Start work on syscalls, advanced tasking, segmentation

4 files changed, 157 insertions, 9 deletions

diff --git a/src/stem/mem/paging.c b/src/stem/mem/paging.c
index 5ce3aae..4cc861c 100644
--- a/src/stem/mem/paging.c
+++ b/src/stem/mem/paging.c
@@ -3,7 +3,9 @@
 #include <stdlib.h>
 #include <core/monitor.h>
 #include "mem.h"
+#include "seg.h"
 #include <core/sys.h>
+#include <task/task.h>
 
 static struct bitset frames;
 
@@ -66,17 +68,45 @@ void pagedir_switch(struct page_directory *pd) {
 	asm volatile("mov %0, %%cr0" : : "r"(cr0));
 }
 
+struct page_directory *pagedir_new() {
+	uint32_t i;
+
+	struct page_directory *pd = kmalloc(sizeof(struct page_directory));
+	pd->tablesPhysical = kmalloc_page(&pd->physicalAddr);
+
+	for (i = 768; i < 1024; i++) {
+		pd->tables[i] = kernel_pagedir->tables[i];
+		pd->tablesPhysical[i] = kernel_pagedir->tablesPhysical[i];
+	}
+
+	return pd;
+}
+
 uint32_t paging_fault(struct registers *regs) {
 	size_t addr;
+	struct segment_map *seg = 0;
 	asm volatile("mov %%cr2, %0" : "=r"(addr));
-	monitor_write("PageFault ");
-	if (regs->err_code & 0x1) monitor_write("present ");
-	if (regs->err_code & 0x2) monitor_write("write ");
-	if (regs->err_code & 0x4) monitor_write("user ");
-	if (regs->err_code & 0x8) monitor_write("rsvd ");
-	if (regs->err_code & 0x10) monitor_write("instructionfetch ");
-	monitor_write("@"); monitor_writeHex(addr); monitor_write("\n");
-	PANIC("Page fault");
+
+	seg = current_pagedir->mappedSegs;
+	while (seg) {
+		if (seg->start >= addr && seg->start + seg->len < addr) break;
+		seg = seg->next;
+	}
+
+	if (seg != 0) {
+		if (seg->seg->handle_fault(seg, addr, (regs->err_code & 0x2)) != 0) seg = 0;
+	}
+
+	if (seg == 0) {
+		monitor_write("PageFault ");
+		if (regs->err_code & 0x1) monitor_write("present ");
+		if (regs->err_code & 0x2) monitor_write("write ");
+		if (regs->err_code & 0x4) monitor_write("user ");
+		if (regs->err_code & 0x8) monitor_write("rsvd ");
+		if (regs->err_code & 0x10) monitor_write("instructionfetch ");
+		monitor_write("@"); monitor_writeHex(addr); monitor_write("\n");
+		return 1;
+	}
 	return 0;
 }
 
@@ -88,6 +118,8 @@ struct page *pagedir_getPage(struct page_directory *pd, uint32_t address, int ma
 		return &pd->tables[table_idx]->pages[address %  1024];
 	} else if (make) {
 		pd->tables[table_idx] = kmalloc_page(pd->tablesPhysical + table_idx);
+		if (table_idx >= 768)
+			tasking_updateKernelPagetable(table_idx, pd->tables[table_idx], pd->tablesPhysical[table_idx]);
 		memset((uint8_t*)pd->tables[table_idx], 0, 0x1000);
 		pd->tablesPhysical[table_idx] |= 0x07;
 		return &pd->tables[table_idx]->pages[address %  1024];
diff --git a/src/stem/mem/paging.h b/src/stem/mem/paging.h
index 72078cf..9ee6c4c 100644
--- a/src/stem/mem/paging.h
+++ b/src/stem/mem/paging.h
@@ -18,10 +18,12 @@ struct page_table {
 	struct page pages[1024];
 };
 
+struct segment_map;
 struct page_directory {
 	struct page_table *tables[1024];	//Virtual addresses of page tables
 	uint32_t *tablesPhysical;			//Pointer to the virtual address of the page directory (contain phys addr of pt)
 	uint32_t physicalAddr;				//Physical address of info above
+	struct segment_map *mappedSegs;
 };
 
 extern struct page_directory *kernel_pagedir;
@@ -32,11 +34,12 @@ void frame_free(uint32_t id);
 void paging_init(size_t totalRam);
 void paging_cleanup();
 void pagedir_switch(struct page_directory *pd);
+struct page_directory *pagedir_new();	//Creates a brand new empty page directory for a process, with kernel pages
 struct page *pagedir_getPage(struct page_directory *pd, uint32_t address, int make);
 void page_map(struct page *page, uint32_t frame, uint32_t user, uint32_t rw);
 void page_unmap(struct page *page);
 void page_unmapFree(struct page *page);
 
-uint32_t paging_fault(struct registers *regs);	//returns a boolean
+uint32_t paging_fault(struct registers *regs);	//returns a boolean : 1 if unhandled, 0 if ok
 
 #endif
diff --git a/src/stem/mem/seg.c b/src/stem/mem/seg.c
new file mode 100644
index 0000000..f340c63
--- /dev/null
+++ b/src/stem/mem/seg.c
@@ -0,0 +1,73 @@
+#include "seg.h"
+#include "mem.h"
+
+struct segment_map *seg_map(struct segment* seg, struct page_directory *pagedir) {
+	struct segment_map *sm = seg->map(seg, pagedir);
+	if (sm == 0) return 0;
+	seg->mappings++;
+	sm->seg = seg;
+	sm->pagedir = pagedir;
+	sm->next = pagedir->mappedSegs;
+	pagedir->mappedSegs = sm->next;
+	return sm;
+}
+
+void seg_unmap(struct segment_map *map) {
+	map->seg->unmap(map);
+	if (map->pagedir->mappedSegs == map) {
+		map->pagedir->mappedSegs = map->pagedir->mappedSegs->next;
+	} else {
+		struct segment_map *m = map->pagedir->mappedSegs;
+		while (m->next != 0 && m->next != map) m = m->next;
+		if (m->next == map) m->next = map->next;
+	}
+	map->seg->mappings--;
+	if (map->seg->mappings == 0) {
+		map->seg->delete(map->seg);
+		kfree(map->seg->seg_data);
+		kfree(map->seg);
+	}
+	kfree (map);
+}
+
+// ************************************   SIMPLESEG stuff *************
+
+struct segment* simpleseg_make(size_t start, size_t len, int writable) {
+	struct simpleseg *ss = kmalloc(sizeof(struct simpleseg));
+	struct segment *se = kmalloc(sizeof(struct segment));
+	se->seg_data = ss;
+	se->mappings = 0;
+	se->map = simpleseg_map;
+	se->unmap = simpleseg_unmap;
+	se->delete = simpleseg_delete;
+	se->handle_fault = simpleseg_handleFault;
+	ss->writable = writable; ss->start = start; ss->len = len;
+	return se;
+}
+
+struct segment_map* simpleseg_map(struct segment* seg, struct page_directory* pagedir) {
+	struct segment_map *sm = kmalloc(sizeof(struct segment_map));
+	sm->start = ((struct simpleseg*)(seg->seg_data))->start;
+	sm->len = ((struct simpleseg*)(seg->seg_data))->len;
+	return sm;
+}
+
+void simpleseg_unmap(struct segment_map* sm) {
+	size_t i;
+	for (i = sm->start; i < sm->start + sm->len; i += 0x1000) {
+		page_unmapFree(pagedir_getPage(sm->pagedir, i, 0));
+	}
+}
+
+int simpleseg_handleFault(struct segment_map* sm, size_t addr, int write) {
+	struct simpleseg *ss = sm->seg->seg_data;
+	if (write && !ss->writable) return 1;
+	addr &= 0xFFFFF000;
+	struct page *p = pagedir_getPage(sm->pagedir, addr, 1);
+	if (p->frame != 0) return 1;
+	page_map(p, frame_alloc(), 1, ss->writable);
+	return 0;
+}
+
+void simpleseg_delete(struct segment* seg) {
+}
diff --git a/src/stem/mem/seg.h b/src/stem/mem/seg.h
new file mode 100644
index 0000000..022d38e
--- /dev/null
+++ b/src/stem/mem/seg.h
@@ -0,0 +1,40 @@
+#ifndef DEF_SEG_H
+#define DEF_SEG_H
+
+#include "paging.h"
+
+struct segment_map;
+struct segment {
+	void* seg_data;
+	int mappings;
+
+	struct segment_map* (*map)(struct segment* seg, struct page_directory* pagedir);
+	void (*unmap)(struct segment_map*);
+	void (*delete)(struct segment* seg);
+	int (*handle_fault)(struct segment_map* map, size_t addr, int write);	//0 if ok, 1 if segfault
+};
+
+struct segment_map {
+	struct segment* seg;
+	struct page_directory* pagedir;
+	size_t start, len;
+	struct segment_map *next;
+};
+
+struct segment_map *seg_map(struct segment* seg, struct page_directory* pagedir);
+void seg_unmap(struct segment_map* map);
+
+/// *************************************     SIMPLESEG stuff *****************
+
+struct simpleseg {
+	int writable;
+	size_t start, len;
+};
+
+struct segment* simpleseg_make(size_t start, size_t len, int writable); 
+struct segment_map* simpleseg_map(struct segment* seg, struct page_directory* pagedir);
+void simpleseg_unmap(struct segment_map*);
+void simpleseg_delete(struct segment *seg);
+int simpleseg_handleFault(struct segment_map* map, size_t addr, int write);
+
+#endif