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 :)
On Tue, Nov 24, 2020 at 5:51 PM Michael Kerrisk (man-pages)
<mtk.manpages@xxxxxxxxx> wrote:
>
> Hi Alex,
>
> On 11/23/20 10:31 PM, Alejandro Colomar (man-pages) wrote:
> > 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?
>
> 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
>
>
> --
> 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/
