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Kernel: Implement WriteCombining memory

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This makes framebuffer much faster on real hardware
This commit is contained in:
Bananymous
2024-07-15 22:08:20 +03:00
parent 42c3fa24f0
commit 0578d41500
8 changed files with 64 additions and 20 deletions
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33
kernel/arch/i686/PageTable.cpp
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@@ -20,6 +20,7 @@ namespace Kernel
static PageTable* s_kernel = nullptr;
static bool s_has_nxe = false;
static bool s_has_pge = false;
static bool s_has_pat = false;
static paddr_t s_global_pdpte = 0;
@@ -32,8 +33,6 @@ namespace Kernel
result |= Flags::Execute;
if (entry & Flags::Reserved)
result |= Flags::Reserved;
if (entry & Flags::CacheDisable)
result |= Flags::CacheDisable;
if (entry & Flags::UserSupervisor)
result |= Flags::UserSupervisor;
if (entry & Flags::ReadWrite)
@@ -51,6 +50,9 @@ namespace Kernel
if (CPUID::has_pge())
s_has_pge = true;
if (CPUID::has_pat())
s_has_pat = true;
ASSERT(s_kernel == nullptr);
s_kernel = new PageTable();
ASSERT(s_kernel);
@@ -82,6 +84,17 @@ namespace Kernel
);
}
if (s_has_pat)
{
asm volatile(
"movl $0x277, %%ecx;"
"rdmsr;"
"movw $0x0401, %%dx;"
"wrmsr;"
::: "eax", "ecx", "edx", "memory"
);
}
// enable write protect
asm volatile(
"movl %%cr0, %%eax;"
@@ -316,7 +329,7 @@ namespace Kernel
unmap_page(page * PAGE_SIZE);
}
void PageTable::map_page_at(paddr_t paddr, vaddr_t vaddr, flags_t flags)
void PageTable::map_page_at(paddr_t paddr, vaddr_t vaddr, flags_t flags, MemoryType memory_type)
{
ASSERT(vaddr);
ASSERT(vaddr != fast_page());
@@ -338,8 +351,14 @@ namespace Kernel
extra_flags |= 1ull << 63;
if (flags & Flags::Reserved)
extra_flags |= Flags::Reserved;
if (flags & Flags::CacheDisable)
extra_flags |= Flags::CacheDisable;
if (s_has_pat)
{
if (memory_type == MemoryType::WriteCombining)
extra_flags |= (1ull << 7);
if (memory_type == MemoryType::WriteThrough)
extra_flags |= (1ull << 7) | (1ull << 3);
}
// NOTE: we add present here, since it has to be available in higher level structures
flags_t uwr_flags = (flags & (Flags::UserSupervisor | Flags::ReadWrite)) | Flags::Present;
@@ -367,7 +386,7 @@ namespace Kernel
invalidate(vaddr);
}
void PageTable::map_range_at(paddr_t paddr, vaddr_t vaddr, size_t size, flags_t flags)
void PageTable::map_range_at(paddr_t paddr, vaddr_t vaddr, size_t size, flags_t flags, MemoryType memory_type)
{
ASSERT(vaddr);
ASSERT(paddr % PAGE_SIZE == 0);
@@ -377,7 +396,7 @@ namespace Kernel
SpinLockGuard _(m_lock);
for (size_t page = 0; page < page_count; page++)
map_page_at(paddr + page * PAGE_SIZE, vaddr + page * PAGE_SIZE, flags);
map_page_at(paddr + page * PAGE_SIZE, vaddr + page * PAGE_SIZE, flags, memory_type);
}
uint64_t PageTable::get_page_data(vaddr_t vaddr) const