Revert "gdb/gdbserver: share some code relating to target description creation"

This reverts commit cd9b374ffe372dcaf7e4c15548cf53a301d8dcdd.

1 files changed, 104 insertions, 44 deletions

diff --git a/gdbserver/linux-x86-low.cc b/gdbserver/linux-x86-low.cc
index 9bf369f..30d876e 100644
--- a/gdbserver/linux-x86-low.cc
+++ b/gdbserver/linux-x86-low.cc
@@ -48,7 +48,6 @@
 #include "nat/x86-linux.h"
 #include "nat/x86-linux-dregs.h"
 #include "linux-x86-tdesc.h"
-#include "nat/x86-linux-tdesc.h"
 
 #ifdef __x86_64__
 static target_desc_up tdesc_amd64_linux_no_xml;
@@ -845,20 +844,32 @@ int have_ptrace_getfpxregs =
 #endif
 ;
 
-/* Cached xcr0 value.  This is initialised the first time
-   x86_linux_read_description is called.  */
-
-static uint64_t xcr0_storage;
-
 /* Get Linux/x86 target description from running target.  */
 
 static const struct target_desc *
 x86_linux_read_description (void)
 {
-  int tid = lwpid_of (current_thread);
+  unsigned int machine;
+  int is_elf64;
+  int xcr0_features;
+  int tid;
+  static uint64_t xcr0;
+  static int xsave_len;
+  struct regset_info *regset;
+
+  tid = lwpid_of (current_thread);
+
+  is_elf64 = linux_pid_exe_is_elf_64_file (tid, &machine);
 
-  const char *error_msg
-    = _("Can't debug 64-bit process with 32-bit GDBserver");
+  if (sizeof (void *) == 4)
+    {
+      if (is_elf64 > 0)
+       error (_("Can't debug 64-bit process with 32-bit GDBserver"));
+#ifndef __x86_64__
+      else if (machine == EM_X86_64)
+       error (_("Can't debug x86-64 process with 32-bit GDBserver"));
+#endif
+    }
 
   /* If we are not allowed to send an XML target description then we need
      to use the hard-wired target descriptions.  This corresponds to GDB's
@@ -868,54 +879,103 @@ x86_linux_read_description (void)
      generate some alternative target descriptions.  */
   if (!use_xml)
     {
-      x86_linux_arch_size arch_size = x86_linux_ptrace_get_arch_size (tid);
-      bool is_64bit = arch_size.is_64bit ();
-      bool is_x32 = arch_size.is_x32 ();
-
-      if (sizeof (void *) == 4 && is_64bit && !is_x32)
-	error ("%s", error_msg);
-
 #ifdef __x86_64__
-      if (is_64bit && !is_x32)
+      if (machine == EM_X86_64)
 	return tdesc_amd64_linux_no_xml.get ();
       else
 #endif
 	return tdesc_i386_linux_no_xml.get ();
     }
 
-  /* 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)
-  {
-    i387_set_xsave_mask (xcr0, x86_xsave_length ());
-  };
+#if !defined __x86_64__ && defined HAVE_PTRACE_GETFPXREGS
+  if (machine == EM_386 && have_ptrace_getfpxregs == -1)
+    {
+      elf_fpxregset_t fpxregs;
 
-  /* If have_ptrace_getregset is changed to true by calling
-     x86_linux_tdesc_for_tid then we will perform some additional
-     initialisation.  */
-  bool have_ptrace_getregset_is_unknown
-    = have_ptrace_getregset == TRIBOOL_UNKNOWN;
+      if (ptrace (PTRACE_GETFPXREGS, tid, 0, (long) &fpxregs) < 0)
+	{
+	  have_ptrace_getfpxregs = 0;
+	  have_ptrace_getregset = TRIBOOL_FALSE;
+	  return i386_linux_read_description (X86_XSTATE_X87);
+	}
+      else
+	have_ptrace_getfpxregs = 1;
+    }
+#endif
 
-  const target_desc *tdesc
-    = x86_linux_tdesc_for_tid (tid, &have_ptrace_getregset, cb, error_msg,
-			       &xcr0_storage);
+  if (have_ptrace_getregset == TRIBOOL_UNKNOWN)
+    {
+      uint64_t xstateregs[(X86_XSTATE_SSE_SIZE / sizeof (uint64_t))];
+      struct iovec iov;
 
-  if (have_ptrace_getregset_is_unknown
-      && have_ptrace_getregset == TRIBOOL_TRUE)
+      iov.iov_base = xstateregs;
+      iov.iov_len = sizeof (xstateregs);
+
+      /* Check if PTRACE_GETREGSET works.  */
+      if (ptrace (PTRACE_GETREGSET, tid,
+		  (unsigned int) NT_X86_XSTATE, (long) &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))];
+
+	  /* No MPX on x32.  */
+	  if (machine == EM_X86_64 && !is_elf64)
+	    xcr0 &= ~X86_XSTATE_MPX;
+
+	  xsave_len = x86_xsave_length ();
+
+	  /* Use PTRACE_GETREGSET if it is available.  */
+	  for (regset = x86_regsets;
+	       regset->fill_function != NULL; regset++)
+	    if (regset->get_request == PTRACE_GETREGSET)
+	      regset->size = xsave_len;
+	    else if (regset->type != GENERAL_REGS)
+	      regset->size = 0;
+	}
+    }
+
+  /* Check the native XCR0 only if PTRACE_GETREGSET is available.  */
+  xcr0_features = (have_ptrace_getregset == TRIBOOL_TRUE
+		   && (xcr0 & X86_XSTATE_ALL_MASK));
+
+  if (xcr0_features)
+    i387_set_xsave_mask (xcr0, xsave_len);
+
+  if (machine == EM_X86_64)
+    {
+#ifdef __x86_64__
+      const target_desc *tdesc = NULL;
+
+      if (xcr0_features)
+	{
+	  tdesc = amd64_linux_read_description (xcr0 & X86_XSTATE_ALL_MASK,
+						!is_elf64);
+	}
+
+      if (tdesc == NULL)
+	tdesc = amd64_linux_read_description (X86_XSTATE_SSE_MASK, !is_elf64);
+      return tdesc;
+#endif
+    }
+  else
     {
-      int xsave_len = x86_xsave_length ();
-
-      /* Use PTRACE_GETREGSET if it is available.  */
-      for (regset_info *regset = x86_regsets;
-	   regset->fill_function != nullptr;
-	   regset++)
-	if (regset->get_request == PTRACE_GETREGSET)
-	  regset->size = xsave_len;
-	else if (regset->type != GENERAL_REGS)
-	  regset->size = 0;
+      const target_desc *tdesc = NULL;
+
+      if (xcr0_features)
+	  tdesc = i386_linux_read_description (xcr0 & X86_XSTATE_ALL_MASK);
+
+      if (tdesc == NULL)
+	tdesc = i386_linux_read_description (X86_XSTATE_SSE);
+
+      return tdesc;
     }
 
-  return tdesc;
+  gdb_assert_not_reached ("failed to return tdesc");
 }
 
 /* Update all the target description of all processes; a new GDB