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-rw-r--r--kernel/Makefile2
-rw-r--r--kernel/include/region.h33
-rw-r--r--kernel/l0/kmain.c29
-rw-r--r--kernel/l0/paging.c12
-rw-r--r--kernel/l0/region.c293
5 files changed, 367 insertions, 2 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index dec8686..58a6339 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -12,7 +12,7 @@ LDFLAGS = -T linker.ld -ffreestanding -O2 -nostdlib -lgcc
OBJ = lib/string.o lib/printf.o \
l0/loader.o l0/kmain.o l0/dbglog.o l0/sys.o \
l0/gdt.o l0/idt.o l0/interrupt.o \
- l0/frame.o l0/paging.o
+ l0/frame.o l0/paging.o l0/region.o
OUT = kernel.bin
all: $(OUT)
diff --git a/kernel/include/region.h b/kernel/include/region.h
new file mode 100644
index 0000000..701e2d9
--- /dev/null
+++ b/kernel/include/region.h
@@ -0,0 +1,33 @@
+#pragma once
+
+// Kernel virtual memory region allocator
+
+#include <sys.h>
+#include <paging.h>
+
+// Region types
+#define REGION_T_KERNEL_BASE 0x00000001 // base kernel code & data
+#define REGION_T_DESCRIPTORS 0x00000002 // contains more region descriptors
+#define REGION_T_PAGEDIR 0x00000010 // used to map a page directory
+#define REGION_T_PAGETABLE 0x00000020 // used to map a page table
+#define REGION_T_CORE_HEAP 0x00000100 // used for the core kernel heap
+#define REGION_T_PROC_HEAP 0x00000200 // used for a kernel process' heap
+#define REGION_T_CACHE 0x00001000 // used for cache
+#define REGION_T_HW 0x00002000 // used for hardware access
+
+struct region_info;
+typedef void (*page_fault_handler_t)(pagedir_t *pd, struct region_info *r, size_t addr);
+
+typedef struct region_info {
+ size_t addr, size;
+ uint32_t type;
+ page_fault_handler_t pf;
+} region_info_t;
+
+void region_allocator_init(void* kernel_data_end);
+
+size_t region_alloc(size_t size, uint32_t type, page_fault_handler_t pf); // returns 0 on error
+region_info_t *find_region(size_t addr);
+void region_free(size_t addr);
+
+void dbg_print_region_stats();
diff --git a/kernel/l0/kmain.c b/kernel/l0/kmain.c
index f6cda4e..cd84cf7 100644
--- a/kernel/l0/kmain.c
+++ b/kernel/l0/kmain.c
@@ -7,6 +7,7 @@
#include <idt.h>
#include <frame.h>
#include <paging.h>
+#include <region.h>
void breakpoint_handler(registers_t *regs) {
dbg_printf("Breakpoint! (int3)\n");
@@ -43,6 +44,34 @@ void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) {
paging_setup(kernel_data_end);
dbg_printf("Paging seems to be working!\n");
+ region_allocator_init(kernel_data_end);
+ dbg_print_region_stats();
+
+ size_t p = region_alloc(0x1000, REGION_T_HW, 0);
+ dbg_printf("Allocated one-page region: 0x%p\n", p);
+ dbg_print_region_stats();
+ size_t q = region_alloc(0x1000, REGION_T_HW, 0);
+ dbg_printf("Allocated one-page region: 0x%p\n", q);
+ dbg_print_region_stats();
+ size_t r = region_alloc(0x2000, REGION_T_HW, 0);
+ dbg_printf("Allocated two-page region: 0x%p\n", r);
+ dbg_print_region_stats();
+ size_t s = region_alloc(0x10000, REGION_T_CORE_HEAP, 0);
+ dbg_printf("Allocated 16-page region: 0x%p\n", s);
+ dbg_print_region_stats();
+ region_free(p);
+ dbg_printf("Freed region 0x%p\n", p);
+ dbg_print_region_stats();
+ region_free(q);
+ dbg_printf("Freed region 0x%p\n", q);
+ dbg_print_region_stats();
+ region_free(r);
+ dbg_printf("Freed region 0x%p\n", r);
+ dbg_print_region_stats();
+ region_free(s);
+ dbg_printf("Freed region 0x%p\n", s);
+ dbg_print_region_stats();
+
// TODO:
// - setup allocator for physical pages (eg: buddy allocator, see OSDev wiki)
// - setup allocator for virtual memory space
diff --git a/kernel/l0/paging.c b/kernel/l0/paging.c
index 9e9df6b..f076aa1 100644
--- a/kernel/l0/paging.c
+++ b/kernel/l0/paging.c
@@ -1,5 +1,7 @@
#include <paging.h>
#include <frame.h>
+#include <idt.h>
+#include <dbglog.h>
typedef union page {
struct {
@@ -38,6 +40,14 @@ static pagedir_t kernel_pd;
static pagedir_t *current_pd;
+void page_fault_handler(registers_t *regs) {
+ size_t addr;
+ asm volatile("movl %%cr2, %0":"=r"(addr));
+ dbg_printf("Page fault at 0x%p\n", addr);
+ PANIC("PAGE FAULT");
+ // not handled yet
+}
+
void paging_setup(void* kernel_data_end) {
size_t n_kernel_pages =
PAGE_ALIGN_UP((size_t)kernel_data_end - K_HIGHHALF_ADDR)/PAGE_SIZE;
@@ -76,7 +86,7 @@ void paging_setup(void* kernel_data_end) {
cr4 &= ~0x00000010;
asm volatile("movl %0, %%cr4":: "r"(cr4));
- // TODO : setup page fault handler
+ idt_set_ex_handler(EX_PAGE_FAULT, page_fault_handler);
}
pagedir_t *get_current_pagedir() {
diff --git a/kernel/l0/region.c b/kernel/l0/region.c
new file mode 100644
index 0000000..421a018
--- /dev/null
+++ b/kernel/l0/region.c
@@ -0,0 +1,293 @@
+#include <region.h>
+#include <dbglog.h>
+
+typedef union region_descriptor {
+ struct {
+ union region_descriptor *next;
+ } unused_descriptor;
+ struct {
+ size_t addr, size;
+ union region_descriptor *next_by_size, *first_bigger;
+ union region_descriptor *next_by_addr;
+ } free;
+ struct {
+ region_info_t i;
+ union region_descriptor *next_by_addr;
+ } used;
+} descriptor_t;
+
+#define N_BASE_DESCRIPTORS 12 // pre-allocate memory for 12 descriptors
+static descriptor_t base_descriptors[N_BASE_DESCRIPTORS];
+
+static descriptor_t *first_unused_descriptor;
+static descriptor_t *first_free_region_by_addr, *first_free_region_by_size;
+static descriptor_t *first_used_region;
+
+// ========================================================= //
+// HELPER FUNCTIONS FOR THE MANIPULATION OF THE REGION LISTS //
+// ========================================================= //
+
+static void add_unused_descriptor(descriptor_t *d) {
+ d->unused_descriptor.next = first_unused_descriptor;
+ first_unused_descriptor = d;
+}
+
+static descriptor_t *get_unused_descriptor() {
+ descriptor_t *r = first_unused_descriptor;
+ if (r != 0) first_unused_descriptor = r->unused_descriptor.next;
+ return r;
+}
+
+static void remove_free_region(descriptor_t *d) {
+ if (first_free_region_by_size == d) {
+ first_free_region_by_size = d->free.next_by_size;
+ } else {
+ for (descriptor_t *i = first_free_region_by_size; i != 0; i = i->free.next_by_size) {
+ if (i->free.next_by_size == d) {
+ i->free.next_by_size = d->free.next_by_size;
+ break;
+ }
+ }
+ }
+ if (first_free_region_by_addr == d) {
+ first_free_region_by_addr = d->free.next_by_addr;
+ } else {
+ for (descriptor_t *i = first_free_region_by_addr; i != 0; i = i->free.next_by_addr) {
+ if (i->free.next_by_addr == d) {
+ i->free.next_by_addr = d->free.next_by_addr;
+ break;
+ }
+ }
+ }
+}
+
+static void add_free_region(descriptor_t *d) {
+ /*dbg_printf("Add free region 0x%p - 0x%p\n", d->free.addr, d->free.size + d->free.addr);*/
+ // Find position of region in address-ordered list
+ // Possibly concatenate free region
+ descriptor_t *i = first_free_region_by_addr;
+ if (i == 0) {
+ ASSERT(first_free_region_by_size == 0);
+ first_free_region_by_addr = first_free_region_by_size = d;
+ d->free.next_by_size = d->free.first_bigger = d->free.next_by_addr = 0;
+ return;
+ } else if (d->free.addr + d->free.size == i->free.addr) {
+ // concatenate d . i
+ remove_free_region(i);
+ d->free.size += i->free.size;
+ add_unused_descriptor(i);
+ add_free_region(d);
+ return;
+ } else if (i->free.addr > d->free.addr) {
+ // insert before i
+ d->free.next_by_addr = i;
+ first_free_region_by_addr = d;
+ } else {
+ while (i != 0) {
+ ASSERT(d->free.addr > i->free.addr);
+ if (i->free.addr + i->free.size == d->free.addr) {
+ // concatenate i . d
+ remove_free_region(i);
+ i->free.size += d->free.size;
+ add_unused_descriptor(d);
+ add_free_region(i);
+ return;
+ } else if (i->free.next_by_addr == 0) {
+ i->free.next_by_addr = d;
+ d->free.next_by_addr = 0;
+ break;
+ } else if (d->free.addr + d->free.size == i->free.next_by_addr->free.addr) {
+ // concatenate d . i->next_by_addr
+ descriptor_t *j = i->free.next_by_addr;
+ remove_free_region(j);
+ d->free.size += j->free.size;
+ add_unused_descriptor(j);
+ add_free_region(d);
+ return;
+ } else if (i->free.next_by_addr->free.addr > d->free.addr) {
+ // insert between i and i->next_by_addr
+ d->free.next_by_addr = i->free.next_by_addr;
+ i->free.next_by_addr = d;
+ break;
+ } else {
+ // continue
+ i = i->free.next_by_addr;
+ }
+ }
+ }
+ // Now add it in size-ordered list
+ i = first_free_region_by_size;
+ ASSERT(i != 0);
+ if (d->free.size <= i->free.size) {
+ d->free.next_by_size = i;
+ d->free.first_bigger = (i->free.size > d->free.size ? i : i->free.first_bigger);
+ first_free_region_by_size = d;
+ } else {
+ while (i != 0) {
+ ASSERT(d->free.size > i->free.size);
+ if (i->free.next_by_size == 0) {
+ i->free.next_by_size = d;
+ if (d->free.size > i->free.size) i->free.first_bigger = d;
+ d->free.next_by_size = 0;
+ d->free.first_bigger = 0;
+ break;
+ } else if (i->free.next_by_size->free.size >= d->free.size) {
+ i->free.next_by_size = d;
+ if (d->free.size > i->free.size) i->free.first_bigger = d;
+ d->free.next_by_size = i->free.next_by_size;
+ d->free.first_bigger =
+ (i->free.next_by_size->free.size > d->free.size
+ ? i->free.next_by_size
+ : i->free.next_by_size->free.first_bigger);
+ break;
+ } else {
+ // continue
+ i = i->free.next_by_size;
+ }
+ }
+ }
+}
+
+static descriptor_t *find_used_region(size_t addr) {
+ for (descriptor_t *i = first_used_region; i != 0; i = i->used.next_by_addr) {
+ if (addr >= i->used.i.addr && addr < i->used.i.addr + i->used.i.size) return i;
+ if (i->used.i.addr > addr) break;
+ }
+ return 0;
+}
+
+static void add_used_region(descriptor_t *d) {
+ descriptor_t *i = first_used_region;
+ ASSERT(i->used.i.addr < d->used.i.addr); // first region by address is never free
+
+ while (i != 0) {
+ ASSERT(i->used.i.addr < d->used.i.addr);
+ if (i->used.next_by_addr == 0 || i->used.next_by_addr->used.i.addr > d->used.i.addr) {
+ d->used.next_by_addr = i->used.next_by_addr;
+ i->used.next_by_addr = d;
+ return;
+ } else {
+ i = i->used.next_by_addr;
+ }
+ }
+ ASSERT(false);
+}
+
+static void remove_used_region(descriptor_t *d) {
+ if (first_used_region == d) {
+ first_used_region = d->used.next_by_addr;
+ } else {
+ for (descriptor_t *i = first_used_region; i != 0; i = i->used.next_by_addr) {
+ if (i->used.i.addr > d->used.i.addr) break;
+ if (i->used.next_by_addr == d) {
+ i->used.next_by_addr = d->used.next_by_addr;
+ break;
+ }
+ }
+ }
+}
+
+// =============== //
+// THE ACTUAL CODE //
+// =============== //
+
+void region_allocator_init(void* kernel_data_end) {
+ descriptor_t *u0 = &base_descriptors[0];
+ u0->used.i.addr = K_HIGHHALF_ADDR;
+ u0->used.i.size = PAGE_ALIGN_UP(kernel_data_end) - K_HIGHHALF_ADDR;
+ u0->used.i.type = REGION_T_KERNEL_BASE;
+ u0->used.i.pf = 0;
+ u0->used.next_by_addr = 0;
+ first_used_region = u0;
+
+ descriptor_t *f0 = &base_descriptors[1];
+ f0->free.addr = PAGE_ALIGN_UP(kernel_data_end);
+ f0->free.size = (0xFFFFF000-f0->free.addr); // last page cannot be used...
+ f0->free.next_by_size = 0;
+ f0->free.first_bigger = 0;
+ first_free_region_by_size = first_free_region_by_addr = f0;
+
+ first_unused_descriptor = 0;
+ for (int i = 2; i < N_BASE_DESCRIPTORS; i++) {
+ add_unused_descriptor(&base_descriptors[i]);
+ }
+}
+
+size_t region_alloc(size_t size, uint32_t type, page_fault_handler_t pf) {
+ size = PAGE_ALIGN_UP(size);
+
+ for (descriptor_t *i = first_free_region_by_size; i != 0; i = i->free.first_bigger) {
+ if (i->free.size >= size) {
+ remove_free_region(i);
+ if (i->free.size > size) {
+ descriptor_t *x = get_unused_descriptor();
+ if (x == 0) {
+ return 0;
+ // TODO: allocate more descriptors
+ }
+ x->free.size = i->free.size - size;
+ if (size >= 0x4000) {
+ x->free.addr = i->free.addr + size;
+ } else {
+ x->free.addr = i->free.addr;
+ i->free.addr += x->free.size;
+ }
+ add_free_region(x);
+ }
+ size_t addr = i->free.addr;
+ i->used.i.addr = addr;
+ i->used.i.size = size;
+ i->used.i.type = type;
+ i->used.i.pf = pf;
+ add_used_region(i);
+ return addr;
+ }
+ }
+ return 0; //Not found
+}
+
+region_info_t *find_region(size_t addr) {
+ descriptor_t *d = find_used_region(addr);
+ if (d == 0) return 0;
+ return &d->used.i;
+}
+
+void region_free(size_t addr) {
+ descriptor_t *d = find_used_region(addr);
+ if (d == 0) return;
+
+ region_info_t i = d->used.i;
+
+ remove_used_region(d);
+ d->free.addr = i.addr;
+ d->free.size = i.size;
+ add_free_region(d);
+}
+
+void dbg_print_region_stats() {
+ dbg_printf("/ Free kernel regions, by address:\n");
+ for (descriptor_t *d = first_free_region_by_addr; d != 0; d = d->free.next_by_addr) {
+ dbg_printf("| 0x%p - 0x%p\n", d->free.addr, d->free.addr + d->free.size);
+ ASSERT(d != d->free.next_by_addr);
+ }
+ dbg_printf("- Free kernel regions, by size:\n");
+ for (descriptor_t *d = first_free_region_by_size; d != 0; d = d->free.next_by_size) {
+ dbg_printf("| 0x%p - 0x%p\n", d->free.addr, d->free.addr + d->free.size);
+ ASSERT(d != d->free.next_by_size);
+ }
+ dbg_printf("- Used kernel regions:\n");
+ for (descriptor_t *d = first_used_region; d != 0; d = d->used.next_by_addr) {
+ dbg_printf("| 0x%p - 0x%p", d->used.i.addr, d->used.i.addr + d->used.i.size);
+ if (d->used.i.type & REGION_T_KERNEL_BASE) dbg_printf(" Kernel code & base data");
+ if (d->used.i.type & REGION_T_DESCRIPTORS) dbg_printf(" Region descriptors");
+ if (d->used.i.type & REGION_T_PAGEDIR) dbg_printf(" Mapped page directory");
+ if (d->used.i.type & REGION_T_PAGETABLE) dbg_printf(" Mapped page table");
+ if (d->used.i.type & REGION_T_CORE_HEAP) dbg_printf(" Core heap");
+ if (d->used.i.type & REGION_T_PROC_HEAP) dbg_printf(" Kernel process heap");
+ if (d->used.i.type & REGION_T_CACHE) dbg_printf(" Cache");
+ if (d->used.i.type & REGION_T_HW) dbg_printf(" Hardware");
+ dbg_printf("\n");
+ ASSERT(d != d->used.next_by_addr);
+ }
+ dbg_printf("\\\n");
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-19 16:29:49 +0000