idle

.gitignore

@@ -1,4 +1,5 @@
 all
+all.raw
 all.raw.gz
 report
 uimage

Makefile

@@ -1,4 +1,4 @@
-load = 0xa0000000
+load = 0x80000000
 
 CXXFLAGS = -Wno-unused-parameter -fno-strict-aliasing -fno-builtin -nostdinc
 CPPFLAGS = -O5 -Wa,-mips32
@@ -8,7 +8,9 @@ LD = $(CROSS)ld
 OBJCOPY = $(CROSS)objcopy
 OBJDUMP = $(CROSS)objdump
 
-BUILT_SOURCES = interrupts.cc panic.cc data.cc test.cc
+kernel_sources = interrupts.cc panic.cc data.cc test.cc
+boot_sources = init.cc
+BUILT_SOURCES = $(kernel_sources) $(boot_sources)
 
 PYPP = /usr/bin/pypp
 %.cc: %.ccp kernel.hh
@@ -17,8 +19,8 @@ PYPP = /usr/bin/pypp
 	$(PYPP) --name $< < $< > $@
 
 # Transform ':' into ';' so vim doesn't think there are errors.
-uimage: all.raw.gz Makefile
+uimage: all.raw Makefile
-	mkimage -A MIPS -O Linux -C gzip -a $(load) -e 0x$(shell /bin/sh -c '$(OBJDUMP) -t all | grep __start$$ | cut -b-8') -n "Shevek's kernel" -d $< $@ | sed -e 's/:/;/g'
+	mkimage -A MIPS -O Linux -C none -a $(load) -e 0x$(shell /bin/sh -c '$(OBJDUMP) -t all | grep __start$$ | cut -b-8') -n "Shevek's kernel" -d $< $@ | sed -e 's/:/;/g'
 
 %.o:%.cc Makefile kernel.hh
 	$(CC) $(CPPFLAGS) $(CXXFLAGS) -c $< -o $@
@@ -26,8 +28,8 @@ uimage: all.raw.gz Makefile
 %.o:%.S Makefile
 	$(CC) $(CPPFLAGS) -DKERNEL_STACK_SIZE=0x2000 -c $< -o $@
 
-# entry.o must be the first file.  For the rest, the order doesn't matter.
+# entry.o must be the first file.  boot.o must be the first of the init objects (which can be dumped after loading).
-all: entry.o $(subst .cc,.o,$(BUILT_SOURCES))
+all: entry.o $(subst .cc,.o,$(kernel_sources)) boot.o $(subst .cc,.o,$(boot_sources))
 	$(LD) --omagic -Ttext $(load) $^ -o $@
 
 junk = mdebug.abi32 reginfo comment pdr

boot.S

@@ -0,0 +1,45 @@
+	// The kernel stack.
+	.lcomm kernel_stack, KERNEL_STACK_SIZE
+
+	.globl __start
+	.set noreorder
+
+#define Status 12
+#define Config 16
+
+__start:
+	bal 1f
+	nop
+	.word _gp
+// For some reason the disassembler considers everything
+// after __start non-code until the next label.  So I add a label.
+start_hack_for_disassembler:
+1:	lw $gp, 0($ra)
+
+	la $sp, kernel_stack + KERNEL_STACK_SIZE
+
+	// Disable interrupts during bootstrap.
+	mtc0 $zero, $Status
+
+	// TODO: flush cache and optionally refill it.
+
+	// Set kseg0 cachable.
+	li $k0, 0x3
+	mtc0 $k0, $Config, 0
+
+	// Jump into cached code.
+	la $t9, 1f
+	jr $t9
+	nop
+1:
+
+	// Clear .bss
+	la $a0, _edata
+	la $a1, _end
+1:	sw $zero, 0($a0)
+	bne $a1, $a0, 1b
+	addu $a0, 4
+
+	la $t9, init
+	jr $t9
+	nop

entry.S

@@ -1,73 +1,15 @@
 	// The kernel stack.
 	.lcomm kernel_stack, KERNEL_STACK_SIZE
 
-	.globl __start
 	.globl run_idle
 	.set noat
-	.set noreorder
 
 #define EntryLo0 2
 #define EntryLo1 3
 #define EntryHi 10
 #define Random 1
 #define Index 0
-#define PageMask 5
-#define Wired 6
-#define Config 16
 #define Status 12
-#define Cause 13
-#define Compare 11
-
-#define save_regs \
-	sw $k0, -0x180($zero) ;\
-	lw $k0, -0x184($zero) ;\
-	sw $at, 12($k0) ;\
-	sw $k1, 108($k0) ;\
-	lw $k1, -0x180($zero) ;\
-	sw $k1, 104($k0) ;\
-	sw $v0, 16($k0) ;\
-	sw $v1, 20($k0) ;\
-	sw $t0, 40($k0) ;\
-	sw $sp, 84($k0) ;\
-	sw $fp, 88($k0) ;\
-	sw $ra, 92($k0) ;\
-	lw $gp, -12($zero) ;\
-	la $sp, kernel_stack + KERNEL_STACK_SIZE ;\
-	move $a0, $k0 ;\
-	la $ra, kernel_exit ;\
-	bal save_args
-
-#define restore_regs \
-	lw $v0, 96($k0) ;\
-	lw $v1, 100($k0) ;\
-	mthi $v0 ;\
-	mtlo $v1 ;\
-	lw $v0, 16($k0) ;\
-	lw $v1, 20($k0) ;\
-	lw $a0, 24($k0) ;\
-	lw $a1, 28($k0) ;\
-	lw $a2, 32($k0) ;\
-	lw $a3, 36($k0) ;\
-	lw $t0, 40($k0) ;\
-	lw $t1, 44($k0) ;\
-	lw $t2, 48($k0) ;\
-	lw $t3, 52($k0) ;\
-	lw $t4, 56($k0) ;\
-	lw $t5, 60($k0) ;\
-	lw $t6, 64($k0) ;\
-	lw $t7, 68($k0) ;\
-	lw $t8, 72($k0) ;\
-	lw $t9, 76($k0) ;\
-	lw $gp, 80($k0) ;\
-	lw $sp, 84($k0) ;\
-	lw $fp, 88($k0) ;\
-	lw $ra, 92($k0) ;\
-	lw $at, 12($k0) ;\
-	lw $k1, 104($k0) ;\
-	sw $k1, -0x180($zero) ;\
-	lw $k1, 108($k0) ;\
-	sw $k0, -0x184($zero) ;\
-	lw $k0, -0x180($zero)
 
 addr_000:
 	// TLB refill
@@ -76,9 +18,10 @@ addr_000:
 	li $a0, 0xffff0000
 	la $t9, panic
 	jr $t9
+	nop
 
-	save_regs
+	sw $ra, -0x188($zero)
-	mfc0 $a1, $EntryHi
+	bal save_regs
 	la $t9, tlb_refill
 	jr $t9
 	nop
@@ -90,8 +33,10 @@ addr_100:
 	li $a0, 0xaaaa0000
 	la $t9, panic
 	jr $t9
+	nop
 
-	save_regs
+	sw $ra, -0x188($zero)
+	bal save_regs
 	la $t9, cache_error
 	jr $t9
 	nop
@@ -100,11 +45,13 @@ addr_180:
 	// General exception
 	// TODO
 
-	li $a0, 0xaaff0000
+	//li $a0, 0xaaff0000
 	la $t9, panic
 	jr $t9
+	nop
 
-	save_regs
+	sw $ra, -0x188($zero)
+	bal save_regs
 	la $t9, exception
 	jr $t9
 	nop
@@ -116,85 +63,83 @@ addr_200:
 	li $a0, 0x0a0f0000
 	la $t9, panic
 	jr $t9
+	nop
 
-	save_regs
+	sw $ra, -0x188($zero)
+	bal save_regs
 	la $t9, interrupt
 	jr $t9
 	nop
-	.fill 0x280 - (. - addr_000)
+	.fill 0x280 - (. - addr_000) - 16
 
-	// space for save_regs.
+	// space for save_regs: k0; current Thread; ra; gp
+	.word 0
 	.word 0
 	.word 0
-
-start_idle:
-	b .
-	nop
-	.word idle_page
-	.word 0x80000000	// A pointer to the current page.
-
-__start:
-	bal 1f
-	nop
 	.word _gp
-// For some reason the disassembler considers everything
-// after __start non-code until the next label.  So I add a label.
-start_hack:
-1:	lw $gp, 0($ra)
 
-	la $sp, kernel_stack + KERNEL_STACK_SIZE
+	.word idle_page		// 280
-
+	.word 0x80000000	// 284  A pointer to the current page.
-	// Disable interrupts during bootstrap.
+start_idle:			// 288
-	mtc0 $zero, $Status
+	// Wait for the next interrupt, then the first thread will be scheduled.
-
+	// It is impractical to try to call schedule, because for that the
-	// TODO: flush cache
+	// idle task would need to own capabilities.
-
+	mfc0 $a0, $9
-	// Set kseg0 cachable.
+	syscall
-	li $k0, 0x3
+1:	wait
-	mtc0 $k0, $Config, 0
+	b 1b
-
-	// Clear .bss
-	la $a0, _edata
-	la $a1, _end
-1:	sw $zero, 0($a0)
-	bne $a1, $a0, 1b
-	addu $a0, 4
-
-	// Set timer to a defined value
-	mtc0 $zero, $Compare, 0
-
-	// Use the interrupt vector for interrupts
-	li $k0, 1 << 23
-	mtc0 $k0, $Cause
-
-	li $a0, 0xff0a0000
-	la $t9, panic
-	jr $t9
-
-	// clear the tlb, hardwire page 0 to 0xffffffff
-	// and soft-wire it to (0x294 << 20) + (0x290 << 10)
-	// (for the idle task).
-
-	// this address doesn't reach the tlb, so it can't trigger exceptions.
-	mtc0 $zero, $PageMask
-	mtc0 $zero, $EntryLo0
-	mtc0 $zero, $EntryLo1
-	li $t0, 0x80000000
-	// There are 32 tlb entries.
-	addi $a0, $zero, 31
-1:	mtc0 $t0, $EntryHi
-	mtc0 $a0, $Index
-	tlbwi
-	addiu $t0, $t0, 1 << 13
-	bgtz $a0, 1b
-	addiu $a0, $a0, -1
-
-	la $t9, init
-	jalr $t9
 	nop
-	sw $gp, -12($zero)
 
-save_args:
+kernel_exit:
+	move $k0, $v0
+	lw $v0, 96($k0)
+	lw $v1, 100($k0)
+	mthi $v0
+	mtlo $v1
+	lw $v0, 16($k0)
+	lw $v1, 20($k0)
+	lw $a0, 24($k0)
+	lw $a1, 28($k0)
+	lw $a2, 32($k0)
+	lw $a3, 36($k0)
+	lw $t0, 40($k0)
+	lw $t1, 44($k0)
+	lw $t2, 48($k0)
+	lw $t3, 52($k0)
+	lw $t4, 56($k0)
+	lw $t5, 60($k0)
+	lw $t6, 64($k0)
+	lw $t7, 68($k0)
+	lw $t8, 72($k0)
+	lw $t9, 76($k0)
+	lw $gp, 80($k0)
+	lw $sp, 84($k0)
+	lw $fp, 88($k0)
+	lw $ra, 92($k0)
+	lw $at, 12($k0)
+	lw $k1, 104($k0)	// Real $k0
+	sw $k1, -0x190($zero)
+	lw $k1, 108($k0)
+	sw $k0, -0x18c($zero)
+	lw $k0, -0x190($zero)
+	eret
+
+save_regs:
+	sw $k0, -0x190($zero)
+	lw $k0, -0x18c($zero)
+	sw $at, 12($k0)
+	sw $gp, 80($k0)
+	sw $sp, 84($k0)
+	sw $fp, 88($k0)
+
+	sw $k1, 108($k0)
+	lw $k1, -0x190($zero)
+	sw $k1, 104($k0)	// Real $k0
+
+	lw $k1, -0x188($zero)
+	sw $k1, 92($k0)		// Real $ra
+	sw $v0, 16($k0)
+	sw $v1, 20($k0)
 	sw $a0, 24($k0)
 	sw $a1, 28($k0)
 	sw $a2, 32($k0)
@@ -208,23 +153,14 @@ save_args:
 	sw $t7, 68($k0)
 	sw $t8, 72($k0)
 	sw $t9, 76($k0)
-	sw $gp, 80($k0)
+	mfhi $v0
-	j $ra
+	mflo $v1
+	sw $v0, 96($k0)
+	sw $v1, 100($k0)
 
-run_idle:
+	lw $gp, -0x184($zero)
-	move $k0, $a0
+	la $sp, kernel_stack + KERNEL_STACK_SIZE
-	move $k1, $gp
+	move $t9, $ra
-	// Prepare enabling interrupts and switching to user mode.
+	la $ra, kernel_exit
-	// The command is executed in the delay slot of the jump.
-	li $t0, 0xff11
-	// Now it's acceptable to receive an exception.  Jump to kuseg,
-	// thereby generating a tlb_refill exception (which is handled).
-	// The address is the virtual address where the idle task is.
-	la $t9, ((0x294 << 20) + (0x290 << 10) + 0x288)
 	jr $t9
-	mtc0 $t0, $Status
+	move $a0, $k0
-
-kernel_exit:
-	move $k0, $v0
-	restore_regs
-	eret

init.ccp

@@ -0,0 +1,125 @@
+#pypp 0
+#include "kernel.hh"
+
+static void init_idle ():
+	// initialize idle task as if it is currently running.
+	idle.size = sizeof (Thread)
+	idle.prev = NULL
+	idle.next = NULL
+	idle.thread_prev = NULL
+	idle.thread_next = NULL
+	idle.schedule_prev = NULL
+	idle.schedule_next = NULL
+	idle.address_space = &idle_memory
+	// initialize idle_memory.
+	idle_memory.size = sizeof (Memory)
+	idle_memory.prev = NULL
+	idle_memory.next = NULL
+	idle_memory.memory_prev = NULL
+	idle_memory.memory_next = NULL
+	idle_memory.pages = &idle_page
+	idle_memory.threads = &idle
+	idle_memory.memories = NULL
+	idle_memory.limit = 0
+	idle_memory.used = 0
+	idle_memory.cpu.directory = (Page ***)0x80000000
+	idle_memory.cpu.asid = 0
+	// initialize idle_page
+	idle_page.size = sizeof (Page)
+	idle_page.prev = NULL
+	idle_page.next = NULL
+	idle_page.page_prev = NULL
+	idle_page.page_next = NULL
+	// Not an error, this is really physical page 0.
+	idle_page.physical = 0
+
+static void init_cp0 ():
+	// Set timer to a defined value (11 is Compare)
+	__asm__ volatile ("mtc0 %0, $11, 0" :: "r"(1000000))
+	// Reset timer (9 is Count)
+	__asm__ volatile ("mtc0 $zero, $9, 0")
+	// Use the interrupt vector for interrupts (13 is Cause)
+	__asm__ volatile ("mtc0 %0, $13" :: "r"(1 << 23))
+
+	// clear the tlb, hardwire page 0 to 0xffffffff
+	// and soft-wire it to (0x294 << 20) + (0x290 << 10)
+	// (for the idle task).
+
+	// 6 is Wired.
+	__asm__ volatile ("mtc0 %0, $6" :: "r"(1))
+	// 5 is PageMask.
+	__asm__ volatile ("mtc0 $zero, $5")
+	// 2 is EntryLo0.
+	__asm__ volatile ("mtc0 $zero, $2")
+	// 3 is EntryLo1.
+	__asm__ volatile ("mtc0 $zero, $3")
+	// Get number of tlb entries (is 31).
+	unsigned num;
+	__asm__ volatile ("mfc0 %0, $16, 1" : "=r"(num))
+	num >>= 25
+	num &= 0x3f
+	// Clear the tlb.
+	#if 0
+	for unsigned i = 1; i < num; ++i:
+		// this address doesn't reach the tlb, so it can't trigger exceptions.
+		// 10 is EntryHi
+		__asm__ volatile ("mtc0 %0, $10" :: "r"(0x70000000 + 0x1000 * i))
+		// 0 is Index.
+		__asm__ volatile ("mtc0 %0, $0" :: "r"(i))
+		// write the data.
+		__asm__ volatile ("tlbwi")
+	#endif
+	// Fill the upper page in kseg3.
+	__asm__ volatile ("mtc0 %0, $10" :: "r"(0xfffff000))
+	__asm__ volatile ("mtc0 %0, $2" :: "r"(0x0000001d))
+	__asm__ volatile ("mtc0 %0, $3" :: "r"(0x0000001f))
+	__asm__ volatile ("mtc0 %0, $0" :: "r"(0))
+	__asm__ volatile ("tlbwi")
+	// Fill the idle task's page in useg.  Set it to non-cachable.
+	__asm__ volatile ("mtc0 %0, $10" :: "r"(0x284a0000))
+	__asm__ volatile ("mtc0 %0, $2" :: "r"(0x00000016))
+	__asm__ volatile ("mtc0 %0, $3" :: "r"(0x00000014))
+	__asm__ volatile ("tlbwr")
+	// Allow eret to be used to jump to the idle task.
+	// 14 is EPC.
+	__asm__ volatile ("mtc0 %0, $14" :: "r"(0x284a0288))
+	// Enable all interrupts and say we're handling an exception.
+	// 12 is Status.
+	__asm__ volatile ("mtc0 %0, $12" :: "r"(0x1000ff13))
+
+/// Initialize the kernel, finish by falling into the idle task.
+extern unsigned _end
+void init ():
+	// Initialize kernel variables to empty.
+	sleepers = NULL
+	runners = NULL
+	zero_pages = NULL
+	// Fill junk pages with all memory not currently used.
+	junk_pages = (FreePage *)(((unsigned)&_end + (1 << 12) - 1) & ~((1 << 12) - 1))
+	FreePage *p, *next
+	unsigned count = 1
+	for p = junk_pages, next = p; (unsigned)next - 0x80000000 < (1 << 27); p = next, next = (FreePage *)((unsigned)p + (1 << 12)):
+		p->next = next
+		++count
+	p->next = NULL
+	// initialize system control coprocessor.
+	init_cp0 ()
+	// initialize everything about the idle task.
+	init_idle ()
+	// initialize top_memory.
+	top_memory.size = sizeof (Memory)
+	top_memory.prev = NULL
+	top_memory.next = NULL
+	top_memory.memory_prev = NULL
+	top_memory.memory_next = NULL
+	top_memory.pages = NULL
+	top_memory.threads = NULL
+	top_memory.memories = NULL
+	top_memory.limit = count
+	top_memory.used = 0
+	top_memory.cpu.directory = NULL
+	top_memory.cpu.asid = 0
+	// TOOO: set up initial threads.
+
+	// Done; return to user space (the idle task).
+	__asm__ volatile ("eret")

interrupts.ccp

@@ -2,7 +2,7 @@
 #include "kernel.hh"
 
 // hi and lo cannot be saved in assemply due to space restrictions.
-#define save_hilo(x) do { __asm__ ("mfhi %0 ; mflo %1" : "=r"((x)->cpu.hi), "=r"((x)->cpu.lo)); } while (0)
+#define save_hilo(x) do { __asm__ volatile ("mfhi %0 ; mflo %1" : "=r"((x)->cpu.hi), "=r"((x)->cpu.lo)); } while (0)
 
 /// A TLB miss has occurred.  This should eventually move to entry.S.
 Thread *tlb_refill (Thread *current, unsigned EntryHi):
@@ -29,7 +29,7 @@ Thread *tlb_refill (Thread *current, unsigned EntryHi):
 		low1 = page1->physical | 0x18 | 0x4 | 0x2
 	else
 		low1 = 0
-	__asm__ ("mtc0 %0, $2; mtc0 %1, $3; tlbwr" :: "r"(low0), "r"(low1))
+	__asm__ volatile ("mtc0 %0, $2; mtc0 %1, $3; tlbwr" :: "r"(low0), "r"(low1))
 	return current
 
 /// An interrupt which is not an exception has occurred.
@@ -49,67 +49,3 @@ Thread *cache_error (Thread *current):
 	save_hilo (current)
 	panic (0x33333333, "cache error")
 	return current
-
-static void init_idle ():
-	// initialize idle task as if it is currently running.
-	idle.size = sizeof (Thread)
-	idle.prev = NULL
-	idle.next = NULL
-	idle.thread_prev = NULL
-	idle.thread_next = NULL
-	idle.schedule_prev = NULL
-	idle.schedule_next = NULL
-	idle.address_space = &idle_memory
-	// initialize idle_memory.
-	idle_memory.size = sizeof (Memory)
-	idle_memory.prev = NULL
-	idle_memory.next = NULL
-	idle_memory.memory_prev = NULL
-	idle_memory.memory_next = NULL
-	idle_memory.pages = &idle_page
-	idle_memory.threads = &idle
-	idle_memory.memories = NULL
-	idle_memory.limit = 0
-	idle_memory.used = 0
-	idle_memory.cpu.directory = (Page ***)0x80000000
-	idle_memory.cpu.asid = 0
-	// initialize idle_page
-	idle_page.size = sizeof (Page)
-	idle_page.prev = NULL
-	idle_page.next = NULL
-	idle_page.page_prev = NULL
-	idle_page.page_next = NULL
-	// Not an error, this is really physical page 0.
-	idle_page.physical = 0
-
-/// Initialize the kernel, finish by falling into the idle task.
-extern unsigned _end
-void init ():
-	// Initialize kernel variables to empty.
-	sleepers = NULL
-	runners = NULL
-	zero_pages = NULL
-	// Fill junk pages with all memory not currently used.
-	junk_pages = (FreePage *)(((unsigned)&_end + (1 << 12) - 1) & ~((1 << 12) - 1))
-	FreePage *p, *next
-	unsigned count = 1
-	for p = junk_pages; (unsigned)next - 0x80000000 < (1 << 27); p = next, next = (FreePage *)((unsigned)p + 1 << 12):
-		p->next = next
-		++count
-	p->next = NULL
-	// initialize everything about the idle task.
-	init_idle ()
-	// initialize top_memory.
-	top_memory.size = sizeof (Memory)
-	top_memory.prev = NULL
-	top_memory.next = NULL
-	top_memory.memory_prev = NULL
-	top_memory.memory_next = NULL
-	top_memory.pages = NULL
-	top_memory.threads = NULL
-	top_memory.memories = NULL
-	top_memory.limit = count
-	top_memory.used = 0
-	top_memory.cpu.directory = NULL
-	top_memory.cpu.asid = 0
-	// TOOO: set up initial threads.

panic.ccp

@@ -4,7 +4,7 @@
 void panic (unsigned n, char const *message):
 	while (1):
 		for unsigned bit = 0x80000000; bit; bit >>= 1:
-			for int i = 0; i < 60000; ++i:
+			for int i = 0; i < 600000; ++i:
-				led (n & bit, i > 20000 && i < 40000)
+				led (n & bit, i > 200000 && i < 400000)
-		for int i = 0; i < 100000; ++i:
+		for int i = 0; i < 1000000; ++i:
 			led (false, false)

start.S

@@ -1,24 +0,0 @@
-	.set noreorder
-	.globl __start
-	.globl kernel_stack
-__start:
-	bal 1f
-	nop
-	.word _gp
-1:	lw $gp, 0($ra)
-	nop
-
-	la $a0, _edata
-	la $a1, _end
-1:	sw $zero, 0($a0)
-	bne $a1, $a0, 1b
-	addu $a0, 4
-
-	la $sp, kernel_stack + KERNEL_STACK_SIZE
-
-	bal kernel_entry
-	nop
-	b .
-	nop
-
-	.lcomm kernel_stack, KERNEL_STACK_SIZE