set_thread_area.2: csky architecture undocumented

DISCUSSION Alejandro Colomar (man-pages) 5 participants 8 messages Nov 23, 2020 – Oct 15, 2023

Subsystems (2)

Man-pages: manual pages for Linux -- Sections 2, 3, 4, 5, and 7 C-sky architecture

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Alejandro Colomar (man-pages)

author

2020-11-23 21:31 UTC #0 lore raw

Hi Michael,

SYNOPSIS

       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.

$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)

See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184

I'd change
- #elif defined __mips__
+ #elif defined(__mips__ || __csky__)

and then change the rest of the text to add csky when appropriate. Am I correct?

Thanks,

Alex

Michael Kerrisk (man-pages)

2020-11-23 21:48 UTC #1 lore raw

Hello Alex,

Quoted 49 lines · Alejandro Colomar (man-pages)

Hi Michael,

SYNOPSIS

       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.

$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)

See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184

I'd change

(quoted diff) +1 -1

-      #elif defined __mips__
+      #elif defined(__mips__ || __csky__)

Quoted 2 lines

and then change the rest of the text to add csky when appropriate. Am I correct?

As far as I can tell, you are correct.

Thanks,

Michael

Signature · 3 lines

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

Michael Kerrisk (man-pages)

2020-11-24 09:51 UTC #2 lore raw

In reply to Alejandro Colomar (man-pages)

Hi Alex,

Quoted 48 lines · Alejandro Colomar (man-pages)

Hi Michael,

SYNOPSIS

       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.

$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)

See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184

I'd change

(quoted diff) +1 -1

-      #elif defined __mips__
+      #elif defined(__mips__ || __csky__)

Quoted 2 lines

and then change the rest of the text to add csky when appropriate. Am I correct?

AFAICT, you are correct. I think the reason that csky is missing is that the architecture was added after this manual pages was added.

Thanks,

Michael

Signature · 3 lines

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

Guo Ren

maintainer

2020-11-24 12:07 UTC #3 lore raw

Thx Michael & Alejandro,

Yes, the man page has no csky's.

C-SKY have abiv1 and abiv2
For abiv1: There is no register for tls saving, We use trap 3 to got tls and use set_thread_area to init ti->tp_value.
For abiv2: The r31 is the tls register. We could directly read r31 to got r31 and use set_thread_area to init reg->tls value.

In glibc:

# ifdef __CSKYABIV2__
/* Define r31 as thread pointer register.  */
#  define READ_THREAD_POINTER() \
        mov r0, r31;
# else
#  define READ_THREAD_POINTER() \
        trap 3;
# endif

/* Code to initially initialize the thread pointer. This might need
special attention since 'errno' is not yet available and if the operation can cause a failure 'errno' must not be touched. */

# define TLS_INIT_TP(tcbp) \
  ({ INTERNAL_SYSCALL_DECL (err);                                       \
     long result_var;                                                   \
     result_var = INTERNAL_SYSCALL (set_thread_area, err, 1,            \
                    (char *) (tcbp) + TLS_TCB_OFFSET);                  \
     INTERNAL_SYSCALL_ERROR_P (result_var, err)                         \
       ? "unknown error" : NULL; })

In kernel:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)

{
        struct thread_info *ti = task_thread_info(current);
        struct pt_regs *reg = current_pt_regs();

        reg->tls = addr;
        ti->tp_value = addr;

        return 0;
}

Any comments are welcome :)

Quoted 60 lines · Michael Kerrisk (man-pages)

Hi Alex,

Quoted 48 lines · Alejandro Colomar (man-pages)

Hi Michael,

SYNOPSIS

       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.

$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)

See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184

I'd change

(quoted diff) +1 -1

-      #elif defined __mips__
+      #elif defined(__mips__ || __csky__)

Quoted 2 lines

and then change the rest of the text to add csky when appropriate. Am I correct?

AFAICT, you are correct. I think the reason that csky is missing is that the architecture was added after this manual pages was added.

Thanks,

Quoted 7 lines

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

--
Best Regards
Guo Ren

ML: https://lore.kernel.org/linux-csky/

Alejandro Colomar (mailing lists; readonly)

2020-11-26 12:16 UTC #4 lore raw

Hi Guo,

Thanks for the details!
I'll try to add csky to the man page, and if I have any doubts I'll ask you. Anyway, I'll CC you in any change I propose.

Cheers,

Alex

Quoted 124 lines · Guo Ren

Thx Michael & Alejandro,
Yes, the man page has no csky's.
C-SKY have abiv1 and abiv2
For abiv1: There is no register for tls saving, We use trap 3 to got tls and use set_thread_area to init ti->tp_value.
For abiv2: The r31 is the tls register. We could directly read r31 to got r31 and use set_thread_area to init reg->tls value.
In glibc:
# ifdef __CSKYABIV2__
/* Define r31 as thread pointer register.  */
#  define READ_THREAD_POINTER() \
        mov r0, r31;
# else
#  define READ_THREAD_POINTER() \
        trap 3;
# endif
/* Code to initially initialize the thread pointer. This might need
special attention since 'errno' is not yet available and if the operation can cause a failure 'errno' must not be touched. */
# define TLS_INIT_TP(tcbp) \
  ({ INTERNAL_SYSCALL_DECL (err);                                       \
     long result_var;                                                   \
     result_var = INTERNAL_SYSCALL (set_thread_area, err, 1,            \
                    (char *) (tcbp) + TLS_TCB_OFFSET);                  \
     INTERNAL_SYSCALL_ERROR_P (result_var, err)                         \
       ? "unknown error" : NULL; })
In kernel:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
{
        struct thread_info *ti = task_thread_info(current);
        struct pt_regs *reg = current_pt_regs();

        reg->tls = addr;
        ti->tp_value = addr;

        return 0;
}
Any comments are welcome :)
Quoted 60 lines · Michael Kerrisk (man-pages)
Hi Alex,
Quoted 48 lines · Alejandro Colomar (man-pages)
Hi Michael,
SYNOPSIS
       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.
$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184
I'd change
(quoted diff) +1 -1
-      #elif defined __mips__
+      #elif defined(__mips__ || __csky__)
Quoted 2 lines
and then change the rest of the text to add csky when appropriate. Am I correct?
AFAICT, you are correct. I think the reason that csky is missing is that the architecture was added after this manual pages was added.
Thanks,
Quoted 7 lines
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/

Alejandro Colomar

maintainer

2023-10-14 23:20 UTC #5 lore raw

In reply to Guo Ren

Hi Guo,

On Tue, Nov 24, 2020 at 08:07:07PM +0800, Guo Ren wrote:

Huh, 3 years already! I've had this in my head for all this time; just didn't find the energy to act on it.

Quoted 3 lines

Thx Michael & Alejandro,
Yes, the man page has no csky's.

I've applied a patch to add initial documentation for it:
<https://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?h=contrib&id=a63979eb24aaf73f4be5799cc9579f84a3874b7d>

Quoted 40 lines

C-SKY have abiv1 and abiv2
For abiv1: There is no register for tls saving, We use trap 3 to got tls and use set_thread_area to init ti->tp_value.
For abiv2: The r31 is the tls register. We could directly read r31 to got r31 and use set_thread_area to init reg->tls value.
In glibc:
# ifdef __CSKYABIV2__
/* Define r31 as thread pointer register.  */
#  define READ_THREAD_POINTER() \
        mov r0, r31;
# else
#  define READ_THREAD_POINTER() \
        trap 3;
# endif
/* Code to initially initialize the thread pointer. This might need
special attention since 'errno' is not yet available and if the operation can cause a failure 'errno' must not be touched. */
# define TLS_INIT_TP(tcbp) \
  ({ INTERNAL_SYSCALL_DECL (err);                                       \
     long result_var;                                                   \
     result_var = INTERNAL_SYSCALL (set_thread_area, err, 1,            \
                    (char *) (tcbp) + TLS_TCB_OFFSET);                  \
     INTERNAL_SYSCALL_ERROR_P (result_var, err)                         \
       ? "unknown error" : NULL; })
In kernel:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
{
        struct thread_info *ti = task_thread_info(current);
        struct pt_regs *reg = current_pt_regs();

        reg->tls = addr;
        ti->tp_value = addr;

        return 0;
}

Quoted 1 line

Any comments are welcome :)

I'm sorry, but I have little understanding of this syscall, and that shounds like gibberish to me :)

Feel free to send a patch to improve the documentation for csky.

Cheers,
Alex

Quoted 79 lines

Quoted 60 lines · Michael Kerrisk (man-pages)
Hi Alex,
Quoted 48 lines · Alejandro Colomar (man-pages)
Hi Michael,
SYNOPSIS
       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.
$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184
I'd change
(quoted diff) +1 -1
-      #elif defined __mips__
+      #elif defined(__mips__ || __csky__)
Quoted 2 lines
and then change the rest of the text to add csky when appropriate. Am I correct?
AFAICT, you are correct. I think the reason that csky is missing is that the architecture was added after this manual pages was added.
Thanks,
Quoted 7 lines
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/

Signature · 1 line

<https://www.alejandro-colomar.es/>

Guo Ren

maintainer

2023-10-15 15:10 UTC #6 lore raw

Quoted 54 lines · Alejandro Colomar

Hi Guo,
On Tue, Nov 24, 2020 at 08:07:07PM +0800, Guo Ren wrote:
Huh, 3 years already! I've had this in my head for all this time; just didn't find the energy to act on it.
Quoted 3 lines
Thx Michael & Alejandro,
Yes, the man page has no csky's.
I've applied a patch to add initial documentation for it:
<https://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?h=contrib&id=a63979eb24aaf73f4be5799cc9579f84a3874b7d>
Quoted 40 lines
C-SKY have abiv1 and abiv2
For abiv1: There is no register for tls saving, We use trap 3 to got tls and use set_thread_area to init ti->tp_value.
For abiv2: The r31 is the tls register. We could directly read r31 to got r31 and use set_thread_area to init reg->tls value.
In glibc:
# ifdef __CSKYABIV2__
/* Define r31 as thread pointer register.  */
#  define READ_THREAD_POINTER() \
        mov r0, r31;
# else
#  define READ_THREAD_POINTER() \
        trap 3;
# endif
/* Code to initially initialize the thread pointer. This might need
special attention since 'errno' is not yet available and if the operation can cause a failure 'errno' must not be touched. */
# define TLS_INIT_TP(tcbp) \
  ({ INTERNAL_SYSCALL_DECL (err);                                       \
     long result_var;                                                   \
     result_var = INTERNAL_SYSCALL (set_thread_area, err, 1,            \
                    (char *) (tcbp) + TLS_TCB_OFFSET);                  \
     INTERNAL_SYSCALL_ERROR_P (result_var, err)                         \
       ? "unknown error" : NULL; })
In kernel:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
{
        struct thread_info *ti = task_thread_info(current);
        struct pt_regs *reg = current_pt_regs();

        reg->tls = addr;
        ti->tp_value = addr;

        return 0;
}

Quoted 6 lines

Quoted 1 line
Any comments are welcome :)
I'm sorry, but I have little understanding of this syscall, and that shounds like gibberish to me :)
Feel free to send a patch to improve the documentation for csky.

Yeah, I've sent a patch for it; please review:
https://lore.kernel.org/linux-csky/[email protected]/

Quoted 86 lines

Cheers,
Alex
Quoted 79 lines
Quoted 60 lines · Michael Kerrisk (man-pages)
Hi Alex,
Quoted 48 lines · Alejandro Colomar (man-pages)
Hi Michael,
SYNOPSIS
       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.
$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184
I'd change
(quoted diff) +1 -1
-      #elif defined __mips__
+      #elif defined(__mips__ || __csky__)
Quoted 2 lines
and then change the rest of the text to add csky when appropriate. Am I correct?
AFAICT, you are correct. I think the reason that csky is missing is that the architecture was added after this manual pages was added.
Thanks,
Quoted 7 lines
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
Signature · 1 line
<https://www.alejandro-colomar.es/>

Alejandro Colomar (mailing lists; readonly)

2020-11-26 12:14 UTC #7 lore raw

In reply to Michael Kerrisk (man-pages)

HI Michael,

Quoted 51 lines · Michael Kerrisk (man-pages)

Hi Alex,

Quoted 48 lines · Alejandro Colomar (man-pages)

Hi Michael,

SYNOPSIS

       #include <linux/unistd.h>

       #if defined __i386__ || defined __x86_64__
       # include <asm/ldt.h>

       int get_thread_area(struct user_desc *u_info);
       int set_thread_area(struct user_desc *u_info);

       #elif defined __m68k__

       int get_thread_area(void);
       int set_thread_area(unsigned long tp);

       #elif defined __mips__

       int set_thread_area(unsigned long addr);

       #endif

       Note: There are no glibc wrappers for these system  calls;  see
       NOTES.

$ grep -rn 'SYSCALL_DEFINE.*et_thread_area'
arch/csky/kernel/syscall.c:6:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/mips/kernel/syscall.c:86:
SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
arch/x86/kernel/tls.c:191:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info)
arch/x86/kernel/tls.c:243:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info)
arch/x86/um/tls_32.c:277:
SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
arch/x86/um/tls_32.c:325:
SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)

See kernel commit 4859bfca11c7d63d55175bcd85a75d6cee4b7184

I'd change

(quoted diff) +1 -1

-      #elif defined __mips__
+      #elif defined(__mips__ || __csky__)

Quoted 5 lines

Quoted 2 lines
and then change the rest of the text to add csky when appropriate. Am I correct?
AFAICT, you are correct. I think the reason that csky is missing is that the architecture was added after this manual pages was added.

Yep, I guessed it was that :)

Thanks,

Alex

Quoted 6 lines

Thanks,
Michael