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Complete r320189 which allows a NULL VM fault handler in the LinuxKPI.

Browse Source 
Instead of mapping a dummy page upon a page fault, map the page
pointed to by the physical address given by IDX_TO_OFF(vmap->vm_pfn).
To simplify the implementation use OBJT_DEVICE to implement our own
linux_cdev_pager_fault() instead of using the existing
linux_cdev_pager_populate().

Some minor code factoring while at it.

Reviewed by:	markj @
MFC after:	1 week
Sponsored by:	Mellanox Technologies
This commit is contained in:
Hans Petter Selasky 2017-07-07 13:44:14 +00:00
parent ea16525413
commit 611572285a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=320775
1 changed files with 77 additions and 12 deletions
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89
sys/compat/linuxkpi/common/src/linux_compat.c
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@ -473,12 +473,58 @@ linux_file_free(struct linux_file *filp)
}
}
static int
linux_cdev_pager_fault(vm_object_t vm_obj, vm_ooffset_t offset, int prot,
vm_page_t *mres)
{
struct vm_area_struct *vmap;
vmap = linux_cdev_handle_find(vm_obj->handle);
MPASS(vmap != NULL);
MPASS(vmap->vm_private_data == vm_obj->handle);
if (likely(vmap->vm_ops != NULL && offset < vmap->vm_len)) {
vm_paddr_t paddr = IDX_TO_OFF(vmap->vm_pfn) + offset;
vm_page_t page;
if (((*mres)->flags & PG_FICTITIOUS) != 0) {
/*
* If the passed in result page is a fake
* page, update it with the new physical
* address.
*/
page = *mres;
vm_page_updatefake(page, paddr, vm_obj->memattr);
} else {
/*
* Replace the passed in "mres" page with our
* own fake page and free up the all of the
* original pages.
*/
VM_OBJECT_WUNLOCK(vm_obj);
page = vm_page_getfake(paddr, vm_obj->memattr);
VM_OBJECT_WLOCK(vm_obj);
vm_page_replace_checked(page, vm_obj,
(*mres)->pindex, *mres);
vm_page_lock(*mres);
vm_page_free(*mres);
vm_page_unlock(*mres);
*mres = page;
}
page->valid = VM_PAGE_BITS_ALL;
return (VM_PAGER_OK);
}
return (VM_PAGER_FAIL);
}
static int
linux_cdev_pager_populate(vm_object_t vm_obj, vm_pindex_t pidx, int fault_type,
vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
{
struct vm_area_struct *vmap;
struct vm_fault vmf;
int err;
linux_set_current(curthread);
@ -488,18 +534,20 @@ linux_cdev_pager_populate(vm_object_t vm_obj, vm_pindex_t pidx, int fault_type,
MPASS(vmap != NULL);
MPASS(vmap->vm_private_data == vm_obj->handle);
/* fill out VM fault structure */
vmf.virtual_address = (void *)((uintptr_t)pidx << PAGE_SHIFT);
vmf.flags = (fault_type & VM_PROT_WRITE) ? FAULT_FLAG_WRITE : 0;
vmf.pgoff = 0;
vmf.page = NULL;
VM_OBJECT_WUNLOCK(vm_obj);
down_write(&vmap->vm_mm->mmap_sem);
if (unlikely(vmap->vm_ops == NULL || vmap->vm_ops->fault == NULL)) {
if (unlikely(vmap->vm_ops == NULL)) {
err = VM_FAULT_SIGBUS;
} else {
struct vm_fault vmf;
/* fill out VM fault structure */
vmf.virtual_address = (void *)((uintptr_t)pidx << PAGE_SHIFT);
vmf.flags = (fault_type & VM_PROT_WRITE) ? FAULT_FLAG_WRITE : 0;
vmf.pgoff = 0;
vmf.page = NULL;
vmap->vm_pfn_count = 0;
vmap->vm_pfn_pcount = &vmap->vm_pfn_count;
vmap->vm_obj = vm_obj;
@ -631,10 +679,19 @@ linux_cdev_pager_dtor(void *handle)
linux_cdev_handle_free(vmap);
}
static struct cdev_pager_ops linux_cdev_pager_ops = {
static struct cdev_pager_ops linux_cdev_pager_ops[2] = {
{
/* OBJT_MGTDEVICE */
.cdev_pg_populate = linux_cdev_pager_populate,
.cdev_pg_ctor = linux_cdev_pager_ctor,
.cdev_pg_dtor = linux_cdev_pager_dtor
},
{
/* OBJT_DEVICE */
.cdev_pg_fault = linux_cdev_pager_fault,
.cdev_pg_ctor = linux_cdev_pager_ctor,
.cdev_pg_dtor = linux_cdev_pager_dtor
},
};
static int
@ -1184,8 +1241,15 @@ linux_dev_mmap_single(struct cdev *dev, vm_ooffset_t *offset,
vmap = linux_cdev_handle_insert(vm_private_data, vmap);
*object = cdev_pager_allocate(vm_private_data, OBJT_MGTDEVICE,
&linux_cdev_pager_ops, size, nprot, *offset, curthread->td_ucred);
if (vmap->vm_ops->fault == NULL) {
*object = cdev_pager_allocate(vm_private_data, OBJT_DEVICE,
&linux_cdev_pager_ops[1], size, nprot, *offset,
curthread->td_ucred);
} else {
*object = cdev_pager_allocate(vm_private_data, OBJT_MGTDEVICE,
&linux_cdev_pager_ops[0], size, nprot, *offset,
curthread->td_ucred);
}
if (*object == NULL) {
linux_cdev_handle_remove(vmap);
@ -1196,7 +1260,8 @@ linux_dev_mmap_single(struct cdev *dev, vm_ooffset_t *offset,
struct sglist *sg;
sg = sglist_alloc(1, M_WAITOK);
sglist_append_phys(sg, (vm_paddr_t)vmap->vm_pfn << PAGE_SHIFT, vmap->vm_len);
sglist_append_phys(sg,
(vm_paddr_t)vmap->vm_pfn << PAGE_SHIFT, vmap->vm_len);
*object = vm_pager_allocate(OBJT_SG, sg, vmap->vm_len,
nprot, 0, curthread->td_ucred);