Per-process kernel stack and real userspace-kernelspace transition close

 #18

src/library/call.c

@@ -6,7 +6,7 @@
  * @param eax, the code of the system call.
  * @param ebx, depends on the system call.
  * @param ecx, depends on the system call.
- * @param edx, depends on the system call. 
+ * @param edx, depends on the system call.
  * @return depends on the system call.
  */
 
@@ -15,7 +15,7 @@ int system_call(int eax, int ebx, int ecx, int edx) {
     int ret;
     __asm__ __volatile__ ( "int $0x80"
             : "=a" (ret)
-            : "0" (eax), "b" (ebx), "c" (ecx), "d" (edx)
+            : "a" (eax), "b" (ebx), "c" (ecx), "d" (edx)
     );
 
     return ret;

src/library/call.h

@@ -1,6 +1,6 @@
 #ifndef __LIBRARY_CALL__
 #define __LIBRARY_CALL__
 
-int system_call(int eax, int ebx, int ecx, int edx);
+inline int system_call(int eax, int ebx, int ecx, int edx);
 
 #endif

src/library/string.c

@@ -13,6 +13,10 @@
  */
 size_t strlen(const char *s) {
 
+    if (s == NULL) {
+        return 0;
+    }
+
     int i = 0;
 
     while (*(s+i) != '\0') {
@@ -303,9 +307,9 @@ char *reverse(char * s) {
  *  @return 1 if the string contains a number, 0 if not.
  */
 int is_a_number(char* str) {
-    
+
     int i = 0;
-    
+
     while(str[0] == ' ') {
         str++;
     }

src/system/fs/fd.h

@@ -2,6 +2,7 @@
 #define __SYSTEM_FS_FD__
 
 #include "system/fs/direntry.h"
+#include "system/fs/inode.h"
 
 struct FileDescriptor;
 

src/system/gdt.c

@@ -1,6 +1,7 @@
 #include "system/gdt.h"
 #include "system/mm.h"
 #include "system/common.h"
+#include "system/task.h"
 
 #pragma pack(1)
 
@@ -33,17 +34,20 @@ static void setupGDTEntry(int num, int base, int limit, short access, short gran
 void setupGDT(void) {
 
     struct GDTR gdtr;
+    struct TaskState* ts = task_create_tss();
 
-    gdt = kalloc(sizeof(struct SegmentDescriptor) * 5);
+    gdt = kalloc(sizeof(struct SegmentDescriptor) * 6);
     setupGDTEntry(0, 0, 0, 0, 0);
     setupGDTEntry(1, 0, 0x000FFFFF, 0x9A, 0xC0);
     setupGDTEntry(2, 0, 0x000FFFFF, 0x92, 0xC0);
-    setupGDTEntry(3, 0, 0x000FFFFF, 0xFA, 0xC0);
+    setupGDTEntry(3, 0, 0x000FFFFF, 0xFC, 0xC0);
     setupGDTEntry(4, 0, 0x000FFFFF, 0xF2, 0xC0);
+    setupGDTEntry(5, (int) ts, (int) (ts + 1) + 1, 0x89, 0);
 
-    gdtr.limit = 5 * sizeof(struct SegmentDescriptor) - 1;
+    gdtr.limit = 6 * sizeof(struct SegmentDescriptor) - 1;
     gdtr.base = (int) gdt;
 
     __asm__ volatile("lgdt (%%eax)"::"A"(&gdtr):);
+    __asm__ volatile("ltr %%ax"::"a"(TASK_STATE_SEGMENT):);
 }
 

src/system/gdt.h

@@ -1,6 +1,12 @@
 #ifndef __SYSTEM_GDT__
 #define __SYSTEM_GDT__
 
+#define KERNEL_CODE_SEGMENT 0x08
+#define KERNEL_DATA_SEGMENT 0x10
+#define USER_CODE_SEGMENT (0x18 | 0x3)
+#define USER_DATA_SEGMENT (0x20 | 0x3)
+#define TASK_STATE_SEGMENT 0x28
+
 void setupGDT(void);
 
 #endif

src/system/interrupt/handler.asm

@@ -1,54 +1,51 @@
-EXTERN  int08, int09, interruptDispatcher, mm_set_kernel_context, mm_set_process_context
+EXTERN  interruptDispatcher, mm_set_kernel_context, mm_set_process_context
 GLOBAL _interruptEnd
 
 ; Defines a macro that takes as an argument the interrupt number.
 ; Calls that interrupt.
-%macro CALLER 1
+%macro CALLER 2
     ; Save the current execution context
     pushad
+    push gs
+    push fs
+    push es
+    push ds
 
     ; Set up the handler execution context
     mov ax, 0x10    
     mov ds, ax 
     mov es, ax
     mov fs, ax
     mov gs, ax
-    mov ss, ax
 
     call mm_set_kernel_context
 
-    call %1
+    call %2
 
     call mm_set_process_context
     
-    mov ax, 0x10
-    mov ds, ax 
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-    mov ss, ax
-
+    pop ds
+    pop es
+    pop fs
+    pop gs
     popad
 
     ; Move the sp to where it when the interrupt was triggered
     add esp, 8
 
-    sti
-    iret
+    iretd
 %endmacro
 
 _interruptEnd:
 
     call mm_set_process_context
 
-    mov ax, 0x10
-    mov ds, ax
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-    mov ss, ax
+    pop ds
+    pop es
+    pop fs
+    pop gs
 
-    iret
+    iretd
 
 
 ; Defines a macro that takes as an argument the interrupt number.
@@ -61,18 +58,16 @@ GLOBAL _int%1Handler
     ; Save the interrupt number (intNum).
     push 0
     push %1h      
-    CALLER %2
+    CALLER %1, %2
 %endmacro
 
 %macro ERR_ISR 2 
 GLOBAL _int%1Handler   
   _int%1Handler:
-    cli
 
     ; Save the interrupt number (intNum).
-    push 0
     push %1h      
-    CALLER %2
+    CALLER %1,%2
 %endmacro
 
 ; Definition of the interrupt handlers

src/system/interrupt/handler.c

@@ -8,6 +8,7 @@
 #include "system/scheduler.h"
 
 typedef struct {
+    int ds, es, fs, gs;
     int edi, esi, ebp, esp, ebx, edx, ecx, eax;
     int intNum, errCode;
     int eip, cs, eflags, useresp, ss;

src/system/interrupt/interrupt.c

@@ -110,7 +110,7 @@ void setupIDT(void) {
     // Disabling interrupts to make sure we're in absolute control.
     reMapPIC(PIC1_BASE_OFFSET,PIC2_BASE_OFFSET);
 
-    setIdtEntry(idt, 0x80, 0x08, (dword)&_int80Handler, ACS_INT);
+    setIdtEntry(idt, 0x80, 0x08, (dword)&_int80Handler, 0xEE);
     setIdtEntry(idt, 0x20, 0x08, (dword)&_int20Handler, ACS_INT);
     setIdtEntry(idt, 0x21, 0x08, (dword)&_int21Handler, ACS_INT);
 

src/system/kernel.c

@@ -48,7 +48,7 @@ void kmain(struct multiboot_info* info, unsigned int magic) {
 
     struct Process* idleProcess = process_table_new(idle, NULL, NULL, 1, NO_TERMINAL, 0);
     struct Process* shellProcess = process_table_new(tty_run, NULL, idleProcess, 1, NO_TERMINAL, 0);
-    enableInterrupts();
+    yield();
 
     while (1) {}
 }

src/system/process/process.c

@@ -9,6 +9,7 @@
 #include "system/kprintf.h"
 #include "library/sys.h"
 #include "library/string.h"
+#include "system/gdt.h"
 #include "debug.h"
 
 static int pid = 0;
@@ -25,6 +26,7 @@ inline static void push(int** esp, int val) {
 void createProcess(struct Process* process, EntryPoint entryPoint, struct Process* parent, char* args, int terminal, int kernel) {
 
     process->pid = ++pid;
+    process->kernel = !!kernel;
     process->terminal = terminal;
     process->active = 0;
 
@@ -35,7 +37,7 @@ void createProcess(struct Process* process, EntryPoint entryPoint, struct Proces
     process->curr_cycles = 0;
     process->prev_cycles = 0;
     process->timeStart = _time(NULL);
-    
+
     process->uid = 0;
     process->gid = 0;
     if (parent != NULL) {
@@ -66,7 +68,7 @@ void createProcess(struct Process* process, EntryPoint entryPoint, struct Proces
 
     process->entryPoint = entryPoint;
     if (args == NULL) {
-        *process->args = 0;
+        process->args[0] = 0;
     } else {
         int i;
         for (i = 0; *(args + i) && i < 255; i++) {
@@ -90,8 +92,10 @@ void createProcess(struct Process* process, EntryPoint entryPoint, struct Proces
         }
     }
 
-    process->mm.pagesInStack = 256;
-    process->mm.stackStart = allocPages(process->mm.pagesInStack);
+    process->mm.pagesInKernelStack = KERNEL_STACK_PAGES;
+    process->mm.kernelStackStart = allocPages(process->mm.pagesInKernelStack);
+    process->mm.esp0 = (char*)process->mm.kernelStackStart + PAGE_SIZE * process->mm.pagesInKernelStack;
+    process->mm.kernelStack = process->mm.esp0;
 
     if (kernel) {
         process->mm.pagesInHeap = 0;
@@ -105,19 +109,49 @@ void createProcess(struct Process* process, EntryPoint entryPoint, struct Proces
         mem_check();
     }
 
-    if (process->mm.stackStart == NULL) {
-        panic();
+    if (!kernel) {
+        process->mm.pagesInStack = 256;
+        process->mm.stackStart = allocPages(process->mm.pagesInStack);
+        if (process->mm.stackStart == NULL) {
+            panic();
+        }
+
+        process->mm.esp = (char*)process->mm.stackStart + PAGE_SIZE * process->mm.pagesInStack;
+        push((int**) &process->mm.esp, (int) process->args);
+        push((int**) &process->mm.esp, (int) exit);
+    } else {
+        process->mm.pagesInStack = 0;
+        process->mm.stackStart = NULL;
+        process->mm.esp = NULL;
+    }
+
+
+    int codeSegment, dataSegment;
+    if (kernel) {
+        codeSegment = KERNEL_CODE_SEGMENT;
+        dataSegment = KERNEL_DATA_SEGMENT;
+
+        push((int**) &process->mm.esp0, (int) process->args);
+        push((int**) &process->mm.esp0, (int) exit);
+        push((int**) &process->mm.esp0, 0x202);
+    } else {
+        codeSegment = USER_CODE_SEGMENT;
+        dataSegment = USER_DATA_SEGMENT;
+
+        push((int**) &process->mm.esp0, dataSegment);
+        push((int**) &process->mm.esp0, (int) process->mm.esp);
+        push((int**) &process->mm.esp0, 0x3202);
     }
 
-    process->mm.esp = (char*)process->mm.stackStart + PAGE_SIZE * process->mm.pagesInStack;
-    push((int**) &process->mm.esp, (int) process->args);
-    push((int**) &process->mm.esp, (int) exit);
-    push((int**) &process->mm.esp, 0x200);
-    push((int**) &process->mm.esp, 0x08);
-    push((int**) &process->mm.esp, (int) entryPoint);
-    push((int**) &process->mm.esp, (int) _interruptEnd);
-    push((int**) &process->mm.esp, (int) signalPIC);
-    push((int**) &process->mm.esp, 0);
+    push((int**) &process->mm.esp0, codeSegment);
+    push((int**) &process->mm.esp0, (int) entryPoint);
+    push((int**) &process->mm.esp0, dataSegment);
+    push((int**) &process->mm.esp0, dataSegment);
+    push((int**) &process->mm.esp0, dataSegment);
+    push((int**) &process->mm.esp0, dataSegment);
+    push((int**) &process->mm.esp0, (int) _interruptEnd);
+    push((int**) &process->mm.esp0, (int) signalPIC);
+    push((int**) &process->mm.esp0, 0);
 }
 
 void exitProcess(struct Process* process) {
@@ -136,17 +170,24 @@ void destroyProcess(struct Process* process) {
     if (process->mm.stackStart) {
         freePages(process->mm.stackStart, process->mm.pagesInStack);
         process->mm.stackStart = NULL;
+    }
 
-        if (process->mm.heap) {
-            mm_set_process_context();
-            mem_check();
-            mm_set_kernel_context();
-            mem_check();
+    if (process->mm.kernelStackStart) {
+        freePages(process->mm.kernelStackStart, process->mm.pagesInKernelStack);
+        process->mm.kernelStackStart = NULL;
+        process->mm.kernelStack = NULL;
+        process->mm.esp0 = NULL;
+    }
 
-            freePages(process->mm.heap, process->mm.pagesInHeap);
-            process->mm.heap = NULL;
-            process->mm.mallocContext = NULL;
-        }
+    if (process->mm.heap) {
+        mm_set_process_context();
+        mem_check();
+        mm_set_kernel_context();
+        mem_check();
+
+        freePages(process->mm.heap, process->mm.pagesInHeap);
+        process->mm.heap = NULL;
+        process->mm.mallocContext = NULL;
     }
 }
 

src/system/process/process.h

@@ -7,6 +7,7 @@
 
 #define NO_TERMINAL -1
 #define MAX_OPEN_FILES 10
+#define KERNEL_STACK_PAGES 10
 
 typedef void (*EntryPoint)(char*);
 
@@ -18,6 +19,11 @@ struct ProcessMemory {
     void* heap;
     void* mallocContext;
     int pagesInHeap;
+
+    void* esp0;
+    void* kernelStack;
+    void* kernelStackStart;
+    int pagesInKernelStack;
 };
 
 enum ProcessStatus {
@@ -37,6 +43,7 @@ struct ProcessSchedule {
 
 struct Process {
     int pid;
+    int kernel;
 
     int ppid;
     struct Process* parent;

src/system/process/table.c

@@ -1,6 +1,7 @@
 #include "system/process/table.h"
 #include "system/scheduler.h"
 #include "drivers/tty/tty.h"
+#include "debug.h"
 
 #define PTABLE_SIZE 64