[PATCH 1/4] io_uring: add structure for registered arguments

[Pavel Begunkov <asml.silence@gmail.com>]

A preparation patch making infra for wait arguments a bit more general
to use in in following patches.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/linux/io_uring_types.h |  9 +++++++--
 io_uring/io_uring.c            | 23 +++--------------------
 io_uring/io_uring.h            | 16 ++++++++++++++++
 io_uring/register.c            |  4 ++--
 4 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 493a8f7fa8e4..49008f00d064 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -83,6 +83,11 @@ struct io_mapped_region {
 	unsigned		flags;
 };
 
+struct io_reg_args {
+	void			*ptr;
+	size_t			size;
+};
+
 /*
  * Arbitrary limit, can be raised if need be
  */
@@ -332,8 +337,8 @@ struct io_ring_ctx {
 		struct io_ev_fd	__rcu	*io_ev_fd;
 		unsigned		cq_extra;
 
-		void			*cq_wait_arg;
-		size_t			cq_wait_size;
+		struct io_reg_args	wait_args;
+
 	} ____cacheline_aligned_in_smp;
 
 	/*
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 5535a72b0ce1..e2b6b256fc9a 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3178,25 +3178,6 @@ void __io_uring_cancel(bool cancel_all)
 	io_uring_cancel_generic(cancel_all, NULL);
 }
 
-static struct io_uring_reg_wait *io_get_ext_arg_reg(struct io_ring_ctx *ctx,
-			const struct io_uring_getevents_arg __user *uarg)
-{
-	unsigned long size = sizeof(struct io_uring_reg_wait);
-	unsigned long offset = (uintptr_t)uarg;
-	unsigned long end;
-
-	if (unlikely(offset % sizeof(long)))
-		return ERR_PTR(-EFAULT);
-
-	/* also protects from NULL ->cq_wait_arg as the size would be 0 */
-	if (unlikely(check_add_overflow(offset, size, &end) ||
-		     end > ctx->cq_wait_size))
-		return ERR_PTR(-EFAULT);
-
-	offset = array_index_nospec(offset, ctx->cq_wait_size - size);
-	return ctx->cq_wait_arg + offset;
-}
-
 static int io_validate_ext_arg(struct io_ring_ctx *ctx, unsigned flags,
 			       const void __user *argp, size_t argsz)
 {
@@ -3233,7 +3214,9 @@ static int io_get_ext_arg(struct io_ring_ctx *ctx, unsigned flags,
 
 		if (ext_arg->argsz != sizeof(struct io_uring_reg_wait))
 			return -EINVAL;
-		w = io_get_ext_arg_reg(ctx, argp);
+
+		w = io_args_get_ptr(&ctx->wait_args, (uintptr_t)argp,
+				    sizeof(struct io_uring_reg_wait));
 		if (IS_ERR(w))
 			return PTR_ERR(w);
 
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index 032758b28d78..a18da74f18e8 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -514,4 +514,20 @@ static inline bool io_has_work(struct io_ring_ctx *ctx)
 	return test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq) ||
 	       io_local_work_pending(ctx);
 }
+
+static inline void *io_args_get_ptr(struct io_reg_args *args,
+				    unsigned long offset, size_t size)
+{
+	unsigned long end;
+
+	if (unlikely(offset % sizeof(long)))
+		return ERR_PTR(-EFAULT);
+
+	/* also protects from NULL as the size would be 0 */
+	if (unlikely(check_add_overflow(offset, size, &end) || end > args->size))
+		return ERR_PTR(-EFAULT);
+
+	return args->ptr + array_index_nospec(offset, args->size - size);
+}
+
 #endif
diff --git a/io_uring/register.c b/io_uring/register.c
index f1698c18c7cb..b926eb053408 100644
--- a/io_uring/register.c
+++ b/io_uring/register.c
@@ -604,8 +604,8 @@ static int io_register_mem_region(struct io_ring_ctx *ctx, void __user *uarg)
 	}
 
 	if (reg.flags & IORING_MEM_REGION_REG_WAIT_ARG) {
-		ctx->cq_wait_arg = io_region_get_ptr(&ctx->param_region);
-		ctx->cq_wait_size = rd.size;
+		ctx->wait_args.ptr = io_region_get_ptr(&ctx->param_region);
+		ctx->wait_args.size = rd.size;
 	}
 	return 0;
 }
-- 
2.47.1