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Added copy-on-write shared memory but untested yet.

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For anonymous shm, mmap now adds a shm_file and devzero behind it
as two vm_objects. Faults are handled by copy_on_write(). Just as
shadows copy r/w pages from original files, it should copy r/w
pages from devzero into the shm_file in front.

shmat/shmget uses mmap to set-up their areas.

Untested yet so bugs expected.

	modified:   tasks/libl4/src/init.c
	modified:   tasks/mm0/include/shm.h
	modified:   tasks/mm0/include/vm_area.h
	modified:   tasks/mm0/src/fault.c
	modified:   tasks/mm0/src/mmap.c
	modified:   tasks/mm0/src/shm.c
This commit is contained in:
Bahadir Balban
2008-03-21 15:40:54 +00:00
parent 466138f125
commit b369ff6efe
6 changed files with 129 additions and 79 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
tasks/libl4/src/init.c
View File

@@ -96,12 +96,10 @@ int utcb_init(void)
/* Use it as a key to create a shared memory region */
BUG_ON((shmid = shmget((key_t)utcb_page,
PAGE_SIZE, IPC_CREAT)) < 0);
printf("Shmget success. shmid: %d\n", shmid);
/* Attach to the region */
BUG_ON((shmaddr = shmat(shmid, utcb_page, 0)) < 0);
BUG_ON(shmaddr != utcb_page);
printf("Shmat success. Attached %d @ 0x%x\n", shmid, (unsigned long)shmaddr);
}
return 0;

17
tasks/mm0/include/shm.h
View File

@@ -1,11 +1,23 @@
/*
* Copyright (C) 2008 Bahadir Balban
*/
#ifndef __SHM_H__
#define __SHM_H__
#include <l4/api/space.h>
#include <l4/lib/list.h>
#include <l4/api/space.h>
#include <l4/macros.h>
#include <l4lib/types.h>
struct shm_descriptor {
int key;
l4id_t shmid;
void *shm_addr;
unsigned long npages;
struct vm_file *devzero;
};
#if 0
struct shm_descriptor {
int key; /* IPC key supplied by user task */
l4id_t shmid; /* SHM area id, allocated by mm0 */
@@ -16,12 +28,13 @@ struct shm_descriptor {
unsigned int flags;
int refcnt;
};
#endif
#define SHM_AREA_MAX 64 /* Up to 64 shm areas */
/* Up to 10 pages per area, and at least 1 byte (implies 1 page) */
#define SHM_SHMMIN 1
#define SHM_SHMMAX (PAGE_SIZE * 10)
#define SHM_SHMMAX 10
/* Initialises shared memory bookkeeping structures */
void shm_init();

1
tasks/mm0/include/vm_area.h
View File

@@ -42,6 +42,7 @@ enum VM_FILE_TYPE {
VM_FILE_DEVZERO = 1,
VM_FILE_REGULAR,
VM_FILE_BOOTFILE,
VM_FILE_SHM,
};
/* Defines the type of object. A file? Just a standalone object? */

24
tasks/mm0/src/fault.c
View File

@@ -302,7 +302,7 @@ int copy_on_write(struct fault_data *fault)
*
* vma->link0->link1
* | |
* V V
* v v
* shadow original
*/
list_add(&shadow_link->list, &vma->vm_obj_list);
@@ -313,7 +313,8 @@ int copy_on_write(struct fault_data *fault)
/* Shadow is the copier object */
copier_link = shadow_link;
} else {
dprintf("No shadows. Going to add to topmost r/w shadow object\n");
dprintf("No new shadows. Going to add to "
"topmost r/w shadow object\n");
/* No new shadows, the topmost r/w vmo is the copier object */
copier_link = vmo_link;
@@ -328,7 +329,7 @@ int copy_on_write(struct fault_data *fault)
/* Traverse the list of read-only vm objects and search for the page */
while (IS_ERR(page = vmo_link->obj->pager->ops.page_in(vmo_link->obj,
file_offset))) {
file_offset))) {
if (!(vmo_link = vma_next_link(&vmo_link->list,
&vma->vm_obj_list))) {
printf("%s:%s: Traversed all shadows and the original "
@@ -367,6 +368,10 @@ int copy_on_write(struct fault_data *fault)
page_align(fault->address), fault->task->tid);
vm_object_print(new_page->owner);
/* Shm faults don't have shadows so we're done here. */
if (vma->flags & VMA_SHARED)
return 0;
/*
* Finished handling the actual fault, now check for possible
* shadow collapses. Does the copier completely shadow the one
@@ -408,8 +413,8 @@ int __do_page_fault(struct fault_data *fault)
unsigned int vma_flags = fault->vma->flags;
unsigned int pte_flags = vm_prot_flags(fault->kdata->pte);
struct vm_area *vma = fault->vma;
unsigned long file_offset;
struct vm_obj_link *vmo_link;
unsigned long file_offset;
struct page *page;
/* Handle read */
@@ -449,8 +454,8 @@ int __do_page_fault(struct fault_data *fault)
/* Handle write */
if ((reason & VM_WRITE) && (pte_flags & VM_READ)) {
/* Copy-on-write */
if (vma_flags & VMA_PRIVATE)
/* Copy-on-write. For all private 'union' all anonymous vmas. */
if ((vma_flags & VMA_PRIVATE) || (vma_flags & VMA_ANONYMOUS))
copy_on_write(fault);
/* Regular files */
@@ -479,13 +484,6 @@ int __do_page_fault(struct fault_data *fault)
page_align(fault->address), fault->task->tid);
vm_object_print(vmo_link->obj);
}
/* FIXME: Just do fs files for now, anon shm objects later. */
/* Things to think about:
* - Is utcb a shm memory really? Then each task must map it in via
* shmget(). FS0 must map all user tasks' utcb via shmget() as well.
* For example to pass on pathnames etc.
*/
BUG_ON((vma_flags & VMA_SHARED) && (vma_flags & VMA_ANONYMOUS));
}
return 0;

49
tasks/mm0/src/mmap.c
View File

@@ -284,9 +284,8 @@ int vma_unmap(struct vm_area **actual, struct vm_area **split,
}
/* Unmaps given address range from its vma. Releases those pages in that vma. */
int do_munmap(void *vaddr, unsigned long size, struct tcb *task)
int do_munmap(void *vaddr, unsigned long npages, struct tcb *task)
{
unsigned long npages = __pfn(size);
unsigned long pfn_start = __pfn(vaddr);
unsigned long pfn_end = pfn_start + npages;
struct vm_area *vma, *vma_new = 0;
@@ -332,7 +331,7 @@ pgtable_unmap:
#endif
int do_munmap(void *vaddr, unsigned long size, struct tcb *task)
int do_munmap(void *vaddr, unsigned long npages, struct tcb *task)
{
return 0;
}
@@ -343,7 +342,7 @@ int sys_munmap(l4id_t sender, void *vaddr, unsigned long size)
BUG_ON(!(task = find_task(sender)));
return do_munmap(vaddr, size, task);
return do_munmap(vaddr, __pfn(page_align_up(size)), task);
}
struct vm_area *vma_new(unsigned long pfn_start, unsigned long npages,
@@ -351,18 +350,11 @@ struct vm_area *vma_new(unsigned long pfn_start, unsigned long npages,
struct vm_file *mapfile)
{
struct vm_area *vma;
struct vm_obj_link *obj_link;
/* Allocate new area */
if (!(vma = kzalloc(sizeof(struct vm_area))))
return 0;
/* Allocate vm object link */
if (!(obj_link = kzalloc(sizeof(struct vm_obj_link)))) {
kfree(vma);
return 0;
}
INIT_LIST_HEAD(&vma->list);
INIT_LIST_HEAD(&vma->vm_obj_list);
@@ -371,11 +363,6 @@ struct vm_area *vma_new(unsigned long pfn_start, unsigned long npages,
vma->flags = flags;
vma->file_offset = file_offset;
INIT_LIST_HEAD(&obj_link->list);
INIT_LIST_HEAD(&obj_link->shref);
obj_link->obj = &mapfile->vm_obj;
list_add(&obj_link->list, &vma->vm_obj_list);
return vma;
}
@@ -469,7 +456,7 @@ int mmap_address_validate(unsigned long map_address, unsigned int vm_flags)
(map_address >= SHM_AREA_START &&
map_address < SHM_AREA_END))
return 1;
else
else
return 0;
} else
BUG();
@@ -487,9 +474,9 @@ int do_mmap(struct vm_file *mapfile, unsigned long file_offset,
unsigned int npages)
{
unsigned long map_pfn = __pfn(map_address);
unsigned long file_npages;
struct vm_area *new, *mapped;
struct vm_obj_link *vmo_link;
struct vm_obj_link *vmo_link, *vmo_link2;
unsigned long file_npages;
/* Set up devzero if none given */
if (!mapfile) {
@@ -550,6 +537,30 @@ int do_mmap(struct vm_file *mapfile, unsigned long file_offset,
mapfile->vm_obj.refcnt++;
list_add_tail(&vmo_link->list, &new->vm_obj_list);
/*
* If the file is a shm file, also map devzero behind it. i.e.
* vma -> vm_link -> vm_link
* | |
* v v
* shm_file devzero
*
* So that faults go through shm file and then devzero, as in
* the shadow object copy_on_write setup in fault.c
*/
if (mapfile->type == VM_FILE_SHM) {
struct vm_file *dzero = get_devzero();
/* Attach the file as the first vm object of this vma */
if (!(vmo_link2 = vm_objlink_create())) {
kfree(new);
kfree(vmo_link);
return -ENOMEM;
}
vmo_link2->obj = &dzero->vm_obj;
dzero->vm_obj.refcnt++;
list_add_tail(&vmo_link2->list, &new->vm_obj_list);
}
/* Finished initialising the vma, add it to task */
printf("%s: Mapping 0x%x - 0x%x\n", __FUNCTION__,
map_address, map_address + npages * PAGE_SIZE);

115
tasks/mm0/src/shm.c
View File

@@ -25,8 +25,11 @@
#include <posix/sys/shm.h>
#include <posix/sys/types.h>
#define shm_file_to_desc(shm_file) \
((struct shm_descriptor *)shm_file->priv_data)
/* The list of shared memory areas that are already set up and working */
static struct list_head shm_desc_list;
static LIST_HEAD(shm_file_list);
/* Unique shared memory ids */
static struct id_pool *shm_ids;
@@ -36,8 +39,6 @@ static struct address_pool shm_vaddr_pool;
void shm_init()
{
INIT_LIST_HEAD(&shm_desc_list);
/* Initialise shm id pool */
shm_ids = id_pool_new_init(SHM_AREA_MAX);
@@ -49,11 +50,11 @@ void shm_init()
* Attaches to given shm segment mapped at shm_addr if the shm descriptor
* does not already have a base address assigned. If neither shm_addr nor
* the descriptor has an address, allocates one from the shm address pool.
* FIXME: This pool is currently outside the range of mmap'able addresses.
*/
static void *do_shmat(struct shm_descriptor *shm, void *shm_addr, int shmflg,
static void *do_shmat(struct vm_file *shm_file, void *shm_addr, int shmflg,
l4id_t tid)
{
struct shm_descriptor *shm = shm_file_to_desc(shm_file);
struct tcb *task = find_task(tid);
unsigned int vmflags;
int err;
@@ -81,12 +82,12 @@ static void *do_shmat(struct shm_descriptor *shm, void *shm_addr, int shmflg,
*/
/* First user? */
if (!shm->refcnt)
if (!shm_file->vm_obj.refcnt)
if (mmap_address_validate((unsigned long)shm_addr, vmflags))
shm->shm_addr = shm_addr;
else
shm->shm_addr = address_new(&shm_vaddr_pool,
__pfn(shm->size));
shm->npages);
else /* Address must be already assigned */
BUG_ON(!shm->shm_addr);
@@ -94,34 +95,34 @@ static void *do_shmat(struct shm_descriptor *shm, void *shm_addr, int shmflg,
* mmap the area to the process as shared. Page fault handler would
* handle allocating and paging-in the shared pages.
*/
if ((err = do_mmap(0, 0, task, (unsigned long)shm->shm_addr,
vmflags, shm->size)) < 0) {
if ((err = do_mmap(shm_file, 0, task, (unsigned long)shm->shm_addr,
vmflags, shm->npages)) < 0) {
printf("do_mmap: Mapping shm area failed with %d.\n", err);
BUG();
}
/* Now update the shared memory descriptor */
shm->refcnt++;
return shm->shm_addr;
}
int sys_shmat(l4id_t requester, l4id_t shmid, void *shmaddr, int shmflg)
{
struct shm_descriptor *shm_desc, *n;
struct vm_file *shm_file, *n;
list_for_each_entry_safe(shm_desc, n, &shm_desc_list, list) {
if (shm_desc->shmid == shmid) {
shmaddr = do_shmat(shm_desc, shmaddr,
list_for_each_entry_safe(shm_file, n, &shm_file_list, list) {
if (shm_file_to_desc(shm_file)->shmid == shmid) {
shmaddr = do_shmat(shm_file, shmaddr,
shmflg, requester);
l4_ipc_return((int)shmaddr);
return 0;
}
}
l4_ipc_return(-EINVAL);
return 0;
}
int do_shmdt(struct shm_descriptor *shm, l4id_t tid)
int do_shmdt(struct vm_file *shm, l4id_t tid)
{
struct tcb *task = find_task(tid);
int err;
@@ -131,64 +132,91 @@ int do_shmdt(struct shm_descriptor *shm, l4id_t tid)
__TASKNAME__, __FUNCTION__, tid);
BUG();
}
if ((err = do_munmap(shm->shm_addr, shm->size, task)) < 0) {
if ((err = do_munmap(shm_file_to_desc(shm)->shm_addr,
shm_file_to_desc(shm)->npages, task)) < 0) {
printf("do_munmap: Unmapping shm segment failed with %d.\n",
err);
BUG();
}
return err;
}
int sys_shmdt(l4id_t requester, const void *shmaddr)
{
struct shm_descriptor *shm_desc, *n;
struct vm_file *shm_file, *n;
int err;
list_for_each_entry_safe(shm_desc, n, &shm_desc_list, list) {
if (shm_desc->shm_addr == shmaddr) {
if ((err = do_shmdt(shm_desc, requester) < 0)) {
list_for_each_entry_safe(shm_file, n, &shm_file_list, list) {
if (shm_file_to_desc(shm_file)->shm_addr == shmaddr) {
if ((err = do_shmdt(shm_file, requester) < 0)) {
l4_ipc_return(err);
return 0;
} else
break;
}
}
l4_ipc_return(0);
l4_ipc_return(-EINVAL);
return 0;
}
static struct shm_descriptor *shm_new(key_t key, unsigned long npages)
{
/* It doesn't exist, so create a new one */
struct shm_descriptor *shm_desc;
if ((shm_desc = kzalloc(sizeof(struct shm_descriptor))) < 0)
/* Creates an shm area and glues its details with shm pager and devzero */
static struct vm_file *shm_new(key_t key, unsigned long npages)
{
struct shm_descriptor *shm_desc;
struct vm_file *shm_file;
BUG_ON(!npages);
/* Allocate file and shm structures */
if (IS_ERR(shm_file = vm_file_create()))
return PTR_ERR(shm_file);
if (!(shm_desc = kzalloc(sizeof(struct shm_descriptor)))) {
kfree(shm_file);
return 0;
}
/* Initialise the shm descriptor */
if ((shm_desc->shmid = id_new(shm_ids)) < 0) {
kfree(shm_file);
kfree(shm_desc);
return 0;
}
BUG_ON(!npages);
shm_desc->key = (int)key;
shm_desc->size = npages;
INIT_LIST_HEAD(&shm_desc->list);
list_add(&shm_desc->list, &shm_desc_list);
shm_desc->npages = npages;
return shm_desc;
/* Initialise the file */
shm_file->length = __pfn_to_addr(npages);
shm_file->type = VM_FILE_SHM;
shm_file->priv_data = shm_desc;
/* Initialise the vm object */
shm_file->vm_obj.pager = &swap_pager;
shm_file->vm_obj.flags = VM_OBJ_FILE;
list_add(&shm_file->list, &shm_file_list);
list_add(&shm_file->vm_obj.list, &vm_object_list);
return shm_file;
}
/*
* FIXME: Make sure hostile tasks don't subvert other tasks' utcbs
* by early-registring their utcb address here.
*/
int sys_shmget(key_t key, int size, int shmflg)
{
struct shm_descriptor *shm_desc;
unsigned long npages;
unsigned long npages = __pfn(page_align_up(size));
struct vm_file *shm;
/* First check argument validity */
if (size > SHM_SHMMAX || size < SHM_SHMMIN) {
if (npages > SHM_SHMMAX || npages < SHM_SHMMIN) {
l4_ipc_return(-EINVAL);
return 0;
} else
npages = __pfn(page_align_up(size));
/*
* IPC_PRIVATE means create a no-key shm area, i.e. private to this
@@ -196,14 +224,16 @@ int sys_shmget(key_t key, int size, int shmflg)
*/
if (key == IPC_PRIVATE) {
key = -1; /* Our meaning of no key */
if (!(shm_desc = shm_new(key, npages)))
if (!(shm = shm_new(key, npages)))
l4_ipc_return(-ENOSPC);
else
l4_ipc_return(shm_desc->shmid);
l4_ipc_return(shm_file_to_desc(shm)->shmid);
return 0;
}
list_for_each_entry(shm_desc, &shm_desc_list, list) {
list_for_each_entry(shm, &shm_file_list, list) {
struct shm_descriptor *shm_desc = shm_file_to_desc(shm);
if (shm_desc->key == key) {
/*
* Exclusive means create request
@@ -213,7 +243,7 @@ int sys_shmget(key_t key, int size, int shmflg)
l4_ipc_return(-EEXIST);
else
/* Found it but do we have a size problem? */
if (shm_desc->size < size)
if (shm_desc->npages < npages)
l4_ipc_return(-EINVAL);
else /* Return shmid of the existing key */
l4_ipc_return(shm_desc->shmid);
@@ -223,14 +253,13 @@ int sys_shmget(key_t key, int size, int shmflg)
/* Key doesn't exist and create is set, so we create */
if (shmflg & IPC_CREAT)
if (!(shm_desc = shm_new(key, npages)))
if (!(shm = shm_new(key, npages)))
l4_ipc_return(-ENOSPC);
else
l4_ipc_return(shm_desc->shmid);
l4_ipc_return(shm_file_to_desc(shm)->shmid);
else /* Key doesn't exist, yet create isn't set, its an -ENOENT */
l4_ipc_return(-ENOENT);
return 0;
}