io_uring: add mapping support for NOMMU archs
That is a bit weird scenario but I find it interesting to run fio loads
using LKL linux, where MMU is disabled. Probably other real archs which
run uClinux can also benefit from this patch.
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 4c030a9..e6fc401 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4402,12 +4402,11 @@ static int io_uring_flush(struct file *file, void *data)
return 0;
}
-static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+static void *io_uring_validate_mmap_request(struct file *file,
+ loff_t pgoff, size_t sz)
{
- loff_t offset = (loff_t) vma->vm_pgoff << PAGE_SHIFT;
- unsigned long sz = vma->vm_end - vma->vm_start;
struct io_ring_ctx *ctx = file->private_data;
- unsigned long pfn;
+ loff_t offset = pgoff << PAGE_SHIFT;
struct page *page;
void *ptr;
@@ -4420,17 +4419,59 @@ static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
ptr = ctx->sq_sqes;
break;
default:
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}
page = virt_to_head_page(ptr);
if (sz > page_size(page))
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
+
+ return ptr;
+}
+
+#ifdef CONFIG_MMU
+
+static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ size_t sz = vma->vm_end - vma->vm_start;
+ unsigned long pfn;
+ void *ptr;
+
+ ptr = io_uring_validate_mmap_request(file, vma->vm_pgoff, sz);
+ if (IS_ERR(ptr))
+ return PTR_ERR(ptr);
pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
}
+#else /* !CONFIG_MMU */
+
+static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -EINVAL;
+}
+
+static unsigned int io_uring_nommu_mmap_capabilities(struct file *file)
+{
+ return NOMMU_MAP_DIRECT | NOMMU_MAP_READ | NOMMU_MAP_WRITE;
+}
+
+static unsigned long io_uring_nommu_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 */
+
SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
u32, min_complete, u32, flags, const sigset_t __user *, sig,
size_t, sigsz)
@@ -4501,6 +4542,10 @@ static const struct file_operations io_uring_fops = {
.release = io_uring_release,
.flush = io_uring_flush,
.mmap = io_uring_mmap,
+#ifndef CONFIG_MMU
+ .get_unmapped_area = io_uring_nommu_get_unmapped_area,
+ .mmap_capabilities = io_uring_nommu_mmap_capabilities,
+#endif
.poll = io_uring_poll,
.fasync = io_uring_fasync,
};
