beenull/ladybird
1
0
Fork 0
mirror of https://github.com/LadybirdBrowser/ladybird.git synced 2024-09-30 08:41:15 +00:00
Code Issues Actions 5 Packages Projects Releases Wiki Activity

Kernel: Create page structures correctly in boot.s

Browse source
This commit is contained in:
etaIneLp 2020-05-25 17:19:37 -04:00 committed by Andreas Kling
parent 4e607192c7
commit 826dc94187
Notes: sideshowbarker 2024-07-19 18:30:45 +09:00 
Committer: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/826dc941879
3 changed files with 76 additions and 100 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

104
Kernel/Arch/i386/Boot/boot.S
View file

@ -42,8 +42,14 @@ boot_pd0:
.global boot_pd3
boot_pd3:
.skip 4096
.global boot_pd3_pde1023_pt
boot_pd3_pde1023_pt:
.global boot_pd0_pt0
boot_pd0_pt0:
.skip 4096 * 4
.global boot_pd3_pts
boot_pd3_pts:
.skip 4096 * 4
.global boot_pd3_pt1023
boot_pd3_pt1023:
.skip 4096
.section .text
@ -69,18 +75,18 @@ pdpt
boot_pd0 : 512 pde's
0: (0-2MB) (id 2MB page)
1: (2-4MB) (id 2MB page)
2: (4-6MB) (id 2MB page)
3: (6-8MB) (id 2MB page)
0: boot_pd0_pt0 (0-2MB) (id 512 4KB pages)
boot_pd3 : 512 pde's
0: boot_pd3_pde0 (3072-3074MB) (pseudo)
1: boot_pd3_pde1 (3074-3076MB) (pseudo)
2: boot_pd3_pde2 (3076-3078MB) (pseudo)
3: boot_pd3_pde3 (3078-3080MB) (pseudo)
4: boot_pd3_pde1023_pt (4094-4096MB) (for page table mappings)
0: boot_pd3_pts[0] (3072-3074MB) (pseudo 512 4KB pages)
1: boot_pd3_pts[1] (3074-3076MB) (pseudo 512 4KB pages)
2: boot_pd3_pts[2] (3076-3078MB) (pseudo 512 4KB pages)
3: boot_pd3_pts[3] (3078-3080MB) (pseudo 512 4KB pages)
4: boot_pd3_pt1023 (4094-4096MB) (for page table mappings)
the 9 page tables each contain 512 pte's that map individual 4KB pages
*/
start:
@ -104,41 +110,74 @@ start:
xorl %eax, %eax
rep stosl
/* identity map bottom 8MB using 2MB pages (only PDE, no PTE) */
movl $4, %ecx
xorl %eax, %eax
movl $(boot_pd0 - 0xc0000000), %edi
1:
movl %eax, 0(%edi)
/* PS(2MB) + R/W + Present */
orl $0x83, 0(%edi)
addl $8, %edi
addl $(1048576 * 2), %eax
loop 1b
/* clear pd3 */
movl $(boot_pd3 - 0xc0000000), %edi
movl $1024, %ecx
xorl %eax, %eax
rep stosl
/* pseudo-identity map first 8MB above 3GB mark using 2MB pages again */
movl $4, %ecx
/* clear pd0's pt's */
movl $(boot_pd0_pt0 - 0xc0000000), %edi
movl $(1024 * 4), %ecx
xorl %eax, %eax
rep stosl
/* clear pd3's pt's */
movl $(boot_pd3_pts - 0xc0000000), %edi
movl $(1024 * 5), %ecx
xorl %eax, %eax
rep stosl
/* add boot_pd0_pt0 to boot_pd0 */
movl $(boot_pd0 - 0xc0000000), %edi
movl $(boot_pd0_pt0 - 0xc0000000), %eax
movl %eax, 0(%edi)
/* R/W + Present */
orl $0x3, 0(%edi)
/* add boot_pd3_pts to boot_pd3 */
movl $4, %ecx
movl $(boot_pd3 - 0xc0000000), %edi
movl $(boot_pd3_pts - 0xc0000000), %eax
1:
movl %eax, 0(%edi)
/* PS(2MB) + R/W + Present */
orl $0x83, 0(%edi)
/* R/W + Present */
orl $0x3, 0(%edi)
addl $8, %edi
addl $(1048576 * 2), %eax
addl $4096, %eax
loop 1b
/* identity map the 0 to 2MB range */
movl $512, %ecx
movl $(boot_pd0_pt0 - 0xc0000000), %edi
/*movl $0x100000, %eax*/
xorl %eax, %eax
1:
movl %eax, 0(%edi)
/* R/W + Present */
orl $0x3, 0(%edi)
addl $8, %edi
addl $4096, %eax
loop 1b
/* pseudo identity map the 3072-3080MB range */
movl $(512 * 4), %ecx
movl $(boot_pd3_pts - 0xc0000000), %edi
xorl %eax, %eax
1:
movl %eax, 0(%edi)
/* R/W + Present */
orl $0x3, 0(%edi)
addl $8, %edi
addl $4096, %eax
loop 1b
/* create an empty page table for the top 2MB at the 4GB mark */
movl $(boot_pd3 - 0xc0000000), %edi
movl $(boot_pd3_pde1023_pt - 0xc0000000), 4088(%edi)
movl $(boot_pd3_pt1023 - 0xc0000000), 4088(%edi)
orl $0x3, 4088(%edi)
movl $0, 4092(%edi)
@ -158,10 +197,9 @@ start:
/* jmp to an address above the 3GB mark */
push %cs
push $1f
push $1f
retf
1:
movl %cr3, %eax
movl %eax, %cr3

70
Kernel/VM/MemoryManager.cpp
View file

@ -62,8 +62,6 @@ MemoryManager::MemoryManager()
m_kernel_page_directory = PageDirectory::create_kernel_page_directory();
parse_memory_map();
write_cr3(kernel_page_directory().cr3());
setup_low_identity_mapping();
setup_low_pseudo_identity_mapping();
protect_kernel_image();
m_shared_zero_page = allocate_user_physical_page();
@ -73,36 +71,6 @@ MemoryManager::~MemoryManager()
{
}
void MemoryManager::setup_low_pseudo_identity_mapping()
{
// This code switches the pseudo-identity mapping (8 first MB above 3G mark) from 2MB pages to 4KB pages.
// The boot code sets it up as 2MB huge pages for convenience. But we need 4KB pages to be able to protect
// the kernel soon!
for (size_t i = 0; i < 4; ++i) {
m_low_pseudo_identity_mapping_pages[i] = allocate_supervisor_physical_page();
FlatPtr base = i * (2 * MB);
auto* page_table = (PageTableEntry*)quickmap_page(*m_low_pseudo_identity_mapping_pages[i]);
for (size_t j = 0; j < 512; ++j) {
auto& pte = page_table[j];
pte.set_physical_page_base(base + j * PAGE_SIZE);
pte.set_writable(true);
pte.set_present(true);
pte.set_execute_disabled(false);
pte.set_user_allowed(false);
}
unquickmap_page();
}
auto* pd = quickmap_pd(*m_kernel_page_directory, 3);
for (size_t i = 0; i < 4; ++i) {
pd[i].set_huge(false);
pd[i].set_page_table_base(m_low_pseudo_identity_mapping_pages[i]->paddr().get());
}
flush_entire_tlb();
}
void MemoryManager::protect_kernel_image()
{
// Disable writing to the kernel text and rodata segments.
@ -120,34 +88,6 @@ void MemoryManager::protect_kernel_image()
}
}
void MemoryManager::setup_low_identity_mapping()
{
m_low_page_table = allocate_user_physical_page(ShouldZeroFill::Yes);
auto* pd_zero = quickmap_pd(kernel_page_directory(), 0);
pd_zero[1].set_present(false);
pd_zero[2].set_present(false);
pd_zero[3].set_present(false);
auto& pde_zero = pd_zero[0];
pde_zero.set_page_table_base(m_low_page_table->paddr().get());
pde_zero.set_present(true);
pde_zero.set_huge(false);
pde_zero.set_writable(true);
pde_zero.set_user_allowed(false);
if (g_cpu_supports_nx)
pde_zero.set_execute_disabled(true);
for (FlatPtr offset = (1 * MB); offset < (2 * MB); offset += PAGE_SIZE) {
auto& page_table_page = m_low_page_table;
auto& pte = quickmap_pt(page_table_page->paddr())[offset / PAGE_SIZE];
pte.set_physical_page_base(offset);
pte.set_user_allowed(false);
pte.set_present(offset != 0);
pte.set_writable(offset < (1 * MB));
}
}
void MemoryManager::parse_memory_map()
{
RefPtr<PhysicalRegion> region;
@ -574,11 +514,11 @@ void MemoryManager::flush_tlb(VirtualAddress vaddr)
: "memory");
}
extern "C" PageTableEntry boot_pd3_pde1023_pt[1024];
extern "C" PageTableEntry boot_pd3_pt1023[1024];
PageDirectoryEntry* MemoryManager::quickmap_pd(PageDirectory& directory, size_t pdpt_index)
{
auto& pte = boot_pd3_pde1023_pt[4];
auto& pte = boot_pd3_pt1023[4];
auto pd_paddr = directory.m_directory_pages[pdpt_index]->paddr();
if (pte.physical_page_base() != pd_paddr.as_ptr()) {
#ifdef MM_DEBUG
@ -595,7 +535,7 @@ PageDirectoryEntry* MemoryManager::quickmap_pd(PageDirectory& directory, size_t
PageTableEntry* MemoryManager::quickmap_pt(PhysicalAddress pt_paddr)
{
auto& pte = boot_pd3_pde1023_pt[8];
auto& pte = boot_pd3_pt1023[8];
if (pte.physical_page_base() != pt_paddr.as_ptr()) {
#ifdef MM_DEBUG
dbg() << "quickmap_pt: Mapping P" << (void*)pt_paddr.as_ptr() << " at 0xffe08000 in pte @ " << &pte;
@ -615,7 +555,7 @@ u8* MemoryManager::quickmap_page(PhysicalPage& physical_page)
ASSERT(!m_quickmap_in_use);
m_quickmap_in_use = true;
auto& pte = boot_pd3_pde1023_pt[0];
auto& pte = boot_pd3_pt1023[0];
if (pte.physical_page_base() != physical_page.paddr().as_ptr()) {
#ifdef MM_DEBUG
dbg() << "quickmap_page: Mapping P" << (void*)physical_page.paddr().as_ptr() << " at 0xffe00000 in pte @ " << &pte;
@ -633,7 +573,7 @@ void MemoryManager::unquickmap_page()
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(m_quickmap_in_use);
auto& pte = boot_pd3_pde1023_pt[0];
auto& pte = boot_pd3_pt1023[0];
pte.clear();
flush_tlb(VirtualAddress(0xffe00000));
m_quickmap_in_use = false;

2
Kernel/VM/MemoryManager.h
View file

@ -160,8 +160,6 @@ private:
void unregister_region(Region&);
void detect_cpu_features();
void setup_low_identity_mapping();
void setup_low_pseudo_identity_mapping();
void protect_kernel_image();
void parse_memory_map();
void flush_entire_tlb();