diff options
Diffstat (limited to 'sysdeps/generic/dl-cache.h')
| -rw-r--r-- | sysdeps/generic/dl-cache.h | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/sysdeps/generic/dl-cache.h b/sysdeps/generic/dl-cache.h index 393cdc5754..72a66b45ee 100644 --- a/sysdeps/generic/dl-cache.h +++ b/sysdeps/generic/dl-cache.h @@ -99,6 +99,23 @@ struct file_entry_new uint64_t hwcap; /* Hwcap entry. */ }; +/* This bit in the hwcap field of struct file_entry_new indicates that + the lower 32 bits contain an index into the + cache_extension_tag_glibc_hwcaps section. Older glibc versions do + not know about this HWCAP bit, so they will ignore these + entries. */ +#define DL_CACHE_HWCAP_EXTENSION (1ULL << 62) + +/* Return true if the ENTRY->hwcap value indicates that + DL_CACHE_HWCAP_EXTENSION is used. */ +static inline bool +dl_cache_hwcap_extension (struct file_entry_new *entry) +{ + /* If DL_CACHE_HWCAP_EXTENSION is set, but other bits as well, this + is a different kind of extension. */ + return (entry->hwcap >> 32) == (DL_CACHE_HWCAP_EXTENSION >> 32); +} + /* See flags member of struct cache_file_new below. */ enum { @@ -182,6 +199,17 @@ enum cache_extension_tag cache file. */ cache_extension_tag_generator, + /* glibc-hwcaps subdirectory information. An array of uint32_t + values, which are indices into the string table. The strings + are sorted lexicographically (according to strcmp). The extra + level of indirection (instead of using string table indices + directly) allows the dynamic loader to compute the preference + order of the hwcaps names more efficiently. + + For this section, 4-byte alignment is required, and the section + size must be a multiple of 4. */ + cache_extension_tag_glibc_hwcaps, + /* Total number of known cache extension tags. */ cache_extension_count }; @@ -236,6 +264,27 @@ struct cache_extension_all_loaded struct cache_extension_loaded sections[cache_extension_count]; }; +/* Performs basic data validation based on section tag, and removes + the sections which are invalid. */ +static void +cache_extension_verify (struct cache_extension_all_loaded *loaded) +{ + { + /* Section must not be empty, it must be aligned at 4 bytes, and + the size must be a multiple of 4. */ + struct cache_extension_loaded *hwcaps + = &loaded->sections[cache_extension_tag_glibc_hwcaps]; + if (hwcaps->size == 0 + || ((uintptr_t) hwcaps->base % 4) != 0 + || (hwcaps->size % 4) != 0) + { + hwcaps->base = NULL; + hwcaps->size = 0; + hwcaps->flags = 0; + } + } +} + static bool __attribute__ ((unused)) cache_extension_load (const struct cache_file_new *cache, const void *file_base, size_t file_size, @@ -282,6 +331,7 @@ cache_extension_load (const struct cache_file_new *cache, loaded->sections[tag].size = ext->sections[i].size; loaded->sections[tag].flags = ext->sections[i].flags; } + cache_extension_verify (loaded); return true; } |