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#include "vm/mmap.h"
#include "errno.h"
#include "fs/file.h"
#include "fs/vfs.h"
#include "fs/vnode.h"
#include "globals.h"
#include "mm/mm.h"
#include "mm/mman.h"
#include "mm/tlb.h"
#include "util/debug.h"
/*
* This function implements the mmap(2) syscall: Add a mapping to the current
* process's address space. Supports the following flags: MAP_SHARED,
* MAP_PRIVATE, MAP_FIXED, and MAP_ANON.
*
* ret - If provided, on success, *ret must point to the start of the mapped area
*
* Return 0 on success, or:
* - EACCES:
* - a file mapping was requested, but fd is not open for reading.
* - MAP_SHARED was requested and PROT_WRITE is set, but fd is
* not open in read/write (O_RDWR) mode.
* - PROT_WRITE is set, but the file has FMODE_APPEND specified.
* - EBADF:
* - fd is not a valid file descriptor and MAP_ANON was
* not set
* - EINVAL:
* - addr is not page aligned and MAP_FIXED is specified
* - addr is out of range of the user address space and MAP_FIXED is specified
* - off is not page aligned
* - len is <= 0 or off < 0
* - flags do not contain MAP_PRIVATE or MAP_SHARED
* - ENODEV:
* - The underlying filesystem of the specified file does not
* support memory mapping or in other words, the file's vnode's mmap
* operation doesn't exist
* - Propagate errors from vmmap_map()
*
* See the errors section of the mmap(2) man page for more details
*
* Hints:
* 1) A lot of error checking.
* 2) Call vmmap_map() to create the mapping.
* a) Use VMMAP_DIR_HILO as default, which will make other stencil code in
* Weenix happy.
* 3) Call tlb_flush_range() on the newly-mapped region. This is because the
* newly-mapped region could have been used by someone else, and you don't
* want to get stale mappings.
* 4) Don't forget to set ret if it was provided.
*
* If you are mapping less than a page, make sure that you are still allocating
* a full page.
*/
long do_mmap(void *addr, size_t len, int prot, int flags, int fd, off_t off,
void **ret)
{
// NOT_YET_IMPLEMENTED("VM: do_mmap");
// check if addr is page aligned when MAP_FIXED is specified
if (PAGE_ALIGNED(addr) == 0 && (flags & MAP_FIXED))
{
return -EINVAL;
}
// check if MAP_FIXED is specified and addr is out of range of the user address space
if ((flags & MAP_FIXED) && ((uintptr_t)addr < USER_MEM_LOW || (uintptr_t)addr + len > USER_MEM_HIGH))
{
return -EINVAL;
}
// check if len is not zero (len is an unsigned value, so it is always positive)
if ((ssize_t) len <= 0)
{
return -EINVAL;
}
// check if offset is positive and aligned
if (off < 0 || PAGE_ALIGNED(off) == 0)
{
return -EINVAL;
}
// check if flags do not contain MAP_PRIVATE or MAP_SHARED
if ((flags & MAP_PRIVATE) == 0 && (flags & MAP_SHARED) == 0)
{
return -EINVAL;
}
// check if the fd is valid and MAP_ANON was not set
if (((fd < 0 || fd >= NFILES) || curproc->p_files[fd] == NULL) && !(flags & MAP_ANON))
{
return -EBADF;
}
// check if a file mapping was requested, but fd is not open for reading
// file error checking is done in if statement below
file_t *file = NULL;
if (fd >= 0 && fd < NFILES)
{
// get the file and check if it is valid
file = curproc->p_files[fd];
if (file == NULL)
{
return -EBADF;
}
// ENODEV CHECKS
// check if the file's vnode's mmap operation doesn't exist
if (file->f_vnode->vn_ops == NULL || file->f_vnode->vn_ops->mmap == NULL)
{
return -ENODEV;
}
// ACCESS CHECKS
// check if thef FMODE_READ flag is not set
if ((file->f_mode & FMODE_READ) == 0)
{
return -EACCES;
}
// check if append mode is set and PROT_WRITE is set
if ((prot & PROT_WRITE) && (file->f_mode & FMODE_APPEND))
{
return -EACCES;
}
// if MAP_SHARED was requested and PROT_WRITE is set, but fd is not open in read/write (O_RDWR) mode.
if ((flags & MAP_SHARED) && (prot & PROT_WRITE) && (file->f_mode & FMODE_WRITE) == 0)
{
return -EACCES;
}
// check if PROT_WRITE is set, but the file has FMODE_APPEND specified
if ((prot & PROT_WRITE) && (file->f_mode & FMODE_APPEND))
{
return -EACCES;
}
}
// Now that error checking is done, we can proceed with the mapping
vmarea_t *vma = NULL;
long err = vmmap_map(
curproc->p_vmmap,
file ? file->f_vnode : NULL,
ADDR_TO_PN(PAGE_ALIGN_DOWN(addr)),
ADDR_TO_PN(PAGE_ALIGN_UP((uintptr_t)addr + len)) - ADDR_TO_PN(PAGE_ALIGN_DOWN(addr)),
prot,
flags,
off,
VMMAP_DIR_HILO,
&vma
);
// check if vmmap_map() failed
if (err < 0)
{
return err;
}
void *start = PN_TO_ADDR(vma->vma_start);
// flush the TLB
tlb_flush_range(
(uintptr_t) start,
PAGE_SIZE * (vma->vma_end - vma->vma_start)
);
// set ret if it was provided and return 0 on success
if (ret)
{
*ret = start;
}
return 0;
}
/*
* This function implements the munmap(2) syscall.
*
* Return 0 on success, or:
* - EINVAL:
* - addr is not aligned on a page boundary
* - the region to unmap is out of range of the user address space
* - len is 0
* - Propagate errors from vmmap_remove()
*
* See the errors section of the munmap(2) man page for more details
*
* Hints:
* - Similar to do_mmap():
* 1) Perform error checking.
* 2) Call vmmap_remove().
*/
long do_munmap(void *addr, size_t len)
{
// NOT_YET_IMPLEMENTED("VM: do_munmap");
// Check if addr is page aligned
if (PAGE_ALIGNED(addr) == 0)
{
return -EINVAL;
}
// Check if len is in bounds
if (len > USER_MEM_HIGH || len <= 0)
{
return -EINVAL;
}
// Check if the addr is out of range of the user address space
if (
(uintptr_t)addr < USER_MEM_LOW
|| (uintptr_t)addr > USER_MEM_HIGH
|| (uintptr_t)addr + len > USER_MEM_HIGH
)
{
return -EINVAL;
}
// Remove the mapping
size_t start = ADDR_TO_PN(addr);
size_t end = ADDR_TO_PN(PAGE_ALIGN_UP((uintptr_t)addr + len));
long ret = vmmap_remove(
curproc->p_vmmap,
start,
end - start);
return ret;
}
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