re PR sanitizer/84761 (AddressSanitizer is not compatible with glibc 2.27 on x86)

	PR sanitizer/84761
	* sanitizer_common/sanitizer_linux_libcdep.cc (__GLIBC_PREREQ):
	Define if not defined.
	(DL_INTERNAL_FUNCTION): Don't define.
	(InitTlsSize): For __i386__ if not compiled against glibc 2.27+
	determine at runtime whether to use regparm(3), stdcall calling
	convention for older glibcs or normal calling convention for
	newer glibcs for call to _dl_get_tls_static_info.

From-SVN: r258663

libsanitizer/ChangeLog

+2018-03-19  Jakub Jelinek  <jakub@redhat.com>
+
+	PR sanitizer/84761
+	* sanitizer_common/sanitizer_linux_libcdep.cc (__GLIBC_PREREQ):
+	Define if not defined.
+	(DL_INTERNAL_FUNCTION): Don't define.
+	(InitTlsSize): For __i386__ if not compiled against glibc 2.27+
+	determine at runtime whether to use regparm(3), stdcall calling
+	convention for older glibcs or normal calling convention for
+	newer glibcs for call to _dl_get_tls_static_info.
+
 2018-03-14  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* sanitizer_common/sanitizer_stacktrace.cc

libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc

@@ -147,29 +147,44 @@ bool SanitizerGetThreadName(char *name, int max_len) {
 #endif
 }
 
+#ifndef __GLIBC_PREREQ
+#define __GLIBC_PREREQ(x, y) 0
+#endif
+
 #if !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO && \
     !SANITIZER_NETBSD
 static uptr g_tls_size;
 
-#ifdef __i386__
-# define DL_INTERNAL_FUNCTION __attribute__((regparm(3), stdcall))
-#else
-# define DL_INTERNAL_FUNCTION
-#endif
-
 void InitTlsSize() {
 // all current supported platforms have 16 bytes stack alignment
   const size_t kStackAlign = 16;
-  typedef void (*get_tls_func)(size_t*, size_t*) DL_INTERNAL_FUNCTION;
-  get_tls_func get_tls;
-  void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
-  CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
-  internal_memcpy(&get_tls, &get_tls_static_info_ptr,
-                  sizeof(get_tls_static_info_ptr));
-  CHECK_NE(get_tls, 0);
   size_t tls_size = 0;
   size_t tls_align = 0;
-  get_tls(&tls_size, &tls_align);
+  void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
+#if defined(__i386__) && !__GLIBC_PREREQ(2, 27)
+  /* On i?86, _dl_get_tls_static_info used to be internal_function, i.e.
+     __attribute__((regparm(3), stdcall)) before glibc 2.27 and is normal
+     function in 2.27 and later.  */
+  if (!dlvsym(RTLD_NEXT, "glob", "GLIBC_2.27")) {
+    typedef void (*get_tls_func)(size_t*, size_t*)
+      __attribute__((regparm(3), stdcall));
+    get_tls_func get_tls;
+    CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
+    internal_memcpy(&get_tls, &get_tls_static_info_ptr,
+                    sizeof(get_tls_static_info_ptr));
+    CHECK_NE(get_tls, 0);
+    get_tls(&tls_size, &tls_align);
+  } else
+#endif
+  {
+    typedef void (*get_tls_func)(size_t*, size_t*);
+    get_tls_func get_tls;
+    CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
+    internal_memcpy(&get_tls, &get_tls_static_info_ptr,
+                    sizeof(get_tls_static_info_ptr));
+    CHECK_NE(get_tls, 0);
+    get_tls(&tls_size, &tls_align);
+  }
   if (tls_align < kStackAlign)
     tls_align = kStackAlign;
   g_tls_size = RoundUpTo(tls_size, tls_align);