Factorize region allocator between kernel and user processes (same code was there twice)

3 files changed, 12 insertions, 392 deletions

diff --git a/src/kernel/core/kmain.c b/src/kernel/core/kmain.c
index 3ee2238..2774e11 100644
--- a/src/kernel/core/kmain.c
+++ b/src/kernel/core/kmain.c
@@ -113,7 +113,8 @@ void kmain(multiboot_info_t *mbd, int32_t mb_magic) {
 	paging_setup(kernel_data_end);
 	dbg_printf("Paging seems to be working!\n");
 
-	region_allocator_init(kernel_data_end);
+	region_allocator_init((void*)K_HIGHHALF_ADDR, (void*)PAGE_ALIGN_UP(kernel_data_end),
+		(void*)LAST_KERNEL_ADDR, alloc_map_single_frame);
 	dbg_printf("Region allocator initialized.\n");
 	TEST_PLACEHOLDER_AFTER_REGION;
 
diff --git a/src/kernel/core/region.c b/src/kernel/core/region.c
index 6a4c7b4..2a55fb3 100644
--- a/src/kernel/core/region.c
+++ b/src/kernel/core/region.c
@@ -1,352 +1,23 @@
 #include <region.h>
-#include <dbglog.h>
 #include <frame.h>
-#include <mutex.h>
+#include <paging.h>
 
-typedef union region_descriptor {
-	struct {
-		union region_descriptor *next;
-	} unused_descriptor;
-	struct {
-		void* addr;
-		size_t size;
-		union region_descriptor *next_by_size, *first_bigger;
-		union region_descriptor *next_by_addr;
-	} free;
-	struct {
-		region_info_t i;
-		union region_descriptor *next_by_addr;
-	} used;
-} descriptor_t;
+bool alloc_map_single_frame(void* addr) {
+	int frame = frame_alloc(1);
+	if (frame == 0) return false;
 
-#define N_RESERVE_DESCRIPTORS 2		// always keep at least 2 unused descriptors
-
-#define N_BASE_DESCRIPTORS 12		// pre-allocate memory for 12 descriptors
-static descriptor_t base_descriptors[N_BASE_DESCRIPTORS];
-
-static descriptor_t *first_unused_descriptor; 
-uint32_t n_unused_descriptors;
-static descriptor_t *first_free_region_by_addr, *first_free_region_by_size;
-static descriptor_t *first_used_region;
-
-STATIC_MUTEX(ra_mutex);	// region allocator mutex
-
-// ========================================================= //
-// HELPER FUNCTIONS FOR THE MANIPULATION OF THE REGION LISTS //
-// ========================================================= //
-
-void add_unused_descriptor(descriptor_t *d) {
-	n_unused_descriptors++;
-	d->unused_descriptor.next = first_unused_descriptor;
-	first_unused_descriptor = d;
-}
-
-descriptor_t *get_unused_descriptor() {
-	descriptor_t *r = first_unused_descriptor;
-	if (r != 0) {
-		first_unused_descriptor = r->unused_descriptor.next;
-		n_unused_descriptors--;
+	if (!pd_map_page(addr, frame, true)) {
+		frame_free(frame, 1);
+		return false;
 	}
-	return r;
-}
 
-void remove_free_region(descriptor_t *d) {
-	if (first_free_region_by_size == d) {
-		first_free_region_by_size = d->free.next_by_size;
-	} else {
-		for (descriptor_t *i = first_free_region_by_size; i != 0; i = i->free.next_by_size) {
-			if (i->free.first_bigger == d) {
-				i->free.first_bigger = d->free.next_by_size;
-			}
-			if (i->free.next_by_size == d) {
-				i->free.next_by_size = d->free.next_by_size;
-				break;
-			}
-		}
-	}
-	if (first_free_region_by_addr == d) {
-		first_free_region_by_addr = d->free.next_by_addr;
-	} else {
-		for (descriptor_t *i = first_free_region_by_addr; i != 0; i = i->free.next_by_addr) {
-			if (i->free.next_by_addr == d) {
-				i->free.next_by_addr = d->free.next_by_addr;
-				break;
-			}
-		}
-	}
-}
-
-void add_free_region(descriptor_t *d) {
-	/*dbg_printf("Add free region 0x%p - 0x%p\n", d->free.addr, d->free.size + d->free.addr);*/
-	// Find position of region in address-ordered list
-	// Possibly concatenate free region
-	descriptor_t *i = first_free_region_by_addr;
-	if (i == 0) {
-		ASSERT(first_free_region_by_size == 0);
-		first_free_region_by_addr = first_free_region_by_size = d;
-		d->free.next_by_size = d->free.first_bigger = d->free.next_by_addr = 0;
-		return;
-	} else if (d->free.addr + d->free.size == i->free.addr) {
-		// concatenate d . i
-		remove_free_region(i);
-		d->free.size += i->free.size;
-		add_unused_descriptor(i);
-		add_free_region(d);
-		return;
-	} else if (i->free.addr > d->free.addr) {
-		// insert before i
-		d->free.next_by_addr = i;
-		first_free_region_by_addr = d;
-	} else {
-		while (i != 0) {
-			ASSERT(d->free.addr > i->free.addr);
-			if (i->free.addr + i->free.size == d->free.addr) {
-				// concatenate i . d
-				remove_free_region(i);
-				i->free.size += d->free.size;
-				add_unused_descriptor(d);
-				add_free_region(i);
-				return;
-			} else if (i->free.next_by_addr == 0 || i->free.next_by_addr->free.addr > d->free.addr) {
-				d->free.next_by_addr = i->free.next_by_addr;
-				i->free.next_by_addr = d;
-				break;
-			} else if (d->free.addr + d->free.size == i->free.next_by_addr->free.addr) {
-				// concatenate d . i->next_by_addr
-				descriptor_t *j = i->free.next_by_addr;
-				remove_free_region(j);
-				d->free.size += j->free.size;
-				add_unused_descriptor(j);
-				add_free_region(d);
-				return;
-			} else {
-				// continue
-				i = i->free.next_by_addr;
-			}
-		}
-	}
-	// Now add it in size-ordered list
-	i = first_free_region_by_size;
-	ASSERT(i != 0);
-	if (d->free.size <= i->free.size) {
-		d->free.next_by_size = i;
-		d->free.first_bigger = (i->free.size > d->free.size ? i : i->free.first_bigger);
-		first_free_region_by_size = d;
-	} else {
-		while (i != 0) {
-			ASSERT(d->free.size > i->free.size);
-			if (i->free.next_by_size == 0) {
-				d->free.next_by_size = 0;
-				d->free.first_bigger = 0;
-				i->free.next_by_size = d;
-				if (d->free.size > i->free.size) i->free.first_bigger = d;
-				break;
-			} else if (i->free.next_by_size->free.size >= d->free.size) {
-				d->free.next_by_size = i->free.next_by_size;
-				d->free.first_bigger =
-					(i->free.next_by_size->free.size > d->free.size
-						? i->free.next_by_size
-						: i->free.next_by_size->free.first_bigger);
-				i->free.next_by_size = d;
-				if (d->free.size > i->free.size) i->free.first_bigger = d;
-				break;
-			} else {
-				// continue
-				i = i->free.next_by_size;
-			}
-		}
-	}
-}
-
-descriptor_t *find_used_region(void* addr) {
-	for (descriptor_t *i = first_used_region; i != 0; i = i->used.next_by_addr) {
-		if (addr >= i->used.i.addr && addr < i->used.i.addr + i->used.i.size) return i;
-		if (i->used.i.addr > addr) break;
-	}
-	return 0;
-}
-
-void add_used_region(descriptor_t *d) {
-	descriptor_t *i = first_used_region;
-	ASSERT(i != 0);
-	ASSERT(i->used.i.addr < d->used.i.addr);	// first region by address is never free
-
-	while (i != 0) {
-		ASSERT(i != d);
-		ASSERT(i->used.i.addr != d->used.i.addr);
-		ASSERT(i->used.i.addr < d->used.i.addr);
-		if (i->used.next_by_addr == 0 || i->used.next_by_addr->used.i.addr > d->used.i.addr) {
-			d->used.next_by_addr = i->used.next_by_addr;
-			i->used.next_by_addr = d;
-			return;
-		} else {
-			i = i->used.next_by_addr;
-		}
-	}
-	ASSERT(false);
-}
-
-void remove_used_region(descriptor_t *d) {
-	if (first_used_region == d) {
-		first_used_region = d->used.next_by_addr;
-	} else {
-		for (descriptor_t *i = first_used_region; i != 0; i = i->used.next_by_addr) {
-			if (i->used.i.addr > d->used.i.addr) break;
-			if (i->used.next_by_addr == d) {
-				i->used.next_by_addr = d->used.next_by_addr;
-				break;
-			}
-		}
-	}
-}
-
-// =============== //
-// THE ACTUAL CODE //
-// =============== //
-
-void region_allocator_init(void* kernel_data_end) {
-	n_unused_descriptors = 0;
-	first_unused_descriptor = 0;
-	for (int i = 0; i < N_BASE_DESCRIPTORS; i++) {
-		add_unused_descriptor(&base_descriptors[i]);
-	}
-
-	descriptor_t *f0 = get_unused_descriptor();
-	f0->free.addr = (void*)PAGE_ALIGN_UP(kernel_data_end);
-	f0->free.size = ((void*)LAST_KERNEL_ADDR - f0->free.addr);
-	f0->free.next_by_size = 0;
-	f0->free.first_bigger = 0;
-	first_free_region_by_size = first_free_region_by_addr = f0;
-
-	descriptor_t *u0 = get_unused_descriptor();
-	u0->used.i.addr = (void*)K_HIGHHALF_ADDR;
-	u0->used.i.size = PAGE_ALIGN_UP(kernel_data_end) - K_HIGHHALF_ADDR;
-	u0->used.i.type = "Kernel code & data";
-	u0->used.next_by_addr = 0;
-	first_used_region = u0;
-}
-
-void region_free_inner(void* addr) {
-	descriptor_t *d = find_used_region(addr);
-	if (d == 0) return;
-
-	region_info_t i = d->used.i;
-
-	remove_used_region(d);
-	d->free.addr = i.addr;
-	d->free.size = i.size;
-	add_free_region(d);
-}
-void region_free(void* addr) {
-	mutex_lock(&ra_mutex);
-	region_free_inner(addr);
-	mutex_unlock(&ra_mutex);
-}
-
-void* region_alloc_inner(size_t size, char* type, bool use_reserve) {
-	size = PAGE_ALIGN_UP(size);
-
-	for (descriptor_t *i = first_free_region_by_size; i != 0; i = i->free.first_bigger) {
-		if (i->free.size >= size) {
-			// region i is the one we want to allocate in
-			descriptor_t *x = 0;
-			if (i->free.size > size) {
-				if (n_unused_descriptors <= N_RESERVE_DESCRIPTORS && !use_reserve) {
-					return 0;
-				}
-
-				// this assert basically means that the allocation function
-				// is called less than N_RESERVE_DESCRIPTORS times with
-				// the use_reserve flag before more descriptors
-				// are allocated.
-				x = get_unused_descriptor();
-				ASSERT(x != 0);
-
-				x->free.size = i->free.size - size;
-				if (size >= 0x4000) {
-					x->free.addr = i->free.addr + size;
-				} else {
-					x->free.addr = i->free.addr;
-					i->free.addr += x->free.size;
-				}
-			}
-			// do the allocation
-			remove_free_region(i);
-			if (x != 0) add_free_region(x);
-
-			void* addr = i->free.addr;
-			i->used.i.addr = addr;
-			i->used.i.size = size;
-			i->used.i.type = type;
-			add_used_region(i);
-
-			return addr;
-		}
-	}
-	return 0;	//No big enough block found
-}
-
-void* region_alloc(size_t size, char* type) {
-	void* result = 0;
-	mutex_lock(&ra_mutex);
-
-	if (n_unused_descriptors <= N_RESERVE_DESCRIPTORS) {
-		uint32_t frame = frame_alloc(1);
-		if (frame == 0) goto try_anyway;
-
-		void* descriptor_region = region_alloc_inner(PAGE_SIZE, "Region descriptors", true);
-		ASSERT(descriptor_region != 0);
-
-		bool map_ok = pd_map_page(descriptor_region, frame, 1);
-		if (!map_ok) {
-			// this can happen if we weren't able to allocate a frame for
-			// a new pagetable
-			frame_free(frame, 1);
-			region_free_inner(descriptor_region);
-			goto try_anyway;
-		}
-		
-		for (descriptor_t *d = (descriptor_t*)descriptor_region;
-				(void*)(d+1) <= (descriptor_region + PAGE_SIZE);
-				d++) {
-			add_unused_descriptor(d);
-		}
-	}
-	try_anyway:
-	// even if we don't have enough unused descriptors, we might find
-	// a free region that has exactly the right size and therefore
-	// does not require splitting, so we try the allocation in all cases
-	result = region_alloc_inner(size, type, false);
-
-	mutex_unlock(&ra_mutex);
-	return result;
-}
-
-region_info_t *find_region(void* addr) {
-	region_info_t *r = 0;
-	mutex_lock(&ra_mutex);
-
-	descriptor_t *d = find_used_region(addr);
-	if (d != 0) r = &d->used.i;
-
-	mutex_unlock(&ra_mutex);
-	return r;
+	return true;
 }
 
 // ========================================================= //
 // HELPER FUNCTIONS : SIMPLE PF HANDLERS ; FREEING FUNCTIONS //
 // ========================================================= //
 
-void pf_handler_unexpected(pagedir_t *pd, struct region_info *r, void* addr) {
-	dbg_printf("Unexpected page fault at 0x%p\n", addr);
-	PANIC("Unexpected page fault");
-}
-
-void pf_handler_stackoverflow(pagedir_t *pd, struct region_info *r, void* addr) {
-	dbg_printf("Kernel stack overflow at 0x%p\n", addr);
-	PANIC("Kernel stack overflow");
-}
-
 void region_free_unmap_free(void* ptr) {
 	region_info_t *i = find_region(ptr);
 	ASSERT(i != 0);
@@ -371,38 +42,4 @@ void region_free_unmap(void* ptr) {
 	region_free(ptr);
 }
 
-// =========================== //
-// DEBUG LOG PRINTING FUNCTION //
-// =========================== //
-
-void dbg_print_region_info() {
-	mutex_lock(&ra_mutex);
-
-	dbg_printf("/ Free kernel regions, by address:\n");
-	for (descriptor_t *d = first_free_region_by_addr; d != 0; d = d->free.next_by_addr) {
-		dbg_printf("| 0x%p - 0x%p\n", d->free.addr, d->free.addr + d->free.size);
-		ASSERT(d != d->free.next_by_addr);
-	}
-	dbg_printf("- Free kernel regions, by size:\n");
-	for (descriptor_t *d = first_free_region_by_size; d != 0; d = d->free.next_by_size) {
-		dbg_printf("| 0x%p - 0x%p ", d->free.addr, d->free.addr + d->free.size);
-		dbg_printf("(0x%p, next in size: 0x%p)\n", d->free.size,
-			(d->free.first_bigger == 0 ? 0 : d->free.first_bigger->free.addr));
-		ASSERT(d != d->free.next_by_size);
-	}
-	dbg_printf("- Used kernel regions:\n");
-	for (descriptor_t *d = first_used_region; d != 0; d = d->used.next_by_addr) {
-		dbg_printf("| 0x%p - 0x%p  %s\n", d->used.i.addr, d->used.i.addr + d->used.i.size, d->used.i.type);
-		ASSERT(d != d->used.next_by_addr);
-	}
-
-	int nfreerd = 0;
-	for (descriptor_t *i = first_unused_descriptor; i != 0; i = i->unused_descriptor.next)
-		nfreerd++;
-
-	dbg_printf("\\ Free region descriptors: %d (%d)\n", nfreerd, n_unused_descriptors);
-
-	mutex_unlock(&ra_mutex);
-}
-
 /* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/src/kernel/include/region.h b/src/kernel/include/region.h
index 2593dba..f4562ac 100644
--- a/src/kernel/include/region.h
+++ b/src/kernel/include/region.h
@@ -1,25 +1,7 @@
 #pragma once
 
-// Kernel virtual memory region allocator
+#include <region_alloc.h>
 
-// This is entirely thread-safe
-
-#include <sys.h>
-#include <paging.h>
-
-struct region_info;
-
-typedef struct region_info {
-	void* addr;
-	size_t size;
-	char* type;
-} region_info_t;
-
-void region_allocator_init(void* kernel_data_end);
-
-void* region_alloc(size_t size, char* type);	// returns 0 on error
-region_info_t *find_region(void* addr);
-void region_free(void* addr);
 
 // some functions for freeing regions and frames
 // region_free_unmap_free : deletes a region and frees all frames that were mapped in it
@@ -27,6 +9,6 @@ void region_free_unmap_free(void* addr);
 // region_free_unmap : deletes a region and unmaps all frames that were mapped in it, without freeing them
 void region_free_unmap(void* addr);
 
-void dbg_print_region_info();
+bool alloc_map_single_frame(void* addr);	// used by kernel region allocator
 
 /* vim: set ts=4 sw=4 tw=0 noet :*/