s390: Fix gdb.base/all-architectures.exp with --enable-targets=all

With 7042632bf79 (s390: Hook s390 into OSABI mechanism) assigning a
default target description was moved from s390_gdbarch_init to
s390_linux_init_abi_*.  This causes problems when GDB is built with
--enable-targets=all and the user sets an unsupported OSABI, e.g. "set
osabi AIX".  In this case there is no valid tdesc, and GDB crashes with an
internal error.  Fix this by reverting parts of 7042632bf79.

gdb/ChangeLog:

	* s390-linux-tdep.c: Remove includes "features/s390-linux32.c" and
	"features/s390x-linux64.c".
	(_initialize_s390_linux_tdep): Remove initialization of tdescs
	s390_linux32 and s390x_linux64.
	(s390_linux_init_abi_31, s390_linux_init_abi_64): Don't set
	default tdesc.
	* s390-tdep.c: Include "features/s390-linux32.c" and
	"features/s390x-linux64.c".
	(s390_tdesc_valid): Add check for tdesc_has_registers.
	(s390_gdbarch_init): Make sure there is always a valid tdesc.
	(_initialize_s390_tdep): Initialize tdesc_s390_linux32 and
	tdesc_s390x_linux64.
	* s390-linux-tdep.h: Move export of tdesc_s390_linux32 and
	tdesc_s390x_linux64 to...
	* s390-tdep.h: ...here.

1 files changed, 21 insertions, 2 deletions

diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c
index 1f2a536..9626e05 100644
--- a/gdb/s390-tdep.c
+++ b/gdb/s390-tdep.c
@@ -40,6 +40,9 @@
 #include "trad-frame.h"
 #include "value.h"
 
+#include "features/s390-linux32.c"
+#include "features/s390x-linux64.c"
+
 /* Holds the current set of options to be passed to the disassembler.  */
 static char *s390_disassembler_options;
 
@@ -6789,6 +6792,9 @@ s390_tdesc_valid (struct gdbarch_tdep *tdep,
   const struct target_desc *tdesc = tdep->tdesc;
   const struct tdesc_feature *feature;
 
+  if (!tdesc_has_registers (tdesc))
+    return false;
+
   /* Core registers, i.e. general purpose and PSW.  */
   feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.core");
   if (feature == NULL)
@@ -6929,7 +6935,6 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   static const char *const stap_register_indirection_suffixes[] = { ")",
 								    NULL };
 
-  /* Otherwise create a new gdbarch for the specified machine type.  */
   struct gdbarch_tdep *tdep = s390_gdbarch_tdep_alloc ();
   struct gdbarch *gdbarch = gdbarch_alloc (&info, tdep);
   struct tdesc_arch_data *tdesc_data = tdesc_data_alloc ();
@@ -7044,8 +7049,19 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   /* Initialize the OSABI.  */
   gdbarch_init_osabi (info, gdbarch);
 
+  /* Always create a default tdesc.  Otherwise commands like 'set osabi'
+     cause GDB to crash with an internal error when the user tries to set
+     an unsupported OSABI.  */
+  if (!tdesc_has_registers (tdesc))
+  {
+    if (info.bfd_arch_info->mach == bfd_mach_s390_31)
+      tdesc = tdesc_s390_linux32;
+    else
+      tdesc = tdesc_s390x_linux64;
+  }
+  tdep->tdesc = tdesc;
+
   /* Check any target description for validity.  */
-  gdb_assert (tdesc_has_registers (tdep->tdesc));
   if (!s390_tdesc_valid (tdep, tdesc_data))
     {
       tdesc_data_cleanup (tdesc_data);
@@ -7120,4 +7136,7 @@ _initialize_s390_tdep (void)
 {
   /* Hook us into the gdbarch mechanism.  */
   register_gdbarch_init (bfd_arch_s390, s390_gdbarch_init);
+
+  initialize_tdesc_s390_linux32 ();
+  initialize_tdesc_s390x_linux64 ();
 }