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Consolidate link map sorting 

Combine the four places where link maps are sorted into a single function.
This also moves the logic to skip the first map (representing the main
binary) to the callers.
This commit is contained in:
Andreas Schwab 2017-11-07 15:24:19 +01:00
parent de61465c04
commit c2c299fd24
8 changed files with 153 additions and 215 deletions
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13
ChangeLog
View File

@ -1,3 +1,16 @@
2017-11-27 Andreas Schwab <schwab@suse.de>
* elf/Makefile (dl-routines): Add dl-sort-maps.
* elf/dl-sort-maps.c: New file.
* sysdeps/generic/ldsodefs.h (_dl_sort_fini): Don't declare.
(_dl_sort_maps): Declare.
* elf/dl-fini.c (_dl_sort_fini): Remove.
(_dl_fini): Use _dl_sort_maps instead of _dl_sort_fini.
* elf/dl-close.c (_dl_close_worker): Likewise.
* elf/dl-deps.c (_dl_map_object_deps): Use _dl_sort_maps instead of
open-coding it.
* elf/dl-open.c (dl_open_worker): Likewise.
2017-11-24 Joseph Myers <joseph@codesourcery.com>
* sysdeps/ieee754/float128/s_fromfpf128.c (fromfpf128): Define

2
elf/Makefile
View File

@ -32,7 +32,7 @@ dl-routines = $(addprefix dl-,load lookup object reloc deps hwcaps \
runtime init fini debug misc \
version profile tls origin scope \
execstack caller open close trampoline \
exception)
exception sort-maps)
ifeq (yes,$(use-ldconfig))
dl-routines += dl-cache
endif

6
elf/dl-close.c
View File

@ -241,8 +241,10 @@ _dl_close_worker (struct link_map *map, bool force)
}
}
/* Sort the entries. */
_dl_sort_fini (maps, nloaded, used, nsid);
/* Sort the entries. We can skip looking for the binary itself which is
at the front of the search list for the main namespace. */
_dl_sort_maps (maps + (nsid == LM_ID_BASE), nloaded - (nsid == LM_ID_BASE),
used + (nsid == LM_ID_BASE), true);
/* Call all termination functions at once. */
#ifdef SHARED

59
elf/dl-deps.c
View File

@ -585,62 +585,9 @@ Filters not supported with LD_TRACE_PRELINKING"));
itself will always be initialize last. */
memcpy (l_initfini, map->l_searchlist.r_list,
nlist * sizeof (struct link_map *));
if (__glibc_likely (nlist > 1))
{
/* We can skip looking for the binary itself which is at the front
of the search list. */
i = 1;
uint16_t seen[nlist];
memset (seen, 0, nlist * sizeof (seen[0]));
while (1)
{
/* Keep track of which object we looked at this round. */
++seen[i];
struct link_map *thisp = l_initfini[i];
/* Find the last object in the list for which the current one is
a dependency and move the current object behind the object
with the dependency. */
unsigned int k = nlist - 1;
while (k > i)
{
struct link_map **runp = l_initfini[k]->l_initfini;
if (runp != NULL)
/* Look through the dependencies of the object. */
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == thisp))
{
/* Move the current object to the back past the last
object with it as the dependency. */
memmove (&l_initfini[i], &l_initfini[i + 1],
(k - i) * sizeof (l_initfini[0]));
l_initfini[k] = thisp;
if (seen[i + 1] > nlist - i)
{
++i;
goto next_clear;
}
uint16_t this_seen = seen[i];
memmove (&seen[i], &seen[i + 1],
(k - i) * sizeof (seen[0]));
seen[k] = this_seen;
goto next;
}
--k;
}
if (++i == nlist)
break;
next_clear:
memset (&seen[i], 0, (nlist - i) * sizeof (seen[0]));
next:;
}
}
/* We can skip looking for the binary itself which is at the front of
the search list. */
_dl_sort_maps (&l_initfini[1], nlist - 1, NULL, false);
/* Terminate the list of dependencies. */
l_initfini[nlist] = NULL;

105
elf/dl-fini.c
View File

@ -25,104 +25,6 @@
typedef void (*fini_t) (void);
void
_dl_sort_fini (struct link_map **maps, size_t nmaps, char *used, Lmid_t ns)
{
/* A list of one element need not be sorted. */
if (nmaps == 1)
return;
/* We can skip looking for the binary itself which is at the front
of the search list for the main namespace. */
unsigned int i = ns == LM_ID_BASE;
uint16_t seen[nmaps];
memset (seen, 0, nmaps * sizeof (seen[0]));
while (1)
{
/* Keep track of which object we looked at this round. */
++seen[i];
struct link_map *thisp = maps[i];
/* Do not handle ld.so in secondary namespaces and object which
are not removed. */
if (thisp != thisp->l_real || thisp->l_idx == -1)
goto skip;
/* Find the last object in the list for which the current one is
a dependency and move the current object behind the object
with the dependency. */
unsigned int k = nmaps - 1;
while (k > i)
{
struct link_map **runp = maps[k]->l_initfini;
if (runp != NULL)
/* Look through the dependencies of the object. */
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == thisp))
{
move:
/* Move the current object to the back past the last
object with it as the dependency. */
memmove (&maps[i], &maps[i + 1],
(k - i) * sizeof (maps[0]));
maps[k] = thisp;
if (used != NULL)
{
char here_used = used[i];
memmove (&used[i], &used[i + 1],
(k - i) * sizeof (used[0]));
used[k] = here_used;
}
if (seen[i + 1] > nmaps - i)
{
++i;
goto next_clear;
}
uint16_t this_seen = seen[i];
memmove (&seen[i], &seen[i + 1], (k - i) * sizeof (seen[0]));
seen[k] = this_seen;
goto next;
}
if (__glibc_unlikely (maps[k]->l_reldeps != NULL))
{
unsigned int m = maps[k]->l_reldeps->act;
struct link_map **relmaps = &maps[k]->l_reldeps->list[0];
/* Look through the relocation dependencies of the object. */
while (m-- > 0)
if (__glibc_unlikely (relmaps[m] == thisp))
{
/* If a cycle exists with a link time dependency,
preserve the latter. */
struct link_map **runp = thisp->l_initfini;
if (runp != NULL)
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == maps[k]))
goto ignore;
goto move;
}
ignore:;
}
--k;
}
skip:
if (++i == nmaps)
break;
next_clear:
memset (&seen[i], 0, (nmaps - i) * sizeof (seen[0]));
next:;
}
}
void
_dl_fini (void)
{
@ -186,8 +88,11 @@ _dl_fini (void)
assert (ns == LM_ID_BASE || i == nloaded || i == nloaded - 1);
unsigned int nmaps = i;
/* Now we have to do the sorting. */
_dl_sort_fini (maps, nmaps, NULL, ns);
/* Now we have to do the sorting. We can skip looking for the
binary itself which is at the front of the search list for
the main namespace. */
_dl_sort_maps (maps + (ns == LM_ID_BASE), nmaps - (ns == LM_ID_BASE),
NULL, true);
/* We do not rely on the linked list of loaded object anymore
from this point on. We have our own list here (maps). The

57
elf/dl-open.c
View File

@ -311,7 +311,7 @@ dl_open_worker (void *a)
/* Sort the objects by dependency for the relocation process. This
allows IFUNC relocations to work and it also means copy
relocation of dependencies are if necessary overwritten. */
size_t nmaps = 0;
unsigned int nmaps = 0;
struct link_map *l = new;
do
{
@ -330,62 +330,11 @@ dl_open_worker (void *a)
l = l->l_next;
}
while (l != NULL);
if (nmaps > 1)
{
uint16_t seen[nmaps];
memset (seen, '\0', sizeof (seen));
size_t i = 0;
while (1)
{
++seen[i];
struct link_map *thisp = maps[i];
/* Find the last object in the list for which the current one is
a dependency and move the current object behind the object
with the dependency. */
size_t k = nmaps - 1;
while (k > i)
{
struct link_map **runp = maps[k]->l_initfini;
if (runp != NULL)
/* Look through the dependencies of the object. */
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == thisp))
{
/* Move the current object to the back past the last
object with it as the dependency. */
memmove (&maps[i], &maps[i + 1],
(k - i) * sizeof (maps[0]));
maps[k] = thisp;
if (seen[i + 1] > nmaps - i)
{
++i;
goto next_clear;
}
uint16_t this_seen = seen[i];
memmove (&seen[i], &seen[i + 1],
(k - i) * sizeof (seen[0]));
seen[k] = this_seen;
goto next;
}
--k;
}
if (++i == nmaps)
break;
next_clear:
memset (&seen[i], 0, (nmaps - i) * sizeof (seen[0]));
next:;
}
}
_dl_sort_maps (maps, nmaps, NULL, false);
int relocation_in_progress = 0;
for (size_t i = nmaps; i-- > 0; )
for (unsigned int i = nmaps; i-- > 0; )
{
l = maps[i];

122
elf/dl-sort-maps.c Normal file
View File

@ -0,0 +1,122 @@
/* Sort array of link maps according to dependencies.
Copyright (C) 2017 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; if not, see
<http://www.gnu.org/licenses/>. */
#include <ldsodefs.h>
/* Sort array MAPS according to dependencies of the contained objects.
Array USED, if non-NULL, is permutated along MAPS. If FOR_FINI this is
called for finishing an object. */
void
_dl_sort_maps (struct link_map **maps, unsigned int nmaps, char *used,
bool for_fini)
{
/* A list of one element need not be sorted. */
if (nmaps <= 1)
return;
unsigned int i = 0;
uint16_t seen[nmaps];
memset (seen, 0, nmaps * sizeof (seen[0]));
while (1)
{
/* Keep track of which object we looked at this round. */
++seen[i];
struct link_map *thisp = maps[i];
if (__glibc_unlikely (for_fini))
{
/* Do not handle ld.so in secondary namespaces and objects which
are not removed. */
if (thisp != thisp->l_real || thisp->l_idx == -1)
goto skip;
}
/* Find the last object in the list for which the current one is
a dependency and move the current object behind the object
with the dependency. */
unsigned int k = nmaps - 1;
while (k > i)
{
struct link_map **runp = maps[k]->l_initfini;
if (runp != NULL)
/* Look through the dependencies of the object. */
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == thisp))
{
move:
/* Move the current object to the back past the last
object with it as the dependency. */
memmove (&maps[i], &maps[i + 1],
(k - i) * sizeof (maps[0]));
maps[k] = thisp;
if (used != NULL)
{
char here_used = used[i];
memmove (&used[i], &used[i + 1],
(k - i) * sizeof (used[0]));
used[k] = here_used;
}
if (seen[i + 1] > nmaps - i)
{
++i;
goto next_clear;
}
uint16_t this_seen = seen[i];
memmove (&seen[i], &seen[i + 1], (k - i) * sizeof (seen[0]));
seen[k] = this_seen;
goto next;
}
if (__glibc_unlikely (for_fini && maps[k]->l_reldeps != NULL))
{
unsigned int m = maps[k]->l_reldeps->act;
struct link_map **relmaps = &maps[k]->l_reldeps->list[0];
/* Look through the relocation dependencies of the object. */
while (m-- > 0)
if (__glibc_unlikely (relmaps[m] == thisp))
{
/* If a cycle exists with a link time dependency,
preserve the latter. */
struct link_map **runp = thisp->l_initfini;
if (runp != NULL)
while (*runp != NULL)
if (__glibc_unlikely (*runp++ == maps[k]))
goto ignore;
goto move;
}
ignore:;
}
--k;
}
skip:
if (++i == nmaps)
break;
next_clear:
memset (&seen[i], 0, (nmaps - i) * sizeof (seen[0]));
next:;
}
}

4
sysdeps/generic/ldsodefs.h
View File

@ -960,8 +960,8 @@ extern void _dl_init (struct link_map *main_map, int argc, char **argv,
extern void _dl_fini (void) attribute_hidden;
/* Sort array MAPS according to dependencies of the contained objects. */
extern void _dl_sort_fini (struct link_map **maps, size_t nmaps, char *used,
Lmid_t ns) attribute_hidden;
extern void _dl_sort_maps (struct link_map **maps, unsigned int nmaps,
char *used, bool for_fini) attribute_hidden;
/* The dynamic linker calls this function before and having changing
any shared object mappings. The `r_state' member of `struct r_debug'