io_uring: move mapping/allocation helpers to a separate file

Move the related code from io_uring.c into memmap.c. No functional
changes in this patch, just cleaning it up a bit now that the full
transition is done.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 336 insertions, 0 deletions

diff --git a/io_uring/memmap.c b/io_uring/memmap.c
new file mode 100644
index 000000000000..523d982af2b0
--- /dev/null
+++ b/io_uring/memmap.c
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/io_uring.h>
+#include <linux/io_uring_types.h>
+#include <asm/shmparam.h>
+
+#include "memmap.h"
+#include "kbuf.h"
+
+static void *io_mem_alloc_compound(struct page **pages, int nr_pages,
+				   size_t size, gfp_t gfp)
+{
+	struct page *page;
+	int i, order;
+
+	order = get_order(size);
+	if (order > MAX_PAGE_ORDER)
+		return ERR_PTR(-ENOMEM);
+	else if (order)
+		gfp |= __GFP_COMP;
+
+	page = alloc_pages(gfp, order);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < nr_pages; i++)
+		pages[i] = page + i;
+
+	return page_address(page);
+}
+
+static void *io_mem_alloc_single(struct page **pages, int nr_pages, size_t size,
+				 gfp_t gfp)
+{
+	void *ret;
+	int i;
+
+	for (i = 0; i < nr_pages; i++) {
+		pages[i] = alloc_page(gfp);
+		if (!pages[i])
+			goto err;
+	}
+
+	ret = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
+	if (ret)
+		return ret;
+err:
+	while (i--)
+		put_page(pages[i]);
+	return ERR_PTR(-ENOMEM);
+}
+
+void *io_pages_map(struct page ***out_pages, unsigned short *npages,
+		   size_t size)
+{
+	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN;
+	struct page **pages;
+	int nr_pages;
+	void *ret;
+
+	nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	pages = kvmalloc_array(nr_pages, sizeof(struct page *), gfp);
+	if (!pages)
+		return ERR_PTR(-ENOMEM);
+
+	ret = io_mem_alloc_compound(pages, nr_pages, size, gfp);
+	if (!IS_ERR(ret))
+		goto done;
+
+	ret = io_mem_alloc_single(pages, nr_pages, size, gfp);
+	if (!IS_ERR(ret)) {
+done:
+		*out_pages = pages;
+		*npages = nr_pages;
+		return ret;
+	}
+
+	kvfree(pages);
+	*out_pages = NULL;
+	*npages = 0;
+	return ret;
+}
+
+void io_pages_unmap(void *ptr, struct page ***pages, unsigned short *npages,
+		    bool put_pages)
+{
+	bool do_vunmap = false;
+
+	if (!ptr)
+		return;
+
+	if (put_pages && *npages) {
+		struct page **to_free = *pages;
+		int i;
+
+		/*
+		 * Only did vmap for the non-compound multiple page case.
+		 * For the compound page, we just need to put the head.
+		 */
+		if (PageCompound(to_free[0]))
+			*npages = 1;
+		else if (*npages > 1)
+			do_vunmap = true;
+		for (i = 0; i < *npages; i++)
+			put_page(to_free[i]);
+	}
+	if (do_vunmap)
+		vunmap(ptr);
+	kvfree(*pages);
+	*pages = NULL;
+	*npages = 0;
+}
+
+void io_pages_free(struct page ***pages, int npages)
+{
+	struct page **page_array = *pages;
+
+	if (!page_array)
+		return;
+
+	unpin_user_pages(page_array, npages);
+	kvfree(page_array);
+	*pages = NULL;
+}
+
+struct page **io_pin_pages(unsigned long uaddr, unsigned long len, int *npages)
+{
+	unsigned long start, end, nr_pages;
+	struct page **pages;
+	int ret;
+
+	end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	start = uaddr >> PAGE_SHIFT;
+	nr_pages = end - start;
+	if (WARN_ON_ONCE(!nr_pages))
+		return ERR_PTR(-EINVAL);
+
+	pages = kvmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
+	if (!pages)
+		return ERR_PTR(-ENOMEM);
+
+	ret = pin_user_pages_fast(uaddr, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
+					pages);
+	/* success, mapped all pages */
+	if (ret == nr_pages) {
+		*npages = nr_pages;
+		return pages;
+	}
+
+	/* partial map, or didn't map anything */
+	if (ret >= 0) {
+		/* if we did partial map, release any pages we did get */
+		if (ret)
+			unpin_user_pages(pages, ret);
+		ret = -EFAULT;
+	}
+	kvfree(pages);
+	return ERR_PTR(ret);
+}
+
+void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
+		     unsigned long uaddr, size_t size)
+{
+	struct page **page_array;
+	unsigned int nr_pages;
+	void *page_addr;
+
+	*npages = 0;
+
+	if (uaddr & (PAGE_SIZE - 1) || !size)
+		return ERR_PTR(-EINVAL);
+
+	nr_pages = 0;
+	page_array = io_pin_pages(uaddr, size, &nr_pages);
+	if (IS_ERR(page_array))
+		return page_array;
+
+	page_addr = vmap(page_array, nr_pages, VM_MAP, PAGE_KERNEL);
+	if (page_addr) {
+		*pages = page_array;
+		*npages = nr_pages;
+		return page_addr;
+	}
+
+	io_pages_free(&page_array, nr_pages);
+	return ERR_PTR(-ENOMEM);
+}
+
+static void *io_uring_validate_mmap_request(struct file *file, loff_t pgoff,
+					    size_t sz)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+	loff_t offset = pgoff << PAGE_SHIFT;
+
+	switch ((pgoff << PAGE_SHIFT) & IORING_OFF_MMAP_MASK) {
+	case IORING_OFF_SQ_RING:
+	case IORING_OFF_CQ_RING:
+		/* Don't allow mmap if the ring was setup without it */
+		if (ctx->flags & IORING_SETUP_NO_MMAP)
+			return ERR_PTR(-EINVAL);
+		return ctx->rings;
+	case IORING_OFF_SQES:
+		/* Don't allow mmap if the ring was setup without it */
+		if (ctx->flags & IORING_SETUP_NO_MMAP)
+			return ERR_PTR(-EINVAL);
+		return ctx->sq_sqes;
+	case IORING_OFF_PBUF_RING: {
+		struct io_buffer_list *bl;
+		unsigned int bgid;
+		void *ptr;
+
+		bgid = (offset & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT;
+		bl = io_pbuf_get_bl(ctx, bgid);
+		if (IS_ERR(bl))
+			return bl;
+		ptr = bl->buf_ring;
+		io_put_bl(ctx, bl);
+		return ptr;
+		}
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
+int io_uring_mmap_pages(struct io_ring_ctx *ctx, struct vm_area_struct *vma,
+			struct page **pages, int npages)
+{
+	unsigned long nr_pages = npages;
+
+	vm_flags_set(vma, VM_DONTEXPAND);
+	return vm_insert_pages(vma, vma->vm_start, pages, &nr_pages);
+}
+
+#ifdef CONFIG_MMU
+
+__cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+	size_t sz = vma->vm_end - vma->vm_start;
+	long offset = vma->vm_pgoff << PAGE_SHIFT;
+	void *ptr;
+
+	ptr = io_uring_validate_mmap_request(file, vma->vm_pgoff, sz);
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	switch (offset & IORING_OFF_MMAP_MASK) {
+	case IORING_OFF_SQ_RING:
+	case IORING_OFF_CQ_RING:
+		return io_uring_mmap_pages(ctx, vma, ctx->ring_pages,
+						ctx->n_ring_pages);
+	case IORING_OFF_SQES:
+		return io_uring_mmap_pages(ctx, vma, ctx->sqe_pages,
+						ctx->n_sqe_pages);
+	case IORING_OFF_PBUF_RING:
+		return io_pbuf_mmap(file, vma);
+	}
+
+	return -EINVAL;
+}
+
+unsigned long io_uring_get_unmapped_area(struct file *filp, unsigned long addr,
+					 unsigned long len, unsigned long pgoff,
+					 unsigned long flags)
+{
+	void *ptr;
+
+	/*
+	 * Do not allow to map to user-provided address to avoid breaking the
+	 * aliasing rules. Userspace is not able to guess the offset address of
+	 * kernel kmalloc()ed memory area.
+	 */
+	if (addr)
+		return -EINVAL;
+
+	ptr = io_uring_validate_mmap_request(filp, pgoff, len);
+	if (IS_ERR(ptr))
+		return -ENOMEM;
+
+	/*
+	 * Some architectures have strong cache aliasing requirements.
+	 * For such architectures we need a coherent mapping which aliases
+	 * kernel memory *and* userspace memory. To achieve that:
+	 * - use a NULL file pointer to reference physical memory, and
+	 * - use the kernel virtual address of the shared io_uring context
+	 *   (instead of the userspace-provided address, which has to be 0UL
+	 *   anyway).
+	 * - use the same pgoff which the get_unmapped_area() uses to
+	 *   calculate the page colouring.
+	 * For architectures without such aliasing requirements, the
+	 * architecture will return any suitable mapping because addr is 0.
+	 */
+	filp = NULL;
+	flags |= MAP_SHARED;
+	pgoff = 0;	/* has been translated to ptr above */
+#ifdef SHM_COLOUR
+	addr = (uintptr_t) ptr;
+	pgoff = addr >> PAGE_SHIFT;
+#else
+	addr = 0UL;
+#endif
+	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
+}
+
+#else /* !CONFIG_MMU */
+
+int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -EINVAL;
+}
+
+unsigned int io_uring_nommu_mmap_capabilities(struct file *file)
+{
+	return NOMMU_MAP_DIRECT | NOMMU_MAP_READ | NOMMU_MAP_WRITE;
+}
+
+unsigned long io_uring_get_unmapped_area(struct file *file, unsigned long addr,
+					 unsigned long len, unsigned long pgoff,
+					 unsigned long flags)
+{
+	void *ptr;
+
+	ptr = io_uring_validate_mmap_request(file, pgoff, len);
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	return (unsigned long) ptr;
+}
+
+#endif /* !CONFIG_MMU */