Re: [PATCH v2 05/10] set_thread_area.2: Use syscall(SYS_...); for system calls without a wrapper

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

Hi Alex,

On 5/25/21 6:19 AM, Alejandro Colomar wrote:
> Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
> ---
>  man2/set_thread_area.2 | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)

Applied.

Thanks,

Michael


> diff --git a/man2/set_thread_area.2 b/man2/set_thread_area.2
> index 284dea390..43f3009f7 100644
> --- a/man2/set_thread_area.2
> +++ b/man2/set_thread_area.2
> @@ -11,28 +11,31 @@
>  get_thread_area, set_thread_area \- manipulate thread-local storage information
>  .SH SYNOPSIS
>  .nf
> -.B #include <linux/unistd.h>
> +.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
> +.B #include <unistd.h>
>  .PP
>  .B #if defined __i386__ || defined __x86_64__
> -.B # include <asm/ldt.h>
> +.BR "# include <asm/ldt.h>" "        /* Definition of " "struct user_desc" " */"
>  .PP
> -.BI "int get_thread_area(struct user_desc *" u_info );
> -.BI "int set_thread_area(struct user_desc *" u_info );
> +.BI "int syscall(SYS_get_thread_area, struct user_desc *" u_info );
> +.BI "int syscall(SYS_set_thread_area, struct user_desc *" u_info );
>  .PP
>  .B #elif defined __m68k__
>  .PP
> -.B "int get_thread_area(void);"
> -.BI "int set_thread_area(unsigned long " tp );
> +.B "int syscall(SYS_get_thread_area);"
> +.BI "int syscall(SYS_set_thread_area, unsigned long " tp );
>  .PP
>  .B #elif defined __mips__
>  .PP
> -.BI "int set_thread_area(unsigned long " addr );
> +.BI "int syscall(SYS_set_thread_area, unsigned long " addr );
>  .PP
>  .B #endif
>  .fi
>  .PP
>  .IR Note :
> -There are no glibc wrappers for these system calls; see NOTES.
> +glibc provides no wrappers for these system calls,
> +necessitating the use of
> +.BR syscall (2).
>  .SH DESCRIPTION
>  These calls provide architecture-specific support for a thread-local storage
>  implementation.
> @@ -172,10 +175,7 @@ and
>  are Linux-specific and should not be used in programs that are intended
>  to be portable.
>  .SH NOTES
> -Glibc does not provide wrappers for these system calls,
> -since they are generally intended for use only by threading libraries.
> -In the unlikely event that you want to call them directly, use
> -.BR syscall (2).
> +These system calls are generally intended for use only by threading libraries.
>  .PP
>  .BR arch_prctl (2)
>  can interfere with
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/