ldconfig/x86: Store ISA level in cache and aux cache

Store ISA level in the portion of the unused upper 32 bits of the hwcaps
field in cache and the unused pad field in aux cache.  ISA level is stored
and checked only for shared objects in glibc-hwcaps subdirectories.  The
shared objects in the default directories aren't checked since there are
no fallbacks for these shared objects.

Tested on x86-64-v2, x86-64-v3 and x86-64-v4 machines with
--disable-hardcoded-path-in-tests and --enable-hardcoded-path-in-tests.

1 files changed, 31 insertions, 8 deletions

diff --git a/elf/cache.c b/elf/cache.c
index 11ce4ad..c01d302 100644
--- a/elf/cache.c
+++ b/elf/cache.c
@@ -146,6 +146,7 @@ struct cache_entry
   struct stringtable_entry *path; /* Path to find library.  */
   int flags;			/* Flags to indicate kind of library.  */
   unsigned int osversion;	/* Required OS version.  */
+  unsigned int isa_level;	/* Required ISA level.  */
   uint64_t hwcap;		/* Important hardware capabilities.  */
   int bits_hwcap;		/* Number of bits set in hwcap.  */
 
@@ -549,6 +550,19 @@ write_extensions (int fd, uint32_t str_offset,
   free (ext);
 }
 
+/* Compute the hwcap value from ENTRY.  */
+static inline uint64_t
+compute_hwcap_value (struct cache_entry *entry)
+{
+  if (entry->isa_level > DL_CACHE_HWCAP_ISA_LEVEL_MASK)
+    error (EXIT_FAILURE, 0, _("%s: ISA level is too high (%d > %d)"),
+	   entry->path->string, entry->isa_level,
+	   DL_CACHE_HWCAP_ISA_LEVEL_MASK);
+  return (DL_CACHE_HWCAP_EXTENSION
+	  | (((uint64_t) entry->isa_level) << 32)
+	  | entry->hwcaps->section_index);
+}
+
 /* Save the contents of the cache.  */
 void
 save_cache (const char *cache_name)
@@ -662,7 +676,7 @@ save_cache (const char *cache_name)
 	    file_entries_new->libs[idx_new].hwcap = entry->hwcap;
 	  else
 	    file_entries_new->libs[idx_new].hwcap
-	      = DL_CACHE_HWCAP_EXTENSION | entry->hwcaps->section_index;
+	      = compute_hwcap_value (entry);
 	  file_entries_new->libs[idx_new].key
 	    = str_offset + entry->lib->offset;
 	  file_entries_new->libs[idx_new].value
@@ -777,7 +791,8 @@ save_cache (const char *cache_name)
 /* Add one library to the cache.  */
 void
 add_to_cache (const char *path, const char *filename, const char *soname,
-	      int flags, unsigned int osversion, uint64_t hwcap,
+	      int flags, unsigned int osversion,
+	      unsigned int isa_level, uint64_t hwcap,
 	      struct glibc_hwcaps_subdirectory *hwcaps)
 {
   struct cache_entry *new_entry = xmalloc (sizeof (*new_entry));
@@ -795,6 +810,7 @@ add_to_cache (const char *path, const char *filename, const char *soname,
   new_entry->path = path_interned;
   new_entry->flags = flags;
   new_entry->osversion = osversion;
+  new_entry->isa_level = isa_level;
   new_entry->hwcap = hwcap;
   new_entry->hwcaps = hwcaps;
   new_entry->bits_hwcap = 0;
@@ -851,6 +867,7 @@ struct aux_cache_entry
   struct aux_cache_entry_id id;
   int flags;
   unsigned int osversion;
+  unsigned int isa_level;
   int used;
   char *soname;
   struct aux_cache_entry *next;
@@ -864,7 +881,7 @@ struct aux_cache_file_entry
   int32_t flags;		/* This is 1 for an ELF library.  */
   uint32_t soname;		/* String table indice.  */
   uint32_t osversion;		/* Required OS version.	 */
-  int32_t pad;
+  uint32_t isa_level;		/* Required ISA level.	 */
 };
 
 /* ldconfig maintains an auxiliary cache file that allows
@@ -915,7 +932,8 @@ init_aux_cache (void)
 
 int
 search_aux_cache (struct stat64 *stat_buf, int *flags,
-		  unsigned int *osversion, char **soname)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname)
 {
   struct aux_cache_entry_id id;
   id.ino = (uint64_t) stat_buf->st_ino;
@@ -933,6 +951,7 @@ search_aux_cache (struct stat64 *stat_buf, int *flags,
       {
 	*flags = entry->flags;
 	*osversion = entry->osversion;
+	*isa_level = entry->isa_level;
 	if (entry->soname != NULL)
 	  *soname = xstrdup (entry->soname);
 	else
@@ -946,7 +965,8 @@ search_aux_cache (struct stat64 *stat_buf, int *flags,
 
 static void
 insert_to_aux_cache (struct aux_cache_entry_id *id, int flags,
-		     unsigned int osversion, const char *soname, int used)
+		     unsigned int osversion, unsigned int isa_level,
+		     const char *soname, int used)
 {
   size_t hash = aux_cache_entry_id_hash (id) % aux_hash_size;
   struct aux_cache_entry *entry;
@@ -962,6 +982,7 @@ insert_to_aux_cache (struct aux_cache_entry_id *id, int flags,
   entry->id = *id;
   entry->flags = flags;
   entry->osversion = osversion;
+  entry->isa_level = isa_level;
   entry->used = used;
   if (soname != NULL)
     entry->soname = memcpy ((char *) (entry + 1), soname, len);
@@ -973,14 +994,15 @@ insert_to_aux_cache (struct aux_cache_entry_id *id, int flags,
 
 void
 add_to_aux_cache (struct stat64 *stat_buf, int flags,
-		  unsigned int osversion, const char *soname)
+		  unsigned int osversion, unsigned int isa_level,
+		  const char *soname)
 {
   struct aux_cache_entry_id id;
   id.ino = (uint64_t) stat_buf->st_ino;
   id.ctime = (uint64_t) stat_buf->st_ctime;
   id.size = (uint64_t) stat_buf->st_size;
   id.dev = (uint64_t) stat_buf->st_dev;
-  insert_to_aux_cache (&id, flags, osversion, soname, 1);
+  insert_to_aux_cache (&id, flags, osversion, isa_level, soname, 1);
 }
 
 /* Load auxiliary cache to search for unchanged entries.   */
@@ -1026,6 +1048,7 @@ load_aux_cache (const char *aux_cache_name)
     insert_to_aux_cache (&aux_cache->libs[i].id,
 			 aux_cache->libs[i].flags,
 			 aux_cache->libs[i].osversion,
+			 aux_cache->libs[i].isa_level,
 			 aux_cache->libs[i].soname == 0
 			 ? NULL : aux_cache_data + aux_cache->libs[i].soname,
 			 0);
@@ -1094,7 +1117,7 @@ save_aux_cache (const char *aux_cache_name)
 	      str_offset += len;
 	    }
 	  file_entries->libs[idx].osversion = entry->osversion;
-	  file_entries->libs[idx++].pad = 0;
+	  file_entries->libs[idx++].isa_level = entry->isa_level;
 	}
 
   /* Write out auxiliary cache file.  */