nptl: Remove pthread_clock_gettime pthread_clock_settime

This patch removes CLOCK_THREAD_CPUTIME_ID and CLOCK_PROCESS_CPUTIME_ID support
from clock_gettime and clock_settime generic implementation.  For Linux, kernel
already provides supports through the syscall and Hurd HTL lacks
__pthread_clock_gettime and __pthread_clock_settime internal implementation.

As described in clock_gettime man-page [1] on 'Historical note for SMP
system', implementing CLOCK_{THREAD,PROCESS}_CPUTIME_ID with timer registers
is error-prone and susceptible to timing and accurary issues that the libc
can not deal without kernel support.

This allows removes unused code which, however, still incur in some runtime
overhead in thread creation (the struct pthread cpuclock_offset
initialization).

If hurd eventually wants to support them it should either either implement as
a kernel facility (or something related due its architecture) or in system
specific implementation.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu. I also
checked on a i686-gnu build.

	* nptl/Makefile (libpthread-routines): Remove pthread_clock_gettime and
	pthread_clock_settime.
	* nptl/pthreadP.h (__find_thread_by_id): Remove prototype.
	* elf/dl-support.c [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset): Remove.
	(_dl_non_dynamic_init): Remove _dl_cpuclock_offset setting.
	* elf/rtld.c (_dl_start_final): Likewise.
	* nptl/allocatestack.c (__find_thread_by_id): Remove function.
	* sysdeps/generic/ldsodefs.h [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset):
	Remove.
	* sysdeps/mach/hurd/dl-sysdep.c [!HP_TIMING_NOAVAIL]
	(_dl_cpuclock_offset): Remove.
	* nptl/descr.h (struct pthread): Rename cpuclock_offset to
	cpuclock_offset_ununsed.
	* nptl/nptl-init.c (__pthread_initialize_minimal_internal): Remove
	cpuclock_offset set.
	* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
	* sysdeps/nptl/fork.c (__libc_fork): Likewise.
	* nptl/pthread_clock_gettime.c: Remove file.
	* nptl/pthread_clock_settime.c: Likewise.
	* sysdeps/unix/clock_gettime.c (hp_timing_gettime): Remove function.
	[HP_TIMING_AVAIL] (realtime_gettime): Remove CLOCK_THREAD_CPUTIME_ID
	and CLOCK_PROCESS_CPUTIME_ID support.
	* sysdeps/unix/clock_settime.c (hp_timing_gettime): Likewise.
	[HP_TIMING_AVAIL] (realtime_gettime): Likewise.
	* sysdeps/posix/clock_getres.c (hp_timing_getres): Likewise.
	[HP_TIMING_AVAIL] (__clock_getres): Likewise.
	* sysdeps/unix/clock_nanosleep.c (CPUCLOCK_P, INVALID_CLOCK_P):
	Likewise.
	(__clock_nanosleep): Remove CPUCLOCK_P and INVALID_CLOCK_P usage.

[1] http://man7.org/linux/man-pages/man2/clock_gettime.2.html

8 files changed, 1 insertions, 192 deletions

diff --git a/nptl/Makefile b/nptl/Makefile
index 5acfdcceff..f9bc5cc887 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -109,7 +109,6 @@ libpthread-routines = nptl-init nptlfreeres vars events version pt-interp \
 		      pthread_once \
 		      old_pthread_atfork \
 		      pthread_getcpuclockid \
-		      pthread_clock_gettime pthread_clock_settime \
 		      shm-directory \
 		      sem_init sem_destroy \
 		      sem_open sem_close sem_unlink \
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index d8e8570a7d..fcbc46f0d7 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -963,54 +963,6 @@ __reclaim_stacks (void)
 }
 
 
-#if HP_TIMING_AVAIL
-# undef __find_thread_by_id
-/* Find a thread given the thread ID.  */
-attribute_hidden
-struct pthread *
-__find_thread_by_id (pid_t tid)
-{
-  struct pthread *result = NULL;
-
-  lll_lock (stack_cache_lock, LLL_PRIVATE);
-
-  /* Iterate over the list with system-allocated threads first.  */
-  list_t *runp;
-  list_for_each (runp, &stack_used)
-    {
-      struct pthread *curp;
-
-      curp = list_entry (runp, struct pthread, list);
-
-      if (curp->tid == tid)
-	{
-	  result = curp;
-	  goto out;
-	}
-    }
-
-  /* Now the list with threads using user-allocated stacks.  */
-  list_for_each (runp, &__stack_user)
-    {
-      struct pthread *curp;
-
-      curp = list_entry (runp, struct pthread, list);
-
-      if (curp->tid == tid)
-	{
-	  result = curp;
-	  goto out;
-	}
-    }
-
- out:
-  lll_unlock (stack_cache_lock, LLL_PRIVATE);
-
-  return result;
-}
-#endif
-
-
 #ifdef SIGSETXID
 static void
 setxid_mark_thread (struct xid_command *cmdp, struct pthread *t)
diff --git a/nptl/descr.h b/nptl/descr.h
index 4ef33ae465..cb7d4c2282 100644
--- a/nptl/descr.h
+++ b/nptl/descr.h
@@ -343,8 +343,7 @@ struct pthread
   unsigned int setxid_futex;
 
 #if HP_TIMING_AVAIL
-  /* Offset of the CPU clock at start thread start time.  */
-  hp_timing_t cpuclock_offset;
+  hp_timing_t cpuclock_offset_ununsed;
 #endif
 
   /* If the thread waits to join another one the ID of the latter is
diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 61ec8ed12a..b845c6e45d 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -267,9 +267,6 @@ __pthread_initialize_minimal_internal (void)
   THREAD_SETMEM (pd, user_stack, true);
   if (LLL_LOCK_INITIALIZER != 0)
     THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
-#if HP_TIMING_AVAIL
-  THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
-#endif
 
   /* Initialize the robust mutex data.  */
   {
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 626bd4b096..f0facfdb7d 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -401,16 +401,6 @@ extern int __pthread_multiple_threads attribute_hidden;
 extern int *__libc_multiple_threads_ptr attribute_hidden;
 #endif
 
-/* Find a thread given its TID.  */
-extern struct pthread *__find_thread_by_id (pid_t tid) attribute_hidden
-#ifdef SHARED
-;
-#else
-weak_function;
-#define __find_thread_by_id(tid) \
-  (__find_thread_by_id ? (__find_thread_by_id) (tid) : (struct pthread *) NULL)
-#endif
-
 extern void __pthread_init_static_tls (struct link_map *) attribute_hidden;
 
 extern size_t __pthread_get_minstack (const pthread_attr_t *attr);
diff --git a/nptl/pthread_clock_gettime.c b/nptl/pthread_clock_gettime.c
deleted file mode 100644
index f1d9104b24..0000000000
--- a/nptl/pthread_clock_gettime.c
+++ /dev/null
@@ -1,67 +0,0 @@
-/* Copyright (C) 2001-2019 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   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; see the file COPYING.LIB.  If
-   not, see <http://www.gnu.org/licenses/>.  */
-
-#include <errno.h>
-#include <stdlib.h>
-#include <time.h>
-#include "pthreadP.h"
-
-
-#if HP_TIMING_AVAIL
-int
-__pthread_clock_gettime (clockid_t clock_id, hp_timing_t freq,
-			 struct timespec *tp)
-{
-  hp_timing_t tsc;
-
-  /* Get the current counter.  */
-  HP_TIMING_NOW (tsc);
-
-  /* This is the ID of the thread we are looking for.  */
-  pid_t tid = ((unsigned int) clock_id) >> CLOCK_IDFIELD_SIZE;
-
-  /* Compute the offset since the start time of the process.  */
-  if (tid == 0 || tid == THREAD_GETMEM (THREAD_SELF, tid))
-    /* Our own clock.  */
-    tsc -= THREAD_GETMEM (THREAD_SELF, cpuclock_offset);
-  else
-    {
-      /* This is more complicated.  We have to locate the thread based
-	 on the ID.  This means walking the list of existing
-	 threads.  */
-      struct pthread *thread = __find_thread_by_id (tid);
-      if (thread == NULL)
-	{
-	  __set_errno (EINVAL);
-	  return -1;
-	}
-
-      /* There is a race here.  The thread might terminate and the stack
-	 become unusable.  But this is the user's problem.  */
-      tsc -= thread->cpuclock_offset;
-    }
-
-  /* Compute the seconds.  */
-  tp->tv_sec = tsc / freq;
-
-  /* And the nanoseconds.  This computation should be stable until
-     we get machines with about 16GHz frequency.  */
-  tp->tv_nsec = ((tsc % freq) * 1000000000ull) / freq;
-
-  return 0;
-}
-#endif
diff --git a/nptl/pthread_clock_settime.c b/nptl/pthread_clock_settime.c
deleted file mode 100644
index 0fe6482f78..0000000000
--- a/nptl/pthread_clock_settime.c
+++ /dev/null
@@ -1,54 +0,0 @@
-/* Copyright (C) 2001-2019 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   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; see the file COPYING.LIB.  If
-   not, see <http://www.gnu.org/licenses/>.  */
-
-#include <errno.h>
-#include <stdlib.h>
-#include <time.h>
-#include "pthreadP.h"
-
-
-#if HP_TIMING_AVAIL
-int
-__pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
-{
-  /* This is the ID of the thread we are looking for.  */
-  pid_t tid = ((unsigned int) clock_id) >> CLOCK_IDFIELD_SIZE;
-
-  /* Compute the offset since the start time of the process.  */
-  if (tid == 0 || tid == THREAD_GETMEM (THREAD_SELF, tid))
-    /* Our own clock.  */
-    THREAD_SETMEM (THREAD_SELF, cpuclock_offset, offset);
-  else
-    {
-      /* This is more complicated.  We have to locate the thread based
-	 on the ID.  This means walking the list of existing
-	 threads.  */
-      struct pthread *thread = __find_thread_by_id (tid);
-      if (thread == NULL)
-	{
-	  __set_errno (EINVAL);
-	  return -1;
-	}
-
-      /* There is a race here.  The thread might terminate and the stack
-	 become unusable.  But this is the user's problem.  */
-      thread->cpuclock_offset = offset;
-    }
-
-  return 0;
-}
-#endif
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 2bd2b10727..18b7bbe765 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -379,13 +379,6 @@ START_THREAD_DEFN
 {
   struct pthread *pd = START_THREAD_SELF;
 
-#if HP_TIMING_AVAIL
-  /* Remember the time when the thread was started.  */
-  hp_timing_t now;
-  HP_TIMING_NOW (now);
-  THREAD_SETMEM (pd, cpuclock_offset, now);
-#endif
-
   /* Initialize resolver state pointer.  */
   __resp = &pd->res;