From: Florian Weimer <fweimer@redhat.com>
To: libc-alpha@sourceware.org
Subject: [PATCH 21/33] elf: Add l_soname accessor function for DT_SONAME values
Date: Tue, 04 Jul 2023 22:03:49 +0200 [thread overview]
Message-ID: <486878d81301cbaf6aeb4467f3aa8d951c4c3d60.1688499219.git.fweimer@redhat.com> (raw)
In-Reply-To: <cover.1688499219.git.fweimer@redhat.com>
It's not necessary to introduce temporaries because the compiler
is able to evaluate l_soname just once in constracts like:
l_soname (l) != NULL && strcmp (l_soname (l), LIBC_SO) != 0
---
elf/dl-load.c | 23 ++++++--------------
elf/dl-open.c | 4 +---
elf/rtld.c | 44 ++++++++++++++++----------------------
elf/setup-vdso.h | 15 +++++++------
elf/sprof.c | 5 +----
sysdeps/generic/ldsodefs.h | 12 +++++++++++
6 files changed, 47 insertions(+), 56 deletions(-)
diff --git a/elf/dl-load.c b/elf/dl-load.c
index f78e23f34a..136297cf46 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1417,17 +1417,13 @@ cannot enable executable stack as shared object requires");
/* When we profile the SONAME might be needed for something else but
loading. Add it right away. */
- if (__glibc_unlikely (GLRO(dl_profile) != NULL)
- && l->l_info[DT_SONAME] != NULL)
- add_name_to_object (l, ((const char *) D_PTR (l, l_info[DT_STRTAB])
- + l->l_info[DT_SONAME]->d_un.d_val));
+ if (__glibc_unlikely (GLRO(dl_profile) != NULL) && l_soname (l) != NULL)
+ add_name_to_object (l, l_soname (l));
/* If we have newly loaded libc.so, update the namespace
description. */
if (GL(dl_ns)[nsid].libc_map == NULL
- && l->l_info[DT_SONAME] != NULL
- && strcmp (((const char *) D_PTR (l, l_info[DT_STRTAB])
- + l->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) == 0)
+ && l_soname (l) != NULL && strcmp (l_soname(l), LIBC_SO) == 0)
GL(dl_ns)[nsid].libc_map = l;
/* _dl_close can only eventually undo the module ID assignment (via
@@ -1917,19 +1913,12 @@ _dl_lookup_map (Lmid_t nsid, const char *name)
continue;
if (!_dl_name_match_p (name, l))
{
- const char *soname;
-
- if (__glibc_likely (l->l_soname_added)
- || l->l_info[DT_SONAME] == NULL)
- continue;
-
- soname = ((const char *) D_PTR (l, l_info[DT_STRTAB])
- + l->l_info[DT_SONAME]->d_un.d_val);
- if (strcmp (name, soname) != 0)
+ if (__glibc_likely (l->l_soname_added) || l_soname (l) == NULL
+ || strcmp (name, l_soname (l)) != 0)
continue;
/* We have a match on a new name -- cache it. */
- add_name_to_object (l, soname);
+ add_name_to_object (l, l_soname (l));
l->l_soname_added = 1;
}
diff --git a/elf/dl-open.c b/elf/dl-open.c
index 9c8d3626e5..cfa508a419 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -606,9 +606,7 @@ dl_open_worker_begin (void *a)
Perform partial initialization in this case. This must
come after the symbol versioning initialization in
_dl_check_map_versions. */
- if (map->l_info[DT_SONAME] != NULL
- && strcmp (((const char *) D_PTR (map, l_info[DT_STRTAB])
- + map->l_info[DT_SONAME]->d_un.d_val), LD_SO) == 0)
+ if (l_soname (map) != NULL && strcmp (l_soname (map), LD_SO) == 0)
__rtld_static_init (map);
#endif
}
diff --git a/elf/rtld.c b/elf/rtld.c
index f086ee1712..de6df9bd96 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1076,13 +1076,9 @@ static void
rtld_chain_load (struct link_map_private *main_map, char *argv0)
{
/* The dynamic loader run against itself. */
- const char *rtld_soname
- = ((const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
- + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val);
- if (main_map->l_info[DT_SONAME] != NULL
- && strcmp (rtld_soname,
- ((const char *) D_PTR (main_map, l_info[DT_STRTAB])
- + main_map->l_info[DT_SONAME]->d_un.d_val)) == 0)
+ const char *rtld_soname = l_soname (&GL(dl_rtld_map));
+ if (l_soname (main_map) != NULL
+ && strcmp (rtld_soname, l_soname (main_map)) == 0)
_dl_fatal_printf ("%s: loader cannot load itself\n", rtld_soname);
/* With DT_NEEDED dependencies, the executable is dynamically
@@ -1654,20 +1650,20 @@ dl_main (const ElfW(Phdr) *phdr,
/* If the current libname is different from the SONAME, add the
latter as well. */
- if (GL(dl_rtld_map).l_info[DT_SONAME] != NULL
- && strcmp (GL(dl_rtld_map).l_libname->name,
- (const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
- + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val) != 0)
- {
- static struct libname_list newname;
- newname.name = ((char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
- + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_ptr);
- newname.next = NULL;
- newname.dont_free = 1;
-
- assert (GL(dl_rtld_map).l_libname->next == NULL);
- GL(dl_rtld_map).l_libname->next = &newname;
- }
+ {
+ const char *soname = l_soname (&GL(dl_rtld_map));
+ if (soname != NULL
+ && strcmp (GL(dl_rtld_map).l_libname->name, soname) != 0)
+ {
+ static struct libname_list newname;
+ newname.name = soname;
+ newname.next = NULL;
+ newname.dont_free = 1;
+
+ assert (GL(dl_rtld_map).l_libname->next == NULL);
+ GL(dl_rtld_map).l_libname->next = &newname;
+ }
+ }
/* The ld.so must be relocated since otherwise loading audit modules
will fail since they reuse the very same ld.so. */
assert (GL(dl_rtld_map).l_relocated);
@@ -1680,10 +1676,8 @@ dl_main (const ElfW(Phdr) *phdr,
/* If the main map is libc.so, update the base namespace to
refer to this map. If libc.so is loaded later, this happens
in _dl_map_object_from_fd. */
- if (main_map->l_info[DT_SONAME] != NULL
- && (strcmp (((const char *) D_PTR (main_map, l_info[DT_STRTAB])
- + main_map->l_info[DT_SONAME]->d_un.d_val), LIBC_SO)
- == 0))
+ if (l_soname (main_map) != NULL
+ && strcmp (l_soname (main_map), LIBC_SO) == 0)
GL(dl_ns)[LM_ID_BASE].libc_map = main_map;
/* Set up our cache of pointers into the hash table. */
diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h
index e4f13ad7e0..0021cdd0cf 100644
--- a/elf/setup-vdso.h
+++ b/elf/setup-vdso.h
@@ -81,13 +81,14 @@ setup_vdso (struct link_map_private *main_map __attribute__ ((unused)),
/* Now that we have the info handy, use the DSO image's soname
so this object can be looked up by name. */
- if (l->l_info[DT_SONAME] != NULL)
- {
- char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
- + l->l_info[DT_SONAME]->d_un.d_val);
- l->l_libname->name = dsoname;
- l->l_public.l_name = dsoname;
- }
+ {
+ const char *dsoname = l_soname (l);
+ if (dsoname != NULL)
+ {
+ l->l_libname->name = dsoname;
+ l->l_public.l_name = (char *) dsoname;
+ }
+ }
/* Add the vDSO to the object list. */
_dl_add_to_namespace_list (l, LM_ID_BASE);
diff --git a/elf/sprof.c b/elf/sprof.c
index 155da1bd03..81f51a7632 100644
--- a/elf/sprof.c
+++ b/elf/sprof.c
@@ -530,10 +530,7 @@ load_shobj (const char *name)
printf ("string table: %p\n", result->dynstrtab);
/* Determine the soname. */
- if (map->l_info[DT_SONAME] == NULL)
- result->soname = NULL;
- else
- result->soname = result->dynstrtab + map->l_info[DT_SONAME]->d_un.d_val;
+ result->soname = l_soname (map);
if (do_test && result->soname != NULL)
printf ("soname: %s\n", result->soname);
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 0af430a266..fb74e9b939 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -88,6 +88,18 @@ dl_relocate_ld (const struct link_map_private *l)
#define D_PTR(map, i) \
((map)->i->d_un.d_ptr + (dl_relocate_ld (map) ? 0 : (map)->l_public.l_addr))
+/* Returns the soname string if the link map has a DT_SONAME tag, or
+ NULL if it does not. */
+static inline const char *
+l_soname (const struct link_map_private *l)
+{
+ if (l->l_info[DT_SONAME] == NULL)
+ return NULL;
+ else
+ return ((const char *) D_PTR (l, l_info[DT_STRTAB])
+ + l->l_info[DT_SONAME]->d_un.d_val);
+}
+
/* Result of the lookup functions and how to retrieve the base address. */
typedef struct link_map_private *lookup_t;
#define LOOKUP_VALUE(map) map
--
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 ` [PATCH 19/33] elf: Move link map fields used by dependency sorting to writable part Florian Weimer
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 ` Florian Weimer [this message]
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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