| 1 | /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1) |
| 2 | * |
| 3 | * wrapper/splice.c |
| 4 | * |
| 5 | * wrapper around splice_to_pipe. Using KALLSYMS to get its address when |
| 6 | * available, else we need to have a kernel that exports this function to GPL |
| 7 | * modules. The export was introduced in kernel 4.2. |
| 8 | * |
| 9 | * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 10 | */ |
| 11 | |
| 12 | #include <lttng-kernel-version.h> |
| 13 | |
| 14 | #if (defined(CONFIG_KALLSYMS) \ |
| 15 | && (LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0))) |
| 16 | |
| 17 | #include <linux/kallsyms.h> |
| 18 | #include <linux/fs.h> |
| 19 | #include <linux/splice.h> |
| 20 | #include <wrapper/kallsyms.h> |
| 21 | |
| 22 | static |
| 23 | ssize_t (*splice_to_pipe_sym)(struct pipe_inode_info *pipe, |
| 24 | struct splice_pipe_desc *spd); |
| 25 | |
| 26 | ssize_t wrapper_splice_to_pipe(struct pipe_inode_info *pipe, |
| 27 | struct splice_pipe_desc *spd) |
| 28 | { |
| 29 | if (!splice_to_pipe_sym) |
| 30 | splice_to_pipe_sym = (void *) kallsyms_lookup_funcptr("splice_to_pipe"); |
| 31 | if (splice_to_pipe_sym) { |
| 32 | return splice_to_pipe_sym(pipe, spd); |
| 33 | } else { |
| 34 | printk_once(KERN_WARNING "LTTng: splice_to_pipe symbol lookup failed.\n"); |
| 35 | return -ENOSYS; |
| 36 | } |
| 37 | } |
| 38 | |
| 39 | /* |
| 40 | * Canary function to check for 'splice_to_pipe()' at compile time. |
| 41 | * |
| 42 | * From 'include/linux/splice.h': |
| 43 | * |
| 44 | * extern ssize_t splice_to_pipe(struct pipe_inode_info *, |
| 45 | * struct splice_pipe_desc *spd); |
| 46 | */ |
| 47 | __attribute__((unused)) static |
| 48 | ssize_t __canary__splice_to_pipe(struct pipe_inode_info *pipe, |
| 49 | struct splice_pipe_desc *spd) |
| 50 | { |
| 51 | return splice_to_pipe(pipe, spd); |
| 52 | } |
| 53 | |
| 54 | #else |
| 55 | |
| 56 | #include <linux/fs.h> |
| 57 | #include <linux/splice.h> |
| 58 | |
| 59 | ssize_t wrapper_splice_to_pipe(struct pipe_inode_info *pipe, |
| 60 | struct splice_pipe_desc *spd) |
| 61 | { |
| 62 | return splice_to_pipe(pipe, spd); |
| 63 | } |
| 64 | |
| 65 | #endif |