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added mm_map() to map addresses and mm_page_alloc() to allocate physical pages

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git-svn-id: svn://anubis/hos/trunk@35 5b3e749e-e535-0410-8002-a9bb6afbdfca
This commit is contained in:
josh 2009-07-02 03:28:25 +00:00
parent 2bddc1d428
commit a8947f8aa3
2 changed files with 84 additions and 3 deletions
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82
kernel/mm/mm.cc
View File

@ -6,6 +6,8 @@
#define MM_MAX_MMAP_ENTRIES 64
static bool mm_use_virtual_offset;
extern "C" {
pagedirectory_t page_directory __attribute__ ((aligned (4096)));
@ -43,6 +45,7 @@ void mm_record_mmap_entry(mb_mmap_t * mmap)
void mm_bootstrap()
{
u32_t max_ram_address = KERNEL_PHYSICAL_ADDRESS + KERNEL_SIZE - 1;
mm_use_virtual_offset = true;
if (mm_mmap_num_entries < 1)
{
@ -78,9 +81,10 @@ void mm_bootstrap()
u32_t * last_page = NULL;
while (base_address < address_limit)
{
/* check to make sure the RAM page isn't overlapping the kernel */
if ( base_address + PAGE_SIZE <= KERNEL_PHYSICAL_ADDRESS
&& base_address >= KERNEL_PHYSICAL_ADDRESS + KERNEL_SIZE )
/* check to make sure the RAM page is ok */
if ( base_address > 0 /* don't map address 0 */
&& ( base_address + PAGE_SIZE <= KERNEL_PHYSICAL_ADDRESS
|| base_address >= KERNEL_PHYSICAL_ADDRESS + KERNEL_SIZE ) )
{
/* we found a page to add to the free list */
u32_t * page_virtual_address =
@ -101,11 +105,83 @@ void mm_bootstrap()
}
}
if (mm_num_free_pages < 10)
{
k_early_panic("Not enough free pages of RAM!");
}
/* Clear the page directory */
for (unsigned int i = 0; i < NUM_PAGETABLE_ENTRIES; i++)
{
page_directory[i] = 0;
}
/* now map all of RAM into the virtual address space
* starting at address 0x0
*/
for (u32_t page_base = 0;
page_base < max_ram_address;
page_base += PAGE_SIZE)
{
mm_map(page_base, page_base, 0, 1);
}
mm_use_virtual_offset = false;
}
} /* extern "C" */
int mm_map(u32_t virtual_address, u32_t physical_address,
u32_t user_mode, u32_t writable)
{
u32_t directory_index = (virtual_address >> 22) & 0x3FF;
u32_t table_index = (virtual_address >> 12) & 0x3FF;
if (page_directory[directory_index] == 0)
{
/* allocate a new page table */
u32_t page_table_address = mm_page_alloc();
if (page_table_address == 0)
{
return 1;
}
page_directory[directory_index] = page_table_address
| 0x1 << 2 /* PTs can be user mode */
| 0x1 << 1 /* writable */
| 0x1; /* present */
}
u32_t page_table_address = page_directory[directory_index] & PAGE_HIGH_MASK;
u32_t * page_table = (u32_t *) page_table_address;
if (mm_use_virtual_offset)
{
page_table = (u32_t *)((u32_t)page_table + (u32_t)KERNEL_OFFSET);
}
page_table[table_index] = (physical_address & PAGE_HIGH_MASK)
| (user_mode & 0x1) << 2
| (writable & 0x1) << 1
| 0x1; /* present */
return 0;
}
/**************************************************************************
* Returns the physical base address of a page in RAM *
* or 0 if no pages were available *
*************************************************************************/
u32_t mm_page_alloc()
{
if (mm_free_page_ptr == NULL)
{
return 0;
}
u32_t * page_ptr = mm_free_page_ptr;
if (mm_use_virtual_offset)
{
page_ptr = (u32_t *) ((u32_t)page_ptr + (u32_t)KERNEL_OFFSET);
}
u32_t page_address = (u32_t) mm_free_page_ptr;
mm_free_page_ptr = (u32_t *) *page_ptr;
mm_num_free_pages--;
return page_address;
}

5
kernel/mm/mm.h
View File

@ -32,5 +32,10 @@ void mm_bootstrap();
}
#endif
int mm_map(u32_t virtual_address, u32_t physical_address,
u32_t user_mode, u32_t writable);
u32_t mm_page_alloc();
#endif