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Subject[PATCH 06/16] IB uverbs: memory pinning implementation
Date
From
Add support for pinning userspace memory regions and returning a list
of pages in the region. This includes tracking pinned memory against
vm_locked and preventing unprivileged users from exceeding RLIMIT_MEMLOCK.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

---
drivers/infiniband/core/uverbs_mem.c | 221 +++++++++++++++++++++++++++++++++++
1 files changed, 221 insertions(+)


--- /dev/null 2005-06-23 14:14:38.423479552 -0700
+++ linux/drivers/infiniband/core/uverbs_mem.c 2005-06-28 15:20:06.718455487 -0700
@@ -0,0 +1,221 @@
+/*
+ * Copyright (c) 2005 Topspin Communications. All rights reserved.
+ * Copyright (c) 2005 Cisco Systems. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * $Id: uverbs_mem.c 2743 2005-06-28 22:27:59Z roland $
+ */
+
+#include <linux/mm.h>
+#include <linux/dma-mapping.h>
+
+#include "uverbs.h"
+
+struct ib_umem_account_work {
+ struct work_struct work;
+ struct mm_struct *mm;
+ unsigned long diff;
+};
+
+
+static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
+{
+ struct ib_umem_chunk *chunk, *tmp;
+ int i;
+
+ list_for_each_entry_safe(chunk, tmp, &umem->chunk_list, list) {
+ dma_unmap_sg(dev->dma_device, chunk->page_list,
+ chunk->nents, DMA_BIDIRECTIONAL);
+ for (i = 0; i < chunk->nents; ++i) {
+ if (umem->writable && dirty)
+ set_page_dirty_lock(chunk->page_list[i].page);
+ put_page(chunk->page_list[i].page);
+ }
+
+ kfree(chunk);
+ }
+}
+
+int ib_umem_get(struct ib_device *dev, struct ib_umem *mem,
+ void *addr, size_t size, int write)
+{
+ struct page **page_list;
+ struct ib_umem_chunk *chunk;
+ unsigned long locked;
+ unsigned long lock_limit;
+ unsigned long cur_base;
+ unsigned long npages;
+ int ret = 0;
+ int off;
+ int i;
+
+ if (!can_do_mlock())
+ return -EPERM;
+
+ page_list = (struct page **) __get_free_page(GFP_KERNEL);
+ if (!page_list)
+ return -ENOMEM;
+
+ mem->user_base = (unsigned long) addr;
+ mem->length = size;
+ mem->offset = (unsigned long) addr & ~PAGE_MASK;
+ mem->page_size = PAGE_SIZE;
+ mem->writable = write;
+
+ INIT_LIST_HEAD(&mem->chunk_list);
+
+ npages = PAGE_ALIGN(size + mem->offset) >> PAGE_SHIFT;
+
+ down_write(&current->mm->mmap_sem);
+
+ locked = npages + current->mm->locked_vm;
+ lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
+
+ if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ cur_base = (unsigned long) addr & PAGE_MASK;
+
+ while (npages) {
+ ret = get_user_pages(current, current->mm, cur_base,
+ min_t(int, npages,
+ PAGE_SIZE / sizeof (struct page *)),
+ 1, !write, page_list, NULL);
+
+ if (ret < 0)
+ goto out;
+
+ cur_base += ret * PAGE_SIZE;
+ npages -= ret;
+
+ off = 0;
+
+ while (ret) {
+ chunk = kmalloc(sizeof *chunk + sizeof (struct scatterlist) *
+ min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK),
+ GFP_KERNEL);
+ if (!chunk) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ chunk->nents = min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK);
+ for (i = 0; i < chunk->nents; ++i) {
+ chunk->page_list[i].page = page_list[i + off];
+ chunk->page_list[i].offset = 0;
+ chunk->page_list[i].length = PAGE_SIZE;
+ }
+
+ chunk->nmap = dma_map_sg(dev->dma_device,
+ &chunk->page_list[0],
+ chunk->nents,
+ DMA_BIDIRECTIONAL);
+ if (chunk->nmap <= 0) {
+ for (i = 0; i < chunk->nents; ++i)
+ put_page(chunk->page_list[i].page);
+ kfree(chunk);
+
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret -= chunk->nents;
+ off += chunk->nents;
+ list_add_tail(&chunk->list, &mem->chunk_list);
+ }
+
+ ret = 0;
+ }
+
+out:
+ if (ret < 0)
+ __ib_umem_release(dev, mem, 0);
+ else
+ current->mm->locked_vm = locked;
+
+ up_write(&current->mm->mmap_sem);
+ free_page((unsigned long) page_list);
+
+ return ret;
+}
+
+void ib_umem_release(struct ib_device *dev, struct ib_umem *umem)
+{
+ __ib_umem_release(dev, umem, 1);
+
+ down_write(&current->mm->mmap_sem);
+ current->mm->locked_vm -=
+ PAGE_ALIGN(umem->length + umem->offset) >> PAGE_SHIFT;
+ up_write(&current->mm->mmap_sem);
+}
+
+static void ib_umem_account(void *work_ptr)
+{
+ struct ib_umem_account_work *work = work_ptr;
+
+ down_write(&work->mm->mmap_sem);
+ work->mm->locked_vm -= work->diff;
+ up_write(&work->mm->mmap_sem);
+ mmput(work->mm);
+ kfree(work);
+}
+
+void ib_umem_release_on_close(struct ib_device *dev, struct ib_umem *umem)
+{
+ struct ib_umem_account_work *work;
+ struct mm_struct *mm;
+
+ __ib_umem_release(dev, umem, 1);
+
+ mm = get_task_mm(current);
+ if (!mm)
+ return;
+
+ /*
+ * We may be called with the mm's mmap_sem already held. This
+ * can happen when a userspace munmap() is the call that drops
+ * the last reference to our file and calls our release
+ * method. If there are memory regions to destroy, we'll end
+ * up here and not be able to take the mmap_sem. Therefore we
+ * defer the vm_locked accounting to the system workqueue.
+ */
+
+ work = kmalloc(sizeof *work, GFP_KERNEL);
+ if (!work)
+ return;
+
+ INIT_WORK(&work->work, ib_umem_account, work);
+ work->mm = mm;
+ work->diff = PAGE_ALIGN(umem->length + umem->offset) >> PAGE_SHIFT;
+
+ schedule_work(&work->work);
+}
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