From 590786950c039260b75db235e81f2ae1633a055e Mon Sep 17 00:00:00 2001
From: Paul Pluzhnikov <ppluzhnikov@google.com>
Date: Tue, 4 Mar 2014 19:07:05 -0800
Subject: Add "fastload" support.

---
 sysdeps/generic/ldsodefs.h | 67 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

(limited to 'sysdeps/generic/ldsodefs.h')

diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 7ea9318..1df593c 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -27,6 +27,7 @@
 #include <stddef.h>
 #include <string.h>
 #include <stdint.h>
+#include <assert.h>
 
 #include <elf.h>
 #include <dlfcn.h>
@@ -275,6 +276,13 @@ typedef void (*receiver_fct) (int, const char *, const char *);
    The `-ldl' library functions in <dlfcn.h> provide a simple
    user interface to run-time dynamic linking.  */
 
+/* To save storage space in the hash table, we use uint16_t, which allows
+   us to support up to 64K of DSOs efficiently.  */
+typedef uint16_t dl_position_table_entry_t;
+
+/* 65535 -- max position that could be recorded in
+   dl_position_table_entry_t.  */
+#define DL_POSITION_MAX UINT16_MAX
 
 #ifndef SHARED
 # define EXTERN extern
@@ -302,6 +310,8 @@ struct rtld_global
   {
     /* A pointer to the map for the main map.  */
     struct link_map *_ns_loaded;
+    /* Tail end of the _ns_loaded link chain.  Computed on demand.  */
+    struct link_map *_ns_last;
     /* Number of object in the _dl_loaded list.  */
     unsigned int _ns_nloaded;
     /* Direct pointer to the searchlist of the main object.  */
@@ -350,7 +360,7 @@ struct rtld_global
   /* The object to be initialized first.  */
   EXTERN struct link_map *_dl_initfirst;
 
-#if HP_SMALL_TIMING_AVAIL
+#if HP_SMALL_TIMING_AVAIL || HP_TIMING_PAD
   /* Start time on CPU clock.  */
   EXTERN hp_timing_t _dl_cpuclock_offset;
 #endif
@@ -487,6 +497,9 @@ struct rtld_global_ro
 #define DL_DEBUG_HELP       (1 << 10)
 #define DL_DEBUG_PRELINK    (1 << 11)
 
+/* Google-local.  */
+#define DL_DEBUG_FASTLOAD   (1 << 12)
+
   /* OS version.  */
   EXTERN unsigned int _dl_osversion;
   /* Platform name.  */
@@ -576,6 +589,29 @@ struct rtld_global_ro
      below.  */
   EXTERN struct r_search_path_elem *_dl_init_all_dirs;
 
+  /* The merged hash table used if we have a lot of shared objects. */
+  EXTERN dl_position_table_entry_t *_dl_position_hash_table;
+  EXTERN int _dl_position_hash_mask;
+  EXTERN int _dl_position_hash_bits;
+  EXTERN int _dl_position_hash_cutoff;
+  EXTERN int _dl_enable_fastload;
+
+#define DL_POSITION_HASH_BITS_MAX       27  /* (1 << 27) entries.  */
+#if defined(__powerpc__) && !defined(__powerpc64__)
+#define DL_POSITION_HASH_CUTOFF_DEFAULT -1  /* Disabled.  */
+#else
+#define DL_POSITION_HASH_CUTOFF_DEFAULT 32  /* > 32 shared libs.  */
+#endif
+
+  /* Colon-separated list of absolute paths to ld.so.cache files
+     we'll load.  */
+  EXTERN const char *_google_ld_so_cache_list;
+
+#if HP_SMALL_TIMING_AVAIL || HP_TIMING_PAD
+  /* Overhead of a high-precision timing measurement.  */
+  EXTERN hp_timing_t _dl_hp_timing_overhead;
+#endif
+
 #ifdef NEED_DL_SYSINFO
   /* Syscall handling improvements.  This is very specific to x86.  */
   EXTERN uintptr_t _dl_sysinfo;
@@ -750,6 +786,8 @@ _dl_dprintf (int fd, const char *fmt, ...)
     }									      \
   while (1)
 
+/* Fill the position hash table used if we have a lot of shared libraries.  */
+extern void _dl_fill_position_hash (struct link_map *main_map);
 
 /* An exception raised by the _dl_signal_error function family and
    caught by _dl_catch_error function family.  Exceptions themselves
@@ -1057,6 +1095,8 @@ extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
 
 extern void _dl_sysdep_start_cleanup (void) attribute_hidden;
 
+extern int _dl_addr_inside_object (struct link_map *l, const ElfW(Addr) addr)
+     attribute_hidden;
 
 /* Determine next available module ID.  */
 extern size_t _dl_next_tls_modid (void) attribute_hidden;
@@ -1193,6 +1233,31 @@ rtld_active (void)
 }
 #endif
 
+/* Find last entry in the given scope.  Cache the result.  */
+static inline struct link_map *
+_dl_last_entry (struct link_namespaces *ns)
+{
+  struct link_map *map = ns->_ns_last;
+  size_t len = 0;
+
+  if (map == NULL)
+    map = ns->_ns_loaded;
+
+  if (map == NULL)
+    return NULL;
+
+  while (map->l_next != NULL)
+    {
+      map = map->l_next;
+      /* If we have more than _ns_nloaded libraries, it's likely we are
+	 looking at a corrupt list.  Fail hard.  */
+      assert (len++ < ns->_ns_nloaded);
+    }
+
+  ns->_ns_last = map;
+  return map;
+}
+
 __END_DECLS
 
 #endif /* ldsodefs.h */
-- 
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