{
return addr - (addr % value);
}
/// @brief Prepares the page frames.
/// @param pfn_virt_start The first virtual page frame.
/// @param pfn_phys_start The first physical page frame.
/// @param pfn_count The number of page frames.
static void __setup_pages(uint32_t pfn_virt_start, uint32_t pfn_phys_start, uint32_t pfn_count)
{
uint32_t base_pgtable = pfn_virt_start / 1024;
@@ -93,7 +110,6 @@ static void __setup_pages(uint32_t pfn_virt_start, uint32_t pfn_phys_start, uint
table->pages[j].global = 0;
table->pages[j].user = 0;
}
boot_pgdir.entries[i].rw = 1;
boot_pgdir.entries[i].present = 1;
boot_pgdir.entries[i].available = 1;
@@ -101,23 +117,19 @@ static void __setup_pages(uint32_t pfn_virt_start, uint32_t pfn_phys_start, uint
}
}
/*
* Setup paging mapping all the low memory to two places:
* one is the physical address of the memory itself
* the other is in the virtual kernel address space
* */
/// @brief Setup paging mapping all the low memory to two places: one is the
/// physical address of the memory itself the other is in the virtual kernel
/// address space.
static inline void __setup_boot_paging()
{
uint32_t kernel_base_phy_page = boot_info.kernel_phy_start >> 12U;
uint32_t kernel_base_virt_page = boot_info.kernel_start >> 12U;
// Compute the last physical page.
uint32_t lowmem_last_phy_page = ((uint32_t)(boot_info.lowmem_phy_end - 1)) >> 12U;
// Compute the number of pages.
uint32_t num_pages = lowmem_last_phy_page - kernel_base_phy_page + 1;
// Map lowmem physical pages also to their physical address (to keep bootloader working)
__setup_pages(0, 0, lowmem_last_phy_page);
// Setup kernel virtual address space + lowmem
__setup_pages(kernel_base_virt_page, kernel_base_phy_page, num_pages);
}
@@ -126,9 +138,7 @@ static inline void __setup_boot_paging()
/// @param elf_hdr The elf header of the kernel.
/// @param virt_low Output variable where we store the lowest address of the kernel.
/// @param virt_high Output variable where we store the highest address of the kernel.
static void __get_kernel_low_high(elf_header_t *elf_hdr,
uint32_t *virt_low,
uint32_t *virt_high)
static void __get_kernel_low_high(elf_header_t *elf_hdr, uint32_t *virt_low, uint32_t *virt_high)
{
// Prepare a pointer to a program header.
elf_program_header_t *program_header;
@@ -208,7 +218,7 @@ static inline void __relocate_kernel_image(elf_header_t *elf_hdr)
/// @param esp The initial stack pointer.
void boot_main(uint32_t magic, multiboot_info_t *header, uint32_t esp)
{
__debug_puts("\nbootloader: Start...\n");
__debug_puts("\n[bootloader] Start...\n");
elf_header_t *elf_hdr = (elf_header_t *)LDVAR(kernel_bin);
// Get the physical addresses of where the kernel starts and ends.
@@ -221,7 +231,7 @@ void boot_main(uint32_t magic, multiboot_info_t *header, uint32_t esp)
__get_kernel_low_high(elf_hdr, &kernel_virt_low, &kernel_virt_high);
// Initialize the boot_info_t structure.
__debug_puts("bootloader: Initializing the boot_info structure...\n");
__debug_puts("[bootloader] Initializing the boot_info structure...\n");
boot_info.magic = magic;
boot_info.bootloader_phy_start = boot_start;
boot_info.bootloader_phy_end = boot_end;
@@ -263,15 +273,15 @@ void boot_main(uint32_t magic, multiboot_info_t *header, uint32_t esp)
boot_info.stack_end = boot_info.lowmem_end;
// Setup the page directory and page tables for the boot.
__debug_puts("bootloader: Setting up paging...\n");
__debug_puts("[bootloader] Setting up paging...\n");
__setup_boot_paging();
// Switch to the newly created page directory.
__debug_puts("bootloader: Switching page directory...\n");
__debug_puts("[bootloader] Switching page directory...\n");
paging_switch_directory(&boot_pgdir);
// Enable paging.
__debug_puts("bootloader: Enabling paging...\n");
__debug_puts("[bootloader] Enabling paging...\n");
paging_enable();
// Reserve space for the kernel stack at the end of lowmem.
@@ -279,20 +289,10 @@ void boot_main(uint32_t magic, multiboot_info_t *header, uint32_t esp)
boot_info.lowmem_phy_end = boot_info.lowmem_phy_end - KERNEL_STACK_SIZE;
boot_info.lowmem_end = boot_info.lowmem_end - KERNEL_STACK_SIZE;
__debug_puts("bootloader: Relocating kernel image...\n");
__debug_puts("[bootloader] Relocating kernel image...\n");
__relocate_kernel_image(elf_hdr);
#if 0
for (int i = 0; i < elf_hdr->shnum; i++) {
struct elf_section_header *section_header =
(elf_section_header_t *)(LDVAR(kernel_bin) + elf_hdr->shoff + elf_hdr->shentsize * i);
for (int j = 0; j < section_header->; j++) {
((char *)section_header->vaddr)[j] = (LDVAR(kernel_bin) + section_header->offset)[j];
}
}
#endif
__debug_puts("bootloader: Calling `boot_kernel`...\n\n");
__debug_puts("[bootloader] Calling `boot_kernel`...\n\n");
boot_kernel(boot_info.stack_base, elf_hdr->entry, &boot_info);
}