Pager virtual address pool bookkeeping added for all pager virtual addresses

Previously virt_to_phys/phys_to_virt macros were used such that they did a
blind offset translation for creating a pager internal virtual address for
user mappings.

This is now changed such that a properly bookkeeped virtual address pool is
used which will avoid any clashes on the virtual space.

src/generic/container.c

@@ -29,7 +29,7 @@ struct container_info cinfo[] = {
 		[0] = {
 			.pager_lma = __pfn(CONFIG_CONT0_PAGER_START),
 			.pager_vma = __pfn(0xE0000000),
-			.pager_size = __pfn(0xa0000),
+			.pager_size = __pfn(0xa2000),
 			.ncaps = 14,
 			.caps = {
 			[0] = {

tasks/libl4/include/l4lib/arch-arm/syslib.h

@@ -263,14 +263,18 @@ static inline int l4_ipc_return(int retval)
 	return l4_ipc(sender, L4_NILTHREAD, 0);
 }
 
+void *l4_new_virtual(int npages);
+void *l4_del_virtual(void *virt, int npages);
+
 /* A helper that translates and maps a physical address to virtual */
 static inline void *l4_map_helper(void *phys, int npages)
 {
 	struct task_ids ids;
+	void *virt = l4_new_virtual(npages);
 
 	l4_getid(&ids);
-	l4_map(phys, phys_to_virt(phys), npages, MAP_USR_RW_FLAGS, ids.tid);
-	return phys_to_virt(phys);
+	l4_map(phys, virt, npages, MAP_USR_RW_FLAGS, ids.tid);
+	return virt;
 }
 
 
@@ -281,7 +285,8 @@ static inline void *l4_unmap_helper(void *virt, int npages)
 
 	l4_getid(&ids);
 	l4_unmap(virt, npages, ids.tid);
-	return virt_to_phys(virt);
+	l4_del_virtual(virt, npages);
+	return 0;
 }
 
 #endif /* __L4LIB_SYSLIB_H__ */

tasks/mm0/TODO

@@ -0,0 +1,13 @@
+MM0 TODO List:
+
+1.) Bootmem needs to be freed.
+2.) Virtual memory regions available as capabilities need to be dynamically
+    allocated to various purposes, i.e. task region, shared memory region,
+    utcb region, etc. by traversing each region and matching to purposes.
+3.) virt_to_phys()/phys_to_virt() uses the fixed offset of INITTASK_OFFSET, this
+    either needs to be discovered at run-time or specified at config-time.
+4.) pager_new_address()/pager_delete_address() needs to use a region inside
+    pager start/end regions, and virt_to_phys()/phys_to_virt() should not clash
+    with those regions.
+5.) read_file_pages()/write_file_pages() needs to be tested and improved in
+    terms of syscalls to microkernel.

tasks/mm0/include/lib/addr.h

@@ -15,6 +15,9 @@ struct address_pool {
 	unsigned long end;
 };
 
+int address_pool_init_with_idpool(struct address_pool *pool,
+				  struct id_pool *idpool,
+				  unsigned long start, unsigned long end);
 int address_pool_init(struct address_pool *pool, unsigned long start,
 		      unsigned long end);
 void *address_new(struct address_pool *pool, int npages);

tasks/mm0/include/linker.lds

@@ -17,7 +17,7 @@ virtual_base = 0xE0000000;
 INCLUDE "include/physical_base.lds"
 
 /* physical_base = 0x228000; */
-offset = virtual_base - physical_base;
+pager_offset = virtual_base - physical_base;
 
 ENTRY(_start)
 
@@ -25,20 +25,20 @@ SECTIONS
 {
 	. = virtual_base;
 	_start_text = .;
-	.text : AT (ADDR(.text) - offset) { crt0.o(.text) *(.text) }
+	.text : AT (ADDR(.text) - pager_offset) { crt0.o(.text) *(.text) }
 	/* rodata is needed else your strings will link at physical! */
-	.rodata : AT (ADDR(.rodata) - offset) { *(.rodata) }
-	.rodata1 : AT (ADDR(.rodata1) - offset) { *(.rodata1) }
-	.data : AT (ADDR(.data) - offset)
+	.rodata : AT (ADDR(.rodata) - pager_offset) { *(.rodata) }
+	.rodata1 : AT (ADDR(.rodata1) - pager_offset) { *(.rodata1) }
+	.data : AT (ADDR(.data) - pager_offset)
 	{
 		*(.data)
 	}
-	.bss : AT (ADDR(.bss) - offset) { *(.bss) }
+	.bss : AT (ADDR(.bss) - pager_offset) { *(.bss) }
 	. = ALIGN(4K);
 	. += 0x2000;	/* BSS doesnt increment link counter??? */
 	/* Below part is to be discarded after boot */
 	_start_init = .;
-	.init : AT (ADDR(.init) - offset)
+	.init : AT (ADDR(.init) - pager_offset)
 	{
 		*(.init.data)
 		*(.init.bootmem)

tasks/mm0/include/memory.h

@@ -25,4 +25,8 @@ void *pager_map_file_range(struct vm_file *f, unsigned long byte_offset,
 			   unsigned long size);
 void *pager_validate_map_user_range2(struct tcb *user, void *userptr,
 				    unsigned long size, unsigned int vm_flags);
+
+void *l4_new_virtual(int npages);
+void *l4_del_virtual(void *virt, int npages);
+
 #endif /* __MEMORY_H__ */

tasks/mm0/src/bootdesc.c

@@ -10,6 +10,7 @@
 #include <l4lib/arch/syslib.h>
 
 extern unsigned long _end[];
+extern unsigned long pager_offset;
 
 void read_bootdesc(struct initdata *initdata)
 {
@@ -21,15 +22,9 @@ void read_bootdesc(struct initdata *initdata)
 	 */
 	bootdesc = (struct bootdesc *)_end;
 
-	/* Check if bootdesc spans across pages, and how many */
-	npages = __pfn((((unsigned long)bootdesc +
-			 bootdesc->desc_size)
-			& ~PAGE_MASK) -
-		       ((unsigned long)bootdesc & ~PAGE_MASK));
-
-	if (npages > 0)
-		l4_map_helper(virt_to_phys((void *)page_align_up(_end)),
-			      PAGE_SIZE * npages);
+	/* Check if bootdesc is on an unmapped page */
+	if (is_page_aligned(bootdesc))
+		l4_map_helper(bootdesc - pager_offset, PAGE_SIZE);
 
 	/* Allocate bootdesc sized structure */
 	initdata->bootdesc = alloc_bootmem(bootdesc->desc_size, 0);

tasks/mm0/src/init.c

@@ -240,15 +240,15 @@ void init_mm(struct initdata *initdata)
 		BUG();
 	}
 
-	/* For supplying contiguous virtual addresses to pager */
-	pager_address_pool_init();
-
 	// printf("%s: Initialised utcb address pool.\n", __TASKNAME__);
 }
 
 
 void init_pager(void)
 {
+	/* For supplying contiguous virtual addresses to pager */
+	pager_address_pool_init();
+
 	read_kernel_capabilities(&initdata);
 
 	read_bootdesc(&initdata);

tasks/mm0/src/lib/addr.c

@@ -11,6 +11,21 @@
 #include <lib/addr.h>
 #include <stdio.h>
 
+/*
+ * Initializes an address pool, but uses an already
+ * allocated id pool for it.
+ */
+int address_pool_init_with_idpool(struct address_pool *pool,
+				  struct id_pool *idpool,
+				  unsigned long start, unsigned long end)
+{
+	pool->idpool = idpool;
+	pool->start = start;
+	pool->end = end;
+
+	return 0;
+}
+
 int address_pool_init(struct address_pool *pool, unsigned long start, unsigned long end)
 {
 	if ((pool->idpool = id_pool_new_init(__pfn(end - start))) < 0)

tasks/mm0/src/memory.c

@@ -20,14 +20,39 @@
 
 struct address_pool pager_vaddr_pool;
 
-void *phys_to_virt(void *addr)
+/* Bitmap size to represent an address pool of 256 MB. */
+#define ADDRESS_POOL_256MB		2048
+
+/* Same as a regular id pool except that its bitmap size is fixed */
+static struct pager_virtual_address_id_pool {
+	int nwords;
+	int bitlimit;
+	u32 bitmap[ADDRESS_POOL_256MB];
+} pager_virtual_address_id_pool = {
+	.nwords = ADDRESS_POOL_256MB,
+	.bitlimit = ADDRESS_POOL_256MB * 32,
+};
+
+int pager_address_pool_init(void)
 {
-	return addr + INITTASK_OFFSET;
+	/* Initialise id pool for pager virtual address allocation */
+	address_pool_init_with_idpool(&pager_vaddr_pool,
+			  	      (struct id_pool *)
+				      &pager_virtual_address_id_pool,
+				      (unsigned long)0xD0000000,
+				      (unsigned long)0xE0000000);
+	return 0;
 }
 
-void *virt_to_phys(void *addr)
+void *l4_new_virtual(int npages)
 {
-	return addr - INITTASK_OFFSET;
+	return pager_new_address(npages);
+}
+
+void *l4_del_virtual(void *virt, int npages)
+{
+	pager_delete_address(virt, npages);
+	return 0;
 }
 
 /* Maps a page from a vm_file to the pager's address space */
@@ -51,20 +76,6 @@ void pager_unmap_page(void *addr)
 	l4_unmap_helper(addr, 1);
 }
 
-int pager_address_pool_init(void)
-{
-	int err;
-
-	/* Initialise the global shm virtual address pool */
-	if ((err = address_pool_init(&pager_vaddr_pool,
-				     (unsigned long)0xD0000000,
-				     (unsigned long)0xE0000000)) < 0) {
-		printf("Pager virtual address pool initialisation failed.\n");
-		return err;
-	}
-	return 0;
-}
-
 void *pager_new_address(int npages)
 {
 	return address_new(&pager_vaddr_pool, npages);
@@ -110,9 +121,6 @@ void pager_unmap_pages(void *addr, unsigned long npages)
 
 	/* Unmap so many pages */
 	l4_unmap_helper(addr, npages);
-
-	/* Free the address range */
-	pager_delete_address(addr, npages);
 }
 
 /*

tasks/mm0/src/pagers.c

@@ -86,7 +86,7 @@ int file_page_out(struct vm_object *vm_obj, unsigned long page_offset)
 		return 0;
 
 	paddr = (void *)page_to_phys(page);
-	vaddr = phys_to_virt(paddr);
+	vaddr = l4_new_virtual(1);
 
 	/* Map the page to vfs task */
 	l4_map(paddr, vaddr, 1, MAP_USR_RW_FLAGS, VFS_TID);
@@ -100,6 +100,7 @@ int file_page_out(struct vm_object *vm_obj, unsigned long page_offset)
 
 	/* Unmap it from vfs */
 	l4_unmap(vaddr, 1, VFS_TID);
+	l4_del_virtual(vaddr, 1);
 
 	/* Clear dirty flag */
 	page->flags &= ~VM_DIRTY;
@@ -108,6 +109,8 @@ int file_page_out(struct vm_object *vm_obj, unsigned long page_offset)
 
 out_err:
 	l4_unmap(vaddr, 1, VFS_TID);
+	l4_del_virtual(vaddr, 1);
+
 	return err;
 }
 
@@ -130,7 +133,7 @@ struct page *file_page_in(struct vm_object *vm_obj, unsigned long page_offset)
 	if (!(page = find_page(vm_obj, page_offset))) {
 		/* Allocate a new page */
 		paddr = alloc_page(1);
-		vaddr = phys_to_virt(paddr);
+		vaddr = l4_new_virtual(1);
 		page = phys_to_page(paddr);
 
 		/* Map the page to vfs task */
@@ -143,6 +146,7 @@ struct page *file_page_in(struct vm_object *vm_obj, unsigned long page_offset)
 
 		/* Unmap it from vfs */
 		l4_unmap(vaddr, 1, VFS_TID);
+		l4_del_virtual(vaddr, 1);
 
 		/* Update vm object details */
 		vm_obj->npages++;
@@ -163,6 +167,7 @@ struct page *file_page_in(struct vm_object *vm_obj, unsigned long page_offset)
 
 out_err:
 	l4_unmap(vaddr, 1, VFS_TID);
+	l4_del_virtual(vaddr, 1);
 	free_page(paddr);
 	return PTR_ERR(err);
 }