From: Florian Weimer via Libc-alpha <libc-alpha@sourceware.org>
To: libc-alpha@sourceware.org
Subject: [PATCH 23/28] elf: Unify old and new format cache handling code in ld.so
Date: Thu, 01 Oct 2020 18:34:05 +0200 [thread overview]
Message-ID: <e1b021451aa66d1c03334a401dde007906d03b34.1601569371.git.fweimer@redhat.com> (raw)
In-Reply-To: <cover.1601569371.git.fweimer@redhat.com>
struct file_entry_new starts with the fields of struct file_entry,
so the code can be shared if the size computation is made dynamic.
---
elf/dl-cache.c | 287 +++++++++++++++++++------------------
sysdeps/generic/dl-cache.h | 17 ++-
2 files changed, 158 insertions(+), 146 deletions(-)
diff --git a/elf/dl-cache.c b/elf/dl-cache.c
index 3aa8ed6c13..02c46ffb0c 100644
--- a/elf/dl-cache.c
+++ b/elf/dl-cache.c
@@ -35,103 +35,141 @@ static struct cache_file *cache;
static struct cache_file_new *cache_new;
static size_t cachesize;
-/* 1 if cache_data + PTR points into the cache. */
-#define _dl_cache_verify_ptr(ptr) (ptr < cache_data_size)
-
-#define SEARCH_CACHE(cache) \
-/* We use binary search since the table is sorted in the cache file. \
- The first matching entry in the table is returned. \
- It is important to use the same algorithm as used while generating \
- the cache file. */ \
-do \
- { \
- left = 0; \
- right = cache->nlibs - 1; \
- \
- while (left <= right) \
- { \
- __typeof__ (cache->libs[0].key) key; \
- \
- middle = (left + right) / 2; \
- \
- key = cache->libs[middle].key; \
- \
- /* Make sure string table indices are not bogus before using \
- them. */ \
- if (! _dl_cache_verify_ptr (key)) \
- { \
- cmpres = 1; \
- break; \
- } \
- \
- /* Actually compare the entry with the key. */ \
- cmpres = _dl_cache_libcmp (name, cache_data + key); \
- if (__glibc_unlikely (cmpres == 0)) \
- { \
- /* Found it. LEFT now marks the last entry for which we \
- know the name is correct. */ \
- left = middle; \
- \
- /* There might be entries with this name before the one we \
- found. So we have to find the beginning. */ \
- while (middle > 0) \
- { \
- __typeof__ (cache->libs[0].key) key; \
- \
- key = cache->libs[middle - 1].key; \
- /* Make sure string table indices are not bogus before \
- using them. */ \
- if (! _dl_cache_verify_ptr (key) \
- /* Actually compare the entry. */ \
- || _dl_cache_libcmp (name, cache_data + key) != 0) \
- break; \
- --middle; \
- } \
- \
- do \
- { \
- int flags; \
- __typeof__ (cache->libs[0]) *lib = &cache->libs[middle]; \
- \
- /* Only perform the name test if necessary. */ \
- if (middle > left \
- /* We haven't seen this string so far. Test whether the \
- index is ok and whether the name matches. Otherwise \
- we are done. */ \
- && (! _dl_cache_verify_ptr (lib->key) \
- || (_dl_cache_libcmp (name, cache_data + lib->key) \
- != 0))) \
- break; \
- \
- flags = lib->flags; \
- if (_dl_cache_check_flags (flags) \
- && _dl_cache_verify_ptr (lib->value)) \
- { \
- if (best == NULL || flags == GLRO(dl_correct_cache_id)) \
- { \
- HWCAP_CHECK; \
- best = cache_data + lib->value; \
- \
- if (flags == GLRO(dl_correct_cache_id)) \
- /* We've found an exact match for the shared \
- object and no general `ELF' release. Stop \
- searching. */ \
- break; \
- } \
- } \
- } \
- while (++middle <= right); \
- break; \
- } \
- \
- if (cmpres < 0) \
- left = middle + 1; \
- else \
- right = middle - 1; \
- } \
- } \
-while (0)
+/* True if PTR is a valid string table index. */
+static inline bool
+_dl_cache_verify_ptr (uint32_t ptr, size_t string_table_size)
+{
+ return ptr < string_table_size;
+}
+
+/* Compute the address of the element INDEX of the array at LIBS.
+ Conceptually, this is &LIBS[INDEX], but use ENTRY_SIZE for the size
+ of *LIBS. */
+static inline const struct file_entry *
+_dl_cache_file_entry (const struct file_entry *libs, size_t entry_size,
+ size_t index)
+{
+ return (const void *) libs + index * entry_size;
+}
+
+/* We use binary search since the table is sorted in the cache file.
+ The first matching entry in the table is returned. It is important
+ to use the same algorithm as used while generating the cache file.
+ STRING_TABLE_SIZE indicates the maximum offset in STRING_TABLE at
+ which data is mapped; it is not exact. */
+static const char *
+search_cache (const char *string_table, uint32_t string_table_size,
+ struct file_entry *libs, uint32_t nlibs, uint32_t entry_size,
+ const char *name)
+{
+ /* Used by the HWCAP check in the struct file_entry_new case. */
+ uint64_t platform = _dl_string_platform (GLRO (dl_platform));
+ if (platform != (uint64_t) -1)
+ platform = 1ULL << platform;
+ uint64_t hwcap_mask = GET_HWCAP_MASK ();
+#define _DL_HWCAP_TLS_MASK (1LL << 63)
+ uint64_t hwcap_exclude = ~((GLRO (dl_hwcap) & hwcap_mask)
+ | _DL_HWCAP_PLATFORM | _DL_HWCAP_TLS_MASK);
+
+ int left = 0;
+ int right = nlibs - 1;
+ const char *best = NULL;
+
+ while (left <= right)
+ {
+ int middle = (left + right) / 2;
+ uint32_t key = _dl_cache_file_entry (libs, entry_size, middle)->key;
+
+ /* Make sure string table indices are not bogus before using
+ them. */
+ if (!_dl_cache_verify_ptr (key, string_table_size))
+ return NULL;
+ /* Actually compare the entry with the key. */
+ int cmpres = _dl_cache_libcmp (name, string_table + key);
+ if (__glibc_unlikely (cmpres == 0))
+ {
+ /* Found it. LEFT now marks the last entry for which we
+ know the name is correct. */
+ left = middle;
+
+ /* There might be entries with this name before the one we
+ found. So we have to find the beginning. */
+ while (middle > 0)
+ {
+ key = _dl_cache_file_entry (libs, entry_size, middle - 1)->key;
+ /* Make sure string table indices are not bogus before
+ using them. */
+ if (!_dl_cache_verify_ptr (key, string_table_size)
+ /* Actually compare the entry. */
+ || _dl_cache_libcmp (name, string_table + key) != 0)
+ break;
+ --middle;
+ }
+
+ do
+ {
+ int flags;
+ const struct file_entry *lib
+ = _dl_cache_file_entry (libs, entry_size, middle);
+
+ /* Only perform the name test if necessary. */
+ if (middle > left
+ /* We haven't seen this string so far. Test whether the
+ index is ok and whether the name matches. Otherwise
+ we are done. */
+ && (! _dl_cache_verify_ptr (lib->key, string_table_size)
+ || (_dl_cache_libcmp (name, string_table + lib->key)
+ != 0)))
+ break;
+
+ flags = lib->flags;
+ if (_dl_cache_check_flags (flags)
+ && _dl_cache_verify_ptr (lib->value, string_table_size))
+ {
+ if (best == NULL || flags == GLRO (dl_correct_cache_id))
+ {
+ if (entry_size >= sizeof (struct file_entry_new))
+ {
+ /* The entry is large enough to include
+ HWCAP data. Check it. */
+ struct file_entry_new *libnew
+ = (struct file_entry_new *) lib;
+
+ if (libnew->hwcap & hwcap_exclude)
+ continue;
+ if (GLRO (dl_osversion)
+ && libnew->osversion > GLRO (dl_osversion))
+ continue;
+ if (_DL_PLATFORMS_COUNT
+ && (libnew->hwcap & _DL_HWCAP_PLATFORM) != 0
+ && ((libnew->hwcap & _DL_HWCAP_PLATFORM)
+ != platform))
+ continue;
+ }
+
+ best = string_table + lib->value;
+
+ if (flags == GLRO (dl_correct_cache_id))
+ /* We've found an exact match for the shared
+ object and no general `ELF' release. Stop
+ searching. */
+ break;
+ }
+ }
+ }
+ while (++middle <= right);
+ break;
+ }
+
+ if (cmpres < 0)
+ left = middle + 1;
+ else
+ right = middle - 1;
+ }
+
+ return best;
+}
int
_dl_cache_libcmp (const char *p1, const char *p2)
@@ -182,12 +220,6 @@ _dl_cache_libcmp (const char *p1, const char *p2)
char *
_dl_load_cache_lookup (const char *name)
{
- int left, right, middle;
- int cmpres;
- const char *cache_data;
- uint32_t cache_data_size;
- const char *best;
-
/* Print a message if the loading of libs is traced. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
_dl_debug_printf (" search cache=%s\n", LD_SO_CACHE);
@@ -265,51 +297,22 @@ _dl_load_cache_lookup (const char *name)
/* Previously looked for the cache file and didn't find it. */
return NULL;
- best = NULL;
-
+ const char *best;
if (cache_new != (void *) -1)
{
- uint64_t platform;
-
- /* This is where the strings start. */
- cache_data = (const char *) cache_new;
-
- /* Now we can compute how large the string table is. */
- cache_data_size = (const char *) cache + cachesize - cache_data;
-
- platform = _dl_string_platform (GLRO(dl_platform));
- if (platform != (uint64_t) -1)
- platform = 1ULL << platform;
-
- uint64_t hwcap_mask = GET_HWCAP_MASK();
-
-#define _DL_HWCAP_TLS_MASK (1LL << 63)
- uint64_t hwcap_exclude = ~((GLRO(dl_hwcap) & hwcap_mask)
- | _DL_HWCAP_PLATFORM | _DL_HWCAP_TLS_MASK);
-
- /* Only accept hwcap if it's for the right platform. */
-#define HWCAP_CHECK \
- if (lib->hwcap & hwcap_exclude) \
- continue; \
- if (GLRO(dl_osversion) && lib->osversion > GLRO(dl_osversion)) \
- continue; \
- if (_DL_PLATFORMS_COUNT \
- && (lib->hwcap & _DL_HWCAP_PLATFORM) != 0 \
- && (lib->hwcap & _DL_HWCAP_PLATFORM) != platform) \
- continue
- SEARCH_CACHE (cache_new);
+ const char *string_table = (const char *) cache_new;
+ best = search_cache (string_table, cachesize,
+ &cache_new->libs[0].entry, cache_new->nlibs,
+ sizeof (cache_new->libs[0]), name);
}
else
{
- /* This is where the strings start. */
- cache_data = (const char *) &cache->libs[cache->nlibs];
-
- /* Now we can compute how large the string table is. */
- cache_data_size = (const char *) cache + cachesize - cache_data;
-
-#undef HWCAP_CHECK
-#define HWCAP_CHECK do {} while (0)
- SEARCH_CACHE (cache);
+ const char *string_table = (const char *) &cache->libs[cache->nlibs];
+ uint32_t string_table_size
+ = (const char *) cache + cachesize - string_table;
+ best = search_cache (string_table, string_table_size,
+ &cache->libs[0], cache->nlibs,
+ sizeof (cache->libs[0]), name);
}
/* Print our result if wanted. */
diff --git a/sysdeps/generic/dl-cache.h b/sysdeps/generic/dl-cache.h
index b154740da9..fec209509d 100644
--- a/sysdeps/generic/dl-cache.h
+++ b/sysdeps/generic/dl-cache.h
@@ -66,8 +66,8 @@
*/
struct file_entry
{
- int flags; /* This is 1 for an ELF library. */
- unsigned int key, value; /* String table indices. */
+ int32_t flags; /* This is 1 for an ELF library. */
+ uint32_t key, value; /* String table indices. */
};
struct cache_file
@@ -84,8 +84,17 @@ struct cache_file
struct file_entry_new
{
- int32_t flags; /* This is 1 for an ELF library. */
- uint32_t key, value; /* String table indices. */
+ union
+ {
+ /* Fields shared with struct file_entry. */
+ struct file_entry entry;
+ /* Also expose these fields directly. */
+ struct
+ {
+ int32_t flags; /* This is 1 for an ELF library. */
+ uint32_t key, value; /* String table indices. */
+ };
+ };
uint32_t osversion; /* Required OS version. */
uint64_t hwcap; /* Hwcap entry. */
};
--
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next prev parent reply other threads:[~2020-10-01 16:34 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 via Libc-alpha
2020-10-01 16:31 ` [PATCH 01/28] elf: Do not search HWCAP subdirectories in statically linked binaries Florian Weimer via Libc-alpha
2020-10-01 18:22 ` Adhemerval Zanella via Libc-alpha
2020-10-01 18:24 ` Carlos O'Donell via Libc-alpha
2020-10-01 18:29 ` Adhemerval Zanella via Libc-alpha
2020-10-01 20:24 ` Carlos O'Donell via Libc-alpha
2020-10-01 16:31 ` [PATCH 02/28] elf: Implement __rtld_malloc_is_full Florian Weimer via Libc-alpha
2020-10-01 18:23 ` Adhemerval Zanella via Libc-alpha
2020-10-08 9:44 ` Florian Weimer via Libc-alpha
2020-10-01 16:31 ` [PATCH 03/28] elf: Implement _dl_write Florian Weimer via Libc-alpha
2020-10-05 19:46 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:31 ` [PATCH 04/28] elf: Extract command-line/environment variables state from rtld.c Florian Weimer via Libc-alpha
2020-10-06 20:45 ` Adhemerval Zanella via Libc-alpha
2020-10-08 11:32 ` Florian Weimer via Libc-alpha
2020-10-01 16:32 ` [PATCH 05/28] elf: Move ld.so error/help output to _dl_usage Florian Weimer via Libc-alpha
2020-10-06 21:06 ` Adhemerval Zanella via Libc-alpha
2020-10-08 12:19 ` Florian Weimer via Libc-alpha
2020-10-01 16:32 ` [PATCH 06/28] elf: Record whether paths come from LD_LIBRARY_PATH or --library-path Florian Weimer via Libc-alpha
2020-10-07 16:39 ` Adhemerval Zanella via Libc-alpha
2020-10-07 16:49 ` Florian Weimer
2020-10-01 16:32 ` [PATCH 07/28] elf: Implement ld.so --help Florian Weimer via Libc-alpha
2020-10-07 17:16 ` Adhemerval Zanella via Libc-alpha
2020-10-08 13:13 ` Florian Weimer via Libc-alpha
2020-10-01 16:32 ` [PATCH 08/28] elf: Implement ld.so --version Florian Weimer via Libc-alpha
2020-10-07 18:36 ` Adhemerval Zanella via Libc-alpha
2020-10-07 18:38 ` Adhemerval Zanella via Libc-alpha
2020-10-08 13:37 ` Florian Weimer via Libc-alpha
2020-10-01 16:32 ` [PATCH 09/28] scripts/update-copyrights: Update csu/version.c, elf/dl-usage.c Florian Weimer via Libc-alpha
2020-10-07 18:41 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:32 ` [PATCH 10/28] elf: Use the term "program interpreter" in the ld.so help message Florian Weimer via Libc-alpha
2020-10-07 21:08 ` Adhemerval Zanella via Libc-alpha
2020-10-08 14:08 ` Florian Weimer via Libc-alpha
2020-10-01 16:32 ` [PATCH 11/28] elf: Print the full name of the dynamic loader " Florian Weimer via Libc-alpha
2020-10-08 12:38 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:32 ` [PATCH 12/28] elf: Make __rtld_env_path_list and __rtld_search_dirs global variables Florian Weimer via Libc-alpha
2020-10-08 13:27 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:32 ` [PATCH 13/28] elf: Add library search path information to ld.so --help Florian Weimer via Libc-alpha
2020-10-08 16:22 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:33 ` [PATCH 14/28] elf: Enhance ld.so --help to print HWCAP subdirectories Florian Weimer via Libc-alpha
2020-10-08 16:27 ` Adhemerval Zanella via Libc-alpha
2020-10-09 8:18 ` Florian Weimer via Libc-alpha
2020-10-09 13:49 ` Matheus Castanho via Libc-alpha
2020-10-09 17:08 ` Florian Weimer via Libc-alpha
2020-10-09 17:12 ` Florian Weimer via Libc-alpha
2020-10-09 18:54 ` Matheus Castanho via Libc-alpha
2020-10-12 9:47 ` Florian Weimer via Libc-alpha
2020-10-01 16:33 ` [PATCH 15/28] elf: Do not pass GLRO(dl_platform), GLRO(dl_platformlen) to _dl_important_hwcaps Florian Weimer via Libc-alpha
2020-10-08 18:04 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:33 ` [PATCH 16/28] elf: Add glibc-hwcaps support for LD_LIBRARY_PATH Florian Weimer via Libc-alpha
2020-10-08 10:13 ` Szabolcs Nagy via Libc-alpha
2020-10-09 9:08 ` Florian Weimer via Libc-alpha
2020-10-09 10:50 ` Szabolcs Nagy via Libc-alpha
2020-10-09 10:55 ` Florian Weimer via Libc-alpha
2020-10-09 11:03 ` Szabolcs Nagy via Libc-alpha
2020-10-08 23:16 ` Paul A. Clarke via Libc-alpha
2020-10-09 8:56 ` Florian Weimer via Libc-alpha
2020-10-09 13:19 ` Adhemerval Zanella via Libc-alpha
2020-10-12 11:54 ` Florian Weimer via Libc-alpha
2020-10-01 16:33 ` [PATCH 17/28] x86_64: Add glibc-hwcaps support Florian Weimer via Libc-alpha
2020-10-01 16:33 ` [PATCH 18/28] powerpc64le: " Florian Weimer via Libc-alpha
2020-10-01 18:56 ` Paul A. Clarke via Libc-alpha
2020-10-05 9:47 ` Florian Weimer via Libc-alpha
2020-10-05 19:15 ` Paul A. Clarke via Libc-alpha
2020-10-06 12:20 ` Florian Weimer via Libc-alpha
2020-10-06 17:45 ` Paul A. Clarke via Libc-alpha
2020-10-09 9:06 ` Florian Weimer via Libc-alpha
2020-10-01 16:33 ` [PATCH 19/28] s390x: Add " Florian Weimer via Libc-alpha
2020-10-01 16:33 ` [PATCH 20/28] aarch64: " Florian Weimer via Libc-alpha
2020-10-14 13:46 ` Adhemerval Zanella via Libc-alpha
2020-10-14 14:08 ` Florian Weimer via Libc-alpha
2020-10-14 14:15 ` Adhemerval Zanella via Libc-alpha
2020-10-14 14:37 ` Szabolcs Nagy via Libc-alpha
2020-10-14 14:43 ` Adhemerval Zanella via Libc-alpha
2020-10-14 15:13 ` Florian Weimer via Libc-alpha
2020-10-14 14:44 ` Florian Weimer via Libc-alpha
2020-10-14 15:09 ` Szabolcs Nagy via Libc-alpha
2020-10-01 16:33 ` [PATCH 21/28] elf: Add endianness markup to ld.so.cache Florian Weimer via Libc-alpha
2020-10-14 14:07 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:33 ` [PATCH 22/28] elf: Add extension mechanism " Florian Weimer via Libc-alpha
2020-10-15 17:52 ` Adhemerval Zanella via Libc-alpha
2020-10-30 12:22 ` Florian Weimer via Libc-alpha
2020-11-03 12:45 ` Adhemerval Zanella via Libc-alpha
2020-11-03 15:30 ` Florian Weimer via Libc-alpha
2020-10-01 16:34 ` Florian Weimer via Libc-alpha [this message]
2020-10-16 14:37 ` [PATCH 23/28] elf: Unify old and new format cache handling code in ld.so Adhemerval Zanella via Libc-alpha
2020-10-30 13:22 ` Florian Weimer via Libc-alpha
2020-11-03 13:02 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:34 ` [PATCH 24/28] elf: Implement a string table for ldconfig, with tail merging Florian Weimer via Libc-alpha
2020-10-20 14:25 ` Adhemerval Zanella via Libc-alpha
2020-10-30 17:08 ` Florian Weimer via Libc-alpha
2020-11-03 13:05 ` Adhemerval Zanella via Libc-alpha
2020-11-03 15:29 ` Florian Weimer via Libc-alpha
2020-10-01 16:34 ` [PATCH 25/28] elf: Implement tail merging of strings in ldconfig Florian Weimer via Libc-alpha
2020-10-22 21:08 ` Adhemerval Zanella via Libc-alpha
2020-10-30 17:36 ` Florian Weimer via Libc-alpha
2020-10-01 16:34 ` [PATCH 26/28] elf: In ldconfig, extract the new_sub_entry function from search_dir Florian Weimer via Libc-alpha
2020-10-27 13:15 ` Adhemerval Zanella via Libc-alpha
2020-10-01 16:34 ` [PATCH 27/28] elf: Process glibc-hwcaps subdirectories in ldconfig Florian Weimer via Libc-alpha
2020-10-27 17:28 ` Adhemerval Zanella via Libc-alpha
2020-11-04 11:57 ` Florian Weimer via Libc-alpha
2020-10-01 16:34 ` [PATCH 28/28] elf: Add glibc-hwcaps subdirectory support to ld.so cache processing Florian Weimer via Libc-alpha
2020-10-01 16:50 ` [PATCH 00/28] glibc-hwcaps support H.J. Lu via Libc-alpha
2020-10-01 16:54 ` Florian Weimer via Libc-alpha
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