From 934229dfe30d2289c1d5e50d0e986120fbb4aab4 Mon Sep 17 00:00:00 2001
From: Bensong Liu <bensl@microsoft.com>
Date: Wed, 30 Dec 2020 18:37:10 +0800
Subject: [PATCH] working on kalloc
---
README.md | 2 +
kernel/include/kutils.hpp | 80 +++++++++++++++++++++++++++++++++++++++
kernel/include/vga.hpp | 12 +++++-
kernel/kernel.cc | 13 +++----
4 files changed, 99 insertions(+), 8 deletions(-)
create mode 100644 kernel/include/kutils.hpp
diff --git a/README.md b/README.md
index 65d7674..634b0ab 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,8 @@ Just used this mode to launch 64bit long mode. No paging enabled.
0x1000 - 0x5000 : 64bit long mode paging table**s**
0x00000000 - 0x00200000 : 512 * 4K pages, before the kernel initializing page table in C++.
+(0x0 - 0x100000 are used by kernel structures, 0x100000-0x200000 are used by kalloc(), defined in kutils.hpp)
+
## bootloader(legacy) disk model
0-511Byte : bootloader.img from boot.asm, MBR flag
diff --git a/kernel/include/kutils.hpp b/kernel/include/kutils.hpp
new file mode 100644
index 0000000..6807753
--- /dev/null
+++ b/kernel/include/kutils.hpp
@@ -0,0 +1,80 @@
+#ifndef ROS_KUTILS_HPP
+#define ROS_KUTILS_HPP
+
+#include "stdint.hpp"
+#include "stdlib.hpp"
+
+namespace impl {
+ constexpr uint64_t kalloc_begin_addr = 0x100000;
+ constexpr uint64_t kalloc_end_addr = 0x200000;
+ // Currently 1MB, must be paged.
+
+ struct __attribute__((packed)) free_slot_head_t {
+ uint32_t size;
+ uint64_t next; // 0x0 means tail.
+ };
+ static_assert(sizeof(free_slot_head_t) == sizeof(uint32_t) + sizeof(uint64_t));
+
+ using allocated_slot_head_t = uint32_t; // contains size EXCEPT the head!
+
+ inline void kalloc_init_pool() {
+ struct __attribute__((packed)) _kalloc_head {
+ uint32_t magic = 0x12230823;
+ free_slot_head_t free_slot_head {kalloc_end_addr - kalloc_begin_addr - sizeof(_kalloc_head), 0x0};
+ } kalloc_head;
+ static_assert(sizeof(kalloc_head) == sizeof(uint32_t)*2 + sizeof(uint64_t));
+
+ memcpy((char *)kalloc_begin_addr, (const char *)&kalloc_head, sizeof(kalloc_head));
+ }
+}
+
+inline void *kalloc(const uint32_t requested_size) {
+ const auto req_size_with_head = requested_size + sizeof(impl::allocated_slot_head_t);
+ uint64_t prev_slot_addr = 0x0;
+ auto curr_slot_addr = impl::kalloc_begin_addr + sizeof(impl::free_slot_head_t::size);
+ while(true) {
+ auto curr_slot = (impl::free_slot_head_t *)curr_slot_addr;
+ if(curr_slot->size >= req_size_with_head) {
+ // Do the alloc
+ curr_slot->size -= req_size_with_head;
+ if(curr_slot->size < 32) {
+ // Give the whole slot
+ if(prev_slot_addr == 0x0) {
+ // No previous slot. I am the first one.
+ // TODO
+ }
+ else {
+ auto prev_slot = (impl::free_slot_head_t *)prev_slot_addr;
+ prev_slot->next = curr_slot->next;
+ }
+ const auto actually_assigned_size = sizeof(impl::free_slot_head_t) + curr_slot->size;
+ *(impl::allocated_slot_head_t *)curr_slot_addr = actually_assigned_size;
+ return (char *)curr_slot_addr + sizeof(impl::allocated_slot_head_t);
+ }
+ else {
+ // Shrink the slot.
+ // TODO
+
+ }
+
+ }
+ else if (curr_slot->next != 0x0){
+ // Failed. Next.
+ prev_slot_addr = curr_slot_addr;
+ curr_slot_addr = curr_slot->next;
+ }
+ else {
+ // No memory
+ return 0x0;
+ }
+
+ }
+
+}
+
+inline void kfree(void *memory) {
+
+}
+
+#endif
+
diff --git a/kernel/include/vga.hpp b/kernel/include/vga.hpp
index 6eab679..ffb9f25 100644
--- a/kernel/include/vga.hpp
+++ b/kernel/include/vga.hpp
@@ -47,4 +47,14 @@ inline void print(const char *cstr, uint8_t color = default_color) {
}
}
-#endif
\ No newline at end of file
+inline void clear_screen() {
+ for(auto y = 0; y < 25; ++y) {
+ for(auto x = 0; x < 80; ++x) {
+ char c = x%10 + '0';
+ char color = x + y*80;
+ set_char(x, y, ' ', 0x0f);
+ }
+ }
+}
+
+#endif
diff --git a/kernel/kernel.cc b/kernel/kernel.cc
index 576ca5a..3fe8438 100644
--- a/kernel/kernel.cc
+++ b/kernel/kernel.cc
@@ -2,6 +2,7 @@
#include "include/vga.hpp"
#include "include/bus_io.hpp"
+#include "include/kutils.hpp"
void test_dummy_function() {
auto tmp = read_byte_from_bus(0x3f2);
@@ -9,14 +10,12 @@ void test_dummy_function() {
write_byte_to_bus(0x3f2, tmp);
}
+void kernel_init() {
+ impl::kalloc_init_pool();
+}
+
void main() {
- for(auto y = 0; y < 25; ++y) {
- for(auto x = 0; x < 80; ++x) {
- char c = x%10 + '0';
- char color = x + y*80;
- set_char(x, y, ' ', 0x0f);
- }
- }
+ clear_screen();
print("Hello world!\n");
print("Hello world!\n", 0xb1);
print("Hello world!\n", 0xae);
--
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