feat(bulb): add new operating system that focuses on virtual memory

Makefile

@@ -39,7 +39,7 @@ clean:
 # Build the different OSes
 build: build-$(BUILD_DEFAULT_TARGET)
 
-buildall: build-chainloader build-thorn
+buildall: build-chainloader build-thorn build-bulb
 
 build-chainloader:
 	$(MAKE) -C chainloader build

thorn/include/common/font.h

@@ -1,8 +1,10 @@
 #ifndef _ROSE_C_FONT_H
 #define _ROSE_C_FONT_H
 
+#ifndef __ASSEMBLER__
+
 #define FONT_SIZE       8
-#define FONT_FACTOR     2
+#define FONT_FACTOR     3
 #define FONT_REAL_WIDTH (FONT_SIZE * FONT_FACTOR)
 
 // Spacing between lines in pixels
@@ -32,11 +34,15 @@ static volatile color_t font_fg;
 const unsigned long long int * font (int c);
 
 void printc (char c);
+void prints (char const * str);
 void printc_location (point_t point, char c);
 
 void putc_screen (void * p, char c);
 
 void font_set_normal (void);
 void font_set_error (void);
 
+void test_print ();
+
 #endif
+#endif

thorn/include/common/utils.h

@@ -9,4 +9,8 @@ extern unsigned int get32 (unsigned long);
 
 extern int get_el (void);
 
+extern void set_pgd (unsigned long pgd);
+
+extern unsigned long get_pgd (void);
+
 #endif /*_ROSE_C_BOOT_H */

thorn/include/kernel/arm/sysregs.h

@@ -43,7 +43,9 @@
 // ESR_EL1, Exception Syndrome Register (EL1). Page 2431 of AArch64-Reference-Manual.
 // ***************************************
 
-#define ESR_ELx_EC_SHIFT 26
-#define ESR_ELx_EC_SVC64 0x15
+#define ESR_ELx_EC_SHIFT     26
+#define ESR_ELx_EC_SVC64     0x15
+#define ESR_ELx_EC_DABT_LOW  0b100100
+#define ESR_ELx_EC_DABT_SAME 0b100101
 
 #endif /*_ROSE_K_A_SYSREGS_H*/

thorn/include/kernel/irq.h

@@ -13,7 +13,7 @@
 
 void enable_interrupt_controller (void);
 
-void show_invalid_entry_message (int type, ptr_t esr, ptr_t address);
+void show_invalid_entry_message (int type, ptr_t esr, ptr_t elr, ptr_t far);
 
 void irq_vector_init (void);
 

thorn/include/kernel/mm.h

@@ -11,7 +11,7 @@
 #define PAGE_SIZE    (1 << PAGE_SHIFT)
 #define SECTION_SIZE (1 << SECTION_SHIFT)
 
-#define LOW_MEMORY  (2 * SECTION_SIZE)
+#define LOW_MEMORY  (1 * SECTION_SIZE)
 #define HIGH_MEMORY 0x70000000
 
 #define PAGING_MEMORY (HIGH_MEMORY - LOW_MEMORY)

thorn/include/kernel/mmu.h

@@ -0,0 +1,53 @@
+#ifndef _ROSE_MMU_H
+#define _ROSE_MMU_H
+
+#ifndef __ASSEMBLER__
+
+// Implementation taken from
+// https://github.com/bztsrc/raspi3-tutorial/blob/master/10_virtualmemory/mmu.c
+
+#include "common/font.h"
+#include "common/logging.h"
+#include "common/status_led.h"
+#include "kernel/irq.h"
+#include "kernel/mini_uart.h"
+#include "kernel/peripherals/base.h"
+#include "kernel/sched.h"
+
+#define PAGESIZE 4096
+
+// granularity
+#define PT_PAGE   0b11// 4k granule
+#define PT_BLOCK  0b01// 2M granule
+// accessibility
+#define PT_KERNEL (0 << 6)   // privileged, supervisor EL1 access only
+#define PT_USER   (1 << 6)   // unprivileged, EL0 access allowed
+#define PT_RW     (0 << 7)   // read-write
+#define PT_RO     (1 << 7)   // read-only
+#define PT_AF     (1 << 10)  // accessed flag
+#define PT_NX     (1UL << 54)// no execute
+// shareability
+#define PT_OSH    (2 << 8)// outter shareable
+#define PT_ISH    (3 << 8)// inner shareable
+// defined in MAIR register
+#define PT_MEM    (0 << 2)// normal memory
+#define PT_DEV    (1 << 2)// device MMIO
+#define PT_NC     (2 << 2)// non-cachable
+
+#define TTBR_CNP 1
+
+#define RAM_IN_GB 8
+
+// get addresses from linker
+extern volatile unsigned char _data;
+extern volatile unsigned char _end;
+
+static volatile unsigned int __attribute__ ((aligned (16))) buffer[32];
+
+void init_pages ();
+void init_mmu (void);
+
+void data_abort_el0 (ptr_t far, ptr_t esr, ptr_t elr);
+
+#endif
+#endif//_ROSE_MMU_H

thorn/include/kernel/sched.h

@@ -1,6 +1,7 @@
 #ifndef _ROSE_K_SCHED_H
 #define _ROSE_K_SCHED_H
 
+#include "common/font.h"
 #include "common/stddef.h"
 
 #define THREAD_CPU_CONTEXT 0// offset of cpu_context in task_struct
@@ -39,14 +40,29 @@ struct cpu_context {
     unsigned long pc;
 };
 
+#define MAX_PROCESS_PAGES 16
+
+struct user_page {
+    unsigned long phys_addr;
+    unsigned long virt_addr;
+};
+
+struct mm_struct {
+    unsigned long    pgd;
+    int              user_pages_count;
+    struct user_page user_pages[MAX_PROCESS_PAGES];
+    int              kernel_pages_count;
+    unsigned long    kernel_pages[MAX_PROCESS_PAGES];
+};
+
 struct task_struct {
     struct cpu_context cpu_context;
     long               state;
     long               counter;
     long               priority;
     long               preempt_count;
-    ptr_t              stack;
-    ptr_t              flags;
+    unsigned long      flags;
+    struct mm_struct   mm;
 };
 
 extern void sched_init (void);
@@ -65,6 +81,8 @@ extern void cpu_switch_to (struct task_struct * prev, struct task_struct * next)
 
 extern void exit_process (void);
 
+extern void kill_process (void);
+
 extern void task_init (void);
 
 #define INIT_TASK                                \

thorn/src/common/font.c

@@ -191,6 +191,12 @@ void printc (char c) {
     }
 }
 
+void prints (char const * str) {
+    while (*str) {
+        printc (*str++);
+    }
+}
+
 void font_set_normal (void) {
     font_fg = font_normal_fg;
 }
@@ -201,3 +207,7 @@ void font_set_error (void) {
 void putc_screen (void * p, char c) {
     printc (c);
 }
+
+void test_print () {
+    prints ("test\r\n");
+}

thorn/src/common/printf.c

@@ -206,6 +206,19 @@ void tfp_format (void * putp, putcf putf, char * fmt, va_list va) {
                                   unsigned int), 16, (ch == 'P'), bf);
                     putchw (putp, putf, w, lz, bf);
                     break;
+                case 'b':
+                case 'B':
+                    putf (putp, '0');
+                    putf (putp, 'b');
+#ifdef PRINTF_LONG_SUPPORT
+                    if (lng)
+                        uli2a (va_arg (va, unsigned long int), 2, (ch == 'B'), bf);
+                    else
+#endif
+                    ui2a (va_arg (va,
+                                  unsigned int), 2, (ch == 'B'), bf);
+                    putchw (putp, putf, w, lz, bf);
+                    break;
                 case '%':
                     putf (putp, ch);
                 default:

thorn/src/common/utils.S

@@ -1,3 +1,5 @@
+#include "common/font.h"
+
 .globl get_el
 get_el:
 	mrs x0, CurrentEL
@@ -19,3 +21,20 @@ delay:
 	subs x0, x0, #1
 	bne delay
 	ret
+
+.globl set_pgd
+set_pgd:
+	msr	ttbr0_el1, x0
+//	tlbi vmalle1is      // Crashes CPU
+	dsb ish              // ensure completion of TLB invalidation
+	isb
+	ret
+
+.globl get_pgd
+get_pgd:
+	mov x1, 0
+	ldr x0, [x1]
+	mov x0, 0x1000
+	msr	ttbr0_el1, x0
+	ldr x0, [x1]
+	ret

thorn/src/kernel/boot.S

@@ -15,22 +15,23 @@ _start:
 	b	master
 
 init_bss:
-    adr	x0, bss_begin
-    adr	x1, bss_end
+    adr	x0, __bss_start
+    adr	x1, __bss_end
     sub	x1, x1, x0
     bl	memzero
 
     adr x0, move_to_el1
-    mov	x1, #0xe0
-    str	x0, [x1]
 
-    mov	x1, #0xe8
-    str	x0, [x1]
-
-    mov	x1, #0xf0
-    str	x0, [x1]
-
-    sev
+//    mov	x1, #0xe0
+//    str	x0, [x1]
+//
+//    mov	x1, #0xe8
+//    str	x0, [x1]
+//
+//    mov	x1, #0xf0
+//    str	x0, [x1]
+//
+//    sev
 
     b move_to_el1
 

thorn/src/kernel/entry.S

@@ -1,12 +1,14 @@
 #include "kernel/arm/sysregs.h"
 #include "kernel/entry.h"
 #include "kernel/sys.h"
+#include "kernel/mmu.h"
 
 	.macro handle_invalid_entry el, type
 	kernel_entry \el
 	mov	x0, #\type
 	mrs	x1, esr_el1
 	mrs	x2, elr_el1
+    mrs x3, far_el1
 	bl	show_invalid_entry_message
 	b	err_hang
 	.endm
@@ -91,19 +93,19 @@ vectors:
 	ventry	error_invalid_el1t			// Error EL1t
 
 	ventry	sync_invalid_el1h			// Synchronous EL1h
-	ventry	el1_irq					// IRQ EL1h
+	ventry	el1_irq					    // IRQ EL1h
 	ventry	fiq_invalid_el1h			// FIQ EL1h
 	ventry	error_invalid_el1h			// Error EL1h
 
-	ventry	el0_sync				// Synchronous 64-bit EL0
-	ventry	el0_irq					// IRQ 64-bit EL0
+	ventry	el0_sync				    // Synchronous 64-bit EL0
+	ventry	el0_irq					    // IRQ 64-bit EL0
 	ventry	fiq_invalid_el0_64			// FIQ 64-bit EL0
-	ventry	error_invalid_el0_64			// Error 64-bit EL0
+	ventry	error_invalid_el0_64		// Error 64-bit EL0
 
 	ventry	sync_invalid_el0_32			// Synchronous 32-bit EL0
 	ventry	irq_invalid_el0_32			// IRQ 32-bit EL0
 	ventry	fiq_invalid_el0_32			// FIQ 32-bit EL0
-	ventry	error_invalid_el0_32			// Error 32-bit EL0
+	ventry	error_invalid_el0_32		// Error 32-bit EL0
 
 sync_invalid_el1t:
 	handle_invalid_entry 1,  SYNC_INVALID_EL1t
@@ -156,43 +158,55 @@ el0_irq:
 
 el0_sync:
 	kernel_entry 0
-	mrs	x25, esr_el1				// read the syndrome register
-	lsr	x24, x25, #ESR_ELx_EC_SHIFT		// exception class
-	cmp	x24, #ESR_ELx_EC_SVC64			// SVC in 64-bit state
-	b.eq	el0_svc
+	mrs	x25, esr_el1									// read the syndrome register
+	lsr	x24, x25, #ESR_ELx_EC_SHIFT						// exception class
+    cmp	x24, #ESR_ELx_EC_SVC64							// SVC in 64-bit state
+    b.eq	el0_svc
+    cmp x24, #ESR_ELx_EC_DABT_LOW
+	b.eq 	el0_da
 	handle_invalid_entry 0, SYNC_ERROR
 
-sc_nr	.req	x25					// number of system calls
-scno	.req	x26					// syscall number
-stbl	.req	x27					// syscall table pointer
+sc_nr	.req	x25															// number of system calls
+scno	.req	x26															// syscall number
+stbl	.req	x27															// syscall table pointer
 
 el0_svc:
-	adr	stbl, sys_call_table			// load syscall table pointer
+	adr	stbl, sys_call_table		// load syscall table pointer
 	uxtw	scno, w8				// syscall number in w8
 	mov	sc_nr, #__NR_syscalls
 	bl	enable_irq
-	cmp     scno, sc_nr                     	// check upper syscall limit
+	cmp     scno, sc_nr             // check upper syscall limit
 	b.hs	ni_sys
 
-	ldr	x16, [stbl, scno, lsl #3]		// address in the syscall table
-	blr	x16					// call sys_* routine
+	ldr	x16, [stbl, scno, lsl #3]	// address in the syscall table
+	blr	x16							// call sys_* routine
 	b	ret_from_syscall
 ni_sys:
 	handle_invalid_entry 0, SYSCALL_ERROR
 ret_from_syscall:
 	bl	disable_irq
-	str	x0, [sp, #S_X0]				// returned x0
+	str	x0, [sp, #S_X0]												// returned x0
 	kernel_exit 0
 
+el0_da:
+    bl preempt_disable
+	mrs x0, far_el1
+	mrs x1, esr_el1
+	mrs	x2, elr_el1
+	bl data_abort_el0
+    bl preempt_enable
+    bl disable_irq
+	eret
+
 .globl ret_from_fork
 ret_from_fork:
 	bl	schedule_tail
-	cbz	x19, ret_to_user			// not a kernel thread
+	cbz	x19, ret_to_user											// not a kernel thread
 	mov	x0, x20
 	blr	x19
 ret_to_user:
 	bl disable_irq
 	kernel_exit 0
 
 .globl err_hang
-err_hang: b err_hang
+err_hang: b err_hang