hurd: Fix using interposable hurd_thread_self

  Create a private hidden __hurd_thread_self alias, and use that one.

Fixes 2f8ecb58a59eb82c43214d000842d99644a662d1
"hurd: Fix x86_64 _hurd_tls_fork" and
c7fcce38c83a2bb665ef5dc4981bf20c7e586123
"hurd: Make sure to not use tcb->self"

Reported-by: Joseph Myers <joseph@codesourcery.com>
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---

This should hopefully fix it (but please test!); I have only checked
that it builds on x86_64-gnu, and that _Fork now calls
__GI___hurd_thread_self without the PLT, and that libpthread.so only
references __hurd_thread_self@GLIBC_PRIVATE.

 hurd/Versions                           | 1 +
 hurd/thread-self.c                      | 5 ++++-
 sysdeps/hurd/include/hurd.h             | 3 +++
 sysdeps/mach/hurd/i386/htl/pt-setup.c   | 2 +-
 sysdeps/mach/hurd/x86_64/htl/pt-setup.c | 2 +-
 sysdeps/mach/hurd/x86_64/tls.h          | 7 +++++--
 6 files changed, 15 insertions(+), 5 deletions(-)
  

Checked and applied, thanks!

Sergey Bugaev, le ven. 19 mai 2023 17:47:24 +0300, a ecrit:
> Create a private hidden __hurd_thread_self alias, and use that one.
> 
> Fixes 2f8ecb58a59eb82c43214d000842d99644a662d1
> "hurd: Fix x86_64 _hurd_tls_fork" and
> c7fcce38c83a2bb665ef5dc4981bf20c7e586123
> "hurd: Make sure to not use tcb->self"
> 
> Reported-by: Joseph Myers <joseph@codesourcery.com>
> Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
> ---
> 
> This should hopefully fix it (but please test!); I have only checked
> that it builds on x86_64-gnu, and that _Fork now calls
> __GI___hurd_thread_self without the PLT, and that libpthread.so only
> references __hurd_thread_self@GLIBC_PRIVATE.
> 
>  hurd/Versions                           | 1 +
>  hurd/thread-self.c                      | 5 ++++-
>  sysdeps/hurd/include/hurd.h             | 3 +++
>  sysdeps/mach/hurd/i386/htl/pt-setup.c   | 2 +-
>  sysdeps/mach/hurd/x86_64/htl/pt-setup.c | 2 +-
>  sysdeps/mach/hurd/x86_64/tls.h          | 7 +++++--
>  6 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/hurd/Versions b/hurd/Versions
> index 3d8b412d..439e8abf 100644
> --- a/hurd/Versions
> +++ b/hurd/Versions
> @@ -156,6 +156,7 @@ libc {
>      __libc_open; __libc_close;
>  
>      # Used by libpthread.
> +    __hurd_thread_self;
>      _hurd_sigstate_set_global_rcv;
>      _hurd_sigstate_lock;
>      _hurd_sigstate_pending;
> diff --git a/hurd/thread-self.c b/hurd/thread-self.c
> index f3718165..af013503 100644
> --- a/hurd/thread-self.c
> +++ b/hurd/thread-self.c
> @@ -19,7 +19,10 @@
>  #include <hurd/signal.h>
>  
>  thread_t
> -hurd_thread_self (void)
> +__hurd_thread_self (void)
>  {
>    return _hurd_self_sigstate ()->thread;
>  }
> +
> +libc_hidden_def (__hurd_thread_self)
> +weak_alias (__hurd_thread_self, hurd_thread_self)
> diff --git a/sysdeps/hurd/include/hurd.h b/sysdeps/hurd/include/hurd.h
> index 7da9af26..5d904e0e 100644
> --- a/sysdeps/hurd/include/hurd.h
> +++ b/sysdeps/hurd/include/hurd.h
> @@ -11,5 +11,8 @@ void _hurd_libc_proc_init (char **argv);
>  libc_hidden_proto (_hurd_exec_paths)
>  libc_hidden_proto (_hurd_init)
>  libc_hidden_proto (_hurd_libc_proc_init)
> +
> +extern thread_t __hurd_thread_self (void);
> +libc_hidden_proto (__hurd_thread_self)
>  #endif
>  #endif
> diff --git a/sysdeps/mach/hurd/i386/htl/pt-setup.c b/sysdeps/mach/hurd/i386/htl/pt-setup.c
> index ba108b96..27e5c98b 100644
> --- a/sysdeps/mach/hurd/i386/htl/pt-setup.c
> +++ b/sysdeps/mach/hurd/i386/htl/pt-setup.c
> @@ -79,7 +79,7 @@ __pthread_setup (struct __pthread *thread,
>  {
>    error_t err;
>  
> -  if (thread->kernel_thread == hurd_thread_self ())
> +  if (thread->kernel_thread == __hurd_thread_self ())
>      /* Fix up the TCB for the main thread.  The C library has already
>         installed a TCB, which we want to keep using.  This TCB must not
>         be freed so don't register it in the thread structure.  On the
> diff --git a/sysdeps/mach/hurd/x86_64/htl/pt-setup.c b/sysdeps/mach/hurd/x86_64/htl/pt-setup.c
> index 7dc62912..8eebaf97 100644
> --- a/sysdeps/mach/hurd/x86_64/htl/pt-setup.c
> +++ b/sysdeps/mach/hurd/x86_64/htl/pt-setup.c
> @@ -56,7 +56,7 @@ __pthread_setup (struct __pthread *thread,
>    struct i386_thread_state state;
>    struct i386_fsgs_base_state fsgs_state;
>  
> -  if (thread->kernel_thread == hurd_thread_self ())
> +  if (thread->kernel_thread == __hurd_thread_self ())
>      /* Fix up the TCB for the main thread.  The C library has already
>         installed a TCB, which we want to keep using.  This TCB must not
>         be freed so don't register it in the thread structure.  On the
> diff --git a/sysdeps/mach/hurd/x86_64/tls.h b/sysdeps/mach/hurd/x86_64/tls.h
> index 468f703f..a5a49a47 100644
> --- a/sysdeps/mach/hurd/x86_64/tls.h
> +++ b/sysdeps/mach/hurd/x86_64/tls.h
> @@ -132,6 +132,10 @@ THREAD_TCB (thread_t thread,
>    ((descr)->pointer_guard						\
>     = THREAD_GETMEM (THREAD_SELF, pointer_guard))
>  
> +/* From hurd.h, reproduced here to avoid a circular include.  */
> +extern thread_t __hurd_thread_self (void);
> +libc_hidden_proto (__hurd_thread_self)
> +
>  /* Set up TLS in the new thread of a fork child, copying from the original.  */
>  static inline kern_return_t __attribute__ ((unused))
>  _hurd_tls_fork (thread_t child, thread_t orig,
> @@ -141,8 +145,7 @@ _hurd_tls_fork (thread_t child, thread_t orig,
>    struct i386_fsgs_base_state state;
>    mach_msg_type_number_t state_count = i386_FSGS_BASE_STATE_COUNT;
>  
> -  extern thread_t hurd_thread_self (void);
> -  if (orig != hurd_thread_self ())
> +  if (orig != __hurd_thread_self ())
>      {
>        err = __thread_get_state (orig, i386_FSGS_BASE_STATE,
>                                  (thread_state_t) &state,
> -- 
> 2.40.1
>