From: Alejandro Colomar <alx.manpages@gmail.com>
To: mtk.manpages@gmail.com
Cc: Florian Weimer <fweimer@redhat.com>, Jakub Wilk <jwilk@jwilk.net>,
Alejandro Colomar <alx.manpages@gmail.com>,
linux-man@vger.kernel.org, libc-alpha@sourceware.org
Subject: [PATCH 23/39] modify_ldt.2: Use syscall(SYS_...); for system calls without a wrapper
Date: Mon, 10 May 2021 19:55:32 +0200 [thread overview]
Message-ID: <20210510175546.28445-24-alx.manpages@gmail.com> (raw)
In-Reply-To: <20210510175546.28445-1-alx.manpages@gmail.com>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
man2/modify_ldt.2 | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/man2/modify_ldt.2 b/man2/modify_ldt.2
index 8ce9ed252..b67a67690 100644
--- a/man2/modify_ldt.2
+++ b/man2/modify_ldt.2
@@ -27,11 +27,19 @@
modify_ldt \- get or set a per-process LDT entry
.SH SYNOPSIS
.nf
-.BI "int modify_ldt(int " func ", void *" ptr ", unsigned long " bytecount );
+.BR "#include <asm/ldt.h>" " /* Definition of " "struct user_desc" " */"
+.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.PP
+.BI "int syscall(SYS_modify_ldt, int " func ", void *" ptr ,
+.BI " unsigned long " bytecount );
.fi
.PP
.IR Note :
-There is no glibc wrapper for this system call; see NOTES.
+glibc provides no wrapper for
+.BR modify_ldt (),
+necessitating the use of
+.BR syscall (2).
.SH DESCRIPTION
.BR modify_ldt ()
reads or writes the local descriptor table (LDT) for a process.
@@ -168,9 +176,6 @@ is neither 0, 1, 2, nor 0x11.
This call is Linux-specific and should not be used in programs intended
to be portable.
.SH NOTES
-Glibc does not provide a wrapper for this system call; call it using
-.BR syscall (2).
-.PP
.BR modify_ldt ()
should not be used for thread-local storage, as it slows down context
switches and only supports a limited number of threads.
--
2.31.1
next prev parent reply other threads:[~2021-05-10 17:56 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 17:55 [PATCH 00/39] man2: SYNOPSIS: Fix headers, use syscall(), and other fixes Alejandro Colomar
2021-05-10 17:55 ` [PATCH 01/39] futex.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 02/39] getdents.2: " Alejandro Colomar
2021-05-11 5:21 ` Michael Kerrisk (man-pages)
2021-05-10 17:55 ` [PATCH 03/39] ioctl_tty.2: Fix includes Alejandro Colomar
2021-05-10 17:55 ` [PATCH 04/39] ioctl_userfaultfd.2: SYNOPSIS: Add <linux/userfaultfd.h> Alejandro Colomar
2021-05-10 17:55 ` [PATCH 05/39] io_destroy.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 06/39] io_getevents.2: " Alejandro Colomar
2021-05-10 17:55 ` [PATCH 07/39] ioperm.2: Remove obvious comment Alejandro Colomar
2021-05-10 17:55 ` [PATCH 08/39] ioprio_set.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 09/39] ipc.2: " Alejandro Colomar
2021-05-10 17:55 ` [PATCH 10/39] ipc.2: Add needed include Alejandro Colomar
2021-05-10 17:55 ` [PATCH 11/39] kcmp.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 12/39] kcmp.2: tfix Alejandro Colomar
2021-05-10 17:55 ` [PATCH 13/39] kexec_load.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 14/39] scripts/bash_aliases: man_lsfunc(): Extract syscall name from syscall(SYS_...) Alejandro Colomar
2021-05-10 17:55 ` [PATCH 15/39] keyctl.2: Use syscall(SYS_...); for system calls without a glibc wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 16/39] link.2: ffix Alejandro Colomar
2021-05-10 17:55 ` [PATCH 17/39] llseek.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 18/39] lookup_dcookie.2: " Alejandro Colomar
2021-05-10 17:55 ` [PATCH 19/39] membarrier.2: " Alejandro Colomar
2021-05-10 17:55 ` [PATCH 20/39] mincore.2: Remove unused include Alejandro Colomar
2021-05-10 17:55 ` [PATCH 21/39] mknod.2: Remove unused includes Alejandro Colomar
2021-05-10 17:55 ` [PATCH 22/39] mmap2.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` Alejandro Colomar [this message]
2021-05-10 17:55 ` [PATCH 24/39] mq_getsetattr.2: " Alejandro Colomar
2021-05-10 17:55 ` [PATCH 25/39] alloc_hugepages.2, arch_prctl.2, capget.2, clone.2, delete_module.2, exit_group.2, get_robust_list.2, getunwind.2, init_module.2: Add note about the use of syscall(2) Alejandro Colomar
2021-05-10 17:55 ` [PATCH 26/39] open.2: Remove unused <sys/stat.h> Alejandro Colomar
2021-05-10 18:02 ` Alejandro Colomar (man-pages)
2021-05-11 5:15 ` Michael Kerrisk (man-pages)
2021-05-10 17:55 ` [PATCH 27/39] openat2.2: Use syscall(SYS_...); for system calls without a wrapper; fix includes too Alejandro Colomar
2021-05-10 17:55 ` [PATCH 28/39] perf_event_open.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 29/39] pidfd_getfd.2: " Alejandro Colomar
2021-05-10 17:55 ` [PATCH 30/39] pidfd_open.2: " Alejandro Colomar
2021-05-10 17:55 ` [PATCH 31/39] pidfd_send_signal.2: Use syscall(SYS_...); for system calls without a wrapper. Fix includes too Alejandro Colomar
2021-05-10 17:55 ` [PATCH 32/39] pipe.2: wfix Alejandro Colomar
2021-05-10 17:55 ` [PATCH 33/39] pivot_root.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 34/39] poll.2: Remove <signal.h> Alejandro Colomar
2021-05-10 17:55 ` [PATCH 35/39] process_madvise.2: Use syscall(SYS_...); for system calls without a wrapper. Fix includes too Alejandro Colomar
2021-05-10 17:55 ` [PATCH 36/39] quotactl.2: Better detail why <xfs/xqm.h> is included Alejandro Colomar
2021-05-10 17:55 ` [PATCH 37/39] readdir.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 17:55 ` [PATCH 38/39] readlink.2: ffix Alejandro Colomar
2021-05-10 17:55 ` [PATCH 39/39] reboot.2: Use syscall(SYS_...); for system calls without a wrapper Alejandro Colomar
2021-05-10 18:02 ` Alejandro Colomar (man-pages)
2021-05-11 5:19 ` Michael Kerrisk (man-pages)
2021-05-11 5:27 ` [PATCH 00/39] man2: SYNOPSIS: Fix headers, use syscall(), and other fixes Michael Kerrisk (man-pages)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210510175546.28445-24-alx.manpages@gmail.com \
--to=alx.manpages@gmail.com \
--cc=fweimer@redhat.com \
--cc=jwilk@jwilk.net \
--cc=libc-alpha@sourceware.org \
--cc=linux-man@vger.kernel.org \
--cc=mtk.manpages@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).