1 files changed, 77 insertions, 14 deletions

diff --git a/gdb/x86-linux-nat.c b/gdb/x86-linux-nat.c
index 872e27e..b39d05c 100644
--- a/gdb/x86-linux-nat.c
+++ b/gdb/x86-linux-nat.c
@@ -42,7 +42,6 @@
 #include "nat/x86-linux.h"
 #include "nat/x86-linux-dregs.h"
 #include "nat/linux-ptrace.h"
-#include "nat/x86-linux-tdesc.h"
 
 /* linux_nat_target::low_new_fork implementation.  */
 
@@ -97,26 +96,90 @@ x86_linux_nat_target::post_startup_inferior (ptid_t ptid)
 const struct target_desc *
 x86_linux_nat_target::read_description ()
 {
-  static uint64_t xcr0_storage;
+  int tid;
+  int is_64bit = 0;
+#ifdef __x86_64__
+  int is_x32;
+#endif
+  static uint64_t xcr0;
+  uint64_t xcr0_features_bits;
 
   if (inferior_ptid == null_ptid)
     return this->beneath ()->read_description ();
 
-  int tid = inferior_ptid.pid ();
+  tid = inferior_ptid.pid ();
+
+#ifdef __x86_64__
+
+  x86_linux_arch_size arch_size = x86_linux_ptrace_get_arch_size (tid);
+  is_64bit = arch_size.is_64bit ();
+  is_x32 = arch_size.is_x32 ();
+
+#elif HAVE_PTRACE_GETFPXREGS
+  if (have_ptrace_getfpxregs == -1)
+    {
+      elf_fpxregset_t fpxregs;
+
+      if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
+	{
+	  have_ptrace_getfpxregs = 0;
+	  have_ptrace_getregset = TRIBOOL_FALSE;
+	  return i386_linux_read_description (X86_XSTATE_X87_MASK);
+	}
+    }
+#endif
+
+  if (have_ptrace_getregset == TRIBOOL_UNKNOWN)
+    {
+      uint64_t xstateregs[(X86_XSTATE_SSE_SIZE / sizeof (uint64_t))];
+      struct iovec iov;
+
+      iov.iov_base = xstateregs;
+      iov.iov_len = sizeof (xstateregs);
+
+      /* Check if PTRACE_GETREGSET works.  */
+      if (ptrace (PTRACE_GETREGSET, tid,
+		  (unsigned int) NT_X86_XSTATE, &iov) < 0)
+	have_ptrace_getregset = TRIBOOL_FALSE;
+      else
+	{
+	  have_ptrace_getregset = TRIBOOL_TRUE;
+
+	  /* Get XCR0 from XSAVE extended state.  */
+	  xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
+			     / sizeof (uint64_t))];
+
+	  m_xsave_layout = x86_fetch_xsave_layout (xcr0, x86_xsave_length ());
+	}
+    }
+
+  /* Check the native XCR0 only if PTRACE_GETREGSET is available.  If
+     PTRACE_GETREGSET is not available then set xcr0_features_bits to
+     zero so that the "no-features" descriptions are returned by the
+     switches below.  */
+  if (have_ptrace_getregset == TRIBOOL_TRUE)
+    xcr0_features_bits = xcr0 & X86_XSTATE_ALL_MASK;
+  else
+    xcr0_features_bits = 0;
+
+  if (is_64bit)
+    {
+#ifdef __x86_64__
+      return amd64_linux_read_description (xcr0_features_bits, is_x32);
+#endif
+    }
+  else
+    {
+      const struct target_desc * tdesc
+	= i386_linux_read_description (xcr0_features_bits);
 
-  const char *error_msg
-    = _("Can't debug 64-bit process with 32-bit GDB");
+      if (tdesc == NULL)
+	tdesc = i386_linux_read_description (X86_XSTATE_SSE_MASK);
 
-  /* Callback that is triggered the first time x86_linux_tdesc_for_tid
-     reads the xcr0 register.  Setup other bits of state */
-  auto cb = [&] (uint64_t xcr0)
-  {
-    this->m_xsave_layout
-      = x86_fetch_xsave_layout (xcr0, x86_xsave_length ());
-  };
+      return tdesc;
+    }
 
-  return x86_linux_tdesc_for_tid (tid, &have_ptrace_getregset, cb,
-				  error_msg, &xcr0_storage);
+  gdb_assert_not_reached ("failed to return tdesc");
 }