Re: [PATCH 1/2] hurd: Don't migrate reply port into __init1_tcbhead

[Samuel Thibault]

Applied, thanks!

Sergey Bugaev, le jeu. 20 avril 2023 21:42:19 +0300, a ecrit:
> Properly differentiate between setting up the real TLS with
> TLS_INIT_TP, and setting up the early TLS (__init1_tcbhead) in static
> builds. In the latter case, don't yet migrate the reply port into the
> TCB, and don't yet set __libc_tls_initialized to 1.
> 
> This also lets us move the __init1_desc assignment inside
> _hurd_tls_init ().
> 
> Fixes cd019ddd892e182277fadd6aedccc57fa3923c8d
> "hurd: Don't leak __hurd_reply_port0"
> 
> Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
> ---
>  sysdeps/mach/hurd/i386/tls.h       | 18 ++++++++++++------
>  sysdeps/mach/hurd/x86/init-first.c |  7 +------
>  sysdeps/mach/hurd/x86_64/tls.h     | 11 ++++++-----
>  3 files changed, 19 insertions(+), 17 deletions(-)
> 
> diff --git a/sysdeps/mach/hurd/i386/tls.h b/sysdeps/mach/hurd/i386/tls.h
> index 0ac8917a..e124fb10 100644
> --- a/sysdeps/mach/hurd/i386/tls.h
> +++ b/sysdeps/mach/hurd/i386/tls.h
> @@ -136,7 +136,7 @@ __LIBC_NO_TLS (void)
>     special attention since 'errno' is not yet available and if the
>     operation can cause a failure 'errno' must not be touched.  */
>  static inline bool __attribute__ ((unused))
> -_hurd_tls_init (tcbhead_t *tcb)
> +_hurd_tls_init (tcbhead_t *tcb, bool full)
>  {
>    HURD_TLS_DESC_DECL (desc, tcb);
>    thread_t self = __mach_thread_self ();
> @@ -148,8 +148,9 @@ _hurd_tls_init (tcbhead_t *tcb)
>    tcb->tcb = tcb;
>    /* We always at least start the sigthread anyway.  */
>    tcb->multiple_threads = 1;
> -  /* Take over the reply port we've been using.  */
> -  tcb->reply_port = __hurd_reply_port0;
> +  if (full)
> +    /* Take over the reply port we've been using.  */
> +    tcb->reply_port = __hurd_reply_port0;
>  
>    /* Get the first available selector.  */
>    int sel = -1;
> @@ -175,15 +176,20 @@ _hurd_tls_init (tcbhead_t *tcb)
>  
>    /* Now install the new selector.  */
>    asm volatile ("mov %w0, %%gs" :: "q" (sel));
> -  /* This port is now owned by the TCB.  */
> -  __hurd_reply_port0 = MACH_PORT_NULL;
> +  if (full)
> +    /* This port is now owned by the TCB.  */
> +    __hurd_reply_port0 = MACH_PORT_NULL;
> +#ifndef SHARED
> +  else
> +    __init1_desc = sel;
> +#endif
>  
>  out:
>    __mach_port_deallocate (__mach_task_self (), self);
>    return success;
>  }
>  
> -# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
> +# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr), 1)
>  #else /* defined (SHARED) && !IS_IN (rtld) */
>  # define __LIBC_NO_TLS() 0
>  #endif
> diff --git a/sysdeps/mach/hurd/x86/init-first.c 
> b/sysdeps/mach/hurd/x86/init-first.c
> index 89a5f44c..d74a3c86 100644
> --- a/sysdeps/mach/hurd/x86/init-first.c
> +++ b/sysdeps/mach/hurd/x86/init-first.c
> @@ -156,12 +156,7 @@ first_init (void)
>  #ifndef SHARED
>    /* In the static case, we need to set up TLS early so that the stack
>       protection guard can be read at gs:0x14 by the gcc-generated snippets.  
> */
> -  _hurd_tls_init (&__init1_tcbhead);
> -
> -  /* Make sure __LIBC_NO_TLS () keeps evaluating to 1.  */
> -# ifndef __x86_64__
> -  asm ("movw %%gs,%w0" : "=m" (__init1_desc));
> -# endif
> +  _hurd_tls_init (&__init1_tcbhead, 0);
>  #endif
>  
>    RUN_RELHOOK (_hurd_preinit_hook, ());
> diff --git a/sysdeps/mach/hurd/x86_64/tls.h b/sysdeps/mach/hurd/x86_64/tls.h
> index 2b7135f6..1274723a 100644
> --- a/sysdeps/mach/hurd/x86_64/tls.h
> +++ b/sysdeps/mach/hurd/x86_64/tls.h
> @@ -173,7 +173,7 @@ extern unsigned char __libc_tls_initialized;
>  #  define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0)
>  
>  static inline bool __attribute__ ((unused))
> -_hurd_tls_init (tcbhead_t *tcb)
> +_hurd_tls_init (tcbhead_t *tcb, bool full)
>  {
>    error_t err;
>    thread_t self = __mach_thread_self ();
> @@ -181,11 +181,12 @@ _hurd_tls_init (tcbhead_t *tcb)
>  
>    /* We always at least start the sigthread anyway.  */
>    tcb->multiple_threads = 1;
> -  /* Take over the reply port we've been using.  */
> -  tcb->reply_port = __hurd_reply_port0;
> +  if (full)
> +    /* Take over the reply port we've been using.  */
> +    tcb->reply_port = __hurd_reply_port0;
>  
>    err = _hurd_tls_new (self, tcb);
> -  if (err == 0)
> +  if (err == 0 && full)
>      {
>        __libc_tls_initialized = 1;
>        /* This port is now owned by the TCB.  */
> @@ -195,7 +196,7 @@ _hurd_tls_init (tcbhead_t *tcb)
>    return err == 0;
>  }
>  
> -#  define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
> +#  define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr), 1)
>  # else /* defined (SHARED) && !IS_IN (rtld) */
>  #  define __LIBC_NO_TLS() 0
>  # endif
> -- 
> 2.40.0
> 

-- 
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.