Trying to track an annoying bug.

11 files changed, 177 insertions, 50 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 2adacbc..0db3d6b 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -7,7 +7,7 @@ CFLAGS = -ffreestanding -O2 -std=gnu99 -Wall -Wextra -I . -I ./include -g -Wno-u
 # CXX = i586-elf-g++
 # CXFLAGS = -ffreestanding -O3 -Wall -Wextra -I . -I ./include -fno-exceptions -fno-rtti
 LD = i586-elf-gcc
-LDFLAGS = -T linker.ld -ffreestanding -O2 -nostdlib -lgcc
+LDFLAGS = -T linker.ld -ffreestanding -O2 -nostdlib -lgcc -Xlinker -Map=kernel.map
 
 OBJ = lib/string.o lib/printf.o lib/slab_alloc.o \
 	l0/loader.o l0/kmain.o l0/dbglog.o l0/sys.o \
diff --git a/kernel/config.h b/kernel/config.h
index d198295..2de43af 100644
--- a/kernel/config.h
+++ b/kernel/config.h
@@ -13,7 +13,6 @@
 #error "This kernel needs to be compiled with a ix86-elf compiler"
 #endif
 
-
 #define K_HIGHHALF_ADDR ((size_t)0xC0000000)
 
 #define OS_NAME "macrO.Scope"
diff --git a/kernel/include/idt.h b/kernel/include/idt.h
index ba344c9..e054ed5 100644
--- a/kernel/include/idt.h
+++ b/kernel/include/idt.h
@@ -88,4 +88,6 @@ void idt_init();
 void idt_set_ex_handler(int number, isr_handler_t func);	//Set exception handler
 void idt_set_irq_handler(int number, isr_handler_t func);	//Set IRQ handler
 
+void dbg_dump_registers(registers_t*);
+
 /* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/kernel/include/slab_alloc.h b/kernel/include/slab_alloc.h
index 5c575ba..5355a66 100644
--- a/kernel/include/slab_alloc.h
+++ b/kernel/include/slab_alloc.h
@@ -8,7 +8,14 @@
 #include <stddef.h>
 #include <stdbool.h>
 
-#include <sys.h>
+#if defined(__linux__)
+//redefine necessary stuff
+#include <assert.h>
+#define ASSERT assert
+#define PAGE_SIZE 0x1000
+#else
+#include <sys.h>	// this is macroscope
+#endif
 
 // expected format for the array of slab_type_t given to slab_create :
 // an array of slab_type descriptors, with last descriptor full of zeroes
diff --git a/kernel/l0/idt.c b/kernel/l0/idt.c
index 3bfcfc5..2d7b3bc 100644
--- a/kernel/l0/idt.c
+++ b/kernel/l0/idt.c
@@ -66,12 +66,6 @@ static isr_handler_t ex_handlers[32] = {0};
 
 /*	Called in interrupt.s when an exception fires (interrupt 0 to 31) */
 void idt_exHandler(registers_t *regs) {
-	/*dbg_printf("/ Exception %i\n", regs->int_no);*/
-	/*dbg_printf("| EAX: 0x%p   EBX: 0x%p   ECX: 0x%p   EDX: 0x%p\n", regs->eax, regs->ebx, regs->ecx, regs->edx);*/
-	/*dbg_printf("| EDI: 0x%p   ESI: 0x%p   ESP: 0x%p   EBP: 0x%p\n", regs->edi, regs->esi, regs->esp, regs->ebp);*/
-	/*dbg_printf("| EIP: 0x%p   CS : 0x%p   DS : 0x%p   SS : 0x%p\n", regs->eip, regs->cs, regs->ds, regs->ss);*/
-	/*dbg_printf("\\ EFl: 0x%p   I# : 0x%p   Err: 0x%p\n", regs->eflags, regs->int_no, regs->err_code);*/
-
 	if (ex_handlers[regs->int_no] != 0) {
 		ex_handlers[regs->int_no](regs);
 	}
@@ -194,4 +188,13 @@ void idt_set_ex_handler(int number, isr_handler_t func) {
 	}
 }
 
+void dbg_dump_registers(registers_t *regs) {
+	dbg_printf("/ Exception %i\n", regs->int_no);
+	dbg_printf("| EAX: 0x%p   EBX: 0x%p   ECX: 0x%p   EDX: 0x%p\n", regs->eax, regs->ebx, regs->ecx, regs->edx);
+	dbg_printf("| EDI: 0x%p   ESI: 0x%p   ESP: 0x%p   EBP: 0x%p\n", regs->edi, regs->esi, regs->esp, regs->ebp);
+	dbg_printf("| EIP: 0x%p   CS : 0x%p   DS : 0x%p   SS : 0x%p\n", regs->eip, regs->cs, regs->ds, regs->ss);
+	dbg_printf("\\ EFl: 0x%p   I# : 0x%p   Err: 0x%p\n", regs->eflags, regs->int_no, regs->err_code);
+}
+
 /* vim: set ts=4 sw=4 tw=0 noet :*/
+
diff --git a/kernel/l0/kmain.c b/kernel/l0/kmain.c
index a935c9c..8cb370a 100644
--- a/kernel/l0/kmain.c
+++ b/kernel/l0/kmain.c
@@ -11,26 +11,37 @@
 
 #include <slab_alloc.h>
 
+extern char k_end_addr;	// defined in linker script : 0xC0000000 plus kernel stuff
+
 void breakpoint_handler(registers_t *regs) {
 	dbg_printf("Breakpoint! (int3)\n");
 	BOCHS_BREAKPOINT;
 }
 
 void test_pf_handler(pagedir_t *pd, region_info_t *i, void* addr) {
-	dbg_printf("0x%p", addr);
+	dbg_printf(" {0x%p", addr);
 
 	uint32_t f = frame_alloc(1);
 	if (f == 0) PANIC("Out Of Memory");
-	dbg_printf(" -> %i", f);
+	dbg_printf(" -> %i} ", f);
 
 	int error = pd_map_page(addr, f, 1);
 	if (error) PANIC("Could not map frame (OOM)");
 }
 
 void* page_alloc_fun_for_kmalloc(size_t bytes) {
-	return region_alloc(bytes, REGION_T_CORE_HEAP, test_pf_handler);
+	void* addr = region_alloc(bytes, REGION_T_CORE_HEAP, test_pf_handler);
+	return addr;
 }
 void page_free_fun_for_kmalloc(void* ptr) {
+	region_info_t *i = find_region(ptr);
+	for (void* x = i->addr; x < i->addr + i->size; x += PAGE_SIZE) {
+		uint32_t f = pd_get_frame(x);
+		if (f != 0) {
+			pd_unmap_page(x);
+			frame_free(f, 1);
+		}
+	}
 	region_free(ptr);
 }
 slab_type_t slab_sizes[] = {
@@ -47,8 +58,6 @@ slab_type_t slab_sizes[] = {
 	{ 0, 0, 0 }
 };
 
-
-extern char k_end_addr;	// defined in linker script : 0xC0000000 plus kernel stuff
  
 void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) {
 	dbglog_setup();
@@ -66,7 +75,6 @@ void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) {
 
 	size_t total_ram = ((mbd->mem_upper + mbd->mem_lower) * 1024);
 	dbg_printf("Total ram: %d Kb\n", total_ram / 1024);
-	// paging_init(totalRam);
 
 	// used for allocation of data structures before malloc is set up
 	// a pointer to this pointer is passed to the functions that might have
@@ -80,6 +88,8 @@ void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) {
 	paging_setup(kernel_data_end);
 	dbg_printf("Paging seems to be working!\n");
 
+	BOCHS_BREAKPOINT;
+
 	region_allocator_init(kernel_data_end);
 	dbg_print_region_stats();
 
@@ -107,9 +117,10 @@ void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) {
 	region_free(s);
 	dbg_printf("Freed region 0x%p\n", s);
 	dbg_print_region_stats();
+	BOCHS_BREAKPOINT;
 
 	// allocate a big region and try to write into it
-	const size_t n = 1000;
+	const size_t n = 200;
 	void* p0 = region_alloc(n * PAGE_SIZE, REGION_T_HW, test_pf_handler);
 	for (size_t i = 0; i < n; i++) {
 		uint32_t *x = (uint32_t*)(p0 + i * PAGE_SIZE);
@@ -119,43 +130,44 @@ void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) {
 		x[1] = (i * 20422) % 122;
 		dbg_printf("]\n", i);
 	}
+	BOCHS_BREAKPOINT;
 	// unmap memory
 	for (size_t i = 0; i < n; i++) {
-		uint32_t *x = (uint32_t*)(p0 + i * PAGE_SIZE);
+		void* p = p0 + i * PAGE_SIZE;
+		uint32_t *x = (uint32_t*)p;
 		ASSERT(x[1] == (i * 20422) % 122);
 
-		uint32_t f = pd_get_frame(x);
+		uint32_t f = pd_get_frame(p);
 		ASSERT(f != 0);
-		pd_unmap_page(x);
+		pd_unmap_page(p);
+		ASSERT(pd_get_frame(p) == 0);
 
 		frame_free(f, 1);
 	}
 	region_free(s);
+	BOCHS_BREAKPOINT;
 
 	// TEST SLAB ALLOCATOR!!!
 	mem_allocator_t *a =
 		create_slab_allocator(slab_sizes, page_alloc_fun_for_kmalloc,
 										  page_free_fun_for_kmalloc);
 	dbg_printf("Created slab allocator at 0x%p\n", a);
-	const int m = 100;
-	void* ptr[m];
-	for (int i = 0; i < m; i++) {
-		size_t s = 1 << ((i * 7) % 12 + 1);
-		ptr[i] = slab_alloc(a, s);
-		dbg_printf("Alloc %i : 0x%p\n", s, ptr[i]);
-		dbg_print_region_stats();
-	}
-	for (int i = 0; i < m; i++) {
-		slab_free(a, ptr[m - i - 1]);
-	}
 	dbg_print_region_stats();
+	const int m = 10000;
+	uint16_t* ptr[m];
 	for (int i = 0; i < m; i++) {
-		size_t s = 1 << ((i * 7) % 12 + 1);
-		ASSERT(slab_alloc(a, s) == ptr[i]);
+		size_t s = 1 << ((i * 7) % 12 + 2);
+		ptr[i] = (uint16_t*)slab_alloc(a, s);
+		ASSERT((void*)ptr[i] >= kernel_data_end && (size_t)ptr[i] < 0xFFC00000);
+		*ptr[i] = ((i * 211) % 1024);
+		dbg_printf("Alloc %i : 0x%p\n", s, ptr[i]);
 	}
 	dbg_print_region_stats();
 	for (int i = 0; i < m; i++) {
-		slab_free(a, ptr[m - i - 1]);
+		for (int j = i; j < m; j++) {
+			ASSERT(*ptr[j] == (j * 211) % 1024);
+		}
+		slab_free(a, ptr[i]);
 	}
 	dbg_print_region_stats();
 	dbg_printf("Destroying slab allocator.\n");
diff --git a/kernel/l0/paging.c b/kernel/l0/paging.c
index ca217c6..adb076c 100644
--- a/kernel/l0/paging.c
+++ b/kernel/l0/paging.c
@@ -58,13 +58,32 @@ void page_fault_handler(registers_t *regs) {
 			return;
 		}
 
+		if ((size_t)vaddr >= PD_MIRROR_ADDR) {
+			dbg_printf("Fault on access to mirrorred PD at 0x%p\n", vaddr);
+
+			uint32_t x = (size_t)vaddr - PD_MIRROR_ADDR;
+			uint32_t page = (x % PAGE_SIZE) / 4;
+			uint32_t pt = x / PAGE_SIZE;
+			dbg_printf("For pt 0x%p, page 0x%p -> addr 0x%p\n", pt, page, ((pt * 1024) + page) * PAGE_SIZE);
+
+			for (int i = 0; i < N_PAGES_IN_PT; i++) {
+				dbg_printf("%i. 0x%p\n", i, kernel_pd.page[i]);
+			}
+
+			dbg_dump_registers(regs);
+			dbg_print_region_stats();
+			PANIC("Unhandled kernel space page fault");
+		}
+
 		region_info_t *i = find_region(vaddr);
 		if (i == 0) {
 			dbg_printf("Kernel pagefault in non-existing region at 0x%p\n", vaddr);
+			dbg_dump_registers(regs);
 			PANIC("Unhandled kernel space page fault");
 		}
 		if (i->pf == 0) {
 			dbg_printf("Kernel pagefault in region with no handler at 0x%p\n", vaddr);
+			dbg_dump_registers(regs);
 			PANIC("Unhandled kernel space page fault");
 		}
 		i->pf(current_pd_d, i, vaddr);
@@ -149,6 +168,8 @@ int pd_map_page(void* vaddr, uint32_t frame_id, bool rw) {
 	uint32_t pt = PT_OF_ADDR(vaddr);
 	uint32_t page = PAGE_OF_ADDR(vaddr);
 
+	ASSERT((size_t)vaddr < PD_MIRROR_ADDR);
+	
 	pagetable_t *pd = ((size_t)vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd);
 
 	if (!pd->page[pt] & PTE_PRESENT) {
@@ -159,12 +180,16 @@ int pd_map_page(void* vaddr, uint32_t frame_id, bool rw) {
 			(new_pt_frame << PTE_FRAME_SHIFT) | PTE_PRESENT | PTE_RW;
 		invlpg(&current_pt[pt]);
 	}
+	dbg_printf("[%p,%i,%i,", vaddr, pt, page);
 
 	current_pt[pt].page[page] =
-		frame_id << PTE_FRAME_SHIFT
+		(frame_id << PTE_FRAME_SHIFT)
 			| PTE_PRESENT
 			| ((size_t)vaddr < K_HIGHHALF_ADDR ? PTE_USER : PTE_GLOBAL)
 			| (rw ? PTE_RW : 0);
+	invlpg(vaddr);
+
+	dbg_printf("]");
 
 	return 0;
 } 
@@ -177,7 +202,9 @@ void pd_unmap_page(void* vaddr) {
 
 	if (!pd->page[pt] & PTE_PRESENT) return;
 	if (!current_pt[pt].page[page] & PTE_PRESENT) return;
-	current_pt[pt].page[page] &= ~PTE_PRESENT;
+
+	current_pt[pt].page[page] = 0;
+	invlpg(vaddr);
 
 	// TODO (?) : if pagetable is completely empty, free it
 }
diff --git a/kernel/l0/sys.c b/kernel/l0/sys.c
index b388eba..2b77463 100644
--- a/kernel/l0/sys.c
+++ b/kernel/l0/sys.c
@@ -10,6 +10,7 @@ static void panic_do(const char* type, const char *msg, const char* file, int li
 	dbg_printf("| File: \t%s:%i\n", file, line);
 	dbg_printf("| System halted -_-'\n");
 	dbg_printf("\\---------------------------------------------------------/");
+	BOCHS_BREAKPOINT;
 	asm volatile("hlt");
 }
 
diff --git a/kernel/lib/slab_alloc.c b/kernel/lib/slab_alloc.c
index 9ec39b0..d9efc4f 100644
--- a/kernel/lib/slab_alloc.c
+++ b/kernel/lib/slab_alloc.c
@@ -32,7 +32,7 @@ struct mem_allocator {
 	const slab_type_t *types;
 	slab_t *slabs;
 	cache_t *first_free_region_descriptor;
-	cache_t *all_regions;
+	cache_t *all_caches, *all_other_regions;;
 
 	page_alloc_fun_t alloc_fun;
 	page_free_fun_t free_fun;
@@ -49,8 +49,13 @@ void add_free_region_descriptor(mem_allocator_t *a, cache_t *c) {
 
 cache_t *take_region_descriptor(mem_allocator_t *a) {
 	if (a->first_free_region_descriptor == 0) {
-		// TODO : allocate more descriptors	(not complicated)
-		return 0;
+		void* p = a->alloc_fun(PAGE_SIZE);
+		if (p == 0) return 0;
+
+		void* end = p + PAGE_SIZE;
+		for (cache_t *i = (cache_t*)p; i + 1 <= (cache_t*)end; i++) {
+			add_free_region_descriptor(a, i);
+		}
 	}
 	cache_t *x = a->first_free_region_descriptor;
 	a->first_free_region_descriptor = x->next_region;
@@ -76,7 +81,7 @@ mem_allocator_t* create_slab_allocator(const slab_type_t *types, page_alloc_fun_
 	mem_allocator_t *a = ptr.a;
 	ptr.a++;
 
-	a->all_regions = 0;
+	a->all_caches = a->all_other_regions = 0;
 	a->alloc_fun = af;
 	a->free_fun = ff;
 
@@ -99,11 +104,13 @@ mem_allocator_t* create_slab_allocator(const slab_type_t *types, page_alloc_fun_
 static void stack_and_destroy_regions(page_free_fun_t ff, cache_t *r) {
 	if (r == 0) return;
 	void* addr = r->region_addr;
+	ASSERT(r != r->next_region);
 	stack_and_destroy_regions(ff, r->next_region);
 	ff(addr);
 }
 void destroy_slab_allocator(mem_allocator_t *a) {
-	stack_and_destroy_regions(a->free_fun, a->all_regions);
+	stack_and_destroy_regions(a->free_fun, a->all_caches);
+	stack_and_destroy_regions(a->free_fun, a->all_other_regions);
 	a->free_fun(a);
 }
 
@@ -140,8 +147,8 @@ void* slab_alloc(mem_allocator_t* a, size_t sz) {
 				}
 				ASSERT(fc->n_free_objs == cache_size / obj_size);
 
-				fc->next_region = a->all_regions;
-				a->all_regions = fc;
+				fc->next_region = a->all_caches;
+				a->all_caches = fc;
 				fc->c.next_cache = a->slabs[i].first_cache;
 				a->slabs[i].first_cache = fc;
 			}
@@ -167,8 +174,8 @@ void* slab_alloc(mem_allocator_t* a, size_t sz) {
 		r->is_a_cache =  0;
 		r->sr.region_size = sz;
 
-		r->next_region = a->all_regions;
-		a->all_regions = r;
+		r->next_region = a->all_other_regions;
+		a->all_other_regions = r;
 
 		return (void*)r->region_addr;
 	}
@@ -186,7 +193,32 @@ void slab_free(mem_allocator_t* a, void* addr) {
 				o->next = r->c.first_free_obj;
 				r->c.first_free_obj = o;
 				r->n_free_objs++;
-				// TODO : if cache is empty, free it
+
+				if (r->n_free_objs == region_size / a->types[i].obj_size) {
+					// region is completely unused, free it.
+					if (a->slabs[i].first_cache == r) {
+						a->slabs[i].first_cache = r->c.next_cache;
+					} else {
+						for (cache_t *it = a->slabs[i].first_cache; it->c.next_cache != 0; it = it->c.next_cache) {
+							if (it->c.next_cache == r) {
+								it->c.next_cache = r->c.next_cache;
+								break;
+							}
+						}
+					}
+					if (a->all_caches == r) {
+						a->all_caches = r->next_region;
+					} else {
+						for (cache_t *it = a->all_caches; it->next_region != 0; it = it->next_region) {
+							if (it->next_region == r) {
+								it->next_region = r->next_region;
+								break;
+							}
+						}
+					}
+					a->free_fun(r->region_addr);
+					add_free_region_descriptor(a, r);
+				}
 				return;
 			}
 		}
@@ -194,15 +226,15 @@ void slab_free(mem_allocator_t* a, void* addr) {
 
 	// otherwise the block was directly allocated : look for it in regions.
 	a->free_fun(addr);
-	ASSERT(a->all_regions != 0);
+	ASSERT(a->all_other_regions != 0);
 
-	if (a->all_regions->region_addr == addr) {
-		cache_t *r = a->all_regions;
+	if (a->all_other_regions->region_addr == addr) {
+		cache_t *r = a->all_other_regions;
 		ASSERT(r->is_a_cache == 0);
-		a->all_regions = r->next_region;
+		a->all_other_regions = r->next_region;
 		add_free_region_descriptor(a, r);
 	} else {
-		for (cache_t *i = a->all_regions; i->next_region != 0; i = i->next_region) {
+		for (cache_t *i = a->all_other_regions; i->next_region != 0; i = i->next_region) {
 			if (i->next_region->region_addr == addr) {
 				cache_t *r = i->next_region;
 				ASSERT(r->is_a_cache == 0);
diff --git a/kernel/lib_tests/Makefile b/kernel/lib_tests/Makefile
new file mode 100644
index 0000000..4a21edf
--- /dev/null
+++ b/kernel/lib_tests/Makefile
@@ -0,0 +1,2 @@
+slab_test.bin: slab_test.c ../include/slab_alloc.h ../lib/slab_alloc.c
+	gcc -m32 -o $@ -std=c99 -I ../include slab_test.c ../lib/slab_alloc.c
diff --git a/kernel/lib_tests/slab_test.c b/kernel/lib_tests/slab_test.c
new file mode 100644
index 0000000..4bfc6b0
--- /dev/null
+++ b/kernel/lib_tests/slab_test.c
@@ -0,0 +1,42 @@
+#include <slab_alloc.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+slab_type_t slab_sizes[] = {
+	{ "8B obj", 8, 1 },
+	{ "16B obj", 16, 2 },
+	{ "32B obj", 32, 2 },
+	{ "64B obj", 64, 2 },
+	{ "128B obj", 128, 2 },
+	{ "256B obj", 256, 4 },
+	{ "512B obj", 512, 4 },
+	{ "1KB obj", 1024, 8 },
+	{ "2KB obj", 2048, 8 },
+	{ "4KB obj", 4096, 16 },
+	{ 0, 0, 0 }
+};
+
+
+int main(int argc, char *argv[]) {
+	mem_allocator_t *a =
+		create_slab_allocator(slab_sizes, malloc, free);
+
+	const int m = 10000;
+	uint32_t* ptr[m];
+	for (int i = 0; i < m; i++) {
+		size_t s = 1 << ((i * 7) % 12 + 2);
+		ptr[i] = (uint32_t*)slab_alloc(a, s);
+		ASSERT(ptr[i] != 0);
+		*ptr[i] = ((i * 2117) % (1<<30));
+		printf("Alloc %i : 0x%p\n", s, ptr[i]);
+	}
+	for (int i = 0; i < m; i++) {
+		for (int j = i; j < m; j++) {
+			ASSERT(*ptr[j] == (j * 2117) % (1<<30));
+		}
+		slab_free(a, ptr[i]);
+	}
+	destroy_slab_allocator(a);
+
+	return 0;
+}