Certain files in procfs are formatted in byteorder dependent ways. For example the IP addresses in /proc/net/udp. Assuming the byteorder of the userspace program is not guaranteed to be correct in the face of emulation as for example with qemu-user. Also this makes it easier for non-compiled applications like shellscripts to discover the byteorder. Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> --- Development of userspace part: https://github.com/util-linux/util-linux/pull/1872 --- Documentation/ABI/testing/procfs-byteorder | 12 +++++++++ fs/proc/Makefile | 1 + fs/proc/byteorder.c | 31 ++++++++++++++++++++++ 3 files changed, 44 insertions(+) create mode 100644 Documentation/ABI/testing/procfs-byteorder create mode 100644 fs/proc/byteorder.c diff --git a/Documentation/ABI/testing/procfs-byteorder b/Documentation/ABI/testing/procfs-byteorder new file mode 100644 index 000000000000..bb80aae889be --- /dev/null +++ b/Documentation/ABI/testing/procfs-byteorder @@ -0,0 +1,12 @@ +What: /proc/byteorder +Date: February 2023 +KernelVersion: 6.2 +Contact: linux-fsdevel@xxxxxxxxxxxxxxx +Description: + The current endianness of the running kernel. + + Access: Read + + Valid values: + "little", "big" +Users: util-linux diff --git a/fs/proc/Makefile b/fs/proc/Makefile index bd08616ed8ba..c790d3665358 100644 --- a/fs/proc/Makefile +++ b/fs/proc/Makefile @@ -12,6 +12,7 @@ proc-$(CONFIG_MMU) := task_mmu.o proc-y += inode.o root.o base.o generic.o array.o \ fd.o proc-$(CONFIG_TTY) += proc_tty.o +proc-y += byteorder.o proc-y += cmdline.o proc-y += consoles.o proc-y += cpuinfo.o diff --git a/fs/proc/byteorder.c b/fs/proc/byteorder.c new file mode 100644 index 000000000000..39644b281da9 --- /dev/null +++ b/fs/proc/byteorder.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <asm/byteorder.h> +#include <linux/fs.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include "internal.h" + +#if defined(__LITTLE_ENDIAN) +#define BYTEORDER_STRING "little" +#elif defined(__BIG_ENDIAN) +#define BYTEORDER_STRING "big" +#else +#error Unknown byteorder +#endif + +static int byteorder_seq_show(struct seq_file *seq, void *) +{ + seq_puts(seq, BYTEORDER_STRING "\n"); + return 0; +} + +static int __init proc_byteorder_init(void) +{ + struct proc_dir_entry *pde; + + pde = proc_create_single("byteorder", 0444, NULL, byteorder_seq_show); + pde_make_permanent(pde); + return 0; +} +fs_initcall(proc_byteorder_init); base-commit: 5aaef24b5c6d4246b2cac1be949869fa36577737 -- 2.38.1
