x86: Check PT_GNU_PROPERTY early

The PT_GNU_PROPERTY segment is scanned before PT_NOTE.  For binaries
with the PT_GNU_PROPERTY segment, we can check it to avoid scan of
the PT_NOTE segment.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

diff --git a/sysdeps/x86/dl-prop.h b/sysdeps/x86/dl-prop.h
index b2836f3..d2c53c2 100644 (file)
--- a/sysdeps/x86/dl-prop.h
+++ b/sysdeps/x86/dl-prop.h
@@ -81,6 +81,60 @@ _dl_open_check (struct link_map *m)
 #endif
 }
 
+/* Check the GNU property and return its value.  It returns:
+   -1: Skip this note.
+    0: Stop checking.
+    1: Continue to check.
+ */
+static inline int
+_dl_check_gnu_property (unsigned int type, unsigned int datasz,
+                       void *ptr, unsigned int *feature_1_and,
+                       unsigned int *needed_1,
+                       unsigned int *isa_1_needed)
+{
+  if (type == GNU_PROPERTY_X86_FEATURE_1_AND
+      || type == GNU_PROPERTY_X86_ISA_1_NEEDED
+      || type == GNU_PROPERTY_1_NEEDED)
+    {
+      /* The sizes of types which we are searching for are
+        4 bytes.  There is no point to continue if this
+        note is ill-formed.  */
+      if (datasz != 4)
+       return -1;
+
+      /* NB: Stop the scan only after seeing all types which
+        we are searching for.  */
+      _Static_assert (((GNU_PROPERTY_X86_ISA_1_NEEDED
+                       > GNU_PROPERTY_X86_FEATURE_1_AND)
+                      && (GNU_PROPERTY_X86_FEATURE_1_AND
+                          > GNU_PROPERTY_1_NEEDED)),
+                     "GNU_PROPERTY_X86_ISA_1_NEEDED > "
+                     "GNU_PROPERTY_X86_FEATURE_1_AND && "
+                     "GNU_PROPERTY_X86_FEATURE_1_AND > "
+                     "GNU_PROPERTY_1_NEEDED");
+      if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
+       *feature_1_and = *(unsigned int *) ptr;
+      else if (type == GNU_PROPERTY_1_NEEDED)
+       *needed_1 = *(unsigned int *) ptr;
+      else
+       {
+         *isa_1_needed = *(unsigned int *) ptr;
+
+         /* Keep searching for the next GNU property note
+            generated by the older linker.  */
+         return 0;
+       }
+    }
+  else if (type > GNU_PROPERTY_X86_ISA_1_NEEDED)
+    {
+      /* Stop the scan since property type is in ascending
+        order.  */
+      return 0;
+    }
+
+  return 1;
+}
+
 static inline void __attribute__ ((unused))
 _dl_process_property_note (struct link_map *l, const ElfW(Nhdr) *note,
                           const ElfW(Addr) size, const ElfW(Addr) align)
@@ -141,45 +195,14 @@ _dl_process_property_note (struct link_map *l, const ElfW(Nhdr) *note,
 
              last_type = type;
 
-             if (type == GNU_PROPERTY_X86_FEATURE_1_AND
-                 || type == GNU_PROPERTY_X86_ISA_1_NEEDED
-                 || type == GNU_PROPERTY_1_NEEDED)
-               {
-                 /* The sizes of types which we are searching for are
-                    4 bytes.  There is no point to continue if this
-                    note is ill-formed.  */
-                 if (datasz != 4)
-                   return;
-
-                 /* NB: Stop the scan only after seeing all types which
-                    we are searching for.  */
-                 _Static_assert (((GNU_PROPERTY_X86_ISA_1_NEEDED
-                                   > GNU_PROPERTY_X86_FEATURE_1_AND)
-                                  && (GNU_PROPERTY_X86_FEATURE_1_AND
-                                      > GNU_PROPERTY_1_NEEDED)),
-                                 "GNU_PROPERTY_X86_ISA_1_NEEDED > "
-                                 "GNU_PROPERTY_X86_FEATURE_1_AND && "
-                                 "GNU_PROPERTY_X86_FEATURE_1_AND > "
-                                 "GNU_PROPERTY_1_NEEDED");
-                 if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
-                   feature_1_and = *(unsigned int *) ptr;
-                 else if (type == GNU_PROPERTY_1_NEEDED)
-                   needed_1 = *(unsigned int *) ptr;
-                 else
-                   {
-                     isa_1_needed = *(unsigned int *) ptr;
-
-                     /* Keep searching for the next GNU property note
-                        generated by the older linker.  */
-                     break;
-                   }
-               }
-             else if (type > GNU_PROPERTY_X86_ISA_1_NEEDED)
-               {
-                 /* Stop the scan since property type is in ascending
-                    order.  */
-                 break;
-               }
+             int result = _dl_check_gnu_property (type, datasz, ptr,
+                                                  &feature_1_and,
+                                                  &needed_1,
+                                                  &isa_1_needed);
+             if (result == -1)
+               return;         /* Skip this note.  */
+             else if (result == 0)
+               break; /* Stop checking.  */
 
              /* Check the next property item.  */
              ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr)));
@@ -217,7 +240,24 @@ static inline int __attribute__ ((always_inline))
 _dl_process_gnu_property (struct link_map *l, int fd, uint32_t type,
                          uint32_t datasz, void *data)
 {
-  return 0;
+  /* This is called on each GNU property.  */
+  unsigned int needed_1 = 0;
+  unsigned int feature_1_and = 0;
+  unsigned int isa_1_needed = 0;
+  int result = _dl_check_gnu_property (type, datasz, data,
+                                      &feature_1_and, &needed_1,
+                                      &isa_1_needed);
+  if (needed_1 != 0)
+    l->l_1_needed = needed_1;
+  if (isa_1_needed != 0)
+    l->l_x86_isa_1_needed = isa_1_needed;
+  if (feature_1_and != 0)
+    l->l_x86_feature_1_and = feature_1_and;
+  if ((needed_1 | isa_1_needed | feature_1_and) != 0)
+    l->l_property = lc_property_valid;
+  else if (l->l_property == lc_property_unknown)
+    l->l_property = lc_property_none;
+  return result <= 0 ? 0 : result;
 }
 
 #endif /* _DL_PROP_H */