Add pager interface ; implement basic functionnality to replace private maps.

1 files changed, 183 insertions, 0 deletions

diff --git a/src/kernel/user/pager.c b/src/kernel/user/pager.c
new file mode 100644
index 0000000..c892599
--- /dev/null
+++ b/src/kernel/user/pager.c
@@ -0,0 +1,183 @@
+#include <string.h>
+
+#include <pager.h>
+#include <vfs.h>
+#include <process.h>
+#include <frame.h>
+
+#define ENT_FRAME_SHIFT 12
+
+
+// ========== //
+// SWAP PAGER //
+// ========== //
+
+static void swap_page_in(pager_t *p, size_t offset, size_t len);
+static void swap_page_out(pager_t *p, size_t offset, size_t len);
+static void swap_page_release(pager_t *p, size_t offset, size_t len);
+
+static pager_ops_t swap_pager_ops = {
+	.page_in = swap_page_in,
+	.page_commit = 0,
+	.page_out = swap_page_out,
+	.page_release = swap_page_release,
+};
+
+pager_t *new_swap_pager(size_t size) {
+	pager_t *p = (pager_t*)malloc(sizeof(pager_t));
+	if (p == 0) return 0;
+
+	p->pages = create_hashtbl(id_key_eq_fun, id_hash_fun, 0);
+	if (p->pages == 0) goto error;
+
+	p->ops = &swap_pager_ops;
+	p->size = size;
+	p->lock = MUTEX_UNLOCKED;
+	p->maps = 0;
+
+	return p;
+
+error:
+	if (p) free(p);
+	return 0;
+}
+
+void swap_page_in(pager_t *p, size_t offset, size_t len) {
+	ASSERT(PAGE_ALIGNED(offset));
+	size_t npages = PAGE_ALIGN_UP(len) / PAGE_SIZE;
+
+	void *region = region_alloc(PAGE_SIZE, "Page zero area", 0);
+	if (region == 0) return;
+
+	for (size_t i = 0; i < npages; i++) {
+		size_t page = offset + (i * PAGE_SIZE);
+		if (hashtbl_find(p->pages, (void*)page) == 0) {
+			uint32_t frame = frame_alloc(1);
+			if (frame != 0) {
+				pd_map_page(region, frame, true);
+				memset(region, 0, PAGE_SIZE);
+				pd_unmap_page(region);
+			}
+			if (!hashtbl_add(p->pages, (void*)page, (void*)(frame << ENT_FRAME_SHIFT))) {
+				frame_free(frame, 1);
+			}
+		}
+	}
+
+	region_free(region);
+}
+
+void swap_page_out(pager_t *p, size_t offset, size_t len) {
+	// later : save to swap file...
+}
+
+void swap_page_release(pager_t *p, size_t offset, size_t len) {
+	ASSERT(PAGE_ALIGNED(offset));
+	size_t npages = PAGE_ALIGN_UP(len) / PAGE_SIZE;
+
+	for (size_t i = 0; i < npages; i++) {
+		size_t page = offset + (i * PAGE_SIZE);
+		uint32_t frame = (uint32_t)hashtbl_find(p->pages, (void*)page) >> ENT_FRAME_SHIFT;
+		if (frame != 0) {
+			hashtbl_remove(p->pages, (void*)page);
+			frame_free(frame, 1);
+		}
+	}
+}
+
+// ======================= //
+// GENERIC PAGER FUNCTIONS //
+// ======================= //
+
+void delete_pager(pager_t *p) {
+	ASSERT(p->maps == 0);
+
+	pager_commit_dirty(p);
+
+	mutex_lock(&p->lock);
+
+	p->ops->page_release(p, 0, p->size);
+	delete_hashtbl(p->pages);
+	free(p);
+}
+
+void pager_access(pager_t *p, size_t offset, size_t len, bool accessed, bool dirty) {
+	mutex_lock(&p->lock);
+
+	ASSERT(PAGE_ALIGNED(offset));
+	size_t npages = PAGE_ALIGN_UP(len) / PAGE_SIZE;
+
+	for (size_t i = 0; i < npages; i++) {
+		size_t page = offset + (i * PAGE_SIZE);
+		uint32_t v = (uint32_t)hashtbl_find(p->pages, (void*)page);
+		if (v != 0) {
+			hashtbl_change(p->pages, (void*)page,
+				(void*)(v | (accessed ? PAGE_ACCESSED : 0) | (dirty ? PAGE_DIRTY : 0)));
+		}
+	}
+
+	mutex_unlock(&p->lock);
+}
+
+void pager_commit_dirty(pager_t *p) {
+	if (!p->ops->page_commit) return;
+
+	mutex_lock(&p->lock);
+
+	for (size_t i = 0; i < p->size; i += PAGE_SIZE) {
+		uint32_t v = (uint32_t)hashtbl_find(p->pages, (void*)i);
+		if (v & PAGE_DIRTY) {
+			p->ops->page_commit(p, i, PAGE_SIZE);
+			hashtbl_change(p->pages, (void*)i, (void*)(v & ~PAGE_DIRTY));
+		}
+
+	}
+
+	mutex_unlock(&p->lock);
+}
+
+int pager_get_frame(pager_t *p, size_t offset) {
+	mutex_lock(&p->lock);
+
+	ASSERT(PAGE_ALIGNED(offset));
+
+	uint32_t v = (uint32_t)hashtbl_find(p->pages, (void*)offset);
+	if (v == 0) {
+		p->ops->page_in(p, offset, PAGE_SIZE);
+	}
+
+	uint32_t ret = (uint32_t)hashtbl_find(p->pages, (void*)offset) >> ENT_FRAME_SHIFT;
+
+	mutex_unlock(&p->lock);
+
+	return ret;
+}
+
+void pager_add_map(pager_t *p, user_region_t *reg) {
+	mutex_lock(&p->lock);
+
+	reg->next_for_pager = p->maps;
+	p->maps = reg;
+
+	mutex_unlock(&p->lock);
+}
+
+void pager_rm_map(pager_t *p, user_region_t *reg) {
+	mutex_lock(&p->lock);
+
+	if (p->maps == reg) {
+		p->maps = reg->next_for_pager;
+	} else {
+		for (user_region_t *it = p->maps; it->next_for_pager != 0; it = it->next_for_pager) {
+			if (it->next_for_pager == reg) {
+				it->next_for_pager = reg->next_for_pager;
+				break;
+			}
+		}
+	}
+	reg->next_for_pager = 0;
+
+	mutex_unlock(&p->lock);
+}
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/