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Kernel: start work on higher half kernel

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This commit is contained in:
Bananymous
2023-05-30 08:00:17 +03:00
parent 79315d318c
commit 0907965dc5
5 changed files with 65 additions and 28 deletions
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25
kernel/arch/x86_64/PageTable.cpp
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@@ -12,6 +12,7 @@
kfree(s); \
} while (false)
extern uint8_t g_kernel_start[];
extern uint8_t g_kernel_end[];
namespace Kernel
@@ -20,6 +21,20 @@ namespace Kernel
static PageTable* s_kernel = nullptr;
static PageTable* s_current = nullptr;
static inline bool is_canonical(uintptr_t addr)
{
static constexpr uintptr_t mask = 0xFFFF800000000000;
addr &= mask;
return addr == mask || addr == 0;
}
static inline void uncanonicalize(uintptr_t& addr)
{
static constexpr uintptr_t mask = 0xFFFF800000000000;
addr &= mask;
ASSERT(addr == mask || addr == 0);
}
void PageTable::initialize()
{
ASSERT(s_kernel == nullptr);
@@ -56,7 +71,7 @@ namespace Kernel
// Identity map 4 KiB -> kernel end. We don't map the first page since nullptr derefs should
// page fault. Also there isn't anything useful in that memory.
identity_map_range(PAGE_SIZE, (uintptr_t)g_kernel_end, Flags::ReadWrite | Flags::Present);
identity_map_range((uintptr_t)g_kernel_start, (uintptr_t)(g_kernel_end - g_kernel_start), Flags::ReadWrite | Flags::Present);
}
BAN::ErrorOr<PageTable*> PageTable::create_userspace()
@@ -169,7 +184,7 @@ namespace Kernel
{
LockGuard _(m_lock);
ASSERT((address >> 48) == 0);
uncanonicalize(address);
address &= PAGE_ADDR_MASK;
@@ -212,8 +227,8 @@ namespace Kernel
{
LockGuard _(m_lock);
ASSERT((paddr >> 48) == 0);
ASSERT((vaddr >> 48) == 0);
ASSERT(is_canonical(paddr));
uncanonicalize(vaddr);
ASSERT(paddr % PAGE_SIZE == 0);
ASSERT(vaddr % PAGE_SIZE == 0);;
@@ -257,7 +272,7 @@ namespace Kernel
{
LockGuard _(m_lock);
ASSERT((address >> 48) == 0);
uncanonicalize(address);
ASSERT(address % PAGE_SIZE == 0);
uint64_t pml4e = (address >> 39) & 0x1FF;