Re: [PATCH v3 37/37] nptl: Remove remnants of the libc/libpthread forwarder interface

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 16/03/2021 14:31, Florian Weimer via Libc-alpha wrote:
> All previously forwarded functions are now implemented in libc.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  nptl/Makefile                    |  1 -
>  nptl/forward.c                   | 31 --------------------
>  nptl/libc_pthread_init.c         | 29 +-----------------
>  nptl/nptl-init.c                 | 11 +------
>  nptl/pthreadP.h                  |  7 ++---
>  sysdeps/nptl/libc-lockP.h        | 28 ++++--------------
>  sysdeps/nptl/pthread-functions.h | 50 --------------------------------
>  7 files changed, 10 insertions(+), 147 deletions(-)
>  delete mode 100644 nptl/forward.c
>  delete mode 100644 sysdeps/nptl/pthread-functions.h
> 
> diff --git a/nptl/Makefile b/nptl/Makefile
> index 1b5038485d..7423967cd2 100644
> --- a/nptl/Makefile
> +++ b/nptl/Makefile
> @@ -38,7 +38,6 @@ routines = \
>    elision-timed \
>    elision-trylock \
>    elision-unlock \
> -  forward \
>    futex-internal \
>    libc-cancellation \
>    libc-cleanup \

Ok.

> diff --git a/nptl/forward.c b/nptl/forward.c
> deleted file mode 100644
> index c819ab6f2a..0000000000
> --- a/nptl/forward.c
> +++ /dev/null
> @@ -1,31 +0,0 @@
> -/* Copyright (C) 2002-2021 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#include <dlfcn.h>
> -#include <pthreadP.h>
> -#include <signal.h>
> -#include <stdlib.h>
> -
> -#include <shlib-compat.h>
> -#include <atomic.h>
> -#include <safe-fatal.h>
> -
> -
> -/* Pointers to the libc functions.  */
> -struct pthread_functions __libc_pthread_functions attribute_hidden;
> -int __libc_pthread_functions_init attribute_hidden;

Ok.

> diff --git a/nptl/libc_pthread_init.c b/nptl/libc_pthread_init.c
> index 85fceff930..c951332666 100644
> --- a/nptl/libc_pthread_init.c
> +++ b/nptl/libc_pthread_init.c
> @@ -34,38 +34,11 @@ extern int __libc_multiple_threads attribute_hidden;
>  
>  int *
>  #endif
> -__libc_pthread_init (void (*reclaim) (void),
> -		     const struct pthread_functions *functions)
> +__libc_pthread_init (void (*reclaim) (void))
>  {
>    /* Called by a child after fork.  */
>    __register_atfork (NULL, NULL, reclaim, NULL);
>  
> -#ifdef SHARED
> -  /* Copy the function pointers into an array in libc.  This enables
> -     access with just one memory reference but moreso, it prevents
> -     hijacking the function pointers with just one pointer change.  We
> -     "encrypt" the function pointers since we cannot write-protect the
> -     array easily enough.  */
> -  union ptrhack
> -  {
> -    struct pthread_functions pf;
> -# define NPTRS (sizeof (struct pthread_functions) / sizeof (void *))
> -    void *parr[NPTRS];
> -  } __attribute__ ((may_alias)) const *src;
> -  union ptrhack *dest;
> -
> -  src = (const void *) functions;
> -  dest = (void *) &__libc_pthread_functions;
> -
> -  for (size_t cnt = 0; cnt < NPTRS; ++cnt)
> -    {
> -      void *p = src->parr[cnt];
> -      PTR_MANGLE (p);
> -      dest->parr[cnt] = p;
> -    }
> -  __libc_pthread_functions_init = 1;
> -#endif
> -
>  #ifndef TLS_MULTIPLE_THREADS_IN_TCB
>    return &__libc_multiple_threads;
>  #endif

Ok.

> diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
> index f4a603b32d..061e3ff8d7 100644
> --- a/nptl/nptl-init.c
> +++ b/nptl/nptl-init.c
> @@ -50,15 +50,6 @@ size_t __static_tls_align_m1;
>  /* Version of the library, used in libthread_db to detect mismatches.  */
>  static const char nptl_version[] __attribute_used__ = VERSION;
>  
> -#ifdef SHARED
> -static const struct pthread_functions pthread_functions =
> -  {
> -  };
> -# define ptr_pthread_functions &pthread_functions
> -#else
> -# define ptr_pthread_functions NULL
> -#endif
> -
>  /* For asynchronous cancellation we use a signal.  This is the handler.  */
>  static void
>  sigcancel_handler (int sig, siginfo_t *si, void *ctx)

Ok.

> @@ -207,7 +198,7 @@ __pthread_initialize_minimal_internal (void)
>  #ifndef TLS_MULTIPLE_THREADS_IN_TCB
>    __libc_multiple_threads_ptr =
>  #endif
> -    __libc_pthread_init (__reclaim_stacks, ptr_pthread_functions);
> +    __libc_pthread_init (__reclaim_stacks);
>  }
>  strong_alias (__pthread_initialize_minimal_internal,
>  	      __pthread_initialize_minimal)

Ok.

> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
> index 9852906b3a..a1d34d5ff1 100644
> --- a/nptl/pthreadP.h
> +++ b/nptl/pthreadP.h
> @@ -30,7 +30,6 @@
>  #include <lowlevellock.h>
>  #include <stackinfo.h>
>  #include <internaltypes.h>
> -#include <pthread-functions.h>
>  #include <atomic.h>
>  #include <kernel-features.h>
>  #include <errno.h>
> @@ -364,11 +363,9 @@ hidden_proto (__nptl_death_event)
>  
>  /* Register the generation counter in the libpthread with the libc.  */
>  #ifdef TLS_MULTIPLE_THREADS_IN_TCB
> -extern void __libc_pthread_init (void (*reclaim) (void),
> -				 const struct pthread_functions *functions);
> +extern void __libc_pthread_init (void (*reclaim) (void));
>  #else
> -extern int *__libc_pthread_init (void (*reclaim) (void),
> -				 const struct pthread_functions *functions);
> +extern int *__libc_pthread_init (void (*reclaim) (void));
>  
>  /* Variable set to a nonzero value either if more than one thread runs or ran,
>     or if a single-threaded process is trying to cancel itself.  See

Maybe move the __libc_pthread_init prototype out of TLS_MULTIPLE_THREADS_IN_TCB
since it is duplicated.

> diff --git a/sysdeps/nptl/libc-lockP.h b/sysdeps/nptl/libc-lockP.h
> index 0dd2ea1147..e573689799 100644
> --- a/sysdeps/nptl/libc-lockP.h
> +++ b/sysdeps/nptl/libc-lockP.h
> @@ -32,7 +32,6 @@
>     ld.so might be used on old kernels with a different libc.so.  */
>  #include <lowlevellock.h>
>  #include <tls.h>
> -#include <pthread-functions.h>
>  
>  #if IS_IN (libpthread)
>  /* This gets us the declarations of the __pthread_* internal names,
> @@ -100,27 +99,12 @@ _Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0");
>    (FUNC != NULL ? FUNC ARGS : ELSE)
>  #endif
>  
> -/* Call thread functions through the function pointer table.  */
> -#if defined SHARED && IS_IN (libc)
> -# define PTFAVAIL(NAME) __libc_pthread_functions_init
> -# define __libc_ptf_call(FUNC, ARGS, ELSE) \
> -  (__libc_pthread_functions_init ? PTHFCT_CALL (ptr_##FUNC, ARGS) : ELSE)
> -# define __libc_ptf_call_always(FUNC, ARGS) \
> -  PTHFCT_CALL (ptr_##FUNC, ARGS)
> -#elif IS_IN (libpthread)
> -# define PTFAVAIL(NAME) 1
> -# define __libc_ptf_call(FUNC, ARGS, ELSE) \
> -  FUNC ARGS
> -# define __libc_ptf_call_always(FUNC, ARGS) \
> -  FUNC ARGS
> -#else
> -# define PTFAVAIL(NAME) (NAME != NULL)
> -# define __libc_ptf_call(FUNC, ARGS, ELSE) \
> -  __libc_maybe_call (FUNC, ARGS, ELSE)
> -# define __libc_ptf_call_always(FUNC, ARGS) \
> -  FUNC ARGS
> -#endif
> -
> +/* All previously forwarded functions are now called directly (either
> +   via local call in libc, or through a __export), but __libc_ptf_call
> +   is still used in generic code shared with Hurd.  */
> +#define PTFAVAIL(NAME) 1
> +#define __libc_ptf_call(FUNC, ARGS, ELSE) FUNC ARGS
> +#define __libc_ptf_call_always(FUNC, ARGS) FUNC ARGS
>  
>  /* Initialize the named lock variable, leaving it in a consistent, unlocked
>     state.  */

Ok.

> diff --git a/sysdeps/nptl/pthread-functions.h b/sysdeps/nptl/pthread-functions.h
> deleted file mode 100644
> index d76b2cdecf..0000000000
> --- a/sysdeps/nptl/pthread-functions.h
> +++ /dev/null
> @@ -1,50 +0,0 @@
> -/* Copyright (C) 2003-2021 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -   Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#ifndef _PTHREAD_FUNCTIONS_H
> -#define _PTHREAD_FUNCTIONS_H	1
> -
> -#include <pthread.h>
> -#include <setjmp.h>
> -#include <internaltypes.h>
> -#include <sysdep.h>
> -
> -struct xid_command;
> -
> -/* Data type shared with libc.  The libc uses it to pass on calls to
> -   the thread functions.  */
> -struct pthread_functions
> -{
> -};
> -
> -/* Variable in libc.so.  */
> -extern struct pthread_functions __libc_pthread_functions attribute_hidden;
> -extern int __libc_pthread_functions_init attribute_hidden;
> -
> -#ifdef PTR_DEMANGLE
> -# define PTHFCT_CALL(fct, params) \
> -  ({ __typeof (__libc_pthread_functions.fct) __p;			      \
> -     __p = __libc_pthread_functions.fct;				      \
> -     PTR_DEMANGLE (__p);						      \
> -     __p params; })
> -#else
> -# define PTHFCT_CALL(fct, params) \
> -  __libc_pthread_functions.fct params
> -#endif
> -
> -#endif	/* pthread-functions.h */
> 

Ok.