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arch/i386: Add multiboot support

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This commit is contained in:
Aaron Lindsay
2012-12-24 12:44:48 -05:00
parent 62755b8f38
commit b98aa76334
6 changed files with 287 additions and 9 deletions
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3
arch/i386/kernel/kernel.mk
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@ -3,7 +3,8 @@ SUBDIRS :=
include $(BASEDIR)/header.mk
OBJS_$(d) := $(d)/mmu.o
OBJS_$(d) := $(d)/mmu.o \
$(d)/multiboot.o
KOBJS += $(OBJS_$(d))

96
arch/i386/kernel/mmu.c
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@ -22,9 +22,101 @@
#include <types.h>
#include <mm.h>
extern uint32 kernel_start_phys, kernel_end_phys;
extern uint32 kernel_start, kernel_end;
#define PAGE_SIZE 0x00400000
#define ROUND_DOWN_PAGE_SIZE(addr) ((typeof(addr))((uint32)(addr) & 0xff800000))
static inline int page_intersects(uint32 *page_start, uint32 *lower, uint32 *upper) {
return (lower >= page_start && lower < (page_start + PAGE_SIZE)) ||
(upper >= page_start && upper < (page_start + PAGE_SIZE)) ||
(lower < page_start && upper >= (page_start + PAGE_SIZE));
}
void mmu_reinit() {
int virt_phys_offset; /* CAUTION: 1 = 4 bytes */
uint32 *curr_tbl_entry;
uint32 *curr_addr;
uint32 *page_dir;
asm("movl %%cr3, %0" : "=r"(page_dir) : : );
virt_phys_offset = &kernel_start - &kernel_start_phys;
curr_tbl_entry = page_dir + virt_phys_offset;
//do first loop iteration outside th eloop, because we have to check against wrapping back around to know we're done
*curr_tbl_entry = 0x83;
curr_tbl_entry++;
//create identity mapping for entire address space using sections.
//BUT, if we've relocated the kernel from where it is in physical
//memory, make sure we keep those mappings correct, and we'll actually
//swap the two mappings so all of memory is addressable.
for (curr_addr = (uint32 *)PAGE_SIZE; curr_addr != 0; curr_addr += (PAGE_SIZE>>2)) {
if (page_intersects(curr_addr, &kernel_start_phys, &kernel_end_phys)) {
*curr_tbl_entry = (uint32)ROUND_DOWN_PAGE_SIZE(curr_addr + virt_phys_offset) | 0x83;
} else if (page_intersects(curr_addr, &kernel_start, &kernel_end)) {
*curr_tbl_entry = (uint32)ROUND_DOWN_PAGE_SIZE(curr_addr - virt_phys_offset) | 0x83;
} else {
*curr_tbl_entry = (uint32)curr_addr | 0x83;
}
/* Force the entries to reload */
asm("invlpg (%0)" : : "r"(curr_addr) : );
curr_tbl_entry++;
}
}
//TODO merge the rest of this file with the similar section in arch/arm. This is clearly mostly duplicated code.
int mmu_region_contains(void *lower_a, void *upper_a, void *lower_b, void *upper_b) {
return lower_b >= lower_a && upper_b <= upper_a;
}
int mmu_region_contains_single(void *lower_a, void *upper_a, void *ptr) {
return lower_a <= ptr && ptr <= upper_a;
}
#define section_round_down(ptr) (((uint32)ptr) & ~(PAGE_SIZE-1))
#define section_round_up(ptr) (((((uint32)ptr) & ~1) + (PAGE_SIZE-1) ) & ~(PAGE_SIZE-1))
/* Called once per physical memory region by bootup code. This function is
* responsible for only adding (via mm_add_free_region()) those parts of the
* memory region which are still available (i.e. aren't in the kernel and
* haven't been remapped anywhere else. */
void declare_memory_region(void *lower, void *upper) {
(void)lower;
(void)upper;
void *k_section_start_phys = (void *)section_round_down(&kernel_start_phys);
void *k_section_end_phys = (void *)(section_round_up(&kernel_end_phys) - 1);
void *k_section_start_virt = (void *)section_round_down(&kernel_start);
void *k_section_end_virt = (void *)(section_round_up(&kernel_end) - 1);
if (upper - lower < 1) {
print("Warning: declare_memory_region() called with lower=%x, upper=%x. Ignoring.\n", lower, upper);
return;
}
//TODO It's possible (though highly unlikely) that the kernel (virtual)
//is split across two different memory regions. We should probably
//handle this.
if (mmu_region_contains(lower, upper, k_section_start_phys, k_section_end_phys)) {
//Don't map any of the physical kernel's memory
declare_memory_region(lower, (void *) ((char *)k_section_start_phys - 1));
declare_memory_region((void *) ((char *)k_section_end_phys + 1), upper);
mm_add_free_region(&kernel_end, k_section_end_virt);
} else if (mmu_region_contains(lower, upper, k_section_start_virt, k_section_end_virt)) {
declare_memory_region(lower, (void *) ((char *)k_section_start_virt - 1));
declare_memory_region((void *) ((char *)k_section_end_virt + 1), upper);
} else if (mmu_region_contains_single(lower, upper, k_section_start_phys)) {
if ((void*)((char*)lower + 1) < k_section_start_phys)
declare_memory_region(lower, (void *) ((char *)k_section_start_phys - 1));
} else if (mmu_region_contains_single(lower, upper, k_section_end_phys)) {
if (k_section_end_phys < (void*)((char*)upper - 1))
declare_memory_region((void *) ((char *)k_section_end_phys + 1), upper);
} else if (mmu_region_contains_single(lower, upper, k_section_start_virt)) {
if ((void*)((char*)lower + 1) < k_section_start_virt)
declare_memory_region(lower, (void *) ((char *)k_section_start_virt - 1));
} else if (mmu_region_contains_single(lower, upper, k_section_end_virt)) {
if (k_section_end_virt < (void*)((char*)upper - 1))
declare_memory_region((void *) ((char *)k_section_end_virt + 1), upper);
} else {
mm_add_free_region(lower, upper);
}
}

64
arch/i386/kernel/multiboot.c Normal file
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@ -0,0 +1,64 @@
/*
Copyright (C) 2012, Aaron Lindsay <aaron@aclindsay.com>
This file is part of Aedrix.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <arch/multiboot.h>
#include <mmu.h>
struct multiboot_mmap {
unsigned int size;
unsigned int base_addr_low, base_addr_high;
unsigned int length_low, length_high;
unsigned int type;
};
extern multiboot_info_t* multiboot_mbd;
extern uint32 multiboot_magic;
int detect_memory_mmap() {
struct multiboot_mmap* mmap = (struct multiboot_mmap*)multiboot_mbd->mmap_addr;
int found_region = 0;
while ((char*)mmap < (char*)multiboot_mbd->mmap_addr + multiboot_mbd->mmap_length) {
if (mmap->base_addr_high || mmap->length_high)
return -1;
if (mmap->type == 0x1) { /* ignore non-usable memory */
declare_memory_region((void*)mmap->base_addr_low,
(void*)(mmap->base_addr_low + mmap->length_low));
found_region = 1;
}
mmap = (struct multiboot_mmap*) ((unsigned int)mmap + mmap->size + sizeof(unsigned int));
}
return !found_region;
}
int detect_memory_contiguous() {
declare_memory_region((void*)0x0, (void*)((uint32)multiboot_mbd->mem_lower * 1024));
declare_memory_region((void*)0x1000000, (void*)((uint32)multiboot_mbd->mem_upper*1024 + 0x100000));
return 0;
}
int detect_memory() {
if (multiboot_mbd->flags & (1<<6))
return detect_memory_mmap();
else if (multiboot_mbd->flags & (1<<0))
return detect_memory_contiguous();
return -1;
}