Many things :

- fix context switching (it actually worked only because of optimizations!)
- complete mchmap implementation
- adjust elf parser to load binaries correctly even without FM_MMAP

9 files changed, 101 insertions, 69 deletions

diff --git a/src/kernel/core/context_switch.s b/src/kernel/core/context_switch.s
index 6738a03..b8f6bb8 100644
--- a/src/kernel/core/context_switch.s
+++ b/src/kernel/core/context_switch.s
@@ -4,11 +4,10 @@
 [GLOBAL save_context_and_enter_scheduler]
 ; void save_context_and_enter_scheduler(struct saved_context *ctx);
 save_context_and_enter_scheduler:
-	pushf
+	pushf					; push flags
 	cli
-	pusha					; Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax
-
-	mov eax, cr3
+	pusha					; push general registers
+	mov eax, cr3			; push CR3
 	push eax
 
 	mov eax, [esp+44]		; get address of saved_context structure
@@ -19,32 +18,10 @@ save_context_and_enter_scheduler:
 	jmp run_scheduler
 
 resume_saved_context:
-	pop eax
-	mov cr3, eax
-
-	popa
-	popf
-	ret
-
-[GLOBAL irq0_save_context_and_enter_scheduler]
-; meant to be called on IRQ0
-; general registers already saved by IRQ handler stub
-; flags already saved by interruption and interruptions disabled
-; only saves CR3
-irq0_save_context_and_enter_scheduler:
-	mov eax, cr3
-	push eax
-
-	mov eax, [esp+8]		; get address of saved_context structure
-	mov [eax], esp			; save esp
-	mov dword [eax+4], resume_saved_irq0_context		; save eip
-
-	mov esp, kernel_stack_top
-	jmp run_scheduler
-
-resume_saved_irq0_context:
-	pop eax
+	pop eax			; restore CR3
 	mov cr3, eax
+	popa			; restore general registers
+	popf			; restore flags
 	ret
 
 
diff --git a/src/kernel/core/dbglog.c b/src/kernel/core/dbglog.c
index e042625..54d396c 100644
--- a/src/kernel/core/dbglog.c
+++ b/src/kernel/core/dbglog.c
@@ -14,9 +14,9 @@
 static const size_t VGA_WIDTH = 80;
 static const size_t VGA_HEIGHT = 25;
 
-static uint8_t vga_color = 7;
-static uint16_t* vga_buffer = 0;
-static uint16_t vga_row = 0, vga_column = 0;
+static uint8_t vga_color;
+static uint16_t* vga_buffer;
+static uint16_t vga_row, vga_column;
 
 static uint16_t make_vgaentry(char c, uint8_t color) {
 	uint16_t c16 = c;
@@ -41,6 +41,7 @@ static void vga_init() {
 	vga_row = 0;
 	vga_column = 0;
 	vga_buffer = (uint16_t*) (K_HIGHHALF_ADDR + 0xB8000);
+	vga_color = 7;
 
 	for (size_t y = 0; y < VGA_HEIGHT; y++) {
 		for (size_t x = 0; x < VGA_WIDTH; x++) {
diff --git a/src/kernel/core/kmain.c b/src/kernel/core/kmain.c
index f5d2ace..9b9a050 100644
--- a/src/kernel/core/kmain.c
+++ b/src/kernel/core/kmain.c
@@ -95,13 +95,15 @@ void kmain(multiboot_info_t *mbd, int32_t mb_magic) {
 	dbg_printf("Paging seems to be working!\n");
 
 	region_allocator_init(kernel_data_end);
-
+	dbg_printf("Region allocator initialized.\n");
 	TEST_PLACEHOLDER_AFTER_REGION;
 
 	kmalloc_setup();
+	dbg_printf("Kernel malloc setup ok.\n");
 	TEST_PLACEHOLDER_AFTER_KMALLOC;
 
 	setup_syscalls();
+	dbg_printf("System calls setup ok.\n");
 
 	// enter multi-threading mode
 	// interrupts are enabled at this moment, so all
@@ -111,6 +113,8 @@ void kmain(multiboot_info_t *mbd, int32_t mb_magic) {
 }
 
 void kernel_init_stage2(void* data) {
+	dbg_printf("Threading setup ok.\n");
+
 	multiboot_info_t *mbd = (multiboot_info_t*)data;
 
 	dbg_print_region_info();
diff --git a/src/kernel/core/paging.c b/src/kernel/core/paging.c
index 5a58c8c..69fb98f 100644
--- a/src/kernel/core/paging.c
+++ b/src/kernel/core/paging.c
@@ -10,17 +10,6 @@
 #define PAGE_OF_ADDR(x)		(((size_t)x >> PAGE_SHIFT) % N_PAGES_IN_PT)
 #define PT_OF_ADDR(x)		((size_t)x >> (PAGE_SHIFT + PT_SHIFT))
 
-#define PTE_PRESENT			(1<<0)
-#define PTE_RW				(1<<1)
-#define PTE_USER			(1<<2)
-#define PTE_WRITE_THROUGH	(1<<3)
-#define PTE_DISABLE_CACHE	(1<<4)
-#define PTE_ACCESSED		(1<<5)
-#define PTE_DIRTY			(1<<6)		// only PTE
-#define PTE_SIZE_4M			(1<<7)		// only PDE
-#define PTE_GLOBAL			(1<<8)		// only PTE
-#define PTE_FRAME_SHIFT		12
-
 typedef struct page_table {
 	uint32_t page[1024];
 } pagetable_t;
@@ -107,7 +96,7 @@ void page_fault_handler(registers_t *regs) {
 
 			if ((size_t)vaddr >= PD_MIRROR_ADDR) {
 				dbg_printf("Fault on access to mirrorred PD at 0x%p\n", vaddr);
-				dbg_print_region_info();
+				dbg_dump_registers(regs);
 				PANIC("Unhandled kernel space page fault");
 			}
 
@@ -164,10 +153,11 @@ void paging_setup(void* kernel_data_end) {
 
 	// paging already enabled in loader, nothing to do.
 
-	// disable 4M pages (remove PSE bit in CR4)
+	
 	uint32_t cr4;
 	asm volatile("movl %%cr4, %0": "=r"(cr4));
-	cr4 &= ~0x00000010;
+	cr4 &= ~(1<<4);		// disable 4M pages (remove PSE bit in CR4)
+	cr4 |= (1<<7);		// enable global PTE/PDE
 	asm volatile("movl %0, %%cr4":: "r"(cr4));
 
 	idt_set_ex_handler(EX_PAGE_FAULT, page_fault_handler);
@@ -191,15 +181,19 @@ void switch_pagedir(pagedir_t *pd) {
 // Mapping and unmapping of pages //
 // ============================== //
 
-uint32_t pd_get_frame(void* vaddr) {
+uint32_t pd_get_entry(void* vaddr) {
 	uint32_t pt = PT_OF_ADDR(vaddr);
 	uint32_t page = PAGE_OF_ADDR(vaddr);
 
 	pagetable_t *pd = ((size_t)vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd);
 
-	if (!pd->page[pt] & PTE_PRESENT) return 0;
-	if (!current_pt[pt].page[page] & PTE_PRESENT) return 0;
-	return current_pt[pt].page[page] >> PTE_FRAME_SHIFT;
+	if (!(pd->page[pt] & PTE_PRESENT)) return 0;
+	if (!(current_pt[pt].page[page] & PTE_PRESENT)) return 0;
+	return current_pt[pt].page[page];
+}
+
+uint32_t pd_get_frame(void* vaddr) {
+	return pd_get_entry(vaddr) >> PTE_FRAME_SHIFT;
 }
 
 bool pd_map_page(void* vaddr, uint32_t frame_id, bool rw) {
@@ -213,7 +207,7 @@ bool pd_map_page(void* vaddr, uint32_t frame_id, bool rw) {
 	pagetable_t *pd = ((size_t)vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd);
 	mutex_lock(&pdd->mutex);
 
-	if (!pd->page[pt] & PTE_PRESENT) {
+	if (!(pd->page[pt] & PTE_PRESENT)) {
 		uint32_t new_pt_frame = frame_alloc(1);
 		if (new_pt_frame == 0) {
 			mutex_unlock(&pdd->mutex);
@@ -243,8 +237,8 @@ void pd_unmap_page(void* vaddr) {
 	pagetable_t *pd = ((size_t)vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd);
 	// no need to lock the PD's mutex
 
-	if (!pd->page[pt] & PTE_PRESENT) return;
-	if (!current_pt[pt].page[page] & PTE_PRESENT) return;
+	if (!(pd->page[pt] & PTE_PRESENT)) return;
+	if (!(current_pt[pt].page[page] & PTE_PRESENT)) return;
 
 	current_pt[pt].page[page] = 0;
 	invlpg(vaddr);
diff --git a/src/kernel/core/thread.c b/src/kernel/core/thread.c
index cc39eb2..e62b5a8 100644
--- a/src/kernel/core/thread.c
+++ b/src/kernel/core/thread.c
@@ -8,7 +8,6 @@
 #include <paging.h>
 
 void save_context_and_enter_scheduler(saved_context_t *ctx);
-void irq0_save_context_and_enter_scheduler(saved_context_t *ctx);
 void resume_context(saved_context_t *ctx);
 
 thread_t *current_thread = 0;
@@ -156,8 +155,9 @@ thread_t *new_thread(entry_t entry, void* data) {
 // ========== //
 
 static void irq0_handler(registers_t *regs) {
-	if (current_thread != 0)
-		irq0_save_context_and_enter_scheduler(&current_thread->ctx);
+	if (current_thread != 0) {
+		save_context_and_enter_scheduler(&current_thread->ctx);
+	}
 }
 void threading_setup(entry_t cont, void* arg) {
 	set_pit_frequency(TASK_SWITCH_FREQUENCY);
diff --git a/src/kernel/include/paging.h b/src/kernel/include/paging.h
index 67f9fef..702391e 100644
--- a/src/kernel/include/paging.h
+++ b/src/kernel/include/paging.h
@@ -11,6 +11,17 @@
 #define PF_RSVD_WRITE_BIT	(1<<3)
 #define PF_OPFETCH_BIT		(1<<4)
 
+#define PTE_PRESENT			(1<<0)
+#define PTE_RW				(1<<1)
+#define PTE_USER			(1<<2)
+#define PTE_WRITE_THROUGH	(1<<3)
+#define PTE_DISABLE_CACHE	(1<<4)
+#define PTE_ACCESSED		(1<<5)
+#define PTE_DIRTY			(1<<6)		// only PTE
+#define PTE_SIZE_4M			(1<<7)		// only PDE
+#define PTE_GLOBAL			(1<<8)		// only PTE
+#define PTE_FRAME_SHIFT		12
+
 struct page_directory;
 typedef struct page_directory pagedir_t;
 
@@ -25,6 +36,7 @@ void switch_pagedir(pagedir_t *pd);
 
 // these functions are always relative to the currently mapped page directory
 uint32_t pd_get_frame(void* vaddr);		// get physical frame for virtual address
+uint32_t pd_get_entry(void* vaddr);		// same as pd_get_frame but returns whole entry with flags
 bool pd_map_page(void* vaddr, uint32_t frame_id, bool rw);		// returns true on success, false on failure
 void pd_unmap_page(void* vaddr);	// does nothing if page not mapped
 
diff --git a/src/kernel/user/elf.c b/src/kernel/user/elf.c
index 00b3c54..a3dada7 100644
--- a/src/kernel/user/elf.c
+++ b/src/kernel/user/elf.c
@@ -34,9 +34,10 @@ proc_entry_t elf_load(fs_handle_t *f, process_t* process) {
 		if (read_phdr_r != sizeof(elf_phdr_t)) goto error;
 
 		if (phdr.p_type == PT_LOAD) {
-			if (phdr.p_flags & PF_W) {
-				mmap(process, (void*)phdr.p_vaddr, phdr.p_memsz,
+			if ((phdr.p_flags & PF_W) || !(file_get_mode(f) & FM_MMAP)) {
+				bool mmap_ok = mmap(process, (void*)phdr.p_vaddr, phdr.p_memsz,
 						((phdr.p_flags & PF_R) ? MM_READ : 0) | MM_WRITE);
+				if (!mmap_ok) goto error;
 
 				size_t read_r = file_read(f, phdr.p_offset, phdr.p_filesz, (char*)phdr.p_vaddr);
 				if (read_r != phdr.p_filesz) goto error;
@@ -44,16 +45,22 @@ proc_entry_t elf_load(fs_handle_t *f, process_t* process) {
 				if (phdr.p_memsz > phdr.p_filesz) {
 					memset((char*)phdr.p_vaddr + phdr.p_filesz, 0, phdr.p_memsz - phdr.p_filesz);
 				}
+
+				if (!(phdr.p_flags & PF_W)) {
+					bool mchmap_ok = mchmap(process, (void*)phdr.p_vaddr,
+							((phdr.p_flags & PF_R) ? MM_READ : 0));
+					if (!mchmap_ok) goto error;
+				}
 			} else {
 				if (phdr.p_filesz != phdr.p_memsz) {
 					dbg_printf("Strange ELF file...\n");
-					goto error;
 				}
 
-				mmap_file(process,
-						f, phdr.p_offset,
-						(void*)phdr.p_vaddr, phdr.p_memsz,
-						((phdr.p_flags & PF_R) ? MM_READ : 0) | ((phdr.p_flags & PF_X) ? MM_EXEC : 0));
+				bool mmap_ok = mmap_file(process,
+							f, phdr.p_offset,
+							(void*)phdr.p_vaddr, phdr.p_memsz,
+							((phdr.p_flags & PF_R) ? MM_READ : 0) | ((phdr.p_flags & PF_X) ? MM_EXEC : 0));
+				if (!mmap_ok) goto error;
 			}
 		}
 	}
diff --git a/src/kernel/user/process.c b/src/kernel/user/process.c
index a4383f7..72042d9 100644
--- a/src/kernel/user/process.c
+++ b/src/kernel/user/process.c
@@ -177,6 +177,10 @@ bool mmap_file(process_t *proc, fs_handle_t *h, size_t offset, void* addr, size_
 
 	if ((uint32_t)addr & (~PAGE_MASK)) return false;
 
+	int fmode = file_get_mode(h);
+	if (!(fmode & FM_MMAP) || !(fmode & FM_READ)) return false;
+	if ((mode & MM_WRITE) && !(fmode & FM_WRITE)) return false;
+
 	user_region_t *r = (user_region_t*)malloc(sizeof(user_region_t));
 	if (r == 0) return false;
 
@@ -212,6 +216,24 @@ bool mchmap(process_t *proc, void* addr, int mode) {
 	if (r == 0) return false;
 	
 	r->mode = mode;
+
+	// change mode on already mapped pages
+	pagedir_t *save_pd = get_current_pagedir();
+	switch_pagedir(proc->pd);
+	for (void* it = r->addr; it < r->addr + r->size; r += PAGE_SIZE) {
+		uint32_t ent = pd_get_entry(it);
+		uint32_t frame = pd_get_frame(it);
+
+		if (ent & PTE_PRESENT) {
+			bool can_w = (ent & PTE_RW) != 0;
+			bool should_w = (mode & MM_WRITE) != 0;
+			if (can_w != should_w) {
+				pd_map_page(it, frame, should_w);
+			}
+		}
+	}
+	switch_pagedir(save_pd);
+
 	return true;
 }
 
@@ -230,12 +252,27 @@ bool munmap(process_t *proc, void* addr) {
 		}
 	}
 
-	// TODO : write modified pages back to file!
-	// TODO : unmap mapped page for region...
+	btree_remove_v(proc->regions_idx, r->addr, r);
+
+	// Unmap that stuff
+	pagedir_t *save_pd = get_current_pagedir();
+	switch_pagedir(proc->pd);
+	for (void* it = r->addr; it < r->addr + r->size; r += PAGE_SIZE) {
+		uint32_t ent = pd_get_entry(it);
+		uint32_t frame = pd_get_frame(it);
+
+		if (ent & PTE_PRESENT) {
+			if ((ent & PTE_DIRTY) && (r->mode & MM_WRITE) && r->file != 0) {
+				file_write(r->file, it - r->addr + r->file_offset, PAGE_SIZE, it);
+			}
+			pd_unmap_page(it);
+			frame_free(frame, 1);
+		}
+	}
+	switch_pagedir(save_pd);
 
 	if (r->file != 0) unref_file(r->file);
 
-	btree_remove_v(proc->regions_idx, r->addr, r);
 	free(r);
 
 	return true;
diff --git a/src/rules.make b/src/rules.make
index 9f4e8ce..14dfe0a 100644
--- a/src/rules.make
+++ b/src/rules.make
@@ -4,11 +4,11 @@ AS = nasm
 ASFLAGS = -felf -g
 
 CC = i586-elf-gcc
-CFLAGS += -ffreestanding -O2 -std=gnu99 -Wall -Wextra -Werror -I . -I ./include -g -Wno-unused-parameter
+CFLAGS += -ffreestanding -std=gnu99 -Wall -Wextra -Werror -Wno-unused-parameter -I . -I ./include -g
 # CXX = i586-elf-g++
 # CXFLAGS = -ffreestanding -O3 -Wall -Wextra -I . -I ./include -fno-exceptions -fno-rtti
 LD = i586-elf-gcc
-LDFLAGS += -ffreestanding -O2 -nostdlib -lgcc
+LDFLAGS += -ffreestanding -nostdlib -lgcc
 
 all: $(OUT)