mmap: Add support for ANONYMOUS flag

so3/arch/arm32/include/asm/mmu.h

@@ -39,6 +39,9 @@
 
 #define USER_SPACE_VADDR 0x1000ul
 
+/* Anonymous start virtual address */
+#define USER_ANONYMOUS_VADDR UL(CONFIG_KERNEL_VADDR / 2)
+
 /* Memory space all I/O mapped registers and additional mappings */
 #define IO_MAPPING_BASE 0xe0000000
 

so3/arch/arm64/include/asm/mmu.h

@@ -35,6 +35,9 @@
 /* Fixmap page used for temporary mapping */
 #define FIXMAP_MAPPING UL(0xffffb00000000000)
 
+/* Anonymous start virtual address */
+#define USER_ANONYMOUS_VADDR UL(0x0000000100000000)
+
 /* The user space can be up to bits [47:0] and uses ttbr0_el1
  * as main L0 page table.
  */
@@ -45,6 +48,9 @@
 /* Fixmap page used for temporary mapping */
 #define FIXMAP_MAPPING UL(0xffffffd800000000)
 
+/* Anonymous start virtual address */
+#define USER_ANONYMOUS_VADDR UL(0x0000000100000000)
+
 /* The user space can be up to bits [38:0] and uses ttbr0_el1
  * as main L0 page table.
  */

so3/fs/vfs.c

@@ -463,6 +463,75 @@ static int do_write(int fd, const void *buffer, int count)
 	return ret;
 }
 
+/* Low Level mmap */
+static int do_mmap(int fd, addr_t virt_addr, uint32_t page_count, off_t offset)
+{
+	int gfd;
+	struct file_operations *fops;
+
+	/* Get the fops associated to the file descriptor. */
+	gfd = vfs_get_gfd(fd);
+	if (-1 == gfd) {
+		printk("%s: could not get global fd.\n", __func__);
+		return -EBADF;
+	}
+
+	mutex_lock(&vfs_lock);
+	fops = vfs_get_fops(gfd);
+	if (!fops) {
+		printk("%s: could not get device fops.\n", __func__);
+		mutex_unlock(&vfs_lock);
+		return -EBADF;
+	}
+
+	mutex_unlock(&vfs_lock);
+
+	if (!fops->mmap) {
+		printk("%s: device doesn't support mmap.\n", __func__);
+		return -EACCES;
+	}
+
+	/* Call the mmap fops that will do the actual mapping. */
+	return (long) fops->mmap(fd, virt_addr, page_count, offset);
+}
+
+/* Low Level mmap - Anonymous case */
+static int do_mmap_anon(int fd, addr_t virt_addr, uint32_t page_count, off_t offset)
+{
+	uint32_t page;
+	pcb_t *pcb;
+	int i;
+
+	if (offset != 0) {
+		printk("%s: Offset should be 0 with MAP_ANONYMOUS flag\n", __func__);
+		return -EINVAL;
+	}
+
+	pcb = current()->pcb;
+
+	/* Start is smaller or NULL than initial virt_addr pointer */
+	if (virt_addr < pcb->next_anon_start)
+		virt_addr = pcb->next_anon_start;
+
+	for (i = 0; i < page_count; i++) {
+		page = get_free_page();
+		BUG_ON(!page);
+
+		create_mapping(pcb->pgtable, virt_addr + (i * PAGE_SIZE), page, PAGE_SIZE, false);
+		add_page_to_proc(pcb, phys_to_page(page));
+	}
+
+	memset((void *) virt_addr, 0, page_count * PAGE_SIZE);
+
+	/* WARNIMG - This is a simple/basic way to set the start virtual address:
+	             It only increment the start address after each mmap call, no algorithm
+	             to search for available spaces.
+	*/
+	pcb->next_anon_start = virt_addr + (page_count * PAGE_SIZE);
+
+	return virt_addr;
+}
+
 SYSCALL_DEFINE3(read, int, fd, void *, buffer, int, count)
 {
 	return do_read(fd, buffer, count);
@@ -738,43 +807,20 @@ SYSCALL_DEFINE2(stat, const char *, path, struct stat *, st)
 /**
  * An mmap() implementation in VFS.
  */
-SYSCALL_DEFINE5(mmap, addr_t, start, size_t, length, int, prot, int, fd, off_t, offset)
+SYSCALL_DEFINE6(mmap, addr_t, start, size_t, length, int, prot, int, flags, int, fd, off_t, offset)
 {
-	int gfd;
 	uint32_t page_count;
-	struct file_operations *fops;
-
-	/* Get the fops associated to the file descriptor. */
-
-	gfd = vfs_get_gfd(fd);
-	if (-1 == gfd) {
-		printk("%s: could not get global fd.\n", __func__);
-		return -EBADF;
-	}
-
-	mutex_lock(&vfs_lock);
-	fops = vfs_get_fops(gfd);
-	if (!fops) {
-		printk("%s: could not get device fops.\n", __func__);
-		mutex_unlock(&vfs_lock);
-		return -EBADF;
-	}
-
-	mutex_unlock(&vfs_lock);
 
 	/* Page count to allocate to the current process to be able to map the desired region. */
 	page_count = length / PAGE_SIZE;
 	if (length % PAGE_SIZE != 0) {
 		page_count++;
 	}
 
-	if (!fops->mmap) {
-		printk("%s: device doesn't support mmap.\n", __func__);
-		return -EACCES;
-	}
-
-	/* Call the mmap fops that will do the actual mapping. */
-	return (long) fops->mmap(fd, start, page_count, offset);
+	if (flags & MAP_ANONYMOUS)
+		return do_mmap_anon(fd, start, page_count, offset);
+	else
+		return do_mmap(fd, start, page_count, offset);
 }
 
 SYSCALL_DEFINE3(ioctl, int, fd, unsigned long, cmd, unsigned long, args)

so3/include/process.h

@@ -76,6 +76,9 @@ struct pcb {
 	/* current position of the heap pointer */
 	addr_t heap_pointer;
 
+	/* next anonymous start pointer */
+	addr_t next_anon_start;
+
 	/* Number of pages required by this process (including binary image) */
 	size_t page_count;
 

so3/include/vfs.h

@@ -91,6 +91,9 @@
 #define DT_LNK 10 /* Symbolic link */
 #define DT_SOCK 12 /* Socket device */
 
+/* mmap flags options  */
+#define MAP_ANONYMOUS 0x10 /* don't use a file */
+
 /* Return error values */
 #define MAP_FAILED ((void *) -1) /* mmap fail */
 
@@ -165,7 +168,7 @@ SYSCALL_DECLARE(close, int fd);
 SYSCALL_DECLARE(dup, int oldfd);
 SYSCALL_DECLARE(dup2, int oldfd, int newfd);
 SYSCALL_DECLARE(stat, const char *path, struct stat *st);
-SYSCALL_DECLARE(mmap, addr_t start, size_t length, int prot, int fd, off_t offset);
+SYSCALL_DECLARE(mmap, addr_t start, size_t length, int prot, int flags, int fd, off_t offset);
 SYSCALL_DECLARE(ioctl, int fd, unsigned long cmd, unsigned long args);
 SYSCALL_DECLARE(fcntl, int fd, unsigned long cmd, unsigned long args);
 SYSCALL_DECLARE(lseek, int fd, off_t off, int whence);

so3/kernel/process.c

@@ -185,6 +185,8 @@ pcb_t *new_process(void)
 
 	pcb->state = PROC_STATE_NEW;
 
+	pcb->next_anon_start = USER_ANONYMOUS_VADDR;
+
 	/* Reset the ptrace request indicator */
 	pcb->ptrace_pending_req = PTRACE_NO_REQUEST;