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Kernel: Rework physical memory allocation 

PhysicalRange is now much simpler bitmap. This makes expanding
PhysicalRange API much easier.
This commit is contained in:
Bananymous 2023-10-08 01:38:51 +03:00
parent f071240b33
commit 03d2bf4002
3 changed files with 85 additions and 128 deletions
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34
kernel/include/kernel/Memory/PhysicalRange.h
View File

@ -3,7 +3,6 @@
#include <kernel/Memory/Types.h> #include <kernel/Memory/Types.h>
#include <stddef.h> #include <stddef.h>
#include <stdint.h>
namespace Kernel namespace Kernel
{ {
@ -12,42 +11,37 @@ namespace Kernel
{ {
public: public:
PhysicalRange(paddr_t, size_t); PhysicalRange(paddr_t, size_t);
paddr_t reserve_page(); paddr_t reserve_page();
void release_page(paddr_t); void release_page(paddr_t);
paddr_t reserve_contiguous_pages(size_t pages);
void release_contiguous_pages(paddr_t paddr, size_t pages);
paddr_t start() const { return m_paddr; } paddr_t start() const { return m_paddr; }
paddr_t end() const { return m_paddr + m_size; } paddr_t end() const { return m_paddr + m_size; }
bool contains(paddr_t addr) const { return m_paddr <= addr && addr < m_paddr + m_size; } bool contains(paddr_t addr) const { return m_paddr <= addr && addr < m_paddr + m_size; }
size_t usable_memory() const { return m_reservable_pages * PAGE_SIZE; } size_t usable_memory() const { return m_data_pages * PAGE_SIZE; }
size_t used_pages() const { return m_used_pages; } size_t used_pages() const { return m_data_pages - m_free_pages; }
size_t free_pages() const { return m_free_pages; } size_t free_pages() const { return m_free_pages; }
private: private:
struct node unsigned long long* ull_bitmap_ptr() { return (unsigned long long*)m_vaddr; }
{
node* next;
node* prev;
};
paddr_t page_address(const node*) const; paddr_t paddr_for_bit(unsigned long long) const;
node* node_address(paddr_t) const; unsigned long long bit_for_paddr(paddr_t paddr) const;
private: private:
paddr_t m_paddr { 0 }; const paddr_t m_paddr { 0 };
const size_t m_size { 0 };
vaddr_t m_vaddr { 0 }; vaddr_t m_vaddr { 0 };
size_t m_size { 0 };
uint64_t m_total_pages { 0 }; const size_t m_bitmap_pages { 0 };
uint64_t m_reservable_pages { 0 }; const size_t m_data_pages { 0 };
uint64_t m_list_pages { 0 };
size_t m_used_pages { 0 };
size_t m_free_pages { 0 }; size_t m_free_pages { 0 };
node* m_free_list { nullptr };
node* m_used_list { nullptr };
}; };
} }

37
kernel/kernel/Memory/Heap.cpp
View File

@ -3,6 +3,8 @@
#include <kernel/Memory/PageTable.h> #include <kernel/Memory/PageTable.h>
#include <kernel/multiboot.h> #include <kernel/multiboot.h>
extern uint8_t g_kernel_end[];
namespace Kernel namespace Kernel
{ {
@ -30,14 +32,22 @@ namespace Kernel
for (size_t i = 0; i < g_multiboot_info->mmap_length;) for (size_t i = 0; i < g_multiboot_info->mmap_length;)
{ {
multiboot_memory_map_t* mmmt = (multiboot_memory_map_t*)P2V(g_multiboot_info->mmap_addr + i); multiboot_memory_map_t* mmmt = (multiboot_memory_map_t*)P2V(g_multiboot_info->mmap_addr + i);
if (mmmt->type == 1) if (mmmt->type == 1)
{ {
PhysicalRange range(mmmt->base_addr, mmmt->length); paddr_t start = mmmt->base_addr;
if (range.usable_memory() > 0) if (start < V2P(g_kernel_end))
MUST(m_physical_ranges.push_back(range)); start = V2P(g_kernel_end);
} if (auto rem = start % PAGE_SIZE)
start += PAGE_SIZE - rem;
paddr_t end = mmmt->base_addr + mmmt->length;
if (auto rem = end % PAGE_SIZE)
end -= rem;
// Physical pages needs atleast 2 pages
if (end > start + PAGE_SIZE)
MUST(m_physical_ranges.emplace_back(start, end - start));
}
i += mmmt->size + sizeof(uint32_t); i += mmmt->size + sizeof(uint32_t);
} }
@ -55,22 +65,17 @@ namespace Kernel
{ {
LockGuard _(m_lock); LockGuard _(m_lock);
for (auto& range : m_physical_ranges) for (auto& range : m_physical_ranges)
if (paddr_t page = range.reserve_page()) if (range.free_pages() >= 1)
return page; return range.reserve_page();
return 0; return 0;
} }
void Heap::release_page(paddr_t addr) void Heap::release_page(paddr_t paddr)
{ {
LockGuard _(m_lock); LockGuard _(m_lock);
for (auto& range : m_physical_ranges) for (auto& range : m_physical_ranges)
{ if (range.contains(paddr))
if (range.contains(addr)) return range.release_page(paddr);
{
range.release_page(addr);
return;
}
}
ASSERT_NOT_REACHED(); ASSERT_NOT_REACHED();
} }

142
kernel/kernel/Memory/PhysicalRange.cpp
View File

@ -3,123 +3,81 @@
#include <kernel/Memory/PageTable.h> #include <kernel/Memory/PageTable.h>
#include <kernel/Memory/PhysicalRange.h> #include <kernel/Memory/PhysicalRange.h>
extern uint8_t g_kernel_end[];
namespace Kernel namespace Kernel
{ {
PhysicalRange::PhysicalRange(paddr_t start, size_t size) using ull = unsigned long long;
static constexpr ull ull_bits = sizeof(ull) * 8;
PhysicalRange::PhysicalRange(paddr_t paddr, size_t size)
: m_paddr(paddr)
, m_size(size)
, m_bitmap_pages(BAN::Math::div_round_up<size_t>(size / PAGE_SIZE, 8))
, m_data_pages((size / PAGE_SIZE) - m_bitmap_pages)
, m_free_pages(m_data_pages)
{ {
// We can't use the memory ovelapping with kernel ASSERT(paddr % PAGE_SIZE == 0);
if (start + size <= V2P(g_kernel_end)) ASSERT(size % PAGE_SIZE == 0);
return; ASSERT(m_bitmap_pages < size / PAGE_SIZE);
// Align start to page boundary and after the kernel memory m_vaddr = PageTable::kernel().reserve_free_contiguous_pages(m_bitmap_pages, KERNEL_OFFSET);
m_paddr = BAN::Math::max(start, V2P(g_kernel_end));
if (auto rem = m_paddr % PAGE_SIZE)
m_paddr += PAGE_SIZE - rem;
if (size <= m_paddr - start)
return;
// Align size to page boundary
m_size = size - (m_paddr - start);
if (auto rem = m_size % PAGE_SIZE)
m_size -= rem;
// We need atleast 2 pages
m_total_pages = m_size / PAGE_SIZE;
if (m_total_pages <= 1)
return;
// FIXME: if total pages is just over multiple of (PAGE_SIZE / sizeof(node)) we might make
// couple of pages unallocatable
m_list_pages = BAN::Math::div_round_up<uint64_t>(m_total_pages * sizeof(node), PAGE_SIZE);
m_reservable_pages = m_total_pages - m_list_pages;
m_used_pages = 0;
m_free_pages = m_reservable_pages;
m_vaddr = PageTable::kernel().reserve_free_contiguous_pages(m_list_pages, KERNEL_OFFSET);
ASSERT(m_vaddr); ASSERT(m_vaddr);
PageTable::kernel().map_range_at(m_paddr, m_vaddr, size, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
PageTable::kernel().map_range_at(m_paddr, m_vaddr, m_list_pages * PAGE_SIZE, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
// Initialize page list so that every page points to the next one memset((void*)m_vaddr, 0x00, m_bitmap_pages * PAGE_SIZE);
node* page_list = (node*)m_vaddr; memset((void*)m_vaddr, 0xFF, m_data_pages / 8);
for (int i = 0; i < m_data_pages % 8; i++)
((uint8_t*)m_vaddr)[m_data_pages / 8] |= 1 << i;
for (uint64_t i = 0; i < m_reservable_pages; i++) dprintln("physical range needs {} pages for bitmap", m_bitmap_pages);
page_list[i] = { page_list + i - 1, page_list + i + 1 }; }
page_list[ 0 ].next = nullptr;
page_list[m_reservable_pages - 1].prev = nullptr;
m_free_list = page_list; paddr_t PhysicalRange::paddr_for_bit(ull bit) const
m_used_list = nullptr; {
return m_paddr + (m_bitmap_pages + bit) * PAGE_SIZE;
}
ull PhysicalRange::bit_for_paddr(paddr_t paddr) const
{
return (paddr - m_paddr) / PAGE_SIZE - m_bitmap_pages;
} }
paddr_t PhysicalRange::reserve_page() paddr_t PhysicalRange::reserve_page()
{ {
if (m_free_list == nullptr) ASSERT(free_pages() > 0);
return 0;
node* page = m_free_list; ull ull_count = BAN::Math::div_round_up<ull>(m_data_pages, ull_bits);
ASSERT(page->next == nullptr);
// Detatch page from top of the free list for (ull i = 0; i < ull_count; i++)
m_free_list = m_free_list->prev; {
if (m_free_list) if (ull_bitmap_ptr()[i] == 0)
m_free_list->next = nullptr; continue;
// Add page to used list int lsb = __builtin_ctzll(ull_bitmap_ptr()[i]);
if (m_used_list)
m_used_list->next = page;
page->prev = m_used_list;
m_used_list = page;
m_used_pages++; ull_bitmap_ptr()[i] &= ~(1ull << lsb);
m_free_pages--; m_free_pages--;
return paddr_for_bit(i * ull_bits + lsb);
}
return page_address(page); ASSERT_NOT_REACHED();
} }
void PhysicalRange::release_page(paddr_t page_address) void PhysicalRange::release_page(paddr_t paddr)
{ {
ASSERT(m_used_list); ASSERT(paddr % PAGE_SIZE == 0);
ASSERT(paddr - m_paddr <= m_size);
node* page = node_address(page_address); ull full_bit = bit_for_paddr(paddr);
ull off = full_bit / ull_bits;
// Detach page from used list ull bit = full_bit % ull_bits;
if (page->prev) ull mask = 1ull << bit;
page->prev->next = page->next;
if (page->next)
page->next->prev = page->prev;
if (m_used_list == page)
m_used_list = page->prev;
// Add page to the top of free list ASSERT(!(ull_bitmap_ptr()[off] & mask));
page->prev = m_free_list; ull_bitmap_ptr()[off] |= mask;
page->next = nullptr;
if (m_free_list)
m_free_list->next = page;
m_free_list = page;
m_used_pages--;
m_free_pages++; m_free_pages++;
}
paddr_t PhysicalRange::page_address(const node* page) const
{
ASSERT((vaddr_t)page <= m_vaddr + m_reservable_pages * sizeof(node));
uint64_t page_index = page - (node*)m_vaddr;
return m_paddr + (page_index + m_list_pages) * PAGE_SIZE;
} }
PhysicalRange::node* PhysicalRange::node_address(paddr_t page_address) const
{
ASSERT(page_address % PAGE_SIZE == 0);
ASSERT(m_paddr + m_list_pages * PAGE_SIZE <= page_address && page_address < m_paddr + m_size);
uint64_t page_offset = page_address - (m_paddr + m_list_pages * PAGE_SIZE);
return (node*)m_vaddr + page_offset / PAGE_SIZE;
}
} }