Added MAP_GROWSDOWN feature to do_mmap. Fixed sys_mmap return.

tasks/mm0/include/mmap.h

@@ -19,6 +19,7 @@
 #define MAP_FIXED	0x10
 #define MAP_SHARED	0x01
 #define MAP_PRIVATE	0x02
+#define MAP_GROWSDOWN	0x00100
 
 struct vm_area *vma_new(unsigned long pfn_start, unsigned long npages,
 			unsigned int flags, unsigned long file_offset);

tasks/mm0/include/vm_area.h

@@ -36,8 +36,11 @@
 #define VMA_PRIVATE			(1 << 6)
 /* For wired pages */
 #define VMA_FIXED			(1 << 7)
+/* For stack, where mmap returns end address */
+#define VMA_GROWSDOWN			(1 << 8)
+
 /* Set when the page is dirty in cache but not written to disk */
-#define VM_DIRTY			(1 << 8)
+#define VM_DIRTY			(1 << 9)
 
 /* Defines the type of file. A device file? Regular file? One used at boot? */
 enum VM_FILE_TYPE {

tasks/mm0/main.c

@@ -20,6 +20,7 @@
 #include <file.h>
 #include <shm.h>
 #include <utcb.h>
+#include <mmap.h>
 
 void handle_requests(void)
 {
@@ -153,6 +154,7 @@ int self_spawn(void)
 {
 	struct task_ids ids;
 	struct tcb *self, *self_child;
+	// void *stack;
 
 	BUG_ON(!(self = find_task(self_tid())));
 
@@ -164,9 +166,6 @@ int self_spawn(void)
 	self_child = task_create(self, &ids, THREAD_CREATE_SAMESPC,
 				 TCB_SHARED_VM | TCB_SHARED_FILES);
 
-	/* Copy self tcb to child. TODO: ??? Not sure about this */
-	copy_tcb(self_child, self, TCB_SHARED_VM | TCB_SHARED_FILES);
-
 	/*
 	 * Create a new utcb. Every pager thread will
 	 * need its own utcb to answer calls.
@@ -180,6 +179,9 @@ int self_spawn(void)
 	 * TODO: Set up a child stack by mmapping an anonymous
 	 * region of mmap's choice. TODO: Time to add MAP_GROWSDOWN ???
 	 */
+	if (do_mmap(0, 0, self, 0,
+		    VM_READ | VM_WRITE | VMA_ANONYMOUS | VMA_PRIVATE, 1) < 0)
+		BUG();
 
 	/* TODO: Notify vfs ??? */
 

tasks/mm0/src/mmap.c

@@ -11,7 +11,7 @@
 #include <mmap.h>
 #include <memory.h>
 #include <l4lib/arch/syscalls.h>
-
+#include <l4lib/arch/syslib.h>
 
 #if 0
 /* TODO: This is to be implemented when fs0 is ready. */
@@ -568,7 +568,14 @@ int do_mmap(struct vm_file *mapfile, unsigned long file_offset,
 		map_address, map_address + npages * PAGE_SIZE);
 	task_add_vma(task, new);
 
-	return 0;
+	/*
+	 * If area is going to be used going downwards, (i.e. as a stack)
+	 * we return the *end* of the area as the start address.
+	 */
+	if (flags & VMA_GROWSDOWN)
+		map_address += npages;
+
+	return map_address;
 }
 
 /* mmap system call implementation */
@@ -580,7 +587,6 @@ int sys_mmap(l4id_t sender, void *start, size_t length, int prot,
 	struct vm_file *file = 0;
 	unsigned int vmflags = 0;
 	struct tcb *task;
-	int err;
 
 	BUG_ON(!(task = find_task(sender)));
 
@@ -619,6 +625,9 @@ int sys_mmap(l4id_t sender, void *start, size_t length, int prot,
 	else	/* This also means COW, if writeable and anonymous */
 		vmflags |= VMA_SHARED;
 
+	if (flags & MAP_GROWSDOWN)
+		vmflags |= VMA_GROWSDOWN;
+
 	if (prot & PROT_READ)
 		vmflags |= VM_READ;
 	if (prot & PROT_WRITE)
@@ -626,10 +635,9 @@ int sys_mmap(l4id_t sender, void *start, size_t length, int prot,
 	if (prot & PROT_EXEC)
 		vmflags |= VM_EXEC;
 
-	if ((err =  do_mmap(file, __pfn_to_addr(pfn), task,
+	base = do_mmap(file, __pfn_to_addr(pfn), task, base, vmflags, npages);
-			    base, vmflags, npages)) < 0)
-		return err;
 
+	l4_ipc_return(base);
 	return 0;
 }