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1319 lines
37 KiB
C
1319 lines
37 KiB
C
/* Copyright (C) 2002-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdint.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <dl-sysdep.h>
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#include <dl-tls.h>
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#include <tls.h>
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#include <list.h>
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#include <lowlevellock.h>
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#include <futex-internal.h>
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#include <kernel-features.h>
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#include <stack-aliasing.h>
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#ifndef NEED_SEPARATE_REGISTER_STACK
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/* Most architectures have exactly one stack pointer. Some have more. */
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# define STACK_VARIABLES void *stackaddr = NULL
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/* How to pass the values to the 'create_thread' function. */
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# define STACK_VARIABLES_ARGS stackaddr
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/* How to declare function which gets there parameters. */
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# define STACK_VARIABLES_PARMS void *stackaddr
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/* How to declare allocate_stack. */
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# define ALLOCATE_STACK_PARMS void **stack
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/* This is how the function is called. We do it this way to allow
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other variants of the function to have more parameters. */
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# define ALLOCATE_STACK(attr, pd) allocate_stack (attr, pd, &stackaddr)
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#else
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/* We need two stacks. The kernel will place them but we have to tell
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the kernel about the size of the reserved address space. */
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# define STACK_VARIABLES void *stackaddr = NULL; size_t stacksize = 0
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/* How to pass the values to the 'create_thread' function. */
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# define STACK_VARIABLES_ARGS stackaddr, stacksize
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/* How to declare function which gets there parameters. */
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# define STACK_VARIABLES_PARMS void *stackaddr, size_t stacksize
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/* How to declare allocate_stack. */
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# define ALLOCATE_STACK_PARMS void **stack, size_t *stacksize
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/* This is how the function is called. We do it this way to allow
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other variants of the function to have more parameters. */
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# define ALLOCATE_STACK(attr, pd) \
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allocate_stack (attr, pd, &stackaddr, &stacksize)
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#endif
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/* Default alignment of stack. */
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#ifndef STACK_ALIGN
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# define STACK_ALIGN __alignof__ (long double)
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#endif
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/* Default value for minimal stack size after allocating thread
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descriptor and guard. */
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#ifndef MINIMAL_REST_STACK
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# define MINIMAL_REST_STACK 4096
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#endif
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/* Newer kernels have the MAP_STACK flag to indicate a mapping is used for
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a stack. Use it when possible. */
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#ifndef MAP_STACK
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# define MAP_STACK 0
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#endif
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/* This yields the pointer that TLS support code calls the thread pointer. */
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#if TLS_TCB_AT_TP
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# define TLS_TPADJ(pd) (pd)
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#elif TLS_DTV_AT_TP
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# define TLS_TPADJ(pd) ((struct pthread *)((char *) (pd) + TLS_PRE_TCB_SIZE))
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#endif
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/* Cache handling for not-yet free stacks. */
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/* Maximum size in kB of cache. */
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static size_t stack_cache_maxsize = 40 * 1024 * 1024; /* 40MiBi by default. */
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static size_t stack_cache_actsize;
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/* Mutex protecting this variable. */
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static int stack_cache_lock = LLL_LOCK_INITIALIZER;
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/* List of queued stack frames. */
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static LIST_HEAD (stack_cache);
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/* List of the stacks in use. */
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static LIST_HEAD (stack_used);
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/* We need to record what list operations we are going to do so that,
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in case of an asynchronous interruption due to a fork() call, we
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can correct for the work. */
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static uintptr_t in_flight_stack;
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/* List of the threads with user provided stacks in use. No need to
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initialize this, since it's done in __pthread_initialize_minimal. */
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list_t __stack_user __attribute__ ((nocommon));
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hidden_data_def (__stack_user)
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/* Check whether the stack is still used or not. */
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#define FREE_P(descr) ((descr)->tid <= 0)
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static void
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stack_list_del (list_t *elem)
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{
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in_flight_stack = (uintptr_t) elem;
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atomic_write_barrier ();
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list_del (elem);
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atomic_write_barrier ();
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in_flight_stack = 0;
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}
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static void
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stack_list_add (list_t *elem, list_t *list)
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{
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in_flight_stack = (uintptr_t) elem | 1;
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atomic_write_barrier ();
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list_add (elem, list);
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atomic_write_barrier ();
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in_flight_stack = 0;
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}
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/* We create a double linked list of all cache entries. Double linked
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because this allows removing entries from the end. */
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/* Get a stack frame from the cache. We have to match by size since
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some blocks might be too small or far too large. */
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static struct pthread *
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get_cached_stack (size_t *sizep, void **memp)
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{
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size_t size = *sizep;
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struct pthread *result = NULL;
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list_t *entry;
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lll_lock (stack_cache_lock, LLL_PRIVATE);
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/* Search the cache for a matching entry. We search for the
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smallest stack which has at least the required size. Note that
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in normal situations the size of all allocated stacks is the
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same. As the very least there are only a few different sizes.
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Therefore this loop will exit early most of the time with an
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exact match. */
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list_for_each (entry, &stack_cache)
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{
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struct pthread *curr;
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curr = list_entry (entry, struct pthread, list);
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if (FREE_P (curr) && curr->stackblock_size >= size)
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{
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if (curr->stackblock_size == size)
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{
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result = curr;
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break;
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}
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if (result == NULL
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|| result->stackblock_size > curr->stackblock_size)
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result = curr;
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}
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}
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if (__builtin_expect (result == NULL, 0)
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/* Make sure the size difference is not too excessive. In that
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case we do not use the block. */
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|| __builtin_expect (result->stackblock_size > 4 * size, 0))
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{
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/* Release the lock. */
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lll_unlock (stack_cache_lock, LLL_PRIVATE);
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return NULL;
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}
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/* Don't allow setxid until cloned. */
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result->setxid_futex = -1;
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/* Dequeue the entry. */
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stack_list_del (&result->list);
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/* And add to the list of stacks in use. */
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stack_list_add (&result->list, &stack_used);
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/* And decrease the cache size. */
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stack_cache_actsize -= result->stackblock_size;
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/* Release the lock early. */
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lll_unlock (stack_cache_lock, LLL_PRIVATE);
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/* Report size and location of the stack to the caller. */
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*sizep = result->stackblock_size;
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*memp = result->stackblock;
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/* Cancellation handling is back to the default. */
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result->cancelhandling = 0;
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result->cleanup = NULL;
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/* No pending event. */
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result->nextevent = NULL;
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/* Clear the DTV. */
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dtv_t *dtv = GET_DTV (TLS_TPADJ (result));
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for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt)
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free (dtv[1 + cnt].pointer.to_free);
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memset (dtv, '\0', (dtv[-1].counter + 1) * sizeof (dtv_t));
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/* Re-initialize the TLS. */
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_dl_allocate_tls_init (TLS_TPADJ (result));
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return result;
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}
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/* Free stacks until cache size is lower than LIMIT. */
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static void
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free_stacks (size_t limit)
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{
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/* We reduce the size of the cache. Remove the last entries until
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the size is below the limit. */
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list_t *entry;
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list_t *prev;
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/* Search from the end of the list. */
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list_for_each_prev_safe (entry, prev, &stack_cache)
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{
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struct pthread *curr;
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curr = list_entry (entry, struct pthread, list);
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if (FREE_P (curr))
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{
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/* Unlink the block. */
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stack_list_del (entry);
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/* Account for the freed memory. */
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stack_cache_actsize -= curr->stackblock_size;
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/* Free the memory associated with the ELF TLS. */
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_dl_deallocate_tls (TLS_TPADJ (curr), false);
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/* Remove this block. This should never fail. If it does
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something is really wrong. */
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if (__munmap (curr->stackblock, curr->stackblock_size) != 0)
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abort ();
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/* Maybe we have freed enough. */
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if (stack_cache_actsize <= limit)
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break;
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}
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}
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}
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/* Free all the stacks on cleanup. */
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void
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__nptl_stacks_freeres (void)
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{
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free_stacks (0);
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}
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/* Add a stack frame which is not used anymore to the stack. Must be
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called with the cache lock held. */
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static inline void
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__attribute ((always_inline))
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queue_stack (struct pthread *stack)
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{
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/* We unconditionally add the stack to the list. The memory may
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still be in use but it will not be reused until the kernel marks
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the stack as not used anymore. */
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stack_list_add (&stack->list, &stack_cache);
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stack_cache_actsize += stack->stackblock_size;
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if (__glibc_unlikely (stack_cache_actsize > stack_cache_maxsize))
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free_stacks (stack_cache_maxsize);
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}
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static int
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change_stack_perm (struct pthread *pd
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#ifdef NEED_SEPARATE_REGISTER_STACK
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, size_t pagemask
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#endif
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)
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{
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#ifdef NEED_SEPARATE_REGISTER_STACK
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void *stack = (pd->stackblock
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+ (((((pd->stackblock_size - pd->guardsize) / 2)
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& pagemask) + pd->guardsize) & pagemask));
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size_t len = pd->stackblock + pd->stackblock_size - stack;
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#elif _STACK_GROWS_DOWN
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void *stack = pd->stackblock + pd->guardsize;
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size_t len = pd->stackblock_size - pd->guardsize;
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#elif _STACK_GROWS_UP
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void *stack = pd->stackblock;
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size_t len = (uintptr_t) pd - pd->guardsize - (uintptr_t) pd->stackblock;
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#else
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# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
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#endif
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if (__mprotect (stack, len, PROT_READ | PROT_WRITE | PROT_EXEC) != 0)
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return errno;
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return 0;
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}
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/* Return the guard page position on allocated stack. */
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static inline char *
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__attribute ((always_inline))
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guard_position (void *mem, size_t size, size_t guardsize, struct pthread *pd,
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size_t pagesize_m1)
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{
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#ifdef NEED_SEPARATE_REGISTER_STACK
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return mem + (((size - guardsize) / 2) & ~pagesize_m1);
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#elif _STACK_GROWS_DOWN
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return mem;
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#elif _STACK_GROWS_UP
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return (char *) (((uintptr_t) pd - guardsize) & ~pagesize_m1);
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#endif
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}
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/* Based on stack allocated with PROT_NONE, setup the required portions with
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'prot' flags based on the guard page position. */
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static inline int
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setup_stack_prot (char *mem, size_t size, char *guard, size_t guardsize,
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const int prot)
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{
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char *guardend = guard + guardsize;
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#if _STACK_GROWS_DOWN && !defined(NEED_SEPARATE_REGISTER_STACK)
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/* As defined at guard_position, for architectures with downward stack
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the guard page is always at start of the allocated area. */
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if (__mprotect (guardend, size - guardsize, prot) != 0)
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return errno;
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#else
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size_t mprots1 = (uintptr_t) guard - (uintptr_t) mem;
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if (__mprotect (mem, mprots1, prot) != 0)
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return errno;
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size_t mprots2 = ((uintptr_t) mem + size) - (uintptr_t) guardend;
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if (__mprotect (guardend, mprots2, prot) != 0)
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return errno;
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#endif
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return 0;
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}
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/* Mark the memory of the stack as usable to the kernel. It frees everything
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except for the space used for the TCB itself. */
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static inline void
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__always_inline
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advise_stack_range (void *mem, size_t size, uintptr_t pd, size_t guardsize)
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{
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uintptr_t sp = (uintptr_t) CURRENT_STACK_FRAME;
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size_t pagesize_m1 = __getpagesize () - 1;
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#if _STACK_GROWS_DOWN && !defined(NEED_SEPARATE_REGISTER_STACK)
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size_t freesize = (sp - (uintptr_t) mem) & ~pagesize_m1;
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assert (freesize < size);
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if (freesize > PTHREAD_STACK_MIN)
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__madvise (mem, freesize - PTHREAD_STACK_MIN, MADV_DONTNEED);
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#else
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/* Page aligned start of memory to free (higher than or equal
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to current sp plus the minimum stack size). */
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uintptr_t freeblock = (sp + PTHREAD_STACK_MIN + pagesize_m1) & ~pagesize_m1;
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uintptr_t free_end = (pd - guardsize) & ~pagesize_m1;
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if (free_end > freeblock)
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{
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size_t freesize = free_end - freeblock;
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assert (freesize < size);
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__madvise ((void*) freeblock, freesize, MADV_DONTNEED);
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}
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#endif
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}
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/* Returns a usable stack for a new thread either by allocating a
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new stack or reusing a cached stack of sufficient size.
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ATTR must be non-NULL and point to a valid pthread_attr.
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PDP must be non-NULL. */
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static int
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allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
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ALLOCATE_STACK_PARMS)
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{
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struct pthread *pd;
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size_t size;
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size_t pagesize_m1 = __getpagesize () - 1;
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assert (powerof2 (pagesize_m1 + 1));
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assert (TCB_ALIGNMENT >= STACK_ALIGN);
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/* Get the stack size from the attribute if it is set. Otherwise we
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use the default we determined at start time. */
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if (attr->stacksize != 0)
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size = attr->stacksize;
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else
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{
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lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
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size = __default_pthread_attr.stacksize;
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lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
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}
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/* Get memory for the stack. */
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if (__glibc_unlikely (attr->flags & ATTR_FLAG_STACKADDR))
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{
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uintptr_t adj;
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char *stackaddr = (char *) attr->stackaddr;
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/* Assume the same layout as the _STACK_GROWS_DOWN case, with struct
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pthread at the top of the stack block. Later we adjust the guard
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location and stack address to match the _STACK_GROWS_UP case. */
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if (_STACK_GROWS_UP)
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stackaddr += attr->stacksize;
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/* If the user also specified the size of the stack make sure it
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is large enough. */
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if (attr->stacksize != 0
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&& attr->stacksize < (__static_tls_size + MINIMAL_REST_STACK))
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return EINVAL;
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/* Adjust stack size for alignment of the TLS block. */
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#if TLS_TCB_AT_TP
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adj = ((uintptr_t) stackaddr - TLS_TCB_SIZE)
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& __static_tls_align_m1;
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assert (size > adj + TLS_TCB_SIZE);
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#elif TLS_DTV_AT_TP
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adj = ((uintptr_t) stackaddr - __static_tls_size)
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& __static_tls_align_m1;
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assert (size > adj);
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#endif
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/* The user provided some memory. Let's hope it matches the
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size... We do not allocate guard pages if the user provided
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the stack. It is the user's responsibility to do this if it
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is wanted. */
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#if TLS_TCB_AT_TP
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pd = (struct pthread *) ((uintptr_t) stackaddr
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- TLS_TCB_SIZE - adj);
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#elif TLS_DTV_AT_TP
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pd = (struct pthread *) (((uintptr_t) stackaddr
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- __static_tls_size - adj)
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- TLS_PRE_TCB_SIZE);
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#endif
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/* The user provided stack memory needs to be cleared. */
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memset (pd, '\0', sizeof (struct pthread));
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/* The first TSD block is included in the TCB. */
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pd->specific[0] = pd->specific_1stblock;
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/* Remember the stack-related values. */
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pd->stackblock = (char *) stackaddr - size;
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pd->stackblock_size = size;
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/* This is a user-provided stack. It will not be queued in the
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stack cache nor will the memory (except the TLS memory) be freed. */
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pd->user_stack = true;
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/* This is at least the second thread. */
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pd->header.multiple_threads = 1;
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#ifndef TLS_MULTIPLE_THREADS_IN_TCB
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__pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
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#endif
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#ifdef NEED_DL_SYSINFO
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SETUP_THREAD_SYSINFO (pd);
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#endif
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/* Don't allow setxid until cloned. */
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|
pd->setxid_futex = -1;
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/* Allocate the DTV for this thread. */
|
|
if (_dl_allocate_tls (TLS_TPADJ (pd)) == NULL)
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{
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|
/* Something went wrong. */
|
|
assert (errno == ENOMEM);
|
|
return errno;
|
|
}
|
|
|
|
|
|
/* Prepare to modify global data. */
|
|
lll_lock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
/* And add to the list of stacks in use. */
|
|
list_add (&pd->list, &__stack_user);
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
}
|
|
else
|
|
{
|
|
/* Allocate some anonymous memory. If possible use the cache. */
|
|
size_t guardsize;
|
|
size_t reqsize;
|
|
void *mem;
|
|
const int prot = (PROT_READ | PROT_WRITE
|
|
| ((GL(dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
|
|
|
|
/* Adjust the stack size for alignment. */
|
|
size &= ~__static_tls_align_m1;
|
|
assert (size != 0);
|
|
|
|
/* Make sure the size of the stack is enough for the guard and
|
|
eventually the thread descriptor. */
|
|
guardsize = (attr->guardsize + pagesize_m1) & ~pagesize_m1;
|
|
if (guardsize < attr->guardsize || size + guardsize < guardsize)
|
|
/* Arithmetic overflow. */
|
|
return EINVAL;
|
|
size += guardsize;
|
|
if (__builtin_expect (size < ((guardsize + __static_tls_size
|
|
+ MINIMAL_REST_STACK + pagesize_m1)
|
|
& ~pagesize_m1),
|
|
0))
|
|
/* The stack is too small (or the guard too large). */
|
|
return EINVAL;
|
|
|
|
/* Try to get a stack from the cache. */
|
|
reqsize = size;
|
|
pd = get_cached_stack (&size, &mem);
|
|
if (pd == NULL)
|
|
{
|
|
/* To avoid aliasing effects on a larger scale than pages we
|
|
adjust the allocated stack size if necessary. This way
|
|
allocations directly following each other will not have
|
|
aliasing problems. */
|
|
#if MULTI_PAGE_ALIASING != 0
|
|
if ((size % MULTI_PAGE_ALIASING) == 0)
|
|
size += pagesize_m1 + 1;
|
|
#endif
|
|
|
|
/* If a guard page is required, avoid committing memory by first
|
|
allocate with PROT_NONE and then reserve with required permission
|
|
excluding the guard page. */
|
|
mem = __mmap (NULL, size, (guardsize == 0) ? prot : PROT_NONE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
|
|
|
|
if (__glibc_unlikely (mem == MAP_FAILED))
|
|
return errno;
|
|
|
|
/* SIZE is guaranteed to be greater than zero.
|
|
So we can never get a null pointer back from mmap. */
|
|
assert (mem != NULL);
|
|
|
|
/* Place the thread descriptor at the end of the stack. */
|
|
#if TLS_TCB_AT_TP
|
|
pd = (struct pthread *) ((char *) mem + size) - 1;
|
|
#elif TLS_DTV_AT_TP
|
|
pd = (struct pthread *) ((((uintptr_t) mem + size
|
|
- __static_tls_size)
|
|
& ~__static_tls_align_m1)
|
|
- TLS_PRE_TCB_SIZE);
|
|
#endif
|
|
|
|
/* Now mprotect the required region excluding the guard area. */
|
|
if (__glibc_likely (guardsize > 0))
|
|
{
|
|
char *guard = guard_position (mem, size, guardsize, pd,
|
|
pagesize_m1);
|
|
if (setup_stack_prot (mem, size, guard, guardsize, prot) != 0)
|
|
{
|
|
__munmap (mem, size);
|
|
return errno;
|
|
}
|
|
}
|
|
|
|
/* Remember the stack-related values. */
|
|
pd->stackblock = mem;
|
|
pd->stackblock_size = size;
|
|
/* Update guardsize for newly allocated guardsize to avoid
|
|
an mprotect in guard resize below. */
|
|
pd->guardsize = guardsize;
|
|
|
|
/* We allocated the first block thread-specific data array.
|
|
This address will not change for the lifetime of this
|
|
descriptor. */
|
|
pd->specific[0] = pd->specific_1stblock;
|
|
|
|
/* This is at least the second thread. */
|
|
pd->header.multiple_threads = 1;
|
|
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
|
|
__pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
|
|
#endif
|
|
|
|
#ifdef NEED_DL_SYSINFO
|
|
SETUP_THREAD_SYSINFO (pd);
|
|
#endif
|
|
|
|
/* Don't allow setxid until cloned. */
|
|
pd->setxid_futex = -1;
|
|
|
|
/* Allocate the DTV for this thread. */
|
|
if (_dl_allocate_tls (TLS_TPADJ (pd)) == NULL)
|
|
{
|
|
/* Something went wrong. */
|
|
assert (errno == ENOMEM);
|
|
|
|
/* Free the stack memory we just allocated. */
|
|
(void) __munmap (mem, size);
|
|
|
|
return errno;
|
|
}
|
|
|
|
|
|
/* Prepare to modify global data. */
|
|
lll_lock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
/* And add to the list of stacks in use. */
|
|
stack_list_add (&pd->list, &stack_used);
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
|
|
/* There might have been a race. Another thread might have
|
|
caused the stacks to get exec permission while this new
|
|
stack was prepared. Detect if this was possible and
|
|
change the permission if necessary. */
|
|
if (__builtin_expect ((GL(dl_stack_flags) & PF_X) != 0
|
|
&& (prot & PROT_EXEC) == 0, 0))
|
|
{
|
|
int err = change_stack_perm (pd
|
|
#ifdef NEED_SEPARATE_REGISTER_STACK
|
|
, ~pagesize_m1
|
|
#endif
|
|
);
|
|
if (err != 0)
|
|
{
|
|
/* Free the stack memory we just allocated. */
|
|
(void) __munmap (mem, size);
|
|
|
|
return err;
|
|
}
|
|
}
|
|
|
|
|
|
/* Note that all of the stack and the thread descriptor is
|
|
zeroed. This means we do not have to initialize fields
|
|
with initial value zero. This is specifically true for
|
|
the 'tid' field which is always set back to zero once the
|
|
stack is not used anymore and for the 'guardsize' field
|
|
which will be read next. */
|
|
}
|
|
|
|
/* Create or resize the guard area if necessary. */
|
|
if (__glibc_unlikely (guardsize > pd->guardsize))
|
|
{
|
|
char *guard = guard_position (mem, size, guardsize, pd,
|
|
pagesize_m1);
|
|
if (__mprotect (guard, guardsize, PROT_NONE) != 0)
|
|
{
|
|
mprot_error:
|
|
lll_lock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
/* Remove the thread from the list. */
|
|
stack_list_del (&pd->list);
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
/* Get rid of the TLS block we allocated. */
|
|
_dl_deallocate_tls (TLS_TPADJ (pd), false);
|
|
|
|
/* Free the stack memory regardless of whether the size
|
|
of the cache is over the limit or not. If this piece
|
|
of memory caused problems we better do not use it
|
|
anymore. Uh, and we ignore possible errors. There
|
|
is nothing we could do. */
|
|
(void) __munmap (mem, size);
|
|
|
|
return errno;
|
|
}
|
|
|
|
pd->guardsize = guardsize;
|
|
}
|
|
else if (__builtin_expect (pd->guardsize - guardsize > size - reqsize,
|
|
0))
|
|
{
|
|
/* The old guard area is too large. */
|
|
|
|
#ifdef NEED_SEPARATE_REGISTER_STACK
|
|
char *guard = mem + (((size - guardsize) / 2) & ~pagesize_m1);
|
|
char *oldguard = mem + (((size - pd->guardsize) / 2) & ~pagesize_m1);
|
|
|
|
if (oldguard < guard
|
|
&& __mprotect (oldguard, guard - oldguard, prot) != 0)
|
|
goto mprot_error;
|
|
|
|
if (__mprotect (guard + guardsize,
|
|
oldguard + pd->guardsize - guard - guardsize,
|
|
prot) != 0)
|
|
goto mprot_error;
|
|
#elif _STACK_GROWS_DOWN
|
|
if (__mprotect ((char *) mem + guardsize, pd->guardsize - guardsize,
|
|
prot) != 0)
|
|
goto mprot_error;
|
|
#elif _STACK_GROWS_UP
|
|
char *new_guard = (char *)(((uintptr_t) pd - guardsize)
|
|
& ~pagesize_m1);
|
|
char *old_guard = (char *)(((uintptr_t) pd - pd->guardsize)
|
|
& ~pagesize_m1);
|
|
/* The guard size difference might be > 0, but once rounded
|
|
to the nearest page the size difference might be zero. */
|
|
if (new_guard > old_guard
|
|
&& __mprotect (old_guard, new_guard - old_guard, prot) != 0)
|
|
goto mprot_error;
|
|
#endif
|
|
|
|
pd->guardsize = guardsize;
|
|
}
|
|
/* The pthread_getattr_np() calls need to get passed the size
|
|
requested in the attribute, regardless of how large the
|
|
actually used guardsize is. */
|
|
pd->reported_guardsize = guardsize;
|
|
}
|
|
|
|
/* Initialize the lock. We have to do this unconditionally since the
|
|
stillborn thread could be canceled while the lock is taken. */
|
|
pd->lock = LLL_LOCK_INITIALIZER;
|
|
|
|
/* The robust mutex lists also need to be initialized
|
|
unconditionally because the cleanup for the previous stack owner
|
|
might have happened in the kernel. */
|
|
pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
|
|
- offsetof (pthread_mutex_t,
|
|
__data.__list.__next));
|
|
pd->robust_head.list_op_pending = NULL;
|
|
#if __PTHREAD_MUTEX_HAVE_PREV
|
|
pd->robust_prev = &pd->robust_head;
|
|
#endif
|
|
pd->robust_head.list = &pd->robust_head;
|
|
|
|
/* We place the thread descriptor at the end of the stack. */
|
|
*pdp = pd;
|
|
|
|
#if _STACK_GROWS_DOWN
|
|
void *stacktop;
|
|
|
|
# if TLS_TCB_AT_TP
|
|
/* The stack begins before the TCB and the static TLS block. */
|
|
stacktop = ((char *) (pd + 1) - __static_tls_size);
|
|
# elif TLS_DTV_AT_TP
|
|
stacktop = (char *) (pd - 1);
|
|
# endif
|
|
|
|
# ifdef NEED_SEPARATE_REGISTER_STACK
|
|
*stack = pd->stackblock;
|
|
*stacksize = stacktop - *stack;
|
|
# else
|
|
*stack = stacktop;
|
|
# endif
|
|
#else
|
|
*stack = pd->stackblock;
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
void
|
|
__deallocate_stack (struct pthread *pd)
|
|
{
|
|
lll_lock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
/* Remove the thread from the list of threads with user defined
|
|
stacks. */
|
|
stack_list_del (&pd->list);
|
|
|
|
/* Not much to do. Just free the mmap()ed memory. Note that we do
|
|
not reset the 'used' flag in the 'tid' field. This is done by
|
|
the kernel. If no thread has been created yet this field is
|
|
still zero. */
|
|
if (__glibc_likely (! pd->user_stack))
|
|
(void) queue_stack (pd);
|
|
else
|
|
/* Free the memory associated with the ELF TLS. */
|
|
_dl_deallocate_tls (TLS_TPADJ (pd), false);
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
}
|
|
|
|
|
|
int
|
|
__make_stacks_executable (void **stack_endp)
|
|
{
|
|
/* First the main thread's stack. */
|
|
int err = _dl_make_stack_executable (stack_endp);
|
|
if (err != 0)
|
|
return err;
|
|
|
|
#ifdef NEED_SEPARATE_REGISTER_STACK
|
|
const size_t pagemask = ~(__getpagesize () - 1);
|
|
#endif
|
|
|
|
lll_lock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
list_t *runp;
|
|
list_for_each (runp, &stack_used)
|
|
{
|
|
err = change_stack_perm (list_entry (runp, struct pthread, list)
|
|
#ifdef NEED_SEPARATE_REGISTER_STACK
|
|
, pagemask
|
|
#endif
|
|
);
|
|
if (err != 0)
|
|
break;
|
|
}
|
|
|
|
/* Also change the permission for the currently unused stacks. This
|
|
might be wasted time but better spend it here than adding a check
|
|
in the fast path. */
|
|
if (err == 0)
|
|
list_for_each (runp, &stack_cache)
|
|
{
|
|
err = change_stack_perm (list_entry (runp, struct pthread, list)
|
|
#ifdef NEED_SEPARATE_REGISTER_STACK
|
|
, pagemask
|
|
#endif
|
|
);
|
|
if (err != 0)
|
|
break;
|
|
}
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
return err;
|
|
}
|
|
|
|
|
|
/* In case of a fork() call the memory allocation in the child will be
|
|
the same but only one thread is running. All stacks except that of
|
|
the one running thread are not used anymore. We have to recycle
|
|
them. */
|
|
void
|
|
__reclaim_stacks (void)
|
|
{
|
|
struct pthread *self = (struct pthread *) THREAD_SELF;
|
|
|
|
/* No locking necessary. The caller is the only stack in use. But
|
|
we have to be aware that we might have interrupted a list
|
|
operation. */
|
|
|
|
if (in_flight_stack != 0)
|
|
{
|
|
bool add_p = in_flight_stack & 1;
|
|
list_t *elem = (list_t *) (in_flight_stack & ~(uintptr_t) 1);
|
|
|
|
if (add_p)
|
|
{
|
|
/* We always add at the beginning of the list. So in this case we
|
|
only need to check the beginning of these lists to see if the
|
|
pointers at the head of the list are inconsistent. */
|
|
list_t *l = NULL;
|
|
|
|
if (stack_used.next->prev != &stack_used)
|
|
l = &stack_used;
|
|
else if (stack_cache.next->prev != &stack_cache)
|
|
l = &stack_cache;
|
|
|
|
if (l != NULL)
|
|
{
|
|
assert (l->next->prev == elem);
|
|
elem->next = l->next;
|
|
elem->prev = l;
|
|
l->next = elem;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* We can simply always replay the delete operation. */
|
|
elem->next->prev = elem->prev;
|
|
elem->prev->next = elem->next;
|
|
}
|
|
}
|
|
|
|
/* Mark all stacks except the still running one as free. */
|
|
list_t *runp;
|
|
list_for_each (runp, &stack_used)
|
|
{
|
|
struct pthread *curp = list_entry (runp, struct pthread, list);
|
|
if (curp != self)
|
|
{
|
|
/* This marks the stack as free. */
|
|
curp->tid = 0;
|
|
|
|
/* Account for the size of the stack. */
|
|
stack_cache_actsize += curp->stackblock_size;
|
|
|
|
if (curp->specific_used)
|
|
{
|
|
/* Clear the thread-specific data. */
|
|
memset (curp->specific_1stblock, '\0',
|
|
sizeof (curp->specific_1stblock));
|
|
|
|
curp->specific_used = false;
|
|
|
|
for (size_t cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
|
|
if (curp->specific[cnt] != NULL)
|
|
{
|
|
memset (curp->specific[cnt], '\0',
|
|
sizeof (curp->specific_1stblock));
|
|
|
|
/* We have allocated the block which we do not
|
|
free here so re-set the bit. */
|
|
curp->specific_used = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Add the stack of all running threads to the cache. */
|
|
list_splice (&stack_used, &stack_cache);
|
|
|
|
/* Remove the entry for the current thread to from the cache list
|
|
and add it to the list of running threads. Which of the two
|
|
lists is decided by the user_stack flag. */
|
|
stack_list_del (&self->list);
|
|
|
|
/* Re-initialize the lists for all the threads. */
|
|
INIT_LIST_HEAD (&stack_used);
|
|
INIT_LIST_HEAD (&__stack_user);
|
|
|
|
if (__glibc_unlikely (THREAD_GETMEM (self, user_stack)))
|
|
list_add (&self->list, &__stack_user);
|
|
else
|
|
list_add (&self->list, &stack_used);
|
|
|
|
/* There is one thread running. */
|
|
__nptl_nthreads = 1;
|
|
|
|
in_flight_stack = 0;
|
|
|
|
/* Initialize locks. */
|
|
stack_cache_lock = LLL_LOCK_INITIALIZER;
|
|
__default_pthread_attr_lock = LLL_LOCK_INITIALIZER;
|
|
}
|
|
|
|
|
|
#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)
|
|
{
|
|
int ch;
|
|
|
|
/* Wait until this thread is cloned. */
|
|
if (t->setxid_futex == -1
|
|
&& ! atomic_compare_and_exchange_bool_acq (&t->setxid_futex, -2, -1))
|
|
do
|
|
futex_wait_simple (&t->setxid_futex, -2, FUTEX_PRIVATE);
|
|
while (t->setxid_futex == -2);
|
|
|
|
/* Don't let the thread exit before the setxid handler runs. */
|
|
t->setxid_futex = 0;
|
|
|
|
do
|
|
{
|
|
ch = t->cancelhandling;
|
|
|
|
/* If the thread is exiting right now, ignore it. */
|
|
if ((ch & EXITING_BITMASK) != 0)
|
|
{
|
|
/* Release the futex if there is no other setxid in
|
|
progress. */
|
|
if ((ch & SETXID_BITMASK) == 0)
|
|
{
|
|
t->setxid_futex = 1;
|
|
futex_wake (&t->setxid_futex, 1, FUTEX_PRIVATE);
|
|
}
|
|
return;
|
|
}
|
|
}
|
|
while (atomic_compare_and_exchange_bool_acq (&t->cancelhandling,
|
|
ch | SETXID_BITMASK, ch));
|
|
}
|
|
|
|
|
|
static void
|
|
setxid_unmark_thread (struct xid_command *cmdp, struct pthread *t)
|
|
{
|
|
int ch;
|
|
|
|
do
|
|
{
|
|
ch = t->cancelhandling;
|
|
if ((ch & SETXID_BITMASK) == 0)
|
|
return;
|
|
}
|
|
while (atomic_compare_and_exchange_bool_acq (&t->cancelhandling,
|
|
ch & ~SETXID_BITMASK, ch));
|
|
|
|
/* Release the futex just in case. */
|
|
t->setxid_futex = 1;
|
|
futex_wake (&t->setxid_futex, 1, FUTEX_PRIVATE);
|
|
}
|
|
|
|
|
|
static int
|
|
setxid_signal_thread (struct xid_command *cmdp, struct pthread *t)
|
|
{
|
|
if ((t->cancelhandling & SETXID_BITMASK) == 0)
|
|
return 0;
|
|
|
|
int val;
|
|
pid_t pid = __getpid ();
|
|
INTERNAL_SYSCALL_DECL (err);
|
|
val = INTERNAL_SYSCALL_CALL (tgkill, err, pid, t->tid, SIGSETXID);
|
|
|
|
/* If this failed, it must have had not started yet or else exited. */
|
|
if (!INTERNAL_SYSCALL_ERROR_P (val, err))
|
|
{
|
|
atomic_increment (&cmdp->cntr);
|
|
return 1;
|
|
}
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
/* Check for consistency across set*id system call results. The abort
|
|
should not happen as long as all privileges changes happen through
|
|
the glibc wrappers. ERROR must be 0 (no error) or an errno
|
|
code. */
|
|
void
|
|
attribute_hidden
|
|
__nptl_setxid_error (struct xid_command *cmdp, int error)
|
|
{
|
|
do
|
|
{
|
|
int olderror = cmdp->error;
|
|
if (olderror == error)
|
|
break;
|
|
if (olderror != -1)
|
|
{
|
|
/* Mismatch between current and previous results. Save the
|
|
error value to memory so that is not clobbered by the
|
|
abort function and preserved in coredumps. */
|
|
volatile int xid_err __attribute__((unused)) = error;
|
|
abort ();
|
|
}
|
|
}
|
|
while (atomic_compare_and_exchange_bool_acq (&cmdp->error, error, -1));
|
|
}
|
|
|
|
int
|
|
attribute_hidden
|
|
__nptl_setxid (struct xid_command *cmdp)
|
|
{
|
|
int signalled;
|
|
int result;
|
|
lll_lock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
__xidcmd = cmdp;
|
|
cmdp->cntr = 0;
|
|
cmdp->error = -1;
|
|
|
|
struct pthread *self = THREAD_SELF;
|
|
|
|
/* Iterate over the list with system-allocated threads first. */
|
|
list_t *runp;
|
|
list_for_each (runp, &stack_used)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self)
|
|
continue;
|
|
|
|
setxid_mark_thread (cmdp, t);
|
|
}
|
|
|
|
/* Now the list with threads using user-allocated stacks. */
|
|
list_for_each (runp, &__stack_user)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self)
|
|
continue;
|
|
|
|
setxid_mark_thread (cmdp, t);
|
|
}
|
|
|
|
/* Iterate until we don't succeed in signalling anyone. That means
|
|
we have gotten all running threads, and their children will be
|
|
automatically correct once started. */
|
|
do
|
|
{
|
|
signalled = 0;
|
|
|
|
list_for_each (runp, &stack_used)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self)
|
|
continue;
|
|
|
|
signalled += setxid_signal_thread (cmdp, t);
|
|
}
|
|
|
|
list_for_each (runp, &__stack_user)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self)
|
|
continue;
|
|
|
|
signalled += setxid_signal_thread (cmdp, t);
|
|
}
|
|
|
|
int cur = cmdp->cntr;
|
|
while (cur != 0)
|
|
{
|
|
futex_wait_simple ((unsigned int *) &cmdp->cntr, cur,
|
|
FUTEX_PRIVATE);
|
|
cur = cmdp->cntr;
|
|
}
|
|
}
|
|
while (signalled != 0);
|
|
|
|
/* Clean up flags, so that no thread blocks during exit waiting
|
|
for a signal which will never come. */
|
|
list_for_each (runp, &stack_used)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self)
|
|
continue;
|
|
|
|
setxid_unmark_thread (cmdp, t);
|
|
}
|
|
|
|
list_for_each (runp, &__stack_user)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self)
|
|
continue;
|
|
|
|
setxid_unmark_thread (cmdp, t);
|
|
}
|
|
|
|
/* This must be last, otherwise the current thread might not have
|
|
permissions to send SIGSETXID syscall to the other threads. */
|
|
INTERNAL_SYSCALL_DECL (err);
|
|
result = INTERNAL_SYSCALL_NCS (cmdp->syscall_no, err, 3,
|
|
cmdp->id[0], cmdp->id[1], cmdp->id[2]);
|
|
int error = 0;
|
|
if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
|
|
{
|
|
error = INTERNAL_SYSCALL_ERRNO (result, err);
|
|
__set_errno (error);
|
|
result = -1;
|
|
}
|
|
__nptl_setxid_error (cmdp, error);
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
return result;
|
|
}
|
|
#endif /* SIGSETXID. */
|
|
|
|
|
|
static inline void __attribute__((always_inline))
|
|
init_one_static_tls (struct pthread *curp, struct link_map *map)
|
|
{
|
|
# if TLS_TCB_AT_TP
|
|
void *dest = (char *) curp - map->l_tls_offset;
|
|
# elif TLS_DTV_AT_TP
|
|
void *dest = (char *) curp + map->l_tls_offset + TLS_PRE_TCB_SIZE;
|
|
# else
|
|
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
|
|
# endif
|
|
|
|
/* Initialize the memory. */
|
|
memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
|
|
'\0', map->l_tls_blocksize - map->l_tls_initimage_size);
|
|
}
|
|
|
|
void
|
|
attribute_hidden
|
|
__pthread_init_static_tls (struct link_map *map)
|
|
{
|
|
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)
|
|
init_one_static_tls (list_entry (runp, struct pthread, list), map);
|
|
|
|
/* Now the list with threads using user-allocated stacks. */
|
|
list_for_each (runp, &__stack_user)
|
|
init_one_static_tls (list_entry (runp, struct pthread, list), map);
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
}
|
|
|
|
|
|
void
|
|
attribute_hidden
|
|
__wait_lookup_done (void)
|
|
{
|
|
lll_lock (stack_cache_lock, LLL_PRIVATE);
|
|
|
|
struct pthread *self = THREAD_SELF;
|
|
|
|
/* Iterate over the list with system-allocated threads first. */
|
|
list_t *runp;
|
|
list_for_each (runp, &stack_used)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
|
|
continue;
|
|
|
|
int *const gscope_flagp = &t->header.gscope_flag;
|
|
|
|
/* We have to wait until this thread is done with the global
|
|
scope. First tell the thread that we are waiting and
|
|
possibly have to be woken. */
|
|
if (atomic_compare_and_exchange_bool_acq (gscope_flagp,
|
|
THREAD_GSCOPE_FLAG_WAIT,
|
|
THREAD_GSCOPE_FLAG_USED))
|
|
continue;
|
|
|
|
do
|
|
futex_wait_simple ((unsigned int *) gscope_flagp,
|
|
THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE);
|
|
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
|
|
}
|
|
|
|
/* Now the list with threads using user-allocated stacks. */
|
|
list_for_each (runp, &__stack_user)
|
|
{
|
|
struct pthread *t = list_entry (runp, struct pthread, list);
|
|
if (t == self || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
|
|
continue;
|
|
|
|
int *const gscope_flagp = &t->header.gscope_flag;
|
|
|
|
/* We have to wait until this thread is done with the global
|
|
scope. First tell the thread that we are waiting and
|
|
possibly have to be woken. */
|
|
if (atomic_compare_and_exchange_bool_acq (gscope_flagp,
|
|
THREAD_GSCOPE_FLAG_WAIT,
|
|
THREAD_GSCOPE_FLAG_USED))
|
|
continue;
|
|
|
|
do
|
|
futex_wait_simple ((unsigned int *) gscope_flagp,
|
|
THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE);
|
|
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
|
|
}
|
|
|
|
lll_unlock (stack_cache_lock, LLL_PRIVATE);
|
|
}
|