74,6 → 74,13 |
#include <syscall/copy.h> |
#include <arch/interrupt.h> |
|
/** This structure contains information associated with the shared address space area. */ |
struct share_info { |
mutex_t lock; /**< This lock must be acquired only when the as_area lock is held. */ |
count_t refcount; /**< This structure can be deallocated if refcount drops to 0. */ |
btree_t pagemap; /**< B+tree containing complete map of anonymous pages of the shared area. */ |
}; |
|
as_operations_t *as_operations = NULL; |
|
/** Address space lock. It protects inactive_as_with_asid_head. Must be acquired before as_t mutex. */ |
89,11 → 96,9 |
as_t *AS_KERNEL = NULL; |
|
static int area_flags_to_page_flags(int aflags); |
static int get_area_flags(as_area_t *a); |
static as_area_t *find_area_and_lock(as_t *as, __address va); |
static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area); |
static int used_space_insert(as_area_t *a, __address page, count_t count); |
static int used_space_remove(as_area_t *a, __address page, count_t count); |
static void sh_info_remove_reference(share_info_t *sh_info); |
|
/** Initialize address space subsystem. */ |
void as_init(void) |
148,10 → 153,13 |
* @param size Size of area. |
* @param base Base address of area. |
* @param attrs Attributes of the area. |
* @param backend Address space area backend. NULL if no backend is used. |
* @param backend_data NULL or a pointer to an array holding two void *. |
* |
* @return Address space area on success or NULL on failure. |
*/ |
as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base, int attrs) |
as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base, int attrs, |
mem_backend_t *backend, void **backend_data) |
{ |
ipl_t ipl; |
as_area_t *a; |
183,6 → 191,12 |
a->attributes = attrs; |
a->pages = SIZE2FRAMES(size); |
a->base = base; |
a->sh_info = NULL; |
a->backend = backend; |
if (backend_data) { |
a->backend_data[0] = backend_data[0]; |
a->backend_data[1] = backend_data[1]; |
} |
btree_create(&a->used_space); |
|
btree_insert(&as->as_area_btree, base, (void *) a, NULL); |
231,6 → 245,16 |
interrupts_restore(ipl); |
return ENOTSUP; |
} |
if (area->sh_info) { |
/* |
* Remapping of shared address space areas |
* is not supported. |
*/ |
mutex_unlock(&area->lock); |
mutex_unlock(&as->lock); |
interrupts_restore(ipl); |
return ENOTSUP; |
} |
|
pages = SIZE2FRAMES((address - area->base) + size); |
if (!pages) { |
302,7 → 326,10 |
page_table_lock(as, false); |
pte = page_mapping_find(as, b + i*PAGE_SIZE); |
ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte)); |
frame_free(ADDR2PFN(PTE_GET_FRAME(pte))); |
if (area->backend && area->backend->backend_frame_free) { |
area->backend->backend_frame_free(area, |
b + i*PAGE_SIZE, PTE_GET_FRAME(pte)); |
} |
page_mapping_remove(as, b + i*PAGE_SIZE); |
page_table_unlock(as, false); |
} |
391,7 → 418,10 |
page_table_lock(as, false); |
pte = page_mapping_find(as, b + i*PAGE_SIZE); |
ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte)); |
frame_free(ADDR2PFN(PTE_GET_FRAME(pte))); |
if (area->backend && area->backend->backend_frame_free) { |
area->backend->backend_frame_free(area, |
b + i*PAGE_SIZE, PTE_GET_FRAME(pte)); |
} |
page_mapping_remove(as, b + i*PAGE_SIZE); |
page_table_unlock(as, false); |
} |
410,6 → 440,10 |
tlb_shootdown_finalize(); |
|
area->attributes |= AS_AREA_ATTR_PARTIAL; |
|
if (area->sh_info) |
sh_info_remove_reference(area->sh_info); |
|
mutex_unlock(&area->lock); |
|
/* |
484,7 → 518,7 |
* attribute set which prevents race condition with |
* preliminary as_page_fault() calls. |
*/ |
dst_area = as_area_create(AS, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL); |
dst_area = as_area_create(AS, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL, &anon_backend, NULL); |
if (!dst_area) { |
/* |
* Destination address space area could not be created. |
568,7 → 602,9 |
panic("Page not part of any as_area.\n"); |
} |
|
page_mapping_insert(as, page, frame, get_area_flags(area)); |
ASSERT(!area->backend); |
|
page_mapping_insert(as, page, frame, as_area_get_flags(area)); |
if (!used_space_insert(area, page, 1)) |
panic("Could not insert used space.\n"); |
|
579,22 → 615,26 |
|
/** Handle page fault within the current address space. |
* |
* This is the high-level page fault handler. |
* This is the high-level page fault handler. It decides |
* whether the page fault can be resolved by any backend |
* and if so, it invokes the backend to resolve the page |
* fault. |
* |
* Interrupts are assumed disabled. |
* |
* @param page Faulting page. |
* @param istate Pointer to interrupted state. |
* |
* @return 0 on page fault, 1 on success or 2 if the fault was caused by copy_to_uspace() or copy_from_uspace(). |
* @return AS_PF_FAULT on page fault, AS_PF_OK on success or AS_PF_DEFER if the |
* fault was caused by copy_to_uspace() or copy_from_uspace(). |
*/ |
int as_page_fault(__address page, istate_t *istate) |
{ |
pte_t *pte; |
as_area_t *area; |
__address frame; |
|
if (!THREAD) |
return 0; |
return AS_PF_FAULT; |
|
ASSERT(AS); |
|
619,7 → 659,15 |
goto page_fault; |
} |
|
ASSERT(!(area->flags & AS_AREA_DEVICE)); |
if (!area->backend || !area->backend->backend_page_fault) { |
/* |
* The address space area is not backed by any backend |
* or the backend cannot handle page faults. |
*/ |
mutex_unlock(&area->lock); |
mutex_unlock(&AS->lock); |
goto page_fault; |
} |
|
page_table_lock(AS, false); |
|
633,45 → 681,26 |
page_table_unlock(AS, false); |
mutex_unlock(&area->lock); |
mutex_unlock(&AS->lock); |
return 1; |
return AS_PF_OK; |
} |
} |
|
/* |
* In general, there can be several reasons that |
* can have caused this fault. |
* |
* - non-existent mapping: the area is a scratch |
* area (e.g. stack) and so far has not been |
* allocated a frame for the faulting page |
* |
* - non-present mapping: another possibility, |
* currently not implemented, would be frame |
* reuse; when this becomes a possibility, |
* do not forget to distinguish between |
* the different causes |
* Resort to the backend page fault handler. |
*/ |
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
memsetb(PA2KA(frame), FRAME_SIZE, 0); |
if (area->backend->backend_page_fault(area, page) != AS_PF_OK) { |
page_table_unlock(AS, false); |
mutex_unlock(&area->lock); |
mutex_unlock(&AS->lock); |
goto page_fault; |
} |
|
/* |
* Map 'page' to 'frame'. |
* Note that TLB shootdown is not attempted as only new information is being |
* inserted into page tables. |
*/ |
page_mapping_insert(AS, page, frame, get_area_flags(area)); |
if (!used_space_insert(area, ALIGN_DOWN(page, PAGE_SIZE), 1)) |
panic("Could not insert used space.\n"); |
page_table_unlock(AS, false); |
|
mutex_unlock(&area->lock); |
mutex_unlock(&AS->lock); |
return AS_PF_OK; |
|
page_fault: |
if (!THREAD) |
return AS_PF_FAULT; |
|
if (THREAD->in_copy_from_uspace) { |
THREAD->in_copy_from_uspace = false; |
istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address); |
793,7 → 822,7 |
* |
* @return Flags to be used in page_mapping_insert(). |
*/ |
int get_area_flags(as_area_t *a) |
int as_area_get_flags(as_area_t *a) |
{ |
return area_flags_to_page_flags(a->flags); |
} |
1381,7 → 1410,152 |
panic("Inconsistency detected while removing %d pages of used space from %P.\n", count, page); |
} |
|
/** Remove reference to address space area share info. |
* |
* If the reference count drops to 0, the sh_info is deallocated. |
* |
* @param sh_info Pointer to address space area share info. |
*/ |
void sh_info_remove_reference(share_info_t *sh_info) |
{ |
bool dealloc = false; |
|
mutex_lock(&sh_info->lock); |
ASSERT(sh_info->refcount); |
if (--sh_info->refcount == 0) { |
dealloc = true; |
bool cond; |
|
/* |
* Now walk carefully the pagemap B+tree and free/remove |
* reference from all frames found there. |
*/ |
for (cond = true; cond;) { |
btree_node_t *node; |
|
ASSERT(!list_empty(&sh_info->pagemap.leaf_head)); |
node = list_get_instance(sh_info->pagemap.leaf_head.next, btree_node_t, leaf_link); |
if ((cond = node->keys)) { |
frame_free(ADDR2PFN((__address) node->value[0])); |
btree_remove(&sh_info->pagemap, node->key[0], node); |
} |
} |
|
} |
mutex_unlock(&sh_info->lock); |
|
if (dealloc) { |
btree_destroy(&sh_info->pagemap); |
free(sh_info); |
} |
} |
|
static int anon_page_fault(as_area_t *area, __address addr); |
static void anon_frame_free(as_area_t *area, __address page, __address frame); |
|
/* |
* Anonymous memory backend. |
*/ |
mem_backend_t anon_backend = { |
.backend_page_fault = anon_page_fault, |
.backend_frame_free = anon_frame_free |
}; |
|
/** Service a page fault in the anonymous memory address space area. |
* |
* The address space area and page tables must be already locked. |
* |
* @param area Pointer to the address space area. |
* @param addr Faulting virtual address. |
* |
* @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced). |
*/ |
int anon_page_fault(as_area_t *area, __address addr) |
{ |
__address frame; |
|
if (area->sh_info) { |
btree_node_t *leaf; |
|
/* |
* The area is shared, chances are that the mapping can be found |
* in the pagemap of the address space area share info structure. |
* In the case that the pagemap does not contain the respective |
* mapping, a new frame is allocated and the mapping is created. |
*/ |
mutex_lock(&area->sh_info->lock); |
frame = (__address) btree_search(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE), &leaf); |
if (!frame) { |
bool allocate = true; |
int i; |
|
/* |
* Zero can be returned as a valid frame address. |
* Just a small workaround. |
*/ |
for (i = 0; i < leaf->keys; i++) { |
if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) { |
allocate = false; |
break; |
} |
} |
if (allocate) { |
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
memsetb(PA2KA(frame), FRAME_SIZE, 0); |
|
/* |
* Insert the address of the newly allocated frame to the pagemap. |
*/ |
btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE), (void *) frame, leaf); |
} |
} |
mutex_unlock(&area->sh_info->lock); |
} else { |
|
/* |
* In general, there can be several reasons that |
* can have caused this fault. |
* |
* - non-existent mapping: the area is an anonymous |
* area (e.g. heap or stack) and so far has not been |
* allocated a frame for the faulting page |
* |
* - non-present mapping: another possibility, |
* currently not implemented, would be frame |
* reuse; when this becomes a possibility, |
* do not forget to distinguish between |
* the different causes |
*/ |
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
memsetb(PA2KA(frame), FRAME_SIZE, 0); |
} |
|
/* |
* Map 'page' to 'frame'. |
* Note that TLB shootdown is not attempted as only new information is being |
* inserted into page tables. |
*/ |
page_mapping_insert(AS, addr, frame, as_area_get_flags(area)); |
if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1)) |
panic("Could not insert used space.\n"); |
|
return AS_PF_OK; |
} |
|
/** Free a frame that is backed by the anonymous memory backend. |
* |
* The address space area and page tables must be already locked. |
* |
* @param area Ignored. |
* @param page Ignored. |
* @param frame Frame to be released. |
*/ |
void anon_frame_free(as_area_t *area, __address page, __address frame) |
{ |
frame_free(ADDR2PFN(frame)); |
} |
|
/* |
* Address space related syscalls. |
*/ |
|
1388,7 → 1562,7 |
/** Wrapper for as_area_create(). */ |
__native sys_as_area_create(__address address, size_t size, int flags) |
{ |
if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE)) |
if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE, &anon_backend, NULL)) |
return (__native) address; |
else |
return (__native) -1; |