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mm: properly implement page locking

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Matheus
2026-07-08 01:37:12 -03:00
parent af30088c0d
commit 1512b2f3c6
14 changed files with 123 additions and 45 deletions
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kernel-src/include/kernel/iovec.h
+4 -2
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@@ -66,10 +66,12 @@ size_t iovec_iterator_read_from_ringbuffer(iovec_iterator_t *iovec_iterator, rin
// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with RINGBUFFER_USER_COPY_FAILED // NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with RINGBUFFER_USER_COPY_FAILED
size_t iovec_iterator_peek_from_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count, uintmax_t ringbuffer_offset); size_t iovec_iterator_peek_from_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count, uintmax_t ringbuffer_offset);
// returns the physical address of the next page in the iovec_iterator, adding a reference count while at it // returns the physical address of the next page in the iovec_iterator, adding a reference count and locking it for DMA.
// The write bool controls whether the hint passed to mm_get_physical_address is a read or write (i.e. reading data from the page or
// writing data to the page)
// sets the page_offset to the offset in the page, page_remaining to the remaining number of bytes in the page and page to the physical address of the page // sets the page_offset to the offset in the page, page_remaining to the remaining number of bytes in the page and page to the physical address of the page
// if no more pages in iovec_iterator, returns success with page being set to NULL // if no more pages in iovec_iterator, returns success with page being set to NULL
// fails with EFAULT if the page is not mapped // fails with EFAULT if the page is not mapped
int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offset, size_t *page_remaining, void **page); int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offset, size_t *page_remaining, void **page, bool write);
#endif #endif
kernel-src/include/kernel/mm.h
+2
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@@ -90,6 +90,8 @@ void mm_switch_context(mm_context_t *ctx);
#define MM_GET_PHYSICAL_ADDRESS_FLAGS_HOLD 1 #define MM_GET_PHYSICAL_ADDRESS_FLAGS_HOLD 1
#define MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK 2 #define MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK 2
#define MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_READ 4
#define MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_WRITE 8
void *mm_get_physical_address(void *addr, int flags); void *mm_get_physical_address(void *addr, int flags);
void mm_apinit(); void mm_apinit();
void mm_init(); void mm_init();
kernel-src/include/kernel/page.h
+4
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@@ -3,6 +3,7 @@
#include <stddef.h> #include <stddef.h>
#include <stdint.h> #include <stdint.h>
#include <stdbool.h>
#define MEMORY_SECTION_COUNT 3 #define MEMORY_SECTION_COUNT 3
#define MEMORY_SECTION_1MB 0 #define MEMORY_SECTION_1MB 0
@@ -44,11 +45,14 @@ page_t *mm_get_page(void *addr);
void *mm_get_page_address(page_t *); void *mm_get_page_address(page_t *);
void mm_hold_page(void *addr); void mm_hold_page(void *addr);
void mm_release_page(void *addr); void mm_release_page(void *addr);
void mm_unlock_and_release_page(void *addr);
void mm_force_free_page(void *address, size_t count); void mm_force_free_page(void *address, size_t count);
void *mm_alloc_pages(size_t size, int section); void *mm_alloc_pages(size_t size, int section);
void mm_release_range(void *addr, size_t size); void mm_release_range(void *addr, size_t size);
void mm_page_init(); void mm_page_init();
void mm_get_page_statistics(size_t *total_pages, size_t *free_pages); void mm_get_page_statistics(size_t *total_pages, size_t *free_pages);
void mm_unlock_page(page_t *page);
bool mm_is_page_locked(page_t *page);
extern uintptr_t hhdm_base; extern uintptr_t hhdm_base;
kernel-src/include/kernel/xhci.h
+1
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@@ -322,6 +322,7 @@ struct xhci_submission {
list_node_t list_node; list_node_t list_node;
// Set whenever a submission is queued // Set whenever a submission is queued
bool valid; bool valid;
bool unlock_pages;
struct xhci_ring *ring; struct xhci_ring *ring;
// The data associated with this submission // The data associated with this submission
kernel-src/io/block/ahci.c
+5 -5
View File
@@ -308,12 +308,12 @@ static int cmd_identify(ahci_t *ahci, int port, identify_t *results_phys) {
static void release_prdt(command_table_t *command_table, uint16_t prdtl) { static void release_prdt(command_table_t *command_table, uint16_t prdtl) {
for (int i = 0; i < prdtl; ++i) { for (int i = 0; i < prdtl; ++i) {
void *address = (void *)((uint64_t)command_table->prdt[i].base_low | ((uint64_t)command_table->prdt[i].base_high << 32)); void *address = (void *)((uint64_t)command_table->prdt[i].base_low | ((uint64_t)command_table->prdt[i].base_high << 32));
mm_release_page(address); mm_unlock_and_release_page(address);
} }
} }
#define PRDTL_LIMIT ((PAGE_SIZE - sizeof(command_table_t)) / sizeof(prdt_t)) #define PRDTL_LIMIT ((PAGE_SIZE - sizeof(command_table_t)) / sizeof(prdt_t))
static int setup_prdt(iovec_iterator_t *iterator, command_table_t *command_table, uint16_t *prdtl, size_t *requested_size) { static int setup_prdt(iovec_iterator_t *iterator, command_table_t *command_table, uint16_t *prdtl, size_t *requested_size, bool write) {
int err; int err;
size_t block_done = 0; size_t block_done = 0;
size_t prdt_done = 0; size_t prdt_done = 0;
@@ -321,14 +321,14 @@ static int setup_prdt(iovec_iterator_t *iterator, command_table_t *command_table
while (block_done < *requested_size && prdt_done < PRDTL_LIMIT) { while (block_done < *requested_size && prdt_done < PRDTL_LIMIT) {
void *page; void *page;
size_t page_offset, page_remaining; size_t page_offset, page_remaining;
err = iovec_iterator_next_page(iterator, &page_offset, &page_remaining, &page); err = iovec_iterator_next_page(iterator, &page_offset, &page_remaining, &page, !write);
if (err) if (err)
goto cleanup; goto cleanup;
__assert(page); __assert(page);
// not block aligned // not block aligned
if (page_remaining % 512) { if (page_remaining % 512) {
mm_release_page(page); mm_unlock_and_release_page(page);
err = EINVAL; err = EINVAL;
goto cleanup; goto cleanup;
} }
@@ -386,7 +386,7 @@ static int rw(port_data_t *port_data, iovec_iterator_t *iterator, uintmax_t lba,
while (done != count) { while (done != count) {
size_t do_count = count - done; size_t do_count = count - done;
uint16_t prdtl_tmp; uint16_t prdtl_tmp;
error = setup_prdt(iterator, command_table, &prdtl_tmp, &do_count); error = setup_prdt(iterator, command_table, &prdtl_tmp, &do_count, write);
if (error) if (error)
break; break;
kernel-src/io/block/nvme.c
+17 -14
View File
@@ -510,26 +510,29 @@ static int iowrite(nvmenamespace_t *namespace, uint64_t prp[2], uint64_t lba, ui
#define PAGES_IN_PRP_PAGE (PAGE_SIZE / sizeof(uint64_t)) #define PAGES_IN_PRP_PAGE (PAGE_SIZE / sizeof(uint64_t))
static void free_prps(uint64_t prp[2], bool has_list) { static void free_prps(uint64_t prp[2], bool has_list) {
mm_release_page((void *)ROUND_DOWN(prp[0], PAGE_SIZE)); void *prp1 = (void *)prp[1];
if (has_list) {
uint64_t *prp_list = MAKE_HHDM((uint64_t *)prp[1]);
for (int i = 0; prp_list[i] && i < PAGES_IN_PRP_PAGE; ++i)
mm_release_page((void *)prp_list[i]);
}
if (prp[1]) mm_unlock_and_release_page((void *)ROUND_DOWN(prp[0], PAGE_SIZE));
mm_release_page((void *)prp[1]); if (has_list) {
uint64_t *prp_list = MAKE_HHDM(prp1);
for (int i = 0; i < PAGES_IN_PRP_PAGE && prp_list[i]; ++i)
mm_unlock_and_release_page((void *)prp_list[i]);
mm_release_page(prp1);
} else if (prp1) {
mm_unlock_and_release_page(prp1);
}
} }
// sets up prps based on an iovec iterator. // sets up prps based on an iovec iterator.
// takes in the wanted block count and outputs an io_count for the i/o operation (for example, if it did not fit entirely on the prp) // takes in the wanted block count and outputs an io_count for the i/o operation (for example, if it did not fit entirely on the prp)
static int setup_prps(nvmenamespace_t *namespace, iovec_iterator_t *iovec_iterator, uint64_t prp[2], size_t count, size_t *io_count, bool *has_list) { static int setup_prps(nvmenamespace_t *namespace, iovec_iterator_t *iovec_iterator, uint64_t prp[2], size_t count, size_t *io_count, bool *has_list, bool write) {
count = min(count, namespace->max_transfer_size_blocks); count = min(count, namespace->max_transfer_size_blocks);
// first page // first page
void *page; void *page;
size_t page_offset, page_remaining; size_t page_offset, page_remaining;
int error = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page); int error = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page, !write);
if (error) if (error)
return error; return error;
__assert(page); __assert(page);
@@ -553,7 +556,7 @@ static int setup_prps(nvmenamespace_t *namespace, iovec_iterator_t *iovec_iterat
} }
// second page // second page
error = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page); error = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page, !write);
if (error) { if (error) {
free_prps(prp, false); free_prps(prp, false);
return error; return error;
@@ -591,7 +594,7 @@ static int setup_prps(nvmenamespace_t *namespace, iovec_iterator_t *iovec_iterat
// loop over the pages // loop over the pages
for (int i = 1; i < PAGES_IN_PRP_PAGE; ++i) { for (int i = 1; i < PAGES_IN_PRP_PAGE; ++i) {
error = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page); error = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page, !write);
if (error) { if (error) {
prp_list[i] = 0; prp_list[i] = 0;
free_prps(prp, true); free_prps(prp, true);
@@ -603,7 +606,7 @@ static int setup_prps(nvmenamespace_t *namespace, iovec_iterator_t *iovec_iterat
if (page_offset || page_remaining % namespace->blocksize) { if (page_offset || page_remaining % namespace->blocksize) {
prp_list[i] = 0; prp_list[i] = 0;
free_prps(prp, true); free_prps(prp, true);
mm_release_page(page); mm_unlock_and_release_page(page);
return EINVAL; return EINVAL;
} }
@@ -641,7 +644,7 @@ static int rwblocks(nvmenamespace_t *namespace, iovec_iterator_t *iovec_iterator
for (;;) { for (;;) {
size_t io_count; size_t io_count;
bool has_list; bool has_list;
error = setup_prps(namespace, iovec_iterator, prp, count, &io_count, &has_list); error = setup_prps(namespace, iovec_iterator, prp, count, &io_count, &has_list, write);
if (error) if (error)
return error; return error;
kernel-src/io/block/vioblk.c
+2 -2
View File
@@ -116,7 +116,7 @@ static int vioblk_rw(vioblkdev_t *blkdev, iovec_iterator_t *iovec_iterator, uint
while (done < count) { while (done < count) {
void *page; void *page;
size_t page_offset, page_remaining; size_t page_offset, page_remaining;
err = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page); err = iovec_iterator_next_page(iovec_iterator, &page_offset, &page_remaining, &page, !write);
if (err) if (err)
break; break;
@@ -133,7 +133,7 @@ static int vioblk_rw(vioblkdev_t *blkdev, iovec_iterator_t *iovec_iterator, uint
vioblk_enqueue(blkdev, header, (void *)((uintptr_t)page + page_offset), PAGE_SIZE, status, write); vioblk_enqueue(blkdev, header, (void *)((uintptr_t)page + page_offset), PAGE_SIZE, status, write);
mm_release_page(page); mm_unlock_and_release_page(page);
// if we didnt use the whole space in the page, set the iterator back a bit // if we didnt use the whole space in the page, set the iterator back a bit
size_t diff_between_available_and_used = page_remaining - docount * 512; size_t diff_between_available_and_used = page_remaining - docount * 512;
kernel-src/io/iovec.c
+6 -2
View File
@@ -235,7 +235,7 @@ size_t iovec_iterator_read_from_ringbuffer(iovec_iterator_t *iovec_iterator, rin
return done; return done;
} }
int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offset, size_t *page_remaining, void **page) { int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offset, size_t *page_remaining, void **page, bool write) {
iovec_iterator_skip(iovec_iterator, 0); // this will skip any zero length entries iovec_iterator_skip(iovec_iterator, 0); // this will skip any zero length entries
void *addr = (void *)((uintptr_t)iovec_iterator->current->addr + iovec_iterator->current_offset); void *addr = (void *)((uintptr_t)iovec_iterator->current->addr + iovec_iterator->current_offset);
size_t offset_in_page = ((uintptr_t)addr % PAGE_SIZE); size_t offset_in_page = ((uintptr_t)addr % PAGE_SIZE);
@@ -246,7 +246,11 @@ int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offs
return 0; return 0;
} }
void *phys = mm_get_physical_address((void *)((uintptr_t)addr - offset_in_page), MM_GET_PHYSICAL_ADDRESS_FLAGS_HOLD | MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK); void *phys = mm_get_physical_address((void *)((uintptr_t)addr - offset_in_page),
MM_GET_PHYSICAL_ADDRESS_FLAGS_HOLD |
MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK |
(write ? MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_WRITE :
MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_READ));
if (phys == NULL) if (phys == NULL)
return EFAULT; return EFAULT;
kernel-src/io/usb/ctrl/xhci.c
+7 -2
View File
@@ -27,8 +27,13 @@ static void xhci_signal_callback_thread(xhci_ctrl_t *xhci) {
static void xhci_release_submission_page(xhci_submission_t *submission) { static void xhci_release_submission_page(xhci_submission_t *submission) {
uint32_t cmd_type = xhci_trb_type(&submission->cmd_trb); uint32_t cmd_type = xhci_trb_type(&submission->cmd_trb);
if ((cmd_type == TRB_NORMAL || cmd_type == TRB_DATA_STAGE) && submission->cmd_trb.parameters != 0) if ((cmd_type == TRB_NORMAL || cmd_type == TRB_DATA_STAGE) && submission->cmd_trb.parameters != 0) {
mm_release_page((void *)(submission->cmd_trb.parameters & ~(PAGE_SIZE - 1))); void *page = (void *)(submission->cmd_trb.parameters & ~(PAGE_SIZE - 1));
if (submission->unlock_pages)
mm_unlock_and_release_page(page);
else
mm_release_page(page);
}
} }
static bool xhci_reclaim_submission_slot(xhci_submission_t *slot, xhci_submission_t *submission) { static bool xhci_reclaim_submission_slot(xhci_submission_t *slot, xhci_submission_t *submission) {
kernel-src/io/usb/ctrl/xhci_ring.c
+2
View File
@@ -83,6 +83,8 @@ xhci_submission_t *xhci_ring_submit_locked(xhci_ring_t *r, xhci_trb_t *trb, xhci
bool old_valid = __atomic_exchange_n(&r_sub->valid, true, __ATOMIC_SEQ_CST); bool old_valid = __atomic_exchange_n(&r_sub->valid, true, __ATOMIC_SEQ_CST);
__assert(!old_valid); __assert(!old_valid);
r_sub->unlock_pages = sub->unlock_pages;
r_sub->ring = r; r_sub->ring = r;
r_sub->device = sub->device; r_sub->device = sub->device;
r_sub->callback = sub->callback; r_sub->callback = sub->callback;
kernel-src/io/usb/ctrl/xhci_xfer.c
+12 -6
View File
@@ -12,7 +12,7 @@ typedef struct {
size_t data_offset; size_t data_offset;
} sg_trb_t; } sg_trb_t;
static int xhci_count_sg_trbs(iovec_iterator_t *iov, size_t total_size, size_t *trb_count) { static int xhci_count_sg_trbs(iovec_iterator_t *iov, size_t total_size, size_t *trb_count, bool write) {
iovec_iterator_t iter = *iov; iovec_iterator_t iter = *iov;
size_t done = 0; size_t done = 0;
size_t count = 0; size_t count = 0;
@@ -21,13 +21,13 @@ static int xhci_count_sg_trbs(iovec_iterator_t *iov, size_t total_size, size_t *
size_t page_offset, page_remaining; size_t page_offset, page_remaining;
void *page; void *page;
int err = iovec_iterator_next_page(&iter, &page_offset, &page_remaining, &page); int err = iovec_iterator_next_page(&iter, &page_offset, &page_remaining, &page, write);
if (err) if (err)
return err; return err;
if (page == NULL) if (page == NULL)
return EFAULT; return EFAULT;
mm_release_page(page); mm_unlock_and_release_page(page);
done += min(page_remaining, total_size - done); done += min(page_remaining, total_size - done);
count++; count++;
@@ -41,6 +41,8 @@ int xhci_data_xfer(xhci_ctrl_t *xhci, xhci_device_t *dev, usb_xfer_t *xfer, xhci
__assert(xfer->ep != NULL); __assert(xfer->ep != NULL);
__assert(xfer->setup == NULL); __assert(xfer->setup == NULL);
sub->unlock_pages = false;
uint32_t ep_num = xfer->ep->desc->bEndpointAddress & USB_ENDPOINT_ADDRESS_NUM_MASK; uint32_t ep_num = xfer->ep->desc->bEndpointAddress & USB_ENDPOINT_ADDRESS_NUM_MASK;
uint32_t ep_index = (ep_num << 1) | (xfer->ep->desc->bEndpointAddress & USB_ENDPOINT_ADDRESS_DIR_IN ? 1 : 0); uint32_t ep_index = (ep_num << 1) | (xfer->ep->desc->bEndpointAddress & USB_ENDPOINT_ADDRESS_DIR_IN ? 1 : 0);
@@ -99,6 +101,7 @@ int xhci_sg_data_xfer(xhci_ctrl_t *xhci, xhci_ring_t *ring, xhci_device_t *dev,
uint16_t max_packet_size = usb_endpoint_max_packet_size(xfer->ep->desc); uint16_t max_packet_size = usb_endpoint_max_packet_size(xfer->ep->desc);
uint32_t td_count = ROUND_UP(xfer->iov->total_size, max_packet_size) / max_packet_size; uint32_t td_count = ROUND_UP(xfer->iov->total_size, max_packet_size) / max_packet_size;
uint32_t done = 0; uint32_t done = 0;
sub->unlock_pages = true;
if (xfer->iov->total_size == 0) { if (xfer->iov->total_size == 0) {
if (sub->callback) if (sub->callback)
@@ -107,7 +110,7 @@ int xhci_sg_data_xfer(xhci_ctrl_t *xhci, xhci_ring_t *ring, xhci_device_t *dev,
} }
size_t trb_count; size_t trb_count;
int err = xhci_count_sg_trbs(xfer->iov, xfer->iov->total_size, &trb_count); int err = xhci_count_sg_trbs(xfer->iov, xfer->iov->total_size, &trb_count, xfer->flags & USB_XFER_FLAG_TO_HOST);
if (err) if (err)
return err; return err;
@@ -127,9 +130,10 @@ int xhci_sg_data_xfer(xhci_ctrl_t *xhci, xhci_ring_t *ring, xhci_device_t *dev,
size_t page_offset, page_remaining; size_t page_offset, page_remaining;
void *page; void *page;
err = iovec_iterator_next_page(&iter, &page_offset, &page_remaining, &page); err = iovec_iterator_next_page(&iter, &page_offset, &page_remaining, &page, xfer->flags & USB_XFER_FLAG_TO_HOST);
if (err) if (err)
goto fail; goto fail;
if (page == NULL) { if (page == NULL) {
err = EFAULT; err = EFAULT;
goto fail; goto fail;
@@ -187,7 +191,7 @@ int xhci_sg_data_xfer(xhci_ctrl_t *xhci, xhci_ring_t *ring, xhci_device_t *dev,
fail: fail:
for (size_t i = 0; i < prepared_count; ++i) for (size_t i = 0; i < prepared_count; ++i)
mm_release_page(prepared[i].page); mm_unlock_and_release_page(prepared[i].page);
free(prepared); free(prepared);
xhci_ring_unreserve(ring, trb_count); xhci_ring_unreserve(ring, trb_count);
return err; return err;
@@ -197,6 +201,8 @@ int xhci_control_xfer(xhci_ctrl_t *xhci, xhci_device_t *dev, usb_xfer_t *xfer, x
__assert(xfer->ep == NULL); __assert(xfer->ep == NULL);
__assert(xfer->setup != NULL); __assert(xfer->setup != NULL);
sub->unlock_pages = false;
// Why would anyone want to do scatter-gather control transfers??? // Why would anyone want to do scatter-gather control transfers???
__assert(!(xfer->flags & USB_XFER_FLAG_IOVEC)); __assert(!(xfer->flags & USB_XFER_FLAG_IOVEC));
kernel-src/mm/mm.c
+36 -11
View File
@@ -161,7 +161,7 @@ int mm_full_page_in(mm_range_t *range, void *vaddr, page_t **resulting_page) {
return ENOMEM; return ENOMEM;
} }
if (cacheable) { if (cacheable && (range->mmuflags & ARCH_MMU_FLAGS_WRITE)) {
VOP_LOCK(range->vnode); VOP_LOCK(range->vnode);
mm_cache_make_dirty(vn_page); mm_cache_make_dirty(vn_page);
VOP_UNLOCK(range->vnode); VOP_UNLOCK(range->vnode);
@@ -318,11 +318,20 @@ bool mm_handle_page_fault(void *addr, bool user, int actions) {
return status; return status;
} }
// TODO read-only permission checking for DMA
// space is expected to be locked on call. // space is expected to be locked on call.
static int lock_page(mm_space_t *space, void *vaddr) { static int lock_page(mm_space_t *space, void *vaddr, int hint) {
// TODO: with a read hint, we could theoretically only partially page in.
mm_range_t *range = mm_get_range(space, vaddr); mm_range_t *range = mm_get_range(space, vaddr);
if (!range) if (!range ||
((hint & MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_WRITE) && !(range->mmuflags & ARCH_MMU_FLAGS_WRITE)) ||
((hint & MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_READ) && !(range->mmuflags & ARCH_MMU_FLAGS_READ)))
return EFAULT;
// since we cannot guarantee the mapping of a character device actually points to physical memory,
// we cannot reliably lock it. returning an error here also protects from trying to DMA into non-physical memory
// like the framebuffer.
// same thing applies to an abstract physical memory mapping.
if (((range->flags & MM_RANGE_FLAGS_FILE) && (range->vnode->type == V_TYPE_CHDEV)) || (range->flags & MM_RANGE_FLAGS_PHYSICAL))
return EFAULT; return EFAULT;
// we need to make sure the address is fully paged in before locking, as it needs // we need to make sure the address is fully paged in before locking, as it needs
@@ -350,7 +359,7 @@ void *mm_get_physical_address(void *addr, int flags) {
MUTEX_ACQUIRE(&space->lock); MUTEX_ACQUIRE(&space->lock);
void *physical; void *physical;
if ((flags & MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK) && lock_page(space, aligned_addr)) { if ((flags & MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK) && lock_page(space, aligned_addr, flags)) {
physical = NULL; physical = NULL;
goto leave; goto leave;
} }
@@ -567,8 +576,6 @@ mm_context_t *mm_fork_context(mm_context_t *old_context) {
if (range->flags & MM_RANGE_FLAGS_FILE) if (range->flags & MM_RANGE_FLAGS_FILE)
VOP_HOLD(range->vnode); VOP_HOLD(range->vnode);
// copy any pages that are mapped
for (uintptr_t offset = 0; offset < new_range->size; offset += PAGE_SIZE) { for (uintptr_t offset = 0; offset < new_range->size; offset += PAGE_SIZE) {
// XXX some types of mappings, like framebuffer shared mappings, will break if done this way // XXX some types of mappings, like framebuffer shared mappings, will break if done this way
void *vaddr = (void *)((uintptr_t)new_range->start + offset); void *vaddr = (void *)((uintptr_t)new_range->start + offset);
@@ -576,12 +583,30 @@ mm_context_t *mm_fork_context(mm_context_t *old_context) {
if (phys == NULL) if (phys == NULL)
continue; continue;
if (arch_mmu_map(new_context->pagetable, phys, vaddr, new_range->mmuflags & ~ARCH_MMU_FLAGS_WRITE) == false) bool writeable = arch_mmu_iswritable(old_context->pagetable, vaddr);
goto error; bool private = !(range->flags & MM_RANGE_FLAGS_SHARED);
page_t *page = mm_get_page(phys);
if (mm_is_page_locked(page) && writeable && private) {
// the page is a private locked page, eagerly copy it to ensure fork/futex correctness
void *new_phys = mm_alloc_page(MEMORY_SECTION_DEFAULT);
if (new_phys == NULL)
goto error;
mm_hold_page(phys); if (arch_mmu_map(new_context->pagetable, new_phys, vaddr, new_range->mmuflags) == false) {
mm_release_page(new_phys);
goto error;
}
arch_mmu_remap(old_context->pagetable, phys, vaddr, new_range->mmuflags & ~ARCH_MMU_FLAGS_WRITE); memcpy(MAKE_HHDM(new_phys), MAKE_HHDM(phys), PAGE_SIZE);
} else {
// go through the normal CoW path
if (arch_mmu_map(new_context->pagetable, phys, vaddr, new_range->mmuflags & ~ARCH_MMU_FLAGS_WRITE) == false)
goto error;
mm_hold_page(phys);
arch_mmu_remap(old_context->pagetable, phys, vaddr, new_range->mmuflags & ~ARCH_MMU_FLAGS_WRITE);
}
} }
rbtree = rbtree_successor(rbtree); rbtree = rbtree_successor(rbtree);
kernel-src/mm/page.c
+15
View File
@@ -146,6 +146,7 @@ void mm_release_page(void *addr) {
MUTEX_ACQUIRE(&free_list_mutex); MUTEX_ACQUIRE(&free_list_mutex);
__assert(page->refcount != 0); __assert(page->refcount != 0);
if (--page->refcount == 0) { if (--page->refcount == 0) {
__assert(!mm_is_page_locked(page));
__assert((page->flags & PAGE_FLAGS_DIRTY) == 0); __assert((page->flags & PAGE_FLAGS_DIRTY) == 0);
insert_in_free_list(page); insert_in_free_list(page);
if (page->backing == NULL) if (page->backing == NULL)
@@ -154,6 +155,20 @@ void mm_release_page(void *addr) {
MUTEX_RELEASE(&free_list_mutex); MUTEX_RELEASE(&free_list_mutex);
} }
void mm_unlock_and_release_page(void *addr) {
page_t *page = &pages[(uintptr_t)addr / PAGE_SIZE];
mm_unlock_page(page);
mm_release_page(addr);
}
bool mm_is_page_locked(page_t *page) {
return __atomic_load_n(&page->lock_count, __ATOMIC_SEQ_CST) > 0;
}
void mm_unlock_page(page_t *page) {
__assert(__atomic_fetch_sub(&page->lock_count, 1, __ATOMIC_SEQ_CST) > 0);
}
static void do_alloc(page_t *page) { static void do_alloc(page_t *page) {
__assert(page->refcount == 0); __assert(page->refcount == 0);
memset(page, 0, sizeof(page_t)); memset(page, 0, sizeof(page_t));
kernel-src/sys/syscalls/futex.c
+10 -1
View File
@@ -62,11 +62,17 @@ syscallret_t syscall_futex(context_t *, uint32_t *futexp, int op, uint32_t value
bool doleave = true; bool doleave = true;
uint32_t word; uint32_t word;
uint32_t *physical = NULL;
ret.errno = usercopy_fromuseratomic32(futexp, &word); ret.errno = usercopy_fromuseratomic32(futexp, &word);
if (unlikely(ret.errno)) if (unlikely(ret.errno))
goto cleanup; goto cleanup;
uint32_t *physical = mm_get_physical_address(futexp, 0); physical = mm_get_physical_address(futexp, MM_GET_PHYSICAL_ADDRESS_FLAGS_HOLD | MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK);
if (unlikely(physical == NULL)) {
ret.errno = EFAULT;
goto cleanup;
}
futex_t *futex = getfutex(physical); futex_t *futex = getfutex(physical);
switch (op) { switch (op) {
@@ -162,6 +168,9 @@ syscallret_t syscall_futex(context_t *, uint32_t *futexp, int op, uint32_t value
poll_destroydesc(&desc); poll_destroydesc(&desc);
if (physical)
mm_unlock_and_release_page(physical);
MUTEX_RELEASE(&futexmutex); MUTEX_RELEASE(&futexmutex);
return ret; return ret;
} }