[PATCH] Backport PR84761 to gcc 7

[Richard Biener]

This backports the glibc 2.27+ fix to ASAN to the GCC 7 branch.
Probably some whitespace issue caused it not to apply 1:1 so I
manually copy-pasted it.

Bootstrapped and tested on x86_64-unknown-linux-gnu (with -m32 testing)
on both a glibc 2.27 and glibc 2.22 host.

Richard.

2018-06-07  Richard Biener  <rguent...@suse.de>

        Backport from mainline
        2018-03-19  Jakub Jelinek  <ja...@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.

Index: libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc
===================================================================
--- libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc    (revision 
261267)
+++ libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc    (working copy)
@@ -153,28 +153,43 @@ bool SanitizerGetThreadName(char *name,
 #endif
 }
 
+#ifndef __GLIBC_PREREQ
+#define __GLIBC_PREREQ(x, y) 0
+#endif
+
 #if !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO
 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);