From: Florian Weimer <fweimer@redhat.com>
To: libc-alpha@sourceware.org
Subject: [PATCH 21/28] elf: Add endianness markup to ld.so.cache
Date: Thu, 01 Oct 2020 18:33:51 +0200 [thread overview]
Message-ID: <b2987a1148ecf4f2a6e697fae3617effcdbf88db.1601569371.git.fweimer@redhat.com> (raw)
In-Reply-To: <cover.1601569371.git.fweimer@redhat.com>
Use a reserved byte in the new format cache header to indicate whether
the file is in little endian or big endian format. Eventually, this
information could be used to provide a unified cache for qemu-user
and similiar scenarios.
---
elf/cache.c | 11 ++++++++++
elf/dl-cache.c | 20 +++++++++++++++++-
sysdeps/generic/dl-cache.h | 43 +++++++++++++++++++++++++++++++++++++-
3 files changed, 72 insertions(+), 2 deletions(-)
diff --git a/elf/cache.c b/elf/cache.c
index 1eb1455883..e0aa616352 100644
--- a/elf/cache.c
+++ b/elf/cache.c
@@ -152,6 +152,14 @@ print_entry (const char *lib, int flag, unsigned int osversion,
printf (") => %s\n", key);
}
+/* Print an error and exit if the new-file cache is internally
+ inconsistent. */
+static void
+check_new_cache (struct cache_file_new *cache)
+{
+ if (! cache_file_new_matches_endian (cache))
+ error (EXIT_FAILURE, 0, _("Cache file has wrong endianness.\n"));
+}
/* Print the whole cache file, if a file contains the new cache format
hidden in the old one, print the contents of the new format. */
@@ -193,6 +201,7 @@ print_cache (const char *cache_name)
|| memcmp (cache_new->version, CACHE_VERSION,
sizeof CACHE_VERSION - 1))
error (EXIT_FAILURE, 0, _("File is not a cache file.\n"));
+ check_new_cache (cache_new);
format = 1;
/* This is where the strings start. */
cache_data = (const char *) cache_new;
@@ -222,6 +231,7 @@ print_cache (const char *cache_name)
&& memcmp (cache_new->version, CACHE_VERSION,
sizeof CACHE_VERSION - 1) == 0)
{
+ check_new_cache (cache_new);
cache_data = (const char *) cache_new;
format = 1;
}
@@ -361,6 +371,7 @@ save_cache (const char *cache_name)
file_entries_new->nlibs = cache_entry_count;
file_entries_new->len_strings = total_strlen;
+ file_entries_new->flags = cache_file_new_flags_endian;
}
/* Pad for alignment of cache_file_new. */
diff --git a/elf/dl-cache.c b/elf/dl-cache.c
index 93d185e788..3aa8ed6c13 100644
--- a/elf/dl-cache.c
+++ b/elf/dl-cache.c
@@ -210,6 +210,11 @@ _dl_load_cache_lookup (const char *name)
&& ((cachesize - sizeof *cache_new) / sizeof (struct file_entry_new)
>= ((struct cache_file_new *) file)->nlibs))
{
+ if (! cache_file_new_matches_endian (file))
+ {
+ __munmap (file, cachesize);
+ file = (void *) -1;
+ }
cache_new = file;
cache = file;
}
@@ -231,7 +236,20 @@ _dl_load_cache_lookup (const char *name)
if (cachesize < (offset + sizeof (struct cache_file_new))
|| memcmp (cache_new->magic, CACHEMAGIC_VERSION_NEW,
sizeof CACHEMAGIC_VERSION_NEW - 1) != 0)
- cache_new = (void *) -1;
+ cache_new = (void *) -1;
+ else
+ {
+ if (! cache_file_new_matches_endian (cache_new))
+ {
+ /* The old-format part of the cache is bogus as well
+ if the endianness does not match. (But it is
+ unclear how the new header can be located if the
+ endianess does not match.) */
+ cache = (void *) -1;
+ cache_new = (void *) -1;
+ __munmap (file, cachesize);
+ }
+ }
}
else
{
diff --git a/sysdeps/generic/dl-cache.h b/sysdeps/generic/dl-cache.h
index 6b310e9e15..1b04211f6b 100644
--- a/sysdeps/generic/dl-cache.h
+++ b/sysdeps/generic/dl-cache.h
@@ -16,6 +16,11 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
+#ifndef _DL_CACHE_H
+#define _DL_CACHE_H
+
+#include <endian.h>
+#include <stdbool.h>
#include <stdint.h>
#ifndef _DL_CACHE_DEFAULT_ID
@@ -83,21 +88,57 @@ struct file_entry_new
uint64_t hwcap; /* Hwcap entry. */
};
+/* See flags member of struct cache_file_new below. */
+enum
+ {
+ cache_file_new_flags_endian = (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ ? 2 : 3)
+ };
+
struct cache_file_new
{
char magic[sizeof CACHEMAGIC_NEW - 1];
char version[sizeof CACHE_VERSION - 1];
uint32_t nlibs; /* Number of entries. */
uint32_t len_strings; /* Size of string table. */
- uint32_t unused[5]; /* Leave space for future extensions
+
+ /* flags & 3 is used to indicate the endianness of the cache.
+ 0: no endianness information available
+ (An old ldconfig version without endianness support wrote the file.)
+ 1: cache is invalid
+ 2: little endian
+ 3: big endian
+
+ The remaining bits are unused and should be generated as zero and
+ ignored by readers. */
+ uint8_t flags;
+
+ uint8_t padding_unsed[3]; /* Not used, for future extensions. */
+
+ uint32_t unused[4]; /* Leave space for future extensions
and align to 8 byte boundary. */
struct file_entry_new libs[0]; /* Entries describing libraries. */
/* After this the string table of size len_strings is found. */
};
+/* Returns false if *CACHE has the wrong endianness for this
+ architecture, and true if the endianness matches (or is
+ unknown). */
+static inline bool
+cache_file_new_matches_endian (const struct cache_file_new *cache)
+{
+ /* A zero value for cache->flags means that no endianness
+ information is available. */
+ return cache->flags == 0
+ || (cache->flags & 3) == cache_file_new_flags_endian;
+}
+
+
/* Used to align cache_file_new. */
#define ALIGN_CACHE(addr) \
(((addr) + __alignof__ (struct cache_file_new) -1) \
& (~(__alignof__ (struct cache_file_new) - 1)))
extern int _dl_cache_libcmp (const char *p1, const char *p2) attribute_hidden;
+
+#endif /* _DL_CACHE_H */
--
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Commercial register: Amtsgericht Muenchen, HRB 153243,
Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill
next prev parent reply other threads:[~2020-10-01 16:33 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 16:31 [PATCH 00/28] glibc-hwcaps support Florian Weimer
2020-10-01 16:31 ` [PATCH 01/28] elf: Do not search HWCAP subdirectories in statically linked binaries Florian Weimer
2020-10-01 18:22 ` Adhemerval Zanella
2020-10-01 18:24 ` Carlos O'Donell
2020-10-01 18:29 ` Adhemerval Zanella
2020-10-01 20:24 ` Carlos O'Donell
2020-10-01 16:31 ` [PATCH 02/28] elf: Implement __rtld_malloc_is_full Florian Weimer
2020-10-01 18:23 ` Adhemerval Zanella
2020-10-08 9:44 ` Florian Weimer
2020-10-01 16:31 ` [PATCH 03/28] elf: Implement _dl_write Florian Weimer
2020-10-05 19:46 ` Adhemerval Zanella
2020-10-01 16:31 ` [PATCH 04/28] elf: Extract command-line/environment variables state from rtld.c Florian Weimer
2020-10-06 20:45 ` Adhemerval Zanella
2020-10-08 11:32 ` Florian Weimer
2020-10-01 16:32 ` [PATCH 05/28] elf: Move ld.so error/help output to _dl_usage Florian Weimer
2020-10-06 21:06 ` Adhemerval Zanella
2020-10-08 12:19 ` Florian Weimer
2020-10-01 16:32 ` [PATCH 06/28] elf: Record whether paths come from LD_LIBRARY_PATH or --library-path Florian Weimer
2020-10-07 16:39 ` Adhemerval Zanella
2020-10-07 16:49 ` Florian Weimer
2020-10-01 16:32 ` [PATCH 07/28] elf: Implement ld.so --help Florian Weimer
2020-10-07 17:16 ` Adhemerval Zanella
2020-10-08 13:13 ` Florian Weimer
2020-10-01 16:32 ` [PATCH 08/28] elf: Implement ld.so --version Florian Weimer
2020-10-07 18:36 ` Adhemerval Zanella
2020-10-07 18:38 ` Adhemerval Zanella
2020-10-08 13:37 ` Florian Weimer
2020-10-01 16:32 ` [PATCH 09/28] scripts/update-copyrights: Update csu/version.c, elf/dl-usage.c Florian Weimer
2020-10-07 18:41 ` Adhemerval Zanella
2020-10-01 16:32 ` [PATCH 10/28] elf: Use the term "program interpreter" in the ld.so help message Florian Weimer
2020-10-07 21:08 ` Adhemerval Zanella
2020-10-08 14:08 ` Florian Weimer
2020-10-01 16:32 ` [PATCH 11/28] elf: Print the full name of the dynamic loader " Florian Weimer
2020-10-08 12:38 ` Adhemerval Zanella
2020-10-01 16:32 ` [PATCH 12/28] elf: Make __rtld_env_path_list and __rtld_search_dirs global variables Florian Weimer
2020-10-08 13:27 ` Adhemerval Zanella
2020-10-01 16:32 ` [PATCH 13/28] elf: Add library search path information to ld.so --help Florian Weimer
2020-10-08 16:22 ` Adhemerval Zanella
2020-10-01 16:33 ` [PATCH 14/28] elf: Enhance ld.so --help to print HWCAP subdirectories Florian Weimer
2020-10-08 16:27 ` Adhemerval Zanella
2020-10-09 8:18 ` Florian Weimer
2020-10-09 13:49 ` Matheus Castanho
2020-10-09 17:08 ` Florian Weimer
2020-10-09 17:12 ` Florian Weimer
2020-10-09 18:54 ` Matheus Castanho
2020-10-12 9:47 ` Florian Weimer
2020-10-01 16:33 ` [PATCH 15/28] elf: Do not pass GLRO(dl_platform), GLRO(dl_platformlen) to _dl_important_hwcaps Florian Weimer
2020-10-08 18:04 ` Adhemerval Zanella
2020-10-01 16:33 ` [PATCH 16/28] elf: Add glibc-hwcaps support for LD_LIBRARY_PATH Florian Weimer
2020-10-08 10:13 ` Szabolcs Nagy
2020-10-09 9:08 ` Florian Weimer
2020-10-09 10:50 ` Szabolcs Nagy
2020-10-09 10:55 ` Florian Weimer
2020-10-09 11:03 ` Szabolcs Nagy
2020-10-08 23:16 ` Paul A. Clarke
2020-10-09 8:56 ` Florian Weimer
2020-10-09 13:19 ` Adhemerval Zanella
2020-10-12 11:54 ` Florian Weimer
2020-10-01 16:33 ` [PATCH 17/28] x86_64: Add glibc-hwcaps support Florian Weimer
2020-10-01 16:33 ` [PATCH 18/28] powerpc64le: " Florian Weimer
2020-10-01 18:56 ` Paul A. Clarke
2020-10-05 9:47 ` Florian Weimer
2020-10-05 19:15 ` Paul A. Clarke
2020-10-06 12:20 ` Florian Weimer
2020-10-06 17:45 ` Paul A. Clarke
2020-10-09 9:06 ` Florian Weimer
2020-10-01 16:33 ` [PATCH 19/28] s390x: Add " Florian Weimer
2020-10-01 16:33 ` [PATCH 20/28] aarch64: " Florian Weimer
2020-10-14 13:46 ` Adhemerval Zanella
2020-10-14 14:08 ` Florian Weimer
2020-10-14 14:15 ` Adhemerval Zanella
2020-10-14 14:37 ` Szabolcs Nagy
2020-10-14 14:43 ` Adhemerval Zanella
2020-10-14 15:13 ` Florian Weimer
2020-10-14 14:44 ` Florian Weimer
2020-10-14 15:09 ` Szabolcs Nagy
2020-10-01 16:33 ` Florian Weimer [this message]
2020-10-14 14:07 ` [PATCH 21/28] elf: Add endianness markup to ld.so.cache Adhemerval Zanella
2020-10-01 16:33 ` [PATCH 22/28] elf: Add extension mechanism " Florian Weimer
2020-10-15 17:52 ` Adhemerval Zanella
2020-10-30 12:22 ` Florian Weimer
2020-11-03 12:45 ` Adhemerval Zanella
2020-11-03 15:30 ` Florian Weimer
2020-10-01 16:34 ` [PATCH 23/28] elf: Unify old and new format cache handling code in ld.so Florian Weimer
2020-10-16 14:37 ` Adhemerval Zanella
2020-10-30 13:22 ` Florian Weimer
2020-11-03 13:02 ` Adhemerval Zanella
2020-10-01 16:34 ` [PATCH 24/28] elf: Implement a string table for ldconfig, with tail merging Florian Weimer
2020-10-20 14:25 ` Adhemerval Zanella
2020-10-30 17:08 ` Florian Weimer
2020-11-03 13:05 ` Adhemerval Zanella
2020-11-03 15:29 ` Florian Weimer
2020-10-01 16:34 ` [PATCH 25/28] elf: Implement tail merging of strings in ldconfig Florian Weimer
2020-10-22 21:08 ` Adhemerval Zanella
2020-10-30 17:36 ` Florian Weimer
2020-10-01 16:34 ` [PATCH 26/28] elf: In ldconfig, extract the new_sub_entry function from search_dir Florian Weimer
2020-10-27 13:15 ` Adhemerval Zanella
2020-10-01 16:34 ` [PATCH 27/28] elf: Process glibc-hwcaps subdirectories in ldconfig Florian Weimer
2020-10-27 17:28 ` Adhemerval Zanella
2020-11-04 11:57 ` Florian Weimer
2020-10-01 16:34 ` [PATCH 28/28] elf: Add glibc-hwcaps subdirectory support to ld.so cache processing Florian Weimer
2020-10-01 16:50 ` [PATCH 00/28] glibc-hwcaps support H.J. Lu
2020-10-01 16:54 ` Florian Weimer
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