From: Florian Weimer <fweimer@redhat.com>
To: libc-alpha@sourceware.org
Subject: [PATCH 19/33] elf: Move link map fields used by dependency sorting to writable part
Date: Tue, 04 Jul 2023 22:03:40 +0200 [thread overview]
Message-ID: <223ff5913a09884c48dc916dbe664735b4ef0eae.1688499219.git.fweimer@redhat.com> (raw)
In-Reply-To: <cover.1688499219.git.fweimer@redhat.com>
Currently, ld.so re-runs dependency sorting during process shutdown
in _dl_fini, instead of simply using the reverse initialization order.
This means that the l_idx and l_visited fields are written to. There
is no way to report errors during shutdown. If these fields are
always writable, this avoids the need to make link maps writable
during _dl_fini, avoiding the error reporting issue.
This commit can be reverted once we stop re-sorting dependencies
in _dl_fini.
---
elf/dl-close.c | 27 ++++++++++++++-------------
elf/dl-fini.c | 2 +-
elf/dl-sort-maps.c | 14 +++++++-------
include/link.h | 12 +++++++-----
4 files changed, 29 insertions(+), 26 deletions(-)
diff --git a/elf/dl-close.c b/elf/dl-close.c
index 4001475056..58a69f9b42 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -147,7 +147,7 @@ _dl_close_worker (struct link_map_private *map, bool force)
{
l->l_map_used = 0;
l->l_map_done = 0;
- l->l_idx = idx;
+ l->l_rw->l_idx = idx;
maps[idx] = l;
++idx;
}
@@ -177,7 +177,7 @@ _dl_close_worker (struct link_map_private *map, bool force)
l->l_map_used = 1;
l->l_map_done = 1;
/* Signal the object is still needed. */
- l->l_idx = IDX_STILL_USED;
+ l->l_rw->l_idx = IDX_STILL_USED;
/* Mark all dependencies as used. */
if (l->l_initfini != NULL)
@@ -187,9 +187,10 @@ _dl_close_worker (struct link_map_private *map, bool force)
struct link_map_private **lp = &l->l_initfini[1];
while (*lp != NULL)
{
- if ((*lp)->l_idx != IDX_STILL_USED)
+ if ((*lp)->l_rw->l_idx != IDX_STILL_USED)
{
- assert ((*lp)->l_idx >= 0 && (*lp)->l_idx < nloaded);
+ assert ((*lp)->l_rw->l_idx >= 0
+ && (*lp)->l_rw->l_idx < nloaded);
if (!(*lp)->l_map_used)
{
@@ -198,8 +199,8 @@ _dl_close_worker (struct link_map_private *map, bool force)
already processed it, then we need to go back
and process again from that point forward to
ensure we keep all of its dependencies also. */
- if ((*lp)->l_idx - 1 < done_index)
- done_index = (*lp)->l_idx - 1;
+ if ((*lp)->l_rw->l_idx - 1 < done_index)
+ done_index = (*lp)->l_rw->l_idx - 1;
}
}
@@ -212,15 +213,15 @@ _dl_close_worker (struct link_map_private *map, bool force)
{
struct link_map_private *jmap = l->l_rw->l_reldeps->list[j];
- if (jmap->l_idx != IDX_STILL_USED)
+ if (jmap->l_rw->l_idx != IDX_STILL_USED)
{
- assert (jmap->l_idx >= 0 && jmap->l_idx < nloaded);
+ assert (jmap->l_rw->l_idx >= 0 && jmap->l_rw->l_idx < nloaded);
if (!jmap->l_map_used)
{
jmap->l_map_used = 1;
- if (jmap->l_idx - 1 < done_index)
- done_index = jmap->l_idx - 1;
+ if (jmap->l_rw->l_idx - 1 < done_index)
+ done_index = jmap->l_rw->l_idx - 1;
}
}
}
@@ -310,7 +311,7 @@ _dl_close_worker (struct link_map_private *map, bool force)
((char *) imap->l_scope[cnt]
- offsetof (struct link_map_private, l_searchlist));
assert (tmap->l_ns == nsid);
- if (tmap->l_idx == IDX_STILL_USED)
+ if (tmap->l_rw->l_idx == IDX_STILL_USED)
++remain;
else
removed_any = true;
@@ -357,7 +358,7 @@ _dl_close_worker (struct link_map_private *map, bool force)
((char *) imap->l_scope[cnt]
- offsetof (struct link_map_private,
l_searchlist)));
- if (tmap->l_idx != IDX_STILL_USED)
+ if (tmap->l_rw->l_idx != IDX_STILL_USED)
{
/* Remove the scope. Or replace with own map's
scope. */
@@ -402,7 +403,7 @@ _dl_close_worker (struct link_map_private *map, bool force)
/* The loader is gone, so mark the object as not having one.
Note: l_idx != IDX_STILL_USED -> object will be removed. */
if (imap->l_loader != NULL
- && imap->l_loader->l_idx != IDX_STILL_USED)
+ && imap->l_loader->l_rw->l_idx != IDX_STILL_USED)
imap->l_loader = NULL;
/* Remember where the first dynamically loaded object is. */
diff --git a/elf/dl-fini.c b/elf/dl-fini.c
index 5c78159fee..2abd63cb08 100644
--- a/elf/dl-fini.c
+++ b/elf/dl-fini.c
@@ -77,7 +77,7 @@ _dl_fini (void)
assert (i < nloaded);
maps[i] = l;
- l->l_idx = i;
+ l->l_rw->l_idx = i;
++i;
/* Bump l_direct_opencount of all objects so that they
diff --git a/elf/dl-sort-maps.c b/elf/dl-sort-maps.c
index bc0801d8a5..f2aa2213d7 100644
--- a/elf/dl-sort-maps.c
+++ b/elf/dl-sort-maps.c
@@ -51,7 +51,7 @@ _dl_sort_maps_original (struct link_map_private **maps, unsigned int nmaps,
{
/* Do not handle ld.so in secondary namespaces and objects which
are not removed. */
- if (thisp != thisp->l_real || thisp->l_idx == -1)
+ if (thisp != thisp->l_real || thisp->l_rw->l_idx == -1)
goto skip;
}
@@ -138,17 +138,17 @@ dfs_traversal (struct link_map_private ***rpo, struct link_map_private *map,
{
/* _dl_map_object_deps ignores l_faked objects when calculating the
number of maps before calling _dl_sort_maps, ignore them as well. */
- if (map->l_visited || map->l_faked)
+ if (map->l_rw->l_visited || map->l_faked)
return;
- map->l_visited = 1;
+ map->l_rw->l_visited = 1;
if (map->l_initfini)
{
for (int i = 0; map->l_initfini[i] != NULL; i++)
{
struct link_map_private *dep = map->l_initfini[i];
- if (dep->l_visited == 0
+ if (dep->l_rw->l_visited == 0
&& dep->l_main_map == 0)
dfs_traversal (rpo, dep, do_reldeps);
}
@@ -163,7 +163,7 @@ dfs_traversal (struct link_map_private ***rpo, struct link_map_private *map,
for (int m = map->l_rw->l_reldeps->act - 1; m >= 0; m--)
{
struct link_map_private *dep = map->l_rw->l_reldeps->list[m];
- if (dep->l_visited == 0
+ if (dep->l_rw->l_visited == 0
&& dep->l_main_map == 0)
dfs_traversal (rpo, dep, do_reldeps);
}
@@ -182,7 +182,7 @@ _dl_sort_maps_dfs (struct link_map_private **maps, unsigned int nmaps,
{
struct link_map_private *first_map = maps[0];
for (int i = nmaps - 1; i >= 0; i--)
- maps[i]->l_visited = 0;
+ maps[i]->l_rw->l_visited = 0;
/* We apply DFS traversal for each of maps[i] until the whole total order
is found and we're at the start of the Reverse-Postorder (RPO) sequence,
@@ -245,7 +245,7 @@ _dl_sort_maps_dfs (struct link_map_private **maps, unsigned int nmaps,
if (do_reldeps)
{
for (int i = nmaps - 1; i >= 0; i--)
- rpo[i]->l_visited = 0;
+ rpo[i]->l_rw->l_visited = 0;
struct link_map_private **maps_head = &maps[nmaps];
for (int i = nmaps - 1; i >= 0; i--)
diff --git a/include/link.h b/include/link.h
index 181cd2e444..a53c652941 100644
--- a/include/link.h
+++ b/include/link.h
@@ -132,6 +132,13 @@ struct link_map_rw
ignored. */
bool l_nodelete_active;
bool l_nodelete_pending;
+
+ /* Used for dependency sorting in dlclose/_dl_fini. These need to
+ be writable all the time because there is no way to report an
+ error in _dl_fini. These flags can be moved into struct
+ link_map_private once _dl_fini no longer re-sorts link maps. */
+ bool l_visited;
+ int l_idx;
};
/* Structure describing a loaded shared object. The `l_next' and `l_prev'
@@ -231,8 +238,6 @@ struct link_map_private
unsigned int l_global:1; /* Nonzero if object in _dl_global_scope. */
unsigned int l_reserved:2; /* Reserved for internal use. */
unsigned int l_main_map:1; /* Nonzero for the map of the main program. */
- unsigned int l_visited:1; /* Used internally for map dependency
- graph traversal. */
unsigned int l_map_used:1; /* These two bits are used during traversal */
unsigned int l_map_done:1; /* of maps in _dl_close_worker. */
unsigned int l_phdr_allocated:1; /* Nonzero if the data structure pointed
@@ -321,9 +326,6 @@ struct link_map_private
ElfW(Word) l_flags_1;
ElfW(Word) l_flags;
- /* Temporarily used in `dl_close'. */
- int l_idx;
-
struct link_map_machine l_mach;
struct
--
2.41.0
next prev parent reply other threads:[~2023-07-04 20:03 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-04 20:02 [PATCH 00/33] RFC: RELRO link maps Florian Weimer
2023-07-04 20:02 ` [PATCH 01/33] support: Add <support/memprobe.h> for protection flags probing Florian Weimer
2023-07-04 20:02 ` [PATCH 02/33] misc: Enable internal use of memory protection keys Florian Weimer
2023-07-04 20:02 ` [PATCH 03/33] elf: Remove _dl_sysdep_open_object hook function Florian Weimer
2023-07-04 20:02 ` [PATCH 04/33] elf: Eliminate second loop in find_version in dl-version.c Florian Weimer
2023-07-04 20:02 ` [PATCH 05/33] elf: In rtld_setup_main_map, assume ld.so has a DYNAMIC segment Florian Weimer
2023-07-04 20:02 ` [PATCH 06/33] elf: Remove version assert in check_match in elf/dl-lookup.c Florian Weimer
2023-07-04 20:02 ` [PATCH 07/33] elf: Disambiguate some failures in _dl_load_cache_lookup Florian Weimer
2023-07-04 20:02 ` [PATCH 08/33] elf: Eliminate alloca in open_verify Florian Weimer
2023-07-04 20:02 ` [PATCH 09/33] Do not export <alloc_buffer.h> functions from libc Florian Weimer
2023-07-04 20:02 ` [PATCH 10/33] elf: Make <alloc_buffer.h> usable in ld.so Florian Weimer
2023-07-04 20:03 ` [PATCH 11/33] elf: Merge the three implementations of _dl_dst_substitute Florian Weimer
2023-07-04 20:03 ` [PATCH 12/33] elf: _dl_find_object may return 1 during early startup (bug 30515) Florian Weimer
2023-07-04 20:03 ` [PATCH 13/33] elf: Move __rtld_malloc_init_stubs call into _dl_start_final Florian Weimer
2023-07-04 20:03 ` [PATCH 14/33] elf: Merge __dl_libc_freemem into __rtld_libc_freeres Florian Weimer
2023-07-04 20:03 ` [PATCH 15/33] elf: Use struct link_map_private for the internal link map Florian Weimer
2023-07-04 20:03 ` [PATCH 16/33] elf: Remove run-time-writable fields from struct link_map_private Florian Weimer
2023-07-04 20:03 ` [PATCH 17/33] elf: Move l_tls_offset into read-write part of link map Florian Weimer
2023-07-04 20:03 ` [PATCH 18/33] elf: Allocate auditor state after read-write " Florian Weimer
2023-07-04 20:03 ` Florian Weimer [this message]
2023-07-04 20:03 ` [PATCH 20/33] elf: Split _dl_lookup_map, _dl_map_new_object from _dl_map_object Florian Weimer
2023-07-04 20:03 ` [PATCH 21/33] elf: Add l_soname accessor function for DT_SONAME values Florian Weimer
2023-07-04 20:03 ` [PATCH 22/33] elf: _dl_rtld_map should not exist in static builds Florian Weimer
2023-07-04 20:03 ` [PATCH 23/33] elf: Introduce GLPM accessor for the protected memory area Florian Weimer
2023-07-04 20:04 ` [PATCH 24/33] elf: Bootstrap allocation for future protected memory allocator Florian Weimer
2023-07-04 20:04 ` [PATCH 25/33] elf: Implement a basic " Florian Weimer
2023-07-04 20:04 ` [PATCH 26/33] elf: Move most of the _dl_find_object data to the protected heap Florian Weimer
2023-07-04 20:04 ` [PATCH 27/33] elf: Switch to a region-based protected memory allocator Florian Weimer
2023-07-04 20:04 ` [PATCH 28/33] elf: Determine the caller link map in _dl_open Florian Weimer
2023-07-04 20:04 ` [PATCH 29/33] elf: Add fast path to dlopen for fully-opened maps Florian Weimer
2023-07-04 20:04 ` [PATCH 30/33] elf: Use _dl_find_object instead of _dl_find_dso_for_object in dlopen Florian Weimer
2023-07-04 20:04 ` [PATCH 31/33] elf: Put critical _dl_find_object pointers into protected memory area Florian Weimer
2023-07-04 20:04 ` [PATCH 32/33] elf: Add hash tables to speed up DT_NEEDED, dlopen lookups Florian Weimer
2023-07-04 20:04 ` [PATCH 33/33] elf: Use memory protection keys for the protected memory allocator Florian Weimer
2023-07-04 20:07 ` [PATCH 00/33] RFC: RELRO link maps Florian Weimer
2023-07-05 15:54 ` Carlos O'Donell
2023-07-05 15:57 ` Florian Weimer
2023-07-05 17:48 ` Carlos O'Donell
2023-07-05 17:58 ` Adhemerval Zanella Netto
2023-07-07 11:10 ` Florian Weimer
2023-07-07 12:42 ` Florian Weimer
2023-07-07 12:48 ` Adhemerval Zanella Netto
2023-07-07 13:18 ` Florian Weimer
2023-07-07 13:58 ` Adhemerval Zanella Netto
2023-07-07 14:55 ` Florian Weimer
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