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This commit is contained in:
Justin C. Miller
2018-04-25 10:48:14 -07:00
parent fd9e0944cb
commit bed882f41c
5 changed files with 310 additions and 144 deletions
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107
src/kernel/memory_bootstrap.cpp
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@@ -273,7 +273,8 @@ gather_block_lists(
}
page_block *
fill_page_with_blocks(uint64_t start) {
fill_page_with_blocks(uint64_t start)
{
uint64_t end = page_align(start);
uint64_t count = (end - start) / sizeof(page_block);
if (count == 0) return nullptr;
@@ -294,7 +295,8 @@ copy_new_table(page_table *base, unsigned index, page_table *new_table)
if(entry & 0x80) return;
if (entry & 0x1) {
page_table *old_next = base->next(index);
page_table *old_next = reinterpret_cast<page_table *>(
base->entries[index] & ~0xffful);
for (int i = 0; i < 512; ++i) new_table->entries[i] = old_next->entries[i];
} else {
for (int i = 0; i < 512; ++i) new_table->entries[i] = 0;
@@ -348,6 +350,58 @@ find_efi_free_aligned_pages(const void *memory_map, size_t map_length, size_t de
return start_phys;
}
static unsigned
check_needs_page_ident(page_table *table, unsigned index, page_table **free_pages)
{
if (table->entries[index] & 0x1 == 1) return 0;
kassert(*free_pages, "check_needs_page_ident needed to allocate but had no free pages");
page_table *new_table = (*free_pages)++;
for (int i=0; i<512; ++i) new_table->entries[i] = 0;
table->entries[index] = reinterpret_cast<uint64_t>(new_table) | 0xb;
return 1;
}
static unsigned
page_in_ident(
page_table *pml4,
uint64_t phys_addr,
uint64_t virt_addr,
uint64_t count,
page_table *free_pages)
{
page_table_indices idx{virt_addr};
page_table *tables[4] = {pml4, nullptr, nullptr, nullptr};
unsigned pages_consumed = 0;
for (; idx[0] < 512; idx[0] += 1) {
pages_consumed += check_needs_page_ident(tables[0], idx[0], &free_pages);
tables[1] = reinterpret_cast<page_table *>(
tables[0]->entries[idx[0]] & ~0xfffull);
for (; idx[1] < 512; idx[1] += 1, idx[2] = 0, idx[3] = 0) {
pages_consumed += check_needs_page_ident(tables[1], idx[1], &free_pages);
tables[2] = reinterpret_cast<page_table *>(
tables[1]->entries[idx[1]] & ~0xfffull);
for (; idx[2] < 512; idx[2] += 1, idx[3] = 0) {
pages_consumed += check_needs_page_ident(tables[2], idx[2], &free_pages);
tables[3] = reinterpret_cast<page_table *>(
tables[2]->entries[idx[2]] & ~0xfffull);
for (; idx[3] < 512; idx[3] += 1) {
tables[3]->entries[idx[3]] = phys_addr | 0xb;
phys_addr += page_manager::page_size;
if (--count == 0) return pages_consumed;
}
}
}
}
kassert(0, "Ran to end of page_in_ident");
}
void
memory_initialize_managers(const void *memory_map, size_t map_length, size_t desc_length)
{
@@ -355,7 +409,9 @@ memory_initialize_managers(const void *memory_map, size_t map_length, size_t des
// The bootloader reserved 16 pages for page tables, which we'll use to bootstrap.
// The first one is the already-installed PML4, so grab it from CR3.
page_table *tables = page_manager::get_pml4();
uint64_t cr3;
__asm__ __volatile__ ( "mov %%cr3, %0" : "=r" (cr3) );
page_table *tables = reinterpret_cast<page_table *>(cr3 & ~0xfffull);
// Now go through EFi's memory map and find a region of scratch space.
const unsigned want_pages = 32;
@@ -375,7 +431,7 @@ memory_initialize_managers(const void *memory_map, size_t map_length, size_t des
copy_new_table(&tables[0], fr_idx[0], &tables[1]);
copy_new_table(&tables[1], fr_idx[1], &tables[2]);
copy_new_table(&tables[2], fr_idx[2], &tables[3]);
page_in(&tables[0], free_region_start_phys, free_region_start_virt, want_pages, nullptr);
page_in_ident(&tables[0], free_region_start_phys, free_region_start_virt, want_pages, nullptr);
// We now have pages starting at "free_next" to bootstrap ourselves. Start by
// taking inventory of free pages.
@@ -385,6 +441,9 @@ memory_initialize_managers(const void *memory_map, size_t map_length, size_t des
free_next, memory_map, map_length, desc_length,
&free_head, &used_head);
page_block::dump(used_head, "original used", true);
page_block::dump(free_head, "original free", true);
// Unused page_block structs go here - finish out the current page with them
page_block *cache_head = fill_page_with_blocks(free_next);
free_next = page_align(free_next);
@@ -414,7 +473,7 @@ memory_initialize_managers(const void *memory_map, size_t map_length, size_t des
// Add it to the used list
removed->virtual_address = free_region_start_virt;
removed->flags = page_block_flags::used;
removed->flags = page_block_flags::used | page_block_flags::mapped;
used_head = page_block::insert(used_head, removed);
// Pull out the block that represents the rest
@@ -435,43 +494,45 @@ memory_initialize_managers(const void *memory_map, size_t map_length, size_t des
// Record that we're about to remap it into the page table address space
removed->virtual_address = pt_start_virt;
removed->flags = page_block_flags::used;
removed->flags = page_block_flags::used | page_block_flags::mapped;
used_head = page_block::insert(used_head, removed);
page_manager *pm = &g_page_manager;
// Actually remap them into page table space
page_out(&tables[0], free_next, remaining_pages);
pm->page_out(&tables[0], free_next, remaining_pages);
page_table_indices pg_idx{pt_start_virt};
copy_new_table(&tables[0], pg_idx[0], &tables[4]);
copy_new_table(&tables[4], pg_idx[1], &tables[5]);
copy_new_table(&tables[5], pg_idx[2], &tables[6]);
page_in(&tables[0], pt_start_phys, pt_start_virt, remaining_pages, tables + 4);
page_in_ident(&tables[0], pt_start_phys, pt_start_virt, remaining_pages, tables + 4);
// Ok, now build an acutal set of kernel page tables that just contains
// what the kernel actually has mapped.
page_table *pages = reinterpret_cast<page_table *>(pt_start_virt);
unsigned consumed_pages = 1; // We're about to make a PML4, start with 1
// Finally, remap the existing mappings, but making everything writable
// Finally, build an acutal set of kernel page tables that just contains
// what the kernel actually has mapped, but making everything writable
// (especially the page tables themselves)
page_table *pml4 = pages++;
page_table *pml4 = reinterpret_cast<page_table *>(pt_start_virt);
for (int i=0; i<512; ++i) pml4->entries[i] = 0;
// Give the rest to the page_manager's cache for use in page_in
pm->free_table_pages(pml4 + 1, remaining_pages - 1);
for (page_block *cur = used_head; cur; cur = cur->next) {
if (!cur->has_flag(page_block_flags::mapped)) continue;
consumed_pages += page_in(pml4, cur->physical_address, cur->virtual_address,
cur->count, pages + consumed_pages);
pm->page_in(pml4, cur->physical_address, cur->virtual_address, cur->count);
}
free_next += (consumed_pages * page_manager::page_size);
page_block::dump(used_head, "used", true);
page_block::dump(free_head, "free", true);
cons->printf("free_region_start: %lx [%3d]\n", free_region_start_virt, used_pages);
pml4->dump();
// Put our new PML4 into CR3 to start using it
// page_manager::set_pml4(pml4);
page_manager::set_pml4(pml4);
// We now have all used memory mapped ourselves. Let the page_manager take
// over from here.
g_page_manager.init(
free_head, used_head, cache_head,
free_region_start_virt, used_pages,
free_next, remaining_pages - consumed_pages);
g_page_manager.init(free_head, used_head, cache_head);
}