Working on reorganizing kernel.c

Syscalls just return an int

.gitignore

@@ -6,7 +6,7 @@ quark-kernel
 autom4te.cache/
 .deps
 .dirstamp
-.vscode
+#.vscode
 aclocal.m4
 ar-lib
 compile

.vscode/c_cpp_properties.json

@@ -0,0 +1,45 @@
+{
+    "configurations": [
+        {
+            "name": "Linux",
+            "includePath": [
+                "${workspaceFolder}/**",
+                "~/.quark/include"
+            ],
+            "defines": [],
+            "compilerPath": "/opt/cross/bin/i686-elf-gcc",
+            "cStandard": "c11",
+            "cppStandard": "c++11",
+            "intelliSenseMode": "linux-gcc-x86",
+            "compilerArgs": [
+                "-ffreestanding",
+                "-nostdlib"
+            ]
+        },
+        {
+            "name": "i686-cross",
+            "includePath": [
+                "/home/nathan/Documents/projects/quark-os/quark-kernel/**",
+                "/opt/quark-os/rootfs/include/",
+                "${workspaceFolder}/include"
+            ],
+            "defines": [],
+            "compilerPath": "/opt/cross/bin/i686-elf-gcc",
+            "cppStandard": "c++14",
+            "intelliSenseMode": "linux-gcc-x86",
+            "compilerArgs": [
+                "-ffreestanding ",
+                "-nostdlib"
+            ],
+            "cStandard": "c11",
+            "mergeConfigurations": false,
+            "browse": {
+                "path": [
+                    "${workspaceFolder}/**"
+                ],
+                "limitSymbolsToIncludedHeaders": true
+            }
+        }
+    ],
+    "version": 4
+}

.vscode/launch.json

@@ -0,0 +1,37 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "(gdb) Launch",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "/opt/quark-os/rootfs/apps/quark-kernel",
+            "args": [],
+            "stopAtEntry": true,
+            "stopAtConnect": true,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "externalConsole": true,
+            "MIMode": "gdb",
+            "miDebuggerServerAddress": "localhost:1234",
+            "setupCommands": [
+                {
+                    "description": "Enable pretty-printing for gdb",
+                    "text": "-enable-pretty-printing",
+                    "ignoreFailures": true
+                }/*,
+                {
+                    "text": "-target-select remote localhost:1234",
+                    "ignoreFailures": false
+                }*/
+            ],
+            "preLaunchTask": "Launch QEMU (i386)"
+            /*"debugServerPath": "/bin/qemu-system-i386",
+            "debugServerArgs": "-hda /opt/quark-os/quark.img -serial stdio -s -S",
+            "serverLaunchTimeout": 2000*/
+        }
+    ]
+}

.vscode/settings.json

@@ -0,0 +1,28 @@
+{
+    "files.exclude": {
+        "**/*.o": true,
+        "**/ar-lib": true,
+        "**/Makefile": true,
+        "**/*.in": true,
+        "**/stamp-h1": true,
+        "**/*.a": true,
+        "aclocal.m4": true,
+        "compile": true,
+        "config.log": true,
+        "config.status": true,
+        "configure*": true,
+        "depcomp": true,
+        "install-sh": true,
+        "missing": true,
+        "**/.deps": true,
+        "autom4te.cache": true,
+        "**/quark-kernel": true
+    },
+    "C_Cpp.default.cStandard": "c11",
+    "files.associations": {
+        "memmap.h": "c",
+        "pid.h": "c",
+        "sighandler.h": "c",
+        "string.h": "c"
+    }
+}

.vscode/tasks.json

@@ -0,0 +1,27 @@
+{
+    // See https://go.microsoft.com/fwlink/?LinkId=733558
+    // for the documentation about the tasks.json format
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "make",
+            "type": "shell",
+            "command": "PATH=\"$PATH:/opt/cross/bin\" make",
+            "problemMatcher": ["$gcc"],
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            }
+        },
+        {
+            "label": "Launch QEMU (i386)",
+            "type": "shell",
+            "command": "qemu-system-i386 -hda /opt/quark-os/quark.img -serial stdio -s -S",
+            "isBackground": true,
+            "group": {
+                "kind": "test",
+                "isDefault": true
+            }
+        }
+    ]
+}

README.md

@@ -14,4 +14,4 @@ To build the kernel for the x86 platform, run:
 - `make`
 
 So far this code has only been tested to compile using GCC. Some modifications might be necessary to build this project using other compilers. For a guide on building
-a cross-compiler, see the article on [osdev.org](https://wiki.osdev.org/GCC_Cross-Compiler).
+a cross-compiler, see the article on [osdev.org](https://wiki.osdev.org/GCC_Cross-Compiler).

include/Makefile.am

@@ -1 +1,3 @@
-nobase_include_HEADERS = types/status.h types/syscallid.h types/physaddr.h types/syscallarg.h
+nobase_include_HEADERS = types/status.h types/syscallid.h types/physaddr.h \ 
+    types/syscallarg.h sys/syscalls.h types/pid.h types/oid.h \
+    types/sigaction.h types/message.h

include/addressspace.h

@@ -0,0 +1,20 @@
+#ifndef QUARK_ADDRESSSPACE_H
+#define QUARK_ADDRESSSPACE_H
+
+#include "types/physaddr.h"
+
+typedef struct address_space_t
+{
+    physaddr_t page_table;
+    int refcount;
+} address_space_t;
+
+address_space_t *address_space_construct();
+
+void address_space_switch(address_space_t *address_space);
+
+address_space_t *address_space_release(address_space_t *address_space);
+
+void address_space_destroy(address_space_t *address_space);
+
+#endif

include/avltree.h

@@ -38,4 +38,12 @@ struct avltree_t *avl_remove(struct avltree_t *tree, int key);
  * @param key 
  * @return void* 
  */
-void *avl_get(struct avltree_t *tree, int key);
+void *avl_get(struct avltree_t *tree, int key);
+
+/**
+ * @brief Removes every node present on the given tree.
+ * 
+ * @param tree
+ * @return NULL
+ */
+void *avl_clear(struct avltree_t *tree);

include/heap.h

@@ -8,13 +8,11 @@
  * This function contructs the heap's internal tables, allocating pages as needed
  * to do so.
  * 
- * @param page_stack Pointer to the page stack descriptor
  * @param base Base location of the heap to contruct
  * @param heap_size Total size in bytes of the heap
- * @param block_size Size in bytes of a single unit of allocation
  * @return a status code
  */
-int kminit(void *base, void* start, size_t heap_size, size_t block_size);
+int kminit(void *base, size_t heap_size);
 
 /**
  * @brief Allocates a block of memory containing at least `size` bytes.

include/kernel.h

@@ -5,13 +5,19 @@
 #include "queue.h"
 #include "mmgr.h"
 #include "syscalls.h"
+#include "addressspace.h"
+#include "process.h"
+#include "types/message.h"
 #include "types/syscallid.h"
 #include "types/status.h"
+#include "types/pid.h"
+#include "types/oid.h"
+#include "types/sighandler.h"
 #include <libmalloc/memmap.h>
 #include <stddef.h>
 
 #define MAX_SYSCALL_ID 256
-#define module_limit 8
+#define MODULE_LIMIT 8
 
 #define IO_OP 1 << 0
 #define IO_SYNC 0 << 0
@@ -22,8 +28,6 @@
 #define IO_PORT 1 << 1
 #define IO_MAILBOX 2 << 1
 
-typedef unsigned long (*signal_handler_t)(void*, void*);
-
 struct process_context_t;
 
 struct module_t
@@ -40,94 +44,42 @@ struct boot_info_t
     size_t memory_size;
     memory_map_t map;
     size_t module_count;
-    struct module_t modules[module_limit];
+    struct module_t modules[MODULE_LIMIT];
-};
-
-struct message_t
-{
-    unsigned long sender;
-    unsigned long code;
-    unsigned long args[6];
-};
-
-enum process_state_t
-{
-    PROCESS_ACTIVE,
-    PROCESS_REQUESTING,
-    PROCESS_SENDING
-};
-
-struct process_t
-{
-    unsigned long pid;
-    int priority;
-    physaddr_t page_table;
-    enum process_state_t state;
-    struct queue_t sending_queue;
-    struct queue_t message_queue;
-    struct message_t *message_buffer;
-    struct process_context_t *ctx;
-};
-
-struct port_t
-{
-    unsigned long id;
-    unsigned long owner_pid;
-};
-
-struct signal_action_t
-{
-    unsigned long pid;
-    signal_handler_t func_ptr;
-    void (*trampoline_ptr)();
-    void *userdata;
-};
-
-struct signal_context_t
-{
-    unsigned long signal_id;
-};
-
-struct kernel_t
-{
-    struct syscall_t syscall_table[MAX_SYSCALL_ID];
-    struct priority_queue_t priority_queue;
-    struct avltree_t *interrupt_handlers;
-    struct avltree_t *port_table;
-    struct avltree_t *process_table;
-    struct process_t *active_process;
-    int next_pid;
 };
 
 void kernel_initialize(struct boot_info_t *boot_info);
 
-error_t set_syscall(int id, int arg_count, int pid, void *func_ptr);
+process_t *kernel_get_process(pid_t pid);
 
-size_t do_syscall(syscall_id_t id, syscall_arg_t arg1, syscall_arg_t arg2, syscall_arg_t arg3, void *pc, void *stack, unsigned long flags);
+process_t *kernel_get_active_process();
+
+error_t kernel_set_syscall(int id, int arg_count, void *func_ptr);
+
+size_t kernel_do_syscall(syscall_id_t id, syscall_arg_t arg1, syscall_arg_t arg2, syscall_arg_t arg3, void *pc, void *stack, unsigned long flags);
 
 error_t kernel_load_module(struct module_t *module);
 
-unsigned long kernel_current_pid();
+pid_t kernel_current_pid();
 
 struct process_context_t *kernel_current_context();
 
 error_t kernel_store_active_context(struct process_context_t *context);
 
-unsigned long kernel_spawn_process(void *program_entry, int priority, physaddr_t address_space);
+pid_t kernel_spawn_process(void *program_entry, int priority, address_space_t *address_space);
 
 struct process_context_t *kernel_advance_scheduler();
 
-error_t kernel_terminate_process(size_t process_id);
+void kernel_schedule_process(process_t *process);
+
+error_t kernel_terminate_process(pid_t process_id);
 
 error_t kernel_create_port(unsigned long id);
 
 error_t kernel_remove_port(unsigned long id);
 
-unsigned long kernel_get_port_owner(unsigned long id);
+pid_t kernel_get_port_owner(unsigned long id);
 
-error_t kernel_send_message(unsigned long recipient, struct message_t *message);
+int kernel_receive_message(struct message_t *buffer, int flags);
-
-error_t kernel_queue_message(unsigned long recipient, struct message_t *message);
 
 error_t kernel_register_interrupt_handler(unsigned long interrupt, signal_handler_t handler, void *userdata);
 
@@ -137,6 +89,10 @@ error_t kernel_execute_interrupt_handler(unsigned long interrupt);
 
 error_t kernel_signal_return();
 
-int receive_message(struct message_t *buffer, int flags);
+error_t kernel_create_object(size_t size, unsigned long flags, oid_t *id);
 
-void panic(const char *message) __attribute__ ((noreturn));
+error_t kernel_attach_object(oid_t id, void *virt_addr);
+
+error_t kernel_release_object(oid_t id);
+
+void kernel_panic(const char *message) __attribute__ ((noreturn));

include/mmgr.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "sharedobject.h"
 #include "platform/paging.h"
 #include "types/physaddr.h"
 #include "types/status.h"
@@ -23,7 +24,7 @@ physaddr_t reserve_pages(size_t size);
  * @param size 
  * @return int 
  */
-int free_pages(physaddr_t location, size_t size);
+size_t free_pages(physaddr_t location);
 
 /**
  * @brief Reserves a single page and returns its physical address.
@@ -92,6 +93,36 @@ physaddr_t create_address_space();
  */
 physaddr_t current_address_space();
 
+/**
+ * @brief Maps a region in virtual memory with the specified flags.
+ * 
+ * @param page
+ * @param frame
+ * @param size
+ * @param flags
+ */
+error_t map_region(void *page, physaddr_t frame, size_t size, int flags);
+
+/**
+ * @brief Maps a shared object into virtual memory.
+ * 
+ * @param location 
+ * @param object 
+ * @return 
+ */
+error_t map_object(void *location, shared_object_t *object);
+
+/**
+ * @brief Unmaps a region in virtual memory. All pages which contain some part
+ * of the region specified will be unmapped.
+ * 
+ * @param page
+ * @param size
+ * 
+ * @returns The physical address of the first page that was unmapped
+ */
+physaddr_t unmap_region(void *page, size_t size);
+
 /**
  * @brief Maps a single page with the specified flags.
  * 
@@ -100,7 +131,7 @@ physaddr_t current_address_space();
  * @param flags 
  * @return int 
  */
-int map_page(void *page, physaddr_t frame, int flags);
+error_t map_page(void *page, physaddr_t frame, int flags);
 
 /**
  * @brief Unmaps a single page, returning the physical address of the frame it

include/platform/context.h

@@ -33,6 +33,8 @@ struct process_context_t
 
 void load_context(struct process_context_t *context);
 
+void context_construct(struct process_context_t *context);
+
 void *get_context_pc(struct process_context_t *context);
 
 void set_context_pc(struct process_context_t *context, void *pc);

include/process.h

@@ -0,0 +1,39 @@
+#ifndef QUARK_PROCESS_H
+#define QUARK_PROCESS_H
+
+#include "types/message.h"
+#include "types/pid.h"
+#include "types/physaddr.h"
+#include "types/status.h"
+#include "queue.h"
+#include "addressspace.h"
+#include "sharedobject.h"
+
+typedef enum process_state_t
+{
+    PROCESS_ACTIVE,
+    PROCESS_REQUESTING,
+    PROCESS_SENDING
+} process_state_t;
+
+typedef struct process_t
+{
+    pid_t pid;
+    int priority;
+    address_space_t *address_space;
+    struct avltree_t *shared_objects;
+    process_state_t state;
+    struct queue_t message_queue;
+    struct message_t *message_buffer;
+    struct process_context_t *ctx;
+} process_t;
+
+process_t *process_construct(pid_t pid, void *entry, void *stack, int priority, address_space_t *address_space);
+
+error_t process_queue_message(process_t *process, message_t *msg);
+
+error_t process_store_object(process_t *process, int id, void *location);
+
+void *process_get_object(process_t *process, int id);
+
+#endif

include/sharedobject.h

@@ -0,0 +1,19 @@
+#ifndef QUARK_SHARED_OBJECT_H
+#define QUARK_SHARED_OBJECT_H
+
+#include "types/physaddr.h"
+#include <stddef.h>
+
+typedef struct shared_object_t
+{
+    physaddr_t phys_addr;
+    size_t size;
+    unsigned long access_flags;
+    unsigned long refcount;
+} shared_object_t;
+
+struct shared_object *create_shared_object(size_t size, unsigned long flags);
+
+void destroy_shared_object(struct shared_object_t *obj);
+
+#endif

include/sys/syscalls.h

@@ -0,0 +1,236 @@
+#ifndef _QUARK_SYSCALLS_H
+#define _QUARK_SYSCALLS_H
+
+#include <types/syscallid.h>
+#include <types/physaddr.h>
+#include <types/pid.h>
+#include <types/sigaction.h>
+#include <stddef.h>
+
+/**
+ * @brief Executes a system call
+ * @param id The ID of the syscall to execute
+ * @return An error code, with 0 indicating success
+ */
+int _do_syscall(syscall_id_t id, ...);
+
+/**
+ * @brief 
+ * @param s The string to print 
+ * @return 
+ */
+static inline int kprint(const char *s)
+{
+    return _do_syscall(SYSCALL_TEST, s);
+}
+
+/**
+ * @brief 
+ * @param addr 
+ * @param length 
+ * @param flags 
+ * @return 
+ */
+static inline int map_anon(void *addr, size_t length, long flags)
+{
+    return _do_syscall(SYSCALL_MAP_ANON, addr, length, flags);
+}
+
+/**
+ * @brief 
+ * @param addr 
+ * @param length 
+ * @return 
+ */
+static inline int unmap_anon(void *addr)
+{
+    return _do_syscall(SYSCALL_UNMAP_ANON, addr);
+}
+
+/**
+ * @brief 
+ * @param addr 
+ * @param phys_addr 
+ * @param length 
+ * @return 
+ */
+static inline int map_physical(void *addr, physaddr_t phys_addr, size_t length)
+{
+    return _do_syscall(SYSCALL_MAP_PHYS, addr, phys_addr, length);
+}
+
+/**
+ * @brief 
+ * @param addr 
+ * @param length 
+ * @return 
+ */
+static inline int unmap_physical(void *addr, size_t length)
+{
+    return _do_syscall(SYSCALL_UNMAP_PHYS, addr, length);
+}
+
+/**
+ * @brief 
+ * @param id 
+ * @return 
+ */
+static inline int open_port(int id)
+{
+    return _do_syscall(SYSCALL_OPEN_PORT, id);
+}
+
+/**
+ * @brief 
+ * @param id 
+ * @return 
+ */
+static inline int close_port(int id)
+{
+    return _do_syscall(SYSCALL_CLOSE_PORT, id);
+}
+
+/**
+ * @brief 
+ * @param recipient 
+ * @param message 
+ * @param flags 
+ * @return 
+ */
+static inline int send_pid(pid_t recipient, void *message, int flags)
+{
+    return _do_syscall(SYSCALL_SEND_PID, recipient, message, flags);
+}
+
+/**
+ * @brief 
+ * @param recipient 
+ * @param message 
+ * @param flags 
+ * @return 
+ */
+static inline int send_port(int recipient, void *message, int flags)
+{
+    return _do_syscall(SYSCALL_SEND_PORT, recipient, message, flags);
+}
+
+/**
+ * @brief 
+ * @param buffer 
+ * @param flags 
+ * @return 
+ */
+static inline int receive(void *buffer, int flags)
+{
+    return _do_syscall(SYSCALL_RECEIVE, buffer, flags);
+}
+
+/**
+ * @brief 
+ * @param location 
+ * @param size 
+ * @param flags 
+ * @return 
+ */
+static inline int create_object(void *location, size_t size, int flags)
+{
+    return _do_syscall(SYSCALL_CREATE_OBJECT, location, size, flags);
+}
+
+/**
+ * @brief 
+ * @param id 
+ * @param location 
+ * @return 
+ */
+static inline int aquire_object(int id, void *location)
+{
+    return _do_syscall(SYSCALL_AQUIRE_OBJECT, id, location);
+}
+
+/**
+ * @brief 
+ * @param id 
+ * @return 
+ */
+static inline int release_object(int id)
+{
+    return _do_syscall(SYSCALL_RELEASE_OBJECT, id);
+}
+
+/**
+ * @brief 
+ * @return 
+ */
+static inline int get_pid()
+{
+    return _do_syscall(SYSCALL_GET_PID);
+}
+
+/**
+ * @brief 
+ * @param entry 
+ * @param arg 
+ * @param stack 
+ * @param flags 
+ * @return 
+ */
+static inline int clone(void (*entry)(void*), void *arg, void *stack, int flags)
+{
+    return _do_syscall(SYSCALL_CLONE, entry, arg, stack, flags);
+}
+
+/**
+ * @brief 
+ * @param id 
+ * @param action 
+ * @param flags 
+ * @return 
+ */
+static inline int signal_action(int id, struct signal_action_t *action, int flags)
+{
+    return _do_syscall(SYSCALL_SIGNAL_ACTION, id, action, flags);
+}
+
+/**
+ * @brief 
+ * @return 
+ */
+static inline int signal_return()
+{
+    return _do_syscall(SYSCALL_SIGNAL_RETURN);
+}
+
+/**
+ * @brief 
+ * @param pid 
+ * @param sigid 
+ * @return 
+ */
+static inline int signal_raise(pid_t pid, int sigid)
+{
+    return _do_syscall(SYSCALL_SIGNAL_RAISE, pid, sigid);
+}
+
+/**
+ * @brief 
+ * @param id 
+ * @param action 
+ * @param flags 
+ * @return 
+ */
+static inline int intr_action(int id, struct signal_action_t *action, int flags)
+{
+    return _do_syscall(SYSCALL_INTR_ACTION, id, action, flags);
+}
+
+/**
+ * @brief 
+ * @return 
+ */
+static inline int intr_return()
+{
+    return _do_syscall(SYSCALL_INTR_RETURN);
+}
+
+#endif

include/syscalls.h

@@ -1,22 +1,27 @@
-#pragma once
+#ifndef QUARK_SYSCALL_DEF_H
+#define QUARK_SYSCALL_DEF_H
 
 #include "types/syscallarg.h"
+#include "types/sigaction.h"
+#include "types/pid.h"
+#include "types/oid.h"
 #include <stdbool.h>
 #include <stddef.h>
 
-typedef size_t (*syscall_ptr_0_t)();
+extern void *syscall_table[];
 
-typedef size_t (*syscall_ptr_1_t)(syscall_arg_t);
+typedef int (*syscall_ptr_0_t)();
 
-typedef size_t (*syscall_ptr_2_t)(syscall_arg_t, syscall_arg_t);
+typedef int (*syscall_ptr_1_t)(syscall_arg_t);
 
-typedef size_t (*syscall_ptr_3_t)(syscall_arg_t, syscall_arg_t, syscall_arg_t);
+typedef int (*syscall_ptr_2_t)(syscall_arg_t, syscall_arg_t);
+
+typedef int (*syscall_ptr_3_t)(syscall_arg_t, syscall_arg_t, syscall_arg_t);
 
 struct syscall_t
 {
     bool defined;
     int arg_count;
-    int process_id;
     union
     {
         syscall_ptr_0_t func_ptr_0;
@@ -26,18 +31,106 @@ struct syscall_t
     };
 };
 
-size_t test_syscall(syscall_arg_t str);
+/**
+ * @brief Outputs the given string from kernel mode.
+ * 
+ * @param str The string to output.
+ */
+int test_syscall(syscall_arg_t str);
 
-size_t mmap(syscall_arg_t location, syscall_arg_t length, syscall_arg_t flags);
+/**
+ * 
+ */
+int syscall_map_anon(syscall_arg_t location, syscall_arg_t length, syscall_arg_t flags);
 
-size_t munmap(syscall_arg_t location, syscall_arg_t length);
+/**
+ * 
+ */
+int syscall_unmap_anon(syscall_arg_t location);
 
-size_t terminate_self();
+/**
+ * 
+ */
+int syscall_map_physical(syscall_arg_t arg_addr, syscall_arg_t arg_phys_addr, syscall_arg_t arg_length);
 
-size_t send(syscall_arg_t recipient, syscall_arg_t message, syscall_arg_t flags);
+/**
+ * 
+ */
+int syscall_unmap_physical(syscall_arg_t arg_addr, syscall_arg_t arg_length);
 
-size_t receive(syscall_arg_t buffer, syscall_arg_t flags);
+/**
+ * 
+ */
+int syscall_open_port(syscall_arg_t id);
 
-size_t open_port(syscall_arg_t id);
+/**
+ * 
+ */
+int syscall_close_port(syscall_arg_t id);
 
-size_t close_port(syscall_arg_t id);
+/**
+ * 
+ */
+int syscall_send_pid(syscall_arg_t recipient, syscall_arg_t message, syscall_arg_t flags);
+
+/**
+ * 
+ */
+int syscall_send_port(syscall_arg_t recipient, syscall_arg_t message, syscall_arg_t flags);
+
+/**
+ * 
+ */
+int syscall_receive(syscall_arg_t buffer, syscall_arg_t flags);
+
+/**
+ * 
+ */
+int syscall_create_object(void *location, size_t size, int flags);
+
+/**
+ * 
+ */
+int syscall_aquire_object(oid_t id, void *location);
+
+/**
+ * 
+ */
+int syscall_release_object(oid_t id);
+
+/**
+ * 
+ */
+int syscall_get_pid();
+
+/**
+ * 
+ */
+int syscall_clone(void (*entry)(void*), void *arg, void *stack, int flags);
+
+/**
+ * 
+ */
+int syscall_signal_action(int id, struct signal_action_t *action, int flags);
+
+/**
+ * 
+ */
+int syscall_signal_return();
+
+/**
+ * 
+ */
+int syscall_signal_raise(pid_t pid, int sigid);
+
+/**
+ * 
+ */
+int syscall_intr_action(int id, struct signal_action_t *action, int flags);
+
+/**
+ * 
+ */
+int syscall_intr_return();
+
+#endif

include/types/message.h

@@ -0,0 +1,13 @@
+#ifndef QUARK_MESSAGE_H
+#define QUARK_MESSAGE_H
+
+#include <types/pid.h>
+
+typedef struct message_t
+{
+    pid_t sender;
+    unsigned long code;
+    unsigned long args[6];
+} message_t;
+
+#endif

include/types/oid.h

@@ -0,0 +1,6 @@
+#ifndef QUARK_OID_H
+#define QUARK_OID_H
+
+typedef unsigned int oid_t;
+
+#endif

include/types/physaddr.h

@@ -1,5 +1,5 @@
-#ifndef _QUARK_PHYSADDR_H
+#ifndef QUARK_PHYSADDR_H
-#define _QUARK_PHYSADDR_H
+#define QUARK_PHYSADDR_H
 
 typedef unsigned long int physaddr_t;
 

include/types/pid.h

@@ -0,0 +1,6 @@
+#ifndef QUARK_PID_H
+#define QUARK_PID_H
+
+typedef unsigned int pid_t;
+
+#endif

include/types/sigaction.h

@@ -0,0 +1,16 @@
+#ifndef QUARK_SIGACTION_H
+#define QUARK_SIGACTION_H
+
+#include "types/pid.h"
+
+typedef unsigned long (*signal_handler_t)(void*, void*);
+
+struct signal_action_t
+{
+    pid_t pid;
+    signal_handler_t func_ptr;
+    void (*trampoline_ptr)();
+    void *userdata;
+};
+
+#endif

include/types/signalid.h

@@ -0,0 +1,10 @@
+#ifndef QUARK_SIGNALID_H
+#define QUARK_SIGNALID_H
+
+typedef enum signalid_t
+{
+    SIG_KILL = 1,
+    SIG_STOP
+} signalid_t;
+
+#endif

include/types/status.h

@@ -1,5 +1,5 @@
-#ifndef _QUARK_ERROR_H
+#ifndef QUARK_ERROR_H
-#define _QUARK_ERROR_H
+#define QUARK_ERROR_H
 
 typedef enum
 {

include/types/syscallarg.h

@@ -1,11 +1,12 @@
-#ifndef _QUARK_SYSCALLARG_H
+#ifndef QUARK_SYSCALLARG_H
-#define _QUARK_SYSCALLARG_H
+#define QUARK_SYSCALLARG_H
 
 typedef union
 {
     long int signed_int;
     unsigned long int unsigned_int;
     void *ptr;
+    char *str;
 } syscall_arg_t;
 
 #endif

include/types/syscallid.h

@@ -4,14 +4,25 @@
 typedef enum
 {
     SYSCALL_TEST = 1,
-    SYSCALL_MMAP,
+    SYSCALL_MAP_ANON,
-    SYSCALL_MUNMAP,
+    SYSCALL_UNMAP_ANON,
-    SYSCALL_YIELD,
+    SYSCALL_MAP_PHYS,
-    SYSCALL_EXIT,
+    SYSCALL_UNMAP_PHYS,
-    SYSCALL_SEND,
-    SYSCALL_RECEIVE,
     SYSCALL_OPEN_PORT,
-    SYSCALL_CLOSE_PORT
+    SYSCALL_CLOSE_PORT,
+    SYSCALL_SEND_PID,
+    SYSCALL_SEND_PORT,
+    SYSCALL_RECEIVE,
+    SYSCALL_CREATE_OBJECT,
+    SYSCALL_AQUIRE_OBJECT,
+    SYSCALL_RELEASE_OBJECT,
+    SYSCALL_GET_PID,
+    SYSCALL_CLONE,
+    SYSCALL_SIGNAL_ACTION,
+    SYSCALL_SIGNAL_RETURN,
+    SYSCALL_SIGNAL_RAISE,
+    SYSCALL_INTR_ACTION,
+    SYSCALL_INTR_RETURN
 } syscall_id_t;
 
 #endif

include/x86/mp.h

@@ -0,0 +1,53 @@
+#include <stdint.h>
+
+#define MP_SIGNATURE (uint32_t) 0x5F504D5F
+
+struct mp_floating_pointer
+{
+    /**
+     * @brief The ASCII string "_MP_" indicates the presence of the pointer structure.
+     * 
+     */
+    uint32_t signature;
+
+    /**
+     * @brief The physical address of the MP configuration table. All zeroes if
+     * the table does not exist.
+     * 
+     */
+    uint32_t physical_addr;
+
+    /**
+     * @brief The length of the floating pointer structure in 16-byte units.
+     * Should contain the value '0x01'.
+     * 
+     */
+    uint8_t length;
+
+    /**
+     * @brief The version number of the MP specification supported.
+     * 
+     */
+    uint8_t spec_rev;
+
+    /**
+     * @brief A checksum of the pointer structure.
+     * 
+     */
+    uint8_t checksum;
+
+    /**
+     * @brief When zero, the configuration table is present. Otherwise, the
+     * value indicates a default configuration.
+     * 
+     */
+    uint8_t config_type;
+
+    uint8_t undef : 7;
+
+    /**
+     * @brief 
+     * 
+     */
+    uint8_t imcrp : 1;
+} __attribute__ ((packed));

src/Makefile.am

@@ -1,9 +1,12 @@
 bin_PROGRAMS = quark-kernel
-quark_kernel_SOURCES = kernel.c mmgr.c priorityqueue.c stdio.c string.c elf.c syscalls.c heap.c avltree.c queue.c math.c
+quark_kernel_SOURCES = kernel.c mmgr.c priorityqueue.c stdio.c string.c elf.c syscalls.c heap.c avltree.c queue.c math.c process.c sharedobject.c addressspace.c
 quark_kernel_LDADD = -lgcc -lmalloc
 quark_kernel_CFLAGS = -I$(top_srcdir)/include -I$(prefix)/include -ffreestanding -mgeneral-regs-only -O0 -Wall -ggdb
 quark_kernel_LDFLAGS = -L$(prefix)/lib -nostdlib
 
+lib_LIBRARIES = libquark-syscall.a
+libquark_syscall_a_CFLAGS = -I$(top_srcdir)/include -I$(prefix)/include -ffreestanding -mgeneral-regs-only -O0 -Wall -ggdb
+
 if x86
 quark_kernel_SOURCES += x86/paging.c \
                         x86/putc.c \
@@ -17,7 +20,8 @@ quark_kernel_SOURCES += x86/paging.c \
                         x86/load_context.S \
                         x86/preempt.S \
                         x86/quark_x86.c \
-                        x86/entry.S 
+                        x86/entry.S
+libquark_syscall_a_SOURCES = x86/do_syscall.S
 quark_kernel_LDFLAGS += -T x86/linker.ld
 quark_kernel_DEPENDENCIES = x86/linker.ld
 endif

src/addressspace.c

@@ -0,0 +1,44 @@
+#include "addressspace.h"
+#include "heap.h"
+#include "mmgr.h"
+
+address_space_t *address_space_construct()
+{
+    address_space_t *as = kmalloc(sizeof(address_space_t));
+    if(as == NULL)
+    {
+        return NULL;
+    }
+
+    as->page_table = create_address_space();
+    if(as->page_table == ENOMEM)
+    {
+        kfree(as);
+        return NULL;
+    }
+
+    as->refcount = 0;
+    return as;
+}
+
+void address_space_switch(address_space_t *address_space)
+{
+    paging_load_address_space(address_space->page_table);
+}
+
+address_space_t *address_space_release(address_space_t *address_space)
+{
+    address_space->refcount--;
+    if(address_space->refcount <= 0)
+    {
+        address_space_destroy(address_space);
+        return NULL;
+    }
+    return address_space;
+}
+
+void address_space_destroy(address_space_t *address_space)
+{
+    // TODO: Not implemented.
+    kfree(address_space);
+}

src/avltree.c

@@ -5,10 +5,13 @@
 struct avltree_t *avl_new(int key, void *value)
 {
     struct avltree_t *new_tree = kmalloc(sizeof(struct avltree_t));
-    new_tree->height = 1;
+    if(new_tree != NULL)
-    new_tree->left = new_tree->right = NULL;
+    {
-    new_tree->key = key;
+        new_tree->height = 1;
-    new_tree->value = value;
+        new_tree->left = new_tree->right = NULL;
+        new_tree->key = key;
+        new_tree->value = value;
+    }
     return new_tree;
 }
 
@@ -195,4 +198,13 @@ void *avl_get(struct avltree_t *tree, int key)
         }
     }
     return NULL;
+}
+
+void *avl_clear(struct avltree_t *tree)
+{
+    while(tree != NULL)
+    {
+        tree = avl_remove(tree, tree->key);
+    }
+    return tree;
 }

src/heap.c

@@ -1,34 +1,24 @@
 #include <stdbool.h>
-#include <libmalloc/bitmap_alloc.h>
+#include <libmalloc/list_alloc.h>
 #include "heap.h"
 #include "mmgr.h"
 #include "math.h"
 #include "stdio.h"
 #include "types/status.h"
 
-bitmap_heap_descriptor_t system_heap;
+list_alloc_descriptor_t system_heap;
-
-static int map_block(void *location, unsigned long size)
-{
-    for(int n = 0; n < size; n += page_size)
-    {
-        if(!(page_type(location + n) & PAGE_PRESENT))
-        {
-            int status = map_page(location + n, reserve_page(), PAGE_RW);
-            if(status)
-            {
-                return status;
-            }
-        }
-    }
-    return ENONE;
-}
 
 static int mmap_callback(void *location, unsigned long size)
 {
+    size += (unsigned long)location % page_size;
+    location -= (unsigned long)location % page_size;
     int status = ENONE;
     for(unsigned long i = 0; i < size; i += page_size)
     {
+        if((page_type(location + i) & PAGE_PRESENT))
+        {
+            continue;
+        }
         physaddr_t frame = reserve_page();
         if(frame == ENOMEM)
         {
@@ -42,44 +32,48 @@ static int mmap_callback(void *location, unsigned long size)
     return status;
 }
 
-int kminit(void *base, void* start, size_t heap_size, size_t block_size)
+int kminit(void *base, size_t heap_size)
 {
-    static unsigned long heap_cache[16];
-    system_heap.bitmap = NULL;
-    system_heap.cache = heap_cache;
-    system_heap.cache_capacity = 16;
-    system_heap.block_bits = 4;
-    system_heap.block_size = block_size;
-    system_heap.offset = (unsigned long)base;
     memory_region_t map_array[8];
     memory_map_t map = {
         .array = map_array,
         .capacity = 8,
         .size = 0
     };
-    memmap_insert_region(&map, 0, heap_size, M_AVAILABLE);
+    memmap_insert_region(&map, base, heap_size, M_AVAILABLE);
-    memmap_insert_region(&map, 0, start - base, M_UNAVAILABLE);
+    physaddr_t phys_addr = reserve_pages(heap_size);
-    return initialize_heap(&system_heap, &map, mmap_callback);
+    if(phys_addr == ENOMEM)
+    {
+        return ENOMEM;
+    }
+    for(unsigned long off = 0; off < heap_size; off += page_size)
+    {
+        if((page_type(base + off) & PAGE_PRESENT))
+        {
+            continue;
+        }
+        else if(map_page(base + off, phys_addr + off, PAGE_RW))
+        {
+            return ENOMEM;
+        }
+    }
+    return list_alloc_init(&system_heap, &map);
 }
 
 void *kmalloc(size_t size)
 {
-    unsigned long loc = reserve_region(&system_heap, size);
+    void *p = list_alloc_reserve(&system_heap, size);
-    if(loc == NOMEM)
+    if(p == NOMEM)
-    {
-        return NULL;
-    }
-    else if(map_block((void*)loc, size))
     {
         return NULL;
     }
     else
     {
-        return (void*)loc;
+        return p;
     }
 }
 
 void kfree(void *ptr)
 {
-    free_region(&system_heap, (unsigned long)ptr, 0);
+    list_alloc_free(&system_heap, (unsigned long)ptr);
 }

src/kernel.c

@@ -7,13 +7,58 @@
 #include "string.h"
 #include "config.h"
 #include "system.h"
+#include "process.h"
 #include "platform/interrupts.h"
 #include "platform/context.h"
 #include "platform/putc.h"
 #include "types/status.h"
 #include "types/syscallid.h"
+#include "types/sigaction.h"
 
-struct kernel_t kernel;
+void *syscall_table[] = {
+    NULL,
+    (void*)test_syscall,
+    (void*)syscall_map_anon,
+    (void*)syscall_unmap_anon,
+    (void*)syscall_map_physical,
+    (void*)syscall_unmap_physical,
+    (void*)syscall_open_port,
+    (void*)syscall_close_port,
+    (void*)syscall_send_pid,
+    (void*)syscall_receive,
+    (void*)syscall_create_object,
+    (void*)syscall_aquire_object,
+    (void*)syscall_release_object,
+    (void*)syscall_get_pid,
+    (void*)syscall_clone,
+    (void*)syscall_signal_action,
+    (void*)syscall_signal_return,
+    (void*)syscall_signal_raise
+};
+
+struct port_t
+{
+    unsigned long id;
+    pid_t owner_pid;
+};
+
+struct signal_context_t
+{
+    unsigned long signal_id;
+};
+
+struct kernel_t
+{
+    struct syscall_t syscall_table[MAX_SYSCALL_ID];
+    struct priority_queue_t priority_queue;
+    struct avltree_t *interrupt_handlers;
+    struct avltree_t *port_table;
+    struct avltree_t *object_table;
+    struct avltree_t *process_table;
+    struct process_t *active_process;
+    pid_t next_pid;
+    oid_t next_oid;
+} kernel;
 
 void kernel_initialize(struct boot_info_t *boot_info)
 {
@@ -38,48 +83,72 @@ void kernel_initialize(struct boot_info_t *boot_info)
     memmap_insert_region(&boot_info->map, (physaddr_t)&_kernel_pstart, (physaddr_t)&_kernel_pend - (physaddr_t)&_kernel_pstart, M_UNAVAILABLE);
     if(initialize_page_map(&boot_info->map, (physaddr_t*)&_kernel_end, boot_info->memory_size, page_size))
     {
-        panic("Failed to initialize page allocator.");
+        kernel_panic("Failed to initialize page allocator.");
     }
 
-    if(kminit(&_kernel_start, page_map_end(), 0xFFC00000 - (size_t)&_kernel_start, 64))
+    if(kminit(page_map_end(), 0xFFC00000 - (size_t)page_map_end()))
     {
-        panic("Failed to initialize heap.");
+        kernel_panic("Failed to initialize heap.");
     }
     
     kernel.active_process = NULL;
     kernel.next_pid = 1;
+    kernel.next_oid = 1;
     kernel.process_table = NULL;
     kernel.port_table = NULL;
+    kernel.object_table = NULL;
     if(construct_priority_queue(&kernel.priority_queue, 512) != ENONE)
     {
-        panic("Failed to construct priority queue.");
+        kernel_panic("Failed to construct priority queue.");
     }
     memset(kernel.syscall_table, 0, sizeof(struct syscall_t) * MAX_SYSCALL_ID);
-    set_syscall(SYSCALL_TEST, 1, 0, test_syscall);
+    kernel_set_syscall(SYSCALL_TEST, 1, test_syscall);
-    set_syscall(SYSCALL_MMAP, 3, 0, mmap);
+    kernel_set_syscall(SYSCALL_MAP_ANON, 3, syscall_map_anon);
-    set_syscall(SYSCALL_MUNMAP, 2, 0, munmap);
+    kernel_set_syscall(SYSCALL_UNMAP_ANON, 1, syscall_unmap_anon);
-    set_syscall(SYSCALL_SEND, 3, 0, send);
+    kernel_set_syscall(SYSCALL_MAP_PHYS, 3, syscall_map_physical);
-    set_syscall(SYSCALL_RECEIVE, 2, 0, receive);
+    kernel_set_syscall(SYSCALL_UNMAP_PHYS, 2, syscall_unmap_physical);
-    set_syscall(SYSCALL_OPEN_PORT, 1, 0, open_port);
+    kernel_set_syscall(SYSCALL_OPEN_PORT, 1, syscall_open_port);
-    set_syscall(SYSCALL_CLOSE_PORT, 1, 0, close_port);
+    kernel_set_syscall(SYSCALL_CLOSE_PORT, 1, syscall_close_port);
+    kernel_set_syscall(SYSCALL_SEND_PID, 3, syscall_send_pid);
+    kernel_set_syscall(SYSCALL_SEND_PORT, 3, syscall_send_port);
+    kernel_set_syscall(SYSCALL_RECEIVE, 2, syscall_receive);
+    kernel_set_syscall(SYSCALL_CREATE_OBJECT, 3, syscall_create_object);
+    kernel_set_syscall(SYSCALL_AQUIRE_OBJECT, 2, syscall_aquire_object);
+    kernel_set_syscall(SYSCALL_RELEASE_OBJECT, 1, syscall_release_object);
+    kernel_set_syscall(SYSCALL_GET_PID, 0, syscall_get_pid);
+    kernel_set_syscall(SYSCALL_SIGNAL_ACTION, 3, syscall_signal_action);
+    kernel_set_syscall(SYSCALL_SIGNAL_RETURN, 0, syscall_signal_return);
+    kernel_set_syscall(SYSCALL_SIGNAL_RAISE, 2, syscall_signal_raise);
+    kernel_set_syscall(SYSCALL_INTR_ACTION, 3, syscall_intr_action);
+    kernel_set_syscall(SYSCALL_INTR_RETURN, 0, syscall_intr_return);
     for(int i = 0; i < boot_info->module_count; i++)
     {
         if(kernel_load_module(&boot_info->modules[i]) != ENONE)
         {
-            panic("Failed to load modules.");
+            kernel_panic("Failed to load modules.");
         }
     }
 
     if(initialize_interrupts() != ENONE)
     {
-        panic("Failed to initialize interrupts.");
+        kernel_panic("Failed to initialize interrupts.");
     }
 
     irq_enable();
     load_context(kernel_advance_scheduler());
 }
 
-error_t set_syscall(int id, int arg_count, int pid, void *func_ptr)
+process_t *kernel_get_process(pid_t pid)
+{
+    return avl_get(kernel.process_table, pid);
+}
+
+process_t *kernel_get_active_process()
+{
+    return kernel.active_process;
+}
+
+error_t kernel_set_syscall(int id, int arg_count, void *func_ptr)
 {
     if(id < 0 || id > MAX_SYSCALL_ID)
     {
@@ -93,22 +162,17 @@ error_t set_syscall(int id, int arg_count, int pid, void *func_ptr)
     {
         return EINVALIDARG;
     }
-    else if(pid != 0 && avl_get(kernel.process_table, pid) == NULL)
-    {
-        return EDOESNTEXIST;
-    }
     else if(func_ptr == NULL)
     {
         return ENULLPTR;
     }
     kernel.syscall_table[id].defined = true;
     kernel.syscall_table[id].arg_count = arg_count;
-    kernel.syscall_table[id].process_id = pid;
     kernel.syscall_table[id].func_ptr_0 = func_ptr;
     return ENONE;
 }
 
-size_t do_syscall(syscall_id_t id, syscall_arg_t arg1, syscall_arg_t arg2, syscall_arg_t arg3, void *pc, void *stack, unsigned long flags)
+size_t kernel_do_syscall(syscall_id_t id, syscall_arg_t arg1, syscall_arg_t arg2, syscall_arg_t arg3, void *pc, void *stack, unsigned long flags)
 {
     if(id < 0 || id > MAX_SYSCALL_ID)
     {
@@ -118,18 +182,6 @@ size_t do_syscall(syscall_id_t id, syscall_arg_t arg1, syscall_arg_t arg2, sysca
     {
         return ENOSYSCALL;
     }
-    bool switched_address_space = false;
-    if(kernel.syscall_table[id].process_id > 0)
-    {
-        struct process_t *callee = avl_get(kernel.process_table, kernel.syscall_table[id].process_id);
-        if(callee == NULL)
-        {
-            kernel.syscall_table[id].defined = false;
-            return ENOSYSCALL;
-        }
-        paging_load_address_space(callee->page_table);
-        switched_address_space = true;
-    }
     set_context_pc(kernel.active_process->ctx, pc);
     set_context_stack(kernel.active_process->ctx, stack);
     set_context_flags(kernel.active_process->ctx, flags);
@@ -149,59 +201,43 @@ size_t do_syscall(syscall_id_t id, syscall_arg_t arg1, syscall_arg_t arg2, sysca
         result = kernel.syscall_table[id].func_ptr_3(arg1, arg2, arg3);
         break;
     }
-    if(switched_address_space)
-    {
-        paging_load_address_space(kernel.active_process->page_table);
-    }
     return result;
 }
 
 error_t kernel_load_module(struct module_t *module)
 {
-    physaddr_t module_address_space = create_address_space();
+    address_space_t *module_address_space = address_space_construct();
-    if(module_address_space == ENOMEM) {
+    if(module_address_space == NULL) {
-        panic("failed to create address space for module: out of memory");
+        kernel_panic("failed to create address space for module: out of memory");
     }
-    paging_load_address_space(module_address_space);
+    address_space_switch(module_address_space);
     void *const load_base = (void*)0x80000000;
-    size_t load_offset = 0;
+    physaddr_t p = module->start & ~(page_size - 1);
-    for(physaddr_t p = module->start & ~(page_size - 1); p < module->end; p += page_size)
+    map_region(load_base, p, module->end - p, PAGE_RW);
-    {
-        int status = map_page(load_base + load_offset, p, PAGE_RW);
-        switch(status)
-        {
-        case ENOMEM:
-            panic("ran out of memory while mapping module");
-        case EOUTOFBOUNDS:
-            panic("got out-of-bounds error while mapping module");
-        }
-        load_offset += page_size;
-
-    }
     int status = load_program(load_base);
     switch(status)
     {
     case ENOMEM:
-        panic("ran out of memory while reading ELF file");
+        kernel_panic("ran out of memory while reading ELF file");
     case EOUTOFBOUNDS:
-        panic("got out-of-bounds error while reading ELF file");
+        kernel_panic("got out-of-bounds error while reading ELF file");
     }
     void *module_entry = ((struct elf_file_header_t*)load_base)->entry;
     printf("loaded module with entry point %08x\n", (unsigned int)module_entry);
-    load_offset = 0;
+    size_t load_offset = 0;
     for(physaddr_t p = module->start & ~(page_size - 1); p < module->end; p += page_size)
     {
         int status = unmap_page(load_base + load_offset);
         switch(status)
         {
         case ENOMEM:
-            panic("ran out of memory while unmapping module");
+            kernel_panic("ran out of memory while unmapping module");
         case EOUTOFBOUNDS:
-            panic("got out-of-bounds error while unmapping module");
+            kernel_panic("got out-of-bounds error while unmapping module");
         }
         load_offset += page_size;
     }
-    if(kernel_spawn_process(module_entry, 1, current_address_space()) > 0)
+    if(kernel_spawn_process(module_entry, 1, module_address_space) > 0)
     {
         return ENONE;
     }
@@ -211,7 +247,7 @@ error_t kernel_load_module(struct module_t *module)
     }
 }
 
-unsigned long kernel_current_pid()
+pid_t kernel_current_pid()
 {
     if(kernel.active_process == NULL)
     {
@@ -235,36 +271,22 @@ struct process_context_t *kernel_current_context()
     }  
 }
 
-unsigned long kernel_spawn_process(void *program_entry, int priority, physaddr_t address_space)
+pid_t kernel_spawn_process(void *program_entry, int priority, address_space_t *address_space)
 {
-    struct process_t *new_process = (struct process_t*) kmalloc(sizeof(struct process_t));
-    if(new_process == NULL)
-    {
-        return 0;
-    }
-    struct process_context_t *initial_context = kmalloc(sizeof(struct process_context_t));
-    if(initial_context == NULL)
-    {
-        return 0;
-    }
     physaddr_t stack_page = reserve_page();
     if(stack_page % page_size)
     {
         return 0;
     }
+
     map_page((void*)&_kernel_start - page_size, stack_page, PAGE_PRESENT | PAGE_USERMODE | PAGE_RW);
-    memset(initial_context, 0, sizeof(struct process_context_t));
+    struct process_t *new_process = process_construct(kernel.next_pid, &_kernel_start, program_entry, priority, address_space);
-    set_context_pc(initial_context, program_entry);
+    if(new_process == NULL)
-    set_context_flags(initial_context, DEFAULT_FLAGS);
+    {
-    set_context_stack(initial_context, &_kernel_start);
+        free_page(stack_page);
-    new_process->priority = priority;
+        return 0;
-    new_process->pid = kernel.next_pid;
+    }
-    new_process->page_table = address_space;
+    
-    new_process->state = PROCESS_ACTIVE;
-    new_process->message_buffer = NULL;
-    new_process->ctx = initial_context;
-    queue_construct(&new_process->sending_queue);
-    queue_construct(&new_process->message_queue);
     kernel.process_table = avl_insert(kernel.process_table, new_process->pid, new_process);
     priorityqueue_insert(&kernel.priority_queue, new_process, new_process->priority);
     kernel.next_pid++;
@@ -280,16 +302,24 @@ struct process_context_t *kernel_advance_scheduler()
     kernel.active_process = priorityqueue_extract_min(&kernel.priority_queue);
     if(kernel.active_process != NULL)
     {
-        paging_load_address_space(kernel.active_process->page_table);
+        address_space_switch(kernel.active_process->address_space);
-        printf("entering process %08x cr3=%08x ctx=%08x sched=%i.\n", kernel.active_process->pid, kernel.active_process->page_table, kernel.active_process->ctx, kernel.priority_queue.size);
+        printf("entering process %08x cr3=%08x ctx=%08x sched=%i.\n", kernel.active_process->pid, kernel.active_process->address_space->page_table, kernel.active_process->ctx, kernel.priority_queue.size);
         return kernel.active_process->ctx;
     }
-    panic("no processes available to enter!");
+    kernel_panic("no processes available to enter!");
 }
 
-error_t kernel_terminate_process(size_t process_id)
+void kernel_schedule_process(process_t *process)
 {
-    struct process_t *process = avl_get(kernel.process_table, process_id);
+    if(priorityqueue_insert(&kernel.priority_queue, process, process->priority))
+    {
+        kernel_panic("Failed to schedule process!");
+    }
+}
+
+error_t kernel_terminate_process(pid_t pid)
+{
+    struct process_t *process = avl_get(kernel.process_table, pid);
     if(process == NULL)
     {
         return EDOESNTEXIST;
@@ -298,18 +328,12 @@ error_t kernel_terminate_process(size_t process_id)
     {
         kernel.active_process = NULL;
     }
-    kernel.process_table = avl_remove(kernel.process_table, process_id);
+    kernel.process_table = avl_remove(kernel.process_table, pid);
     priorityqueue_remove(&kernel.priority_queue, process);
     for(struct message_t *msg = queue_get_next(&process->message_queue); msg != NULL; msg = queue_get_next(&process->message_queue))
     {
         kfree(msg);
     }
-    for(struct process_t *sender = queue_get_next(&process->sending_queue); sender != NULL; sender = queue_get_next(&process->sending_queue))
-    {
-        sender->state = PROCESS_ACTIVE;
-        set_context_return(sender->ctx, EEXITED);
-        priorityqueue_insert(&kernel.priority_queue, sender, sender->priority);
-    }
     kfree(process->ctx);
     kfree(process);
     return ENONE;
@@ -359,7 +383,7 @@ error_t kernel_remove_port(unsigned long id)
     return ENONE;
 }
 
-unsigned long kernel_get_port_owner(unsigned long id)
+pid_t kernel_get_port_owner(unsigned long id)
 {
     struct port_t *port = avl_get(kernel.port_table, id);
     if(port == NULL)
@@ -372,56 +396,7 @@ unsigned long kernel_get_port_owner(unsigned long id)
     }
 }
 
-error_t kernel_send_message(unsigned long recipient, struct message_t *message)
+int kernel_receive_message(struct message_t *buffer, int flags)
-{
-    struct process_t *dest = avl_get(kernel.process_table, recipient);
-    if(dest == NULL)
-    {
-        return EDOESNTEXIST;
-    }
-    else if(dest->message_buffer != NULL && dest->state == PROCESS_REQUESTING)
-    {
-        printf("Sending message directly from %i to %i\n", kernel.active_process->pid, dest->pid);
-        struct message_t kernel_buffer;
-        memcpy(&kernel_buffer, message, sizeof(struct message_t));
-        kernel_buffer.sender = kernel.active_process->pid;
-        paging_load_address_space(dest->page_table);
-        memcpy(dest->message_buffer, &kernel_buffer, sizeof(struct message_t));
-        paging_load_address_space(kernel.active_process->page_table);
-        dest->message_buffer = NULL;
-        dest->state = PROCESS_ACTIVE;
-        set_context_return(dest->ctx, ENONE);
-        priorityqueue_insert(&kernel.priority_queue, dest, dest->priority);
-        return ENONE;
-    }
-    else
-    {
-        return EBUSY;
-    }
-}
-
-error_t kernel_queue_message(unsigned long recipient, struct message_t *message)
-{
-    struct process_t *dest = avl_get(kernel.process_table, recipient);
-    if(dest != NULL)
-    {
-        printf("Queueing message from %i to %i\n", kernel.active_process->pid, dest->pid);
-        struct message_t *queued_msg = kmalloc(sizeof(struct message_t));
-        if(queued_msg == NULL)
-        {
-            return ENOMEM;
-        }
-        memcpy(queued_msg, message, sizeof(struct message_t));
-        queue_insert(&dest->message_queue, queued_msg);
-        return ENONE;
-    }
-    else
-    {
-        return EDOESNTEXIST;
-    }
-}
-
-int receive_message(struct message_t *buffer, int flags)
 {
     if(kernel.active_process->message_queue.count > 0)
     {
@@ -484,7 +459,7 @@ error_t kernel_execute_interrupt_handler(unsigned long interrupt)
         return EDOESNTEXIST;
     }
 
-    paging_load_address_space(process->page_table);
+    address_space_switch(process->address_space);
 
     struct signal_context_t siginfo = {
         .signal_id = interrupt
@@ -499,7 +474,7 @@ error_t kernel_execute_interrupt_handler(unsigned long interrupt)
         priorityqueue_insert(&kernel.priority_queue, process, process->priority);
     }
 
-    paging_load_address_space(kernel.active_process->page_table);
+    address_space_switch(kernel.active_process->address_space);
 
     return ENONE;
 }
@@ -511,13 +486,52 @@ error_t kernel_signal_return()
     context_stack_pop_struct(kernel.active_process->ctx, kernel.active_process->ctx, sizeof(*kernel.active_process->ctx));
     if(kernel.active_process->state == PROCESS_REQUESTING)
     {
-        receive_message(kernel.active_process->message_buffer, 0);
+        kernel_receive_message(kernel.active_process->message_buffer, 0);
         load_context(kernel.active_process->ctx);
     }
     return ENONE;
 }
 
-void panic(const char *message)
+error_t kernel_create_object(size_t size, unsigned long flags, oid_t *id)
+{
+    physaddr_t phys_addr = reserve_pages(size);
+    if(phys_addr == ENOMEM)
+    {
+        return ENOMEM;
+    }
+
+    struct shared_object_t *obj = kmalloc(sizeof(struct shared_object_t));
+    if(obj == NULL)
+    {
+        free_pages(phys_addr);
+        return ENOMEM;
+    }
+
+    obj->phys_addr = phys_addr;
+    obj->size = size;
+    obj->access_flags = flags;
+    obj->refcount = 0;
+    kernel.object_table = avl_insert(kernel.object_table, kernel.next_oid, obj);
+    *id = kernel.next_oid;
+    kernel.next_oid++;
+    if(kernel.next_oid <= 0)
+    {
+        kernel.next_oid = 1;
+    }
+    return ENONE;
+}
+
+error_t kernel_attach_object(oid_t id, void *virt_addr)
+{
+    
+}
+
+error_t kernel_release_object(oid_t id)
+{
+
+}
+
+void kernel_panic(const char *message)
 {
     printf("panic: %s", message);
     asm("cli");

src/mmgr.c

@@ -4,17 +4,18 @@
 #include "platform/paging.h"
 #include "types/status.h"
 #include "stdio.h"
-#include <libmalloc/bitmap_alloc.h>
+#include <libmalloc/buddy_alloc.h>
 #include <stdint.h>
 #include <stdbool.h>
 
-#define MAX_CACHE_SIZE 32
+#define AVAIL_LIST_SIZE 20
 
-bitmap_heap_descriptor_t page_map;
+buddy_descriptor_t page_alloc;
 
 physaddr_t reserve_pages(size_t size)
 {
-    unsigned long location = reserve_region(&page_map, size);
+    unsigned long location = buddy_reserve(&page_alloc, size);
+    printf("Reserved  >=%08x pages at %08x\n", size, location);
     if(location != NOMEM)
     {
         return location;
@@ -25,63 +26,61 @@ physaddr_t reserve_pages(size_t size)
     }
 }
 
-int free_pages(physaddr_t location, size_t size)
+size_t free_pages(physaddr_t location)
 {
-    free_region(&page_map, location, size);
+    return buddy_free(&page_alloc, location);
-    return ENONE;
 }
 
 physaddr_t reserve_page()
 {
-    unsigned long loc = reserve_region(&page_map, page_size);
+    unsigned long loc = buddy_reserve(&page_alloc, page_size);
+    printf("Reserved %08x\n", loc);
     if(loc == NOMEM)
     {
         return ENOMEM;
     }
     else
     {
-        printf("Reserved %08x\n", loc);
         return loc;
     }
 }
 
 int free_page(physaddr_t location)
 {
-    free_region(&page_map, location, page_size);
+    buddy_free_size(&page_alloc, location, page_size);
     return ENONE;
 }
 
 size_t free_page_count()
 {
-    return page_map.free_block_count;
+    return page_alloc.free_block_count;
 }
 
 void *page_map_base()
 {
-    return (void*)page_map.bitmap;
+    return (void*)page_alloc.block_map;
 }
 
 void *page_map_end()
 {
-    return (void*)page_map.bitmap + page_map.bitmap_size;
+    return (void*)page_alloc.block_map + page_alloc.block_map_size;
 }
 
 error_t initialize_page_map(memory_map_t *map, void *base, size_t memory_size, unsigned long block_size)
 {
-    static unsigned long page_map_cache[MAX_CACHE_SIZE];
+    static unsigned long avail_list[AVAIL_LIST_SIZE];
     // Round memory_size up to nearest power of 2
     memory_size = 1 << llog2(memory_size);
 
-    page_map.block_size = block_size;
+    page_alloc.avail = avail_list;
-    page_map.block_bits = 1;
+    page_alloc.block_map = (buddy_block_t*) base;
-    page_map.offset = 0;
+    page_alloc.block_size = block_size;
-    page_map.cache = page_map_cache;
+    page_alloc.mmap = NULL;
-    page_map.cache_capacity = MAX_CACHE_SIZE;
+    page_alloc.offset = 0;
-    page_map.bitmap = (unsigned long*) base;
 
     /* Allocate pages for bitmap */
     int pages_mapped = 0;
-    int pages_needed = (bitmap_size(map, block_size, 1) + page_size - 1) / page_size;
+    int pages_needed = (buddy_map_size(map, block_size) + page_size - 1) / page_size;
     for(int i = 0; i < map->size && (pages_mapped < pages_needed); i++)
     {
         if(map->array[i].type != M_AVAILABLE)
@@ -92,7 +91,7 @@ error_t initialize_page_map(memory_map_t *map, void *base, size_t memory_size, u
         physaddr_t region_end = map->array[i].location + map->array[i].size;
         while(location + page_size <= region_end && (pages_mapped < pages_needed))
         {
-            void *page = (void*)page_map.bitmap + pages_mapped * page_size;
+            void *page = (void*)page_alloc.block_map + pages_mapped * page_size;
             for(int level = 0; level < page_table_levels; level++)
             {
                 if(!(get_pte_type(page, level) & PAGE_PRESENT))
@@ -118,7 +117,7 @@ error_t initialize_page_map(memory_map_t *map, void *base, size_t memory_size, u
         }
     }
  
-    if(initialize_heap(&page_map, map, NULL))
+    if(buddy_alloc_init(&page_alloc, map))
     {
         return ENOMEM;
     }
@@ -151,26 +150,35 @@ physaddr_t current_address_space()
     return paging_current_address_space();
 }
 
-int map_page(void *page, physaddr_t frame, int flags)
+error_t map_region(void *page, physaddr_t frame, size_t size, int flags)
+{
+    if(frame % page_size != 0)
+    {
+        return EINVALIDARG;
+    }
+    for(size_t p = 0; p < size; p += page_size)
+    {
+        set_pte(page + p, page_table_levels - 1, PAGE_PRESENT | flags, frame + p);
+    }
+    return ENONE;
+}
+
+physaddr_t unmap_region(void *page, size_t size)
+{
+    physaddr_t frame = get_pte_address(page, page_table_levels - 1);
+    for(size_t p = 0; p < size; p += page_size)
+    {
+        set_pte(page + p, page_table_levels - 1, 0, 0);
+    }
+    return frame;
+}
+
+error_t map_page(void *page, physaddr_t frame, int flags)
 {
     if (frame % page_size != 0)
     {
         return EINVALIDARG;
     }
-    for(int level = 0; level < page_table_levels - 1; level++)
-    {
-        int present = get_pte_type(page, level) & PAGE_PRESENT;
-        if(present == 0)
-        {
-            physaddr_t new_table = reserve_page();
-            if(new_table == ENOMEM)
-            {
-                return ENOMEM;
-            }
-            set_pte(page, level, PAGE_PRESENT | PAGE_USERMODE | PAGE_RW, new_table);
-            wipe_page_table(page, level + 1);
-        }
-    }
     set_pte(page, page_table_levels - 1, PAGE_PRESENT | flags, frame);
     return ENONE;
 }

src/process.c

@@ -0,0 +1,70 @@
+#include "process.h"
+#include "heap.h"
+#include "mmgr.h"
+#include "platform/context.h"
+#include "string.h"
+#include "avltree.h"
+
+process_t *process_construct(pid_t pid, void *entry, void *stack, int priority, address_space_t *address_space)
+{
+    process_t *new_process = (process_t*) kmalloc(sizeof(process_t));
+    if(new_process == NULL) 
+    {
+        return NULL;
+    }
+
+    struct process_context_t *initial_context = kmalloc(sizeof(struct process_context_t));
+    if(initial_context == NULL)
+    {
+        return NULL;
+    }
+
+    if(address_space == NULL 
+        && (address_space = address_space_construct()) == NULL)
+    {
+        return NULL;
+    }
+
+    context_construct(initial_context);
+    set_context_pc(initial_context, entry);
+    set_context_stack(initial_context, stack);
+    new_process->priority = priority;
+    new_process->pid = pid;
+    new_process->address_space = address_space;
+    new_process->address_space->refcount++;
+    new_process->shared_objects = NULL;
+    new_process->state = PROCESS_ACTIVE;
+    new_process->message_buffer = NULL;
+    new_process->ctx = initial_context;
+    queue_construct(&new_process->message_queue);
+    return new_process;
+}
+
+error_t process_queue_message(process_t *process, message_t *msg)
+{
+    return queue_insert(&process->message_queue, msg);
+}
+
+error_t process_receive_message(process_t *process, message_t *buffer)
+{
+    if(process->message_queue.count == 0)
+    {
+        return EDOESNTEXIST;
+    }
+
+    message_t *queued_message = queue_get_next(&process->message_queue);
+    memcpy(buffer, queued_message, sizeof(message_t));
+    kfree(queued_message);
+    return ENONE;
+}
+
+error_t process_store_object(process_t *process, int id, void *location)
+{
+    process->shared_objects = avl_insert(process->shared_objects, id, location);
+    return ENONE;
+}
+
+void *process_get_object(process_t *process, int id)
+{
+    return avl_get(process->shared_objects, id);
+}

src/sharedobject.c

@@ -0,0 +1,35 @@
+#include "sharedobject.h"
+#include "avltree.h"
+#include "mmgr.h"
+#include "heap.h"
+
+struct shared_object *create_shared_object(size_t size, unsigned long flags)
+{
+    physaddr_t phys_addr = reserve_pages(size);
+    if(phys_addr == NULL)
+    {
+        return NULL;
+    }
+
+    struct shared_object_t *obj = kmalloc(sizeof(struct shared_object_t));
+    if(obj == NULL)
+    {
+        free_pages(phys_addr);
+        return NULL;
+    }
+
+    obj->phys_addr = phys_addr;
+    obj->size = size;
+    obj->access_flags = flags;
+    obj->refcount = 0;
+    return obj;
+}
+
+void destroy_shared_object(struct shared_object_t *obj)
+{
+    if(obj != NULL)
+    {
+        free_pages(obj->phys_addr);
+        kfree(obj);
+    }
+}

src/stdio.c

@@ -18,7 +18,18 @@ enum format_flags_t
 
 };
 
-char *itoa(unsigned int n, unsigned int base, unsigned int width)
+typedef enum
+{
+    LOG_PANIC,
+    LOG_ERROR,
+    LOG_WARNING,
+    LOG_INFO,
+    LOG_DEBUG
+} log_levels_t;
+
+
+
+static char *itoa(unsigned int n, unsigned int base, unsigned int width)
 {
     if (base < 2 || base > 16)
     {

src/syscalls.c

@@ -2,16 +2,23 @@
 #include "kernel.h"
 #include "mmgr.h"
 #include "stdio.h"
+#include "process.h"
+#include "sharedobject.h"
+#include "system.h"
+#include "heap.h"
 #include "platform/context.h"
 #include "types/status.h"
 
-size_t test_syscall(syscall_arg_t str)
+int test_syscall(syscall_arg_t str)
 {
-    printf("%s", (char*)str.ptr);
+    if(str.ptr != NULL)
+    {
+        printf("%s", (char*)str.ptr);
+    }
     return 17;
 }
 
-size_t mmap(syscall_arg_t arg_location, syscall_arg_t arg_length, syscall_arg_t arg_flags)
+int syscall_map_anon(syscall_arg_t arg_location, syscall_arg_t arg_length, syscall_arg_t arg_flags)
 {
     unsigned long location = arg_location.unsigned_int;
     unsigned long length = arg_length.unsigned_int;
@@ -24,6 +31,7 @@ size_t mmap(syscall_arg_t arg_location, syscall_arg_t arg_length, syscall_arg_t
     {
         return ENULLPTR;
     }
+    
     for(size_t i = 0; i < length; i += page_size)
     {
         if(page_type((void*)(location + i)) & PAGE_PRESENT)
@@ -31,107 +39,226 @@ size_t mmap(syscall_arg_t arg_location, syscall_arg_t arg_length, syscall_arg_t
             return EEXISTS;
         }
     }
-    size_t n = 0;
+
-    int status = ENONE;
+    physaddr_t frame = reserve_pages(length);
-    while(n < length && status == ENONE)
+    if(frame % page_size != 0)
     {
-        physaddr_t frame = reserve_page();
+        return frame % page_size;
-        status = frame % page_size;
+    }
-        if(status == ENONE)
+
-        {
+    error_t status = map_region(location, frame, length, PAGE_USERMODE | PAGE_RW);
-            status = map_page((void*)(location + n), frame, PAGE_USERMODE | PAGE_RW);
+    if(status != ENONE)
-            if(status != ENONE && free_page(frame) != ENONE)
+    {
-            {
+        kernel_panic("Unexpected failure to map virtual memory.");
-                panic("critical error reached during mmap.");
+    }
-            }
+    return ENONE;
-            n += page_size;
+}
-        }
+
-        else
+int syscall_unmap_anon(syscall_arg_t arg_location)
+{
+    void *addr = arg_location.ptr;
+    if((size_t)addr % page_size != 0)
+    {
+        return EINVALIDARG;
+    }
+    else if(addr == NULL)
+    {
+        return ENULLPTR;
+    }
+    else if(addr >= _kernel_start)
+    {
+        return EPERM;
+    }
+    unmap_region(arg_location.ptr, free_pages(physical_address(arg_location.ptr)));
+    return ENONE;
+}
+
+int syscall_map_physical(syscall_arg_t arg_addr, syscall_arg_t arg_phys_addr, syscall_arg_t arg_length)
+{
+    void *addr = arg_addr.ptr;
+    physaddr_t frame = arg_phys_addr.unsigned_int;
+    unsigned long length = arg_length.unsigned_int;
+    int status = ENONE;
+    for(unsigned long offset = 0; offset < length; offset += page_size)
+    {
+        status = map_page(addr + offset, frame + offset, PAGE_USERMODE | PAGE_RW);
+        if(status)
         {
             break;
         }
     }
-    if(status != ENONE && munmap(arg_location, arg_length) != ENONE)
-    {
-        panic("critical error reached during mmap.");
-    }
     return status;
 }
 
-size_t munmap(syscall_arg_t arg_location, syscall_arg_t arg_length)
+int syscall_unmap_physical(syscall_arg_t arg_addr, syscall_arg_t arg_length)
 {
-    unsigned long location = arg_location.unsigned_int;
+    void *addr = arg_addr.ptr;
     unsigned long length = arg_length.unsigned_int;
-    if(location % page_size != 0 || length % page_size != 0)
-    {
-        return EINVALIDARG;
-    }
-    else if(location == 0)
-    {
-        return ENULLPTR;
-    }
-    size_t n = 0;
     int status = ENONE;
-    while(n < length && status == ENONE)
+    for(unsigned long offset = 0; offset < length; offset += page_size)
     {
-        int type = page_type((void*)(location + n));
+        status = unmap_page(addr + offset);
-        physaddr_t frame;
+        if(status != ENONE)
-        if(type & PAGE_PRESENT)
         {
-            frame = unmap_page((void*)(location + n));
+            break;
-            if(type & PAGE_ANON)
-            {
-                status = free_page(frame);
-            }
         }
     }
     return status;
 }
 
-size_t terminate_self()
+int syscall_open_port(syscall_arg_t id)
-{
-    return kernel_terminate_process(kernel_current_pid());
-}
-
-size_t send(syscall_arg_t recipient, syscall_arg_t message, syscall_arg_t flags)
-{
-    unsigned long op_type = flags.unsigned_int & IO_OP;
-    unsigned long dest_type = flags.unsigned_int & IO_RECIPIENT_TYPE;
-    if((flags.unsigned_int & ~(IO_OP | IO_RECIPIENT_TYPE)) != 0 || dest_type >= IO_MAILBOX)
-    {
-        printf("Invalid flags on send()\n");
-        return EINVALIDARG;
-    }
-    if(dest_type == IO_PORT)
-    {
-        recipient.unsigned_int = kernel_get_port_owner(recipient.unsigned_int);
-        if(recipient.unsigned_int == 0)
-        {
-            return EDOESNTEXIST;
-        }
-    }
-    error_t status = kernel_send_message(recipient.unsigned_int, message.ptr);
-    if(status == EBUSY/* && op_type == IO_ASYNC*/)
-    {
-        return kernel_queue_message(recipient.unsigned_int, message.ptr);
-    }
-    else
-    {
-        return status;
-    }
-}
-
-size_t receive(syscall_arg_t buffer, syscall_arg_t flags)
-{
-    return receive_message(buffer.ptr, flags.unsigned_int);
-}
-
-size_t open_port(syscall_arg_t id)
 {
     return kernel_create_port(id.unsigned_int);
 }
 
-size_t close_port(syscall_arg_t id)
+int syscall_close_port(syscall_arg_t id)
 {
     return kernel_remove_port(id.unsigned_int);
 }
+
+int syscall_send_pid(syscall_arg_t recipient, syscall_arg_t message, syscall_arg_t flags)
+{
+    if(message.ptr == NULL)
+    {
+        return ENULLPTR;
+    }
+
+    process_t *process = kernel_get_process(recipient.unsigned_int);
+    if(process == NULL)
+    {
+        return EEXITED;
+    }
+
+    message_t *buffer = kmalloc(sizeof(message_t));
+    if(buffer == NULL)
+    {
+        return ENOMEM;
+    }
+    memcpy(buffer, message.ptr, sizeof(message_t));
+    buffer->sender = kernel_current_pid();
+
+    address_space_switch(process->address_space);
+    int status = process_queue_message(process, buffer);
+    address_space_switch(kernel_get_active_process()->address_space);
+    if(status == ENOMEM)
+    {
+        kfree(buffer);
+        kernel_terminate_process(recipient.unsigned_int);
+        return EEXITED;
+    }
+    else
+    {
+        return ENONE;
+    }
+}
+
+int syscall_send_port(syscall_arg_t recipient, syscall_arg_t message, syscall_arg_t flags)
+{
+    if(message.ptr == NULL)
+    {
+        return ENULLPTR;
+    }
+
+    pid_t recipient_pid = kernel_get_port_owner(recipient.unsigned_int);
+    if(recipient_pid == 0)
+    {
+        return EDOESNTEXIST;
+    }
+
+    process_t *process = kernel_get_process(recipient_pid);
+    if(process == NULL)
+    {
+        return EEXITED;
+    }
+
+    message_t *buffer = kmalloc(sizeof(message_t));
+    if(buffer == NULL)
+    {
+        return ENOMEM;
+    }
+    memcpy(buffer, message.ptr, sizeof(message_t));
+    buffer->sender = kernel_current_pid();
+
+    address_space_switch(process->address_space);
+    int status = process_queue_message(process, buffer);
+    address_space_switch(kernel_get_active_process()->address_space);
+    if(status == ENOMEM)
+    {
+        kfree(buffer);
+        kernel_terminate_process(recipient_pid);
+        return EEXITED;
+    }
+    else
+    {
+        return ENONE;
+    }
+}
+
+int syscall_receive(syscall_arg_t buffer, syscall_arg_t flags)
+{
+    return kernel_receive_message(buffer.ptr, flags.unsigned_int);
+}
+
+int syscall_create_object(void *location, size_t size, int flags)
+{
+    shared_object_t *object = create_shared_object(size, flags);
+    if(object == NULL)
+    {
+        return ENOMEM;
+    }
+
+    if(map_region(location, object->phys_addr, object->size, object->access_flags))
+    {
+        destroy_shared_object(object);
+        return ENOMEM;
+    }
+
+    object->refcount++;
+    process_store_object(kernel_get_active_process(), 0, location);
+    return ENONE;
+}
+
+int syscall_aquire_object(oid_t id, void *location)
+{
+    return ENOSYSCALL;
+}
+
+int syscall_release_object(oid_t id)
+{
+    return ENOSYSCALL;
+}
+
+int syscall_get_pid()
+{
+    return kernel_current_pid();
+}
+
+int syscall_clone(void (*entry)(void*), void *arg, void *stack, int flags)
+{
+    return ENOSYSCALL;
+}
+
+int syscall_signal_action(int id, struct signal_action_t *action, int flags)
+{
+    return ENOSYSCALL;
+}
+
+int syscall_signal_return()
+{
+    return ENOSYSCALL;
+}
+
+int syscall_signal_raise(pid_t pid, int sigid)
+{
+    return ENOSYSCALL;
+}
+
+int syscall_intr_action(int id, struct signal_action_t *action, int flags)
+{
+    return ENOSYSCALL;
+}
+
+int syscall_intr_return()
+{
+    return ENOSYSCALL;
+}

src/x86/context.c

@@ -6,6 +6,12 @@
 #include "system.h"
 #include <stdarg.h>
 
+void context_construct(struct process_context_t *context)
+{
+    memset(context, 0, sizeof(struct process_context_t));
+    context->flags = DEFAULT_FLAGS;
+}
+
 void *get_context_pc(struct process_context_t *context)
 {
     return (void*) context->eip;

src/x86/do_syscall.S

@@ -0,0 +1,19 @@
+.global _do_syscall
+.type _do_syscall, @function
+_do_syscall:
+    push %ebp
+    mov %esp, %ebp
+    push %esi
+    push %edi
+    push %ebx
+    mov 0x08(%ebp), %eax
+    mov 0x0C(%ebp), %ebx
+    mov 0x10(%ebp), %ecx
+    mov 0x14(%ebp), %edx
+    int $0x80
+    pop %ebx
+    pop %edi
+    pop %esi
+    pop %ebp
+    ret
+.size _do_syscall, . - _do_syscall

src/x86/isr.c

@@ -2,6 +2,9 @@
 #include "stdio.h"
 #include "x86/apic.h"
 #include "platform/interrupts.h"
+#include "mmgr.h"
+#include "string.h"
+#include "kernel.h"
 
 #include <stdint.h>
 
@@ -14,6 +17,18 @@ struct interrupt_frame_t
     uint32_t ss;
 };
 
+typedef struct page_fault_code_t
+{
+    uint32_t present : 1;
+    uint32_t write : 1;
+    uint32_t usermode : 1;
+    uint32_t reserved : 1;
+    uint32_t inst_fetch : 1;
+    uint32_t pk : 1;
+    uint32_t shadow_stack : 1;
+    uint32_t padding : 25;
+} page_fault_code_t;
+
 void isr_generic(struct interrupt_frame_t *frame)
 {
     printf("Generic interrupt.\n");
@@ -46,6 +61,7 @@ void isr_gp_fault(struct interrupt_frame_t *frame, unsigned int error)
 
 void isr_page_fault(struct interrupt_frame_t *frame, unsigned int error)
 {
+    page_fault_code_t *code = &error;
     uint32_t addr;
     asm("mov %%cr2, %0"
         : "=r"(addr));
@@ -55,8 +71,28 @@ void isr_page_fault(struct interrupt_frame_t *frame, unsigned int error)
         "mov %%ax, %%fs; "
         "mov %%ax, %%gs; " ::
             : "ax");
-    printf("Exception: Page fault, code %08x, linear address %08x\n", error, addr);
+    if(code->usermode == 0
-    asm("hlt");
+        && code->present == 0
+        && addr >= 0xFFC00000
+        && addr < 0xFFFFF000)
+    {
+        printf("Allocating new page table %08x within fault handler.\n", addr);
+        physaddr_t new_table = reserve_page();
+        if(new_table == ENOMEM)
+        {
+            kernel_panic("Out of memory while allocating page table.\n");
+        }
+        set_pte((void*)addr, 1, PAGE_PRESENT | PAGE_USERMODE | PAGE_RW, new_table);
+        asm volatile("mov %%cr3, %%eax;"
+                     "mov %%eax, %%cr3" ::
+                        : "eax", "memory");
+        memset((void*)(addr & ~0xFFF), 0, page_size);
+    }
+    else
+    {
+        printf("Exception: Page fault, code %08x, linear address %08x\n", error, addr);
+        kernel_panic("Unhandled page fault.\n");
+    }
 }
 
 void isr_double_fault(struct interrupt_frame_t *frame, unsigned int error)

src/x86/linker.ld

@@ -2,7 +2,7 @@ ENTRY(_start)
 
 SECTIONS
 {
-	. = 0xFF400000;
+	. = 0xFF000000;
 	VIRTUAL_BASE = .;
 	PHYSICAL_BASE = 0x100000;
 	BASE_DIFF = VIRTUAL_BASE - PHYSICAL_BASE;

src/x86/paging.c

@@ -32,7 +32,7 @@ struct page_table_entry_t *page_tables = (struct page_table_entry_t *)0xFFC00000
 
 struct page_table_entry_t *page_directory = (struct page_table_entry_t *)0xFFFFF000;
 
-struct page_table_entry_t *get_pte_pointer(void *page, int level)
+struct page_table_entry_t *get_pte_pointer_chk(void *page, int level)
 {
     unsigned int directory_index = (unsigned int)page >> 22;
     struct page_table_entry_t *entry = NULL;
@@ -48,6 +48,22 @@ struct page_table_entry_t *get_pte_pointer(void *page, int level)
     return entry;
 }
 
+struct page_table_entry_t *get_pte_pointer(void *page, int level)
+{
+    if(level == 0)
+    {
+        return &page_directory[(unsigned int)page >> 22];
+    }
+    else if(level == 1)
+    {
+        return &page_tables[(unsigned int)page >> page_bits];
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
 int start_paging(void *linear_addr, physaddr_t start, physaddr_t end, uint32_t *directory, uint32_t *table, uint32_t *identity_table)
 {
     unsigned int directory_index = (unsigned int) linear_addr >> 22;
@@ -114,7 +130,7 @@ void paging_load_address_space(physaddr_t table)
 
 int get_pte_type(void *page, int level)
 {
-    struct page_table_entry_t *entry = get_pte_pointer(page, level);
+    struct page_table_entry_t *entry = get_pte_pointer_chk(page, level);
     if(entry != NULL)
     {
         int flags = (entry->present ? PAGE_PRESENT | PAGE_EXECUTABLE : 0)
@@ -146,7 +162,7 @@ int set_pte_type(void *page, int level, int flags)
 
 physaddr_t get_pte_address(void *page, int level)
 {
-    struct page_table_entry_t *entry = get_pte_pointer(page, level);
+    struct page_table_entry_t *entry = get_pte_pointer_chk(page, level);
     if(entry != NULL)
     {
         return entry->physical_address << page_bits | ((size_t)page & 0xFFF);

src/x86/preempt.S

@@ -20,7 +20,7 @@ isr_syscall:
     mov %ax, %es
     mov %ax, %fs
     mov %ax, %gs
-    call do_syscall
+    call kernel_do_syscall
     mov %ebp, %esp
     mov $0x23, %cx
     mov %cx, %ds