/* Support for reading /etc/ld.so.cache files written by Linux ldconfig.
- Copyright (C) 1996-2020 Free Software Foundation, Inc.
+ Copyright (C) 1996-2022 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
#include <stdint.h>
#include <_itoa.h>
#include <dl-hwcaps.h>
+#include <dl-isa-level.h>
#ifndef _DL_PLATFORMS_COUNT
# define _DL_PLATFORMS_COUNT 0
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)
+#ifdef SHARED
+/* This is used to cache the priorities of glibc-hwcaps
+ subdirectories. The elements of _dl_cache_priorities correspond to
+ the strings in the cache_extension_tag_glibc_hwcaps section. */
+static uint32_t *glibc_hwcaps_priorities;
+static uint32_t glibc_hwcaps_priorities_length;
+static uint32_t glibc_hwcaps_priorities_allocated;
+/* True if the full malloc was used to allocated the array. */
+static bool glibc_hwcaps_priorities_malloced;
+
+/* Deallocate the glibc_hwcaps_priorities array. */
+static void
+glibc_hwcaps_priorities_free (void)
+{
+ /* When the minimal malloc is in use, free does not do anything,
+ so it does not make sense to call it. */
+ if (glibc_hwcaps_priorities_malloced)
+ free (glibc_hwcaps_priorities);
+ glibc_hwcaps_priorities = NULL;
+ glibc_hwcaps_priorities_allocated = 0;
+}
+
+/* Ordered comparison of a hwcaps string from the cache on the left
+ (identified by its string table index) and a _dl_hwcaps_priorities
+ element on the right. */
+static int
+glibc_hwcaps_compare (uint32_t left_index, struct dl_hwcaps_priority *right)
+{
+ const char *left_name = (const char *) cache + left_index;
+ uint32_t left_name_length = strlen (left_name);
+ uint32_t to_compare;
+ if (left_name_length < right->name_length)
+ to_compare = left_name_length;
+ else
+ to_compare = right->name_length;
+ int cmp = memcmp (left_name, right->name, to_compare);
+ if (cmp != 0)
+ return cmp;
+ if (left_name_length < right->name_length)
+ return -1;
+ else if (left_name_length > right->name_length)
+ return 1;
+ else
+ return 0;
+}
+
+/* Initialize the glibc_hwcaps_priorities array and its length,
+ glibc_hwcaps_priorities_length. */
+static void
+glibc_hwcaps_priorities_init (void)
+{
+ struct cache_extension_all_loaded ext;
+ if (!cache_extension_load (cache_new, cache, cachesize, &ext))
+ return;
+
+ uint32_t length = (ext.sections[cache_extension_tag_glibc_hwcaps].size
+ / sizeof (uint32_t));
+ if (length > glibc_hwcaps_priorities_allocated)
+ {
+ glibc_hwcaps_priorities_free ();
+
+ uint32_t *new_allocation = malloc (length * sizeof (uint32_t));
+ if (new_allocation == NULL)
+ /* This effectively disables hwcaps on memory allocation
+ errors. */
+ return;
+
+ glibc_hwcaps_priorities = new_allocation;
+ glibc_hwcaps_priorities_allocated = length;
+ glibc_hwcaps_priorities_malloced = __rtld_malloc_is_complete ();
+ }
+
+ /* Compute the priorities for the subdirectories by merging the
+ array in the cache with the dl_hwcaps_priorities array. */
+ const uint32_t *left = ext.sections[cache_extension_tag_glibc_hwcaps].base;
+ const uint32_t *left_end = left + length;
+ struct dl_hwcaps_priority *right = _dl_hwcaps_priorities;
+ struct dl_hwcaps_priority *right_end = right + _dl_hwcaps_priorities_length;
+ uint32_t *result = glibc_hwcaps_priorities;
+
+ while (left < left_end && right < right_end)
+ {
+ if (*left < cachesize)
+ {
+ int cmp = glibc_hwcaps_compare (*left, right);
+ if (cmp == 0)
+ {
+ *result = right->priority;
+ ++result;
+ ++left;
+ ++right;
+ }
+ else if (cmp < 0)
+ {
+ *result = 0;
+ ++result;
+ ++left;
+ }
+ else
+ ++right;
+ }
+ else
+ {
+ *result = 0;
+ ++result;
+ }
+ }
+ while (left < left_end)
+ {
+ *result = 0;
+ ++result;
+ ++left;
+ }
+
+ glibc_hwcaps_priorities_length = length;
+}
+
+/* Return the priority of the cache_extension_tag_glibc_hwcaps section
+ entry at INDEX. Zero means do not use. Otherwise, lower values
+ indicate greater preference. */
+static uint32_t
+glibc_hwcaps_priority (uint32_t index)
+{
+ /* This does not need to repeated initialization attempts because
+ this function is only called if there is glibc-hwcaps data in the
+ cache, so the first call initializes the glibc_hwcaps_priorities
+ array. */
+ if (glibc_hwcaps_priorities_length == 0)
+ glibc_hwcaps_priorities_init ();
+
+ if (index < glibc_hwcaps_priorities_length)
+ return glibc_hwcaps_priorities[index];
+ else
+ return 0;
+}
+#endif /* SHARED */
+
+/* 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;
+#ifdef SHARED
+ uint32_t best_priority = 0;
+#endif
+
+ 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))
+ {
+ /* Named/extension hwcaps get slightly different
+ treatment: We keep searching for a better
+ match. */
+ bool named_hwcap = false;
+
+ 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;
+
+#ifdef SHARED
+ named_hwcap = dl_cache_hwcap_extension (libnew);
+ if (named_hwcap
+ && !dl_cache_hwcap_isa_level_compatible (libnew))
+ continue;
+#endif
+
+ /* The entries with named/extension hwcaps have
+ been exhausted (they are listed before all
+ other entries). Return the best match
+ encountered so far if there is one. */
+ if (!named_hwcap && best != NULL)
+ break;
+
+ if ((libnew->hwcap & hwcap_exclude) && !named_hwcap)
+ continue;
+ if (_DL_PLATFORMS_COUNT
+ && (libnew->hwcap & _DL_HWCAP_PLATFORM) != 0
+ && ((libnew->hwcap & _DL_HWCAP_PLATFORM)
+ != platform))
+ continue;
+
+#ifdef SHARED
+ /* For named hwcaps, determine the priority and
+ see if beats what has been found so far. */
+ if (named_hwcap)
+ {
+ uint32_t entry_priority
+ = glibc_hwcaps_priority (libnew->hwcap);
+ if (entry_priority == 0)
+ /* Not usable at all. Skip. */
+ continue;
+ else if (best == NULL
+ || entry_priority < best_priority)
+ /* This entry is of higher priority
+ than the previous one, or it is the
+ first entry. */
+ best_priority = entry_priority;
+ else
+ /* An entry has already been found,
+ but it is a better match. */
+ continue;
+ }
+#endif /* SHARED */
+ }
+
+ best = string_table + lib->value;
+
+ if (!named_hwcap && flags == _DL_CACHE_DEFAULT_ID)
+ /* With named hwcaps, we need to keep searching to
+ see if we find a better match. A better match
+ is also possible if the flags of the current
+ entry do not match the expected cache flags.
+ But if the flags match, no better entry will be
+ found. */
+ 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)
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);
&& ((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;
}
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
{
/* 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. */
__munmap (cache, cachesize);
cache = NULL;
}
+#ifdef SHARED
+ /* This marks the glibc_hwcaps_priorities array as out-of-date. */
+ glibc_hwcaps_priorities_length = 0;
+#endif
}
#endif
projects / thirdparty / glibc.git / blobdiff