[PATCH/RFA] Add OS/ABI infrastructure to SuperH target

[Jason R Thorpe <thorpej@wasabisystems.com>]

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The following adds OS/ABI handling a'la the ARM and Alpha targets
to the SuperH target.

Once this is in, I'll be able to commit my NetBSD/sh variant.

OK to commit?

	* sh-tdep.c (sh_abi_names): Declare.
	(process_note_abi_tag_sections): New function.
	(get_elfosabi): Ditto.
	(sh_gdbarch_register_os_abi): Ditto.
	(sh_dump_tdep): Ditto.
	(_initialize_sh_tdep): Use gdbarch_register to register
	sh_gdbarch_init and sh_dump_tdep.
	* config/sh/tm-sh.h (sh_abi): Declare.
	(gdbarch_tdep): Add sh_abi and abi_name members.

-- 
        -- Jason R. Thorpe <thorpej@wasabisystems.com>

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Index: sh-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/sh-tdep.c,v
retrieving revision 1.52
diff -u -r1.52 sh-tdep.c
--- sh-tdep.c	12 Apr 2002 18:18:57 -0000	1.52
+++ sh-tdep.c	7 May 2002 08:21:59 -0000
@@ -41,6 +41,8 @@
 #include "regcache.h"
 #include "doublest.h"
 
+#include "elf-bfd.h"
+
 #include "solib-svr4.h"
 
 void (*sh_show_regs) (void);
@@ -1895,6 +1897,182 @@
 }
 #endif /* SVR4_SHARED_LIBS */
 
+\f
+/* This table matches the indices assigned to enum sh_abi.  Keep
+   them in sync.  */
+static const char * const sh_abi_names[] =
+{
+  "<unknown>",
+  "GNU/Linux",
+  "NetBSD ELF",
+  NULL
+};
+
+static void
+process_note_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
+{
+  enum sh_abi *os_ident_ptr = obj;
+  const char *name;
+  unsigned int sectsize;
+
+  name = bfd_get_section_name (abfd, sect);
+  sectsize = bfd_section_size (abfd, sect);
+
+  if (strcmp (name, ".note.ABI-tag") == 0 && sectsize > 0)
+    {
+      unsigned int name_length, data_length, note_type;
+      char *note;
+
+      /* If the section is larger than this, it's probably not what we are
+	 looking for.  */
+      if (sectsize > 128)
+	sectsize = 128;
+
+      note = alloca (sectsize);
+
+      bfd_get_section_contents (abfd, sect, note,
+				(file_ptr) 0, (bfd_size_type) sectsize);
+
+      name_length = bfd_h_get_32 (abfd, note);
+      data_length = bfd_h_get_32 (abfd, note + 4);
+      note_type   = bfd_h_get_32 (abfd, note + 8);
+
+      if (name_length == 4 && data_length == 16 && note_type == 1
+	  && strcmp (note + 12, "GNU") == 0)
+	{
+	  int os_number = bfd_h_get_32 (abfd, note + 16);
+
+	  /* The case numbers are from abi-tags in glibc.  */
+	  switch (os_number)
+	    {
+	    case 0:
+	      *os_ident_ptr = SH_ABI_LINUX;
+	      break;
+
+	    case 1:
+	      internal_error
+		(__FILE__, __LINE__,
+		 "process_note_abi_sections: Hurd objects not supported");
+	      break;
+
+	    case 2:
+	      internal_error
+		(__FILE__, __LINE__,
+		 "process_note_abi_sections: Solaris objects not supported");
+	      break;
+
+	    default:
+	      internal_error
+		(__FILE__, __LINE__,
+		 "process_note_abi_sections: unknown OS number %d",
+		 os_number);
+	    }
+	}
+    }
+  /* NetBSD uses a similar trick.  */
+  else if (strcmp (name, ".note.netbsd.ident") == 0 && sectsize > 0)
+    {
+      unsigned int name_length, desc_length, note_type;
+      char *note;
+
+      /* If the section is larger than this, it's probably not what we are
+	 looking for.  */
+      if (sectsize > 128)
+	sectsize = 128;
+
+      note = alloca (sectsize);
+
+      bfd_get_section_contents (abfd, sect, note,
+				(file_ptr) 0, (bfd_size_type) sectsize);
+
+      name_length = bfd_h_get_32 (abfd, note);
+      desc_length = bfd_h_get_32 (abfd, note + 4);
+      note_type   = bfd_h_get_32 (abfd, note + 8);
+
+      if (name_length == 7 && desc_length == 4 && note_type == 1
+	  && strcmp (note + 12, "NetBSD") == 0)
+	/* XXX Should we check the version here?
+	   Probably not necessary yet.  */
+	*os_ident_ptr = SH_ABI_NETBSD_ELF;
+    }
+}
+
+static int
+get_elfosabi (bfd *abfd)
+{
+  int elfosabi;
+  enum sh_abi sh_abi = SH_ABI_UNKNOWN;
+
+  elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
+
+  /* When elfosabi is 0 (ELFOSABI_NONE), this is supposed to indicate
+     that we're on a SYSV system.  However, GNU/Linux uses a note section
+     to record OS/ABI info, but leaves e_ident[EI_OSABI] zero.  So we
+     have to check the note sections too.  */
+  if (elfosabi == 0)
+    {
+      bfd_map_over_sections (abfd,
+			     process_note_abi_tag_sections,
+			     &sh_abi);
+    }
+
+  if (sh_abi != SH_ABI_UNKNOWN)
+    return sh_abi;
+
+  switch (elfosabi)
+    {
+    case ELFOSABI_NONE:
+      /* Leave it as unknown.  */
+      break;
+
+    case ELFOSABI_NETBSD:
+      return SH_ABI_NETBSD_ELF;
+
+    case ELFOSABI_LINUX:
+      return SH_ABI_LINUX;
+    }
+
+  return SH_ABI_UNKNOWN;
+}
+
+struct sh_abi_handler
+{
+  struct sh_abi_handler *next;
+  enum sh_abi abi;
+  void (*init_abi)(struct gdbarch_info, struct gdbarch *);
+};
+
+struct sh_abi_handler *sh_abi_handler_list = NULL;
+
+void
+sh_gdbarch_register_os_abi (enum sh_abi abi,
+                            void (*init_abi)(struct gdbarch_info,
+					     struct gdbarch *))
+{
+  struct sh_abi_handler **handler_p;
+
+  for (handler_p = &sh_abi_handler_list; *handler_p != NULL;
+       handler_p = &(*handler_p)->next)
+    {
+      if ((*handler_p)->abi == abi)
+	{
+	  internal_error
+	    (__FILE__, __LINE__,
+	     "sh_gdbarch_register_os_abi: A handler for this ABI variant "
+	     "(%d) has already been registered", (int) abi);
+	  /* If user wants to continue, override previous definition.  */
+	  (*handler_p)->init_abi = init_abi;
+	  return;
+	}
+    }
+
+  (*handler_p)
+    = (struct sh_abi_handler *) xmalloc (sizeof (struct sh_abi_handler));
+  (*handler_p)->next = NULL;
+  (*handler_p)->abi = abi;
+  (*handler_p)->init_abi = init_abi;
+}
+
 static gdbarch_init_ftype sh_gdbarch_init;
 
 static struct gdbarch *
@@ -1906,17 +2084,51 @@
   gdbarch_register_name_ftype *sh_register_name;
   gdbarch_store_return_value_ftype *sh_store_return_value;
   gdbarch_register_virtual_type_ftype *sh_register_virtual_type;
+  enum sh_abi sh_abi = SH_ABI_UNKNOWN;
+  struct sh_abi_handler *abi_handler;
+
+  /* Try to determine the ABI of the object we are loading.  */
+
+  if (info.abfd != NULL)
+    {
+      switch (bfd_get_flavour (info.abfd))
+	{
+	case bfd_target_elf_flavour:
+	  sh_abi = get_elfosabi (info.abfd);
+	  break;
+
+	default:
+	  /* Just leave it as "unkown".  */
+	  break;
+	}
+    }
 
   /* Find a candidate among the list of pre-declared architectures. */
-  arches = gdbarch_list_lookup_by_info (arches, &info);
-  if (arches != NULL)
-    return arches->gdbarch;
+  for (arches = gdbarch_list_lookup_by_info (arches, &info);
+       arches != NULL;
+       arches = gdbarch_list_lookup_by_info (arches->next, &info))
+    {
+      /* Make sure the ABI selection matches.  */
+      tdep = gdbarch_tdep (arches->gdbarch);
+      if (tdep && tdep->sh_abi == sh_abi)
+	return arches->gdbarch;
+    }
 
   /* None found, create a new architecture from the information
      provided. */
   tdep = XMALLOC (struct gdbarch_tdep);
   gdbarch = gdbarch_alloc (&info, tdep);
 
+  tdep->sh_abi = sh_abi;
+  if (sh_abi < SH_ABI_INVALID)
+    tdep->abi_name = sh_abi_names[sh_abi];
+  else
+    {
+      internal_error (__FILE__, __LINE__, "Invalid setting of sh_abi %d",
+		      (int) sh_abi);
+      tdep->abi_name = "<invalid>";
+    }
+
   /* Initialize the register numbers that are not common to all the
      variants to -1, if necessary thse will be overwritten in the case
      statement below. */
@@ -2167,15 +2379,58 @@
   set_gdbarch_frame_num_args (gdbarch, frame_num_args_unknown);
   set_gdbarch_believe_pcc_promotion (gdbarch, 1);
 
+  /* Hook in ABI-specific overrides, if they have been registered.  If
+     the ABI is unknown, this is probably an embedded target, so we
+     should not warn about this situation.  */
+  if (sh_abi != SH_ABI_UNKNOWN)
+    {
+      for (abi_handler = sh_abi_handler_list; abi_handler != NULL;
+	   abi_handler = abi_handler->next)
+	if (abi_handler->abi == sh_abi)
+	  break;
+
+      if (abi_handler)
+        abi_handler->init_abi (info, gdbarch);
+      else
+        {
+	  /* We assume that if GDB_MULTI_ARCH is less than
+	     GDB_MULTI_ARCH_TM that an ABI variant can be supported by 
+	     overriding definitions in this file.  */
+	  if (GDB_MULTI_ARCH > GDB_MULTI_ARCH_PARTIAL) 
+	    fprintf_filtered
+	      (gdb_stderr,
+	       "A handler for the ABI variant \"%s\" is not built into this "
+	       "configuration of GDB.  "
+	       "Attempting to continue with the default SuperH settings",
+	       sh_abi_names[sh_abi]);
+        }
+    }
+
   return gdbarch;
 }
 
+static void
+sh_dump_tdep (struct gdbarch *current_gdbarch, struct ui_file *file)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
+
+  if (tdep == NULL)
+    return;
+
+  if (tdep->abi_name != NULL)
+    fprintf_unfiltered (file, "sh_dump_tdep: ABI = %s\n", tdep->abi_name);
+  else
+    internal_error (__FILE__, __LINE__,
+		    "sh_dump_tdep: illegal setting of tdep->sh_abi (%d)",
+		    (int) tdep->sh_abi);
+}
+
 void
 _initialize_sh_tdep (void)
 {
   struct cmd_list_element *c;
   
-  register_gdbarch_init (bfd_arch_sh, sh_gdbarch_init);
+  gdbarch_register (bfd_arch_sh, sh_gdbarch_init, sh_dump_tdep);
 
   add_com ("regs", class_vars, sh_show_regs_command, "Print all registers");
 }
Index: config/sh/tm-sh.h
===================================================================
RCS file: /cvs/src/src/gdb/config/sh/tm-sh.h,v
retrieving revision 1.16
diff -u -r1.16 tm-sh.h
--- config/sh/tm-sh.h	12 Jul 2001 02:29:33 -0000	1.16
+++ config/sh/tm-sh.h	7 May 2002 08:22:00 -0000
@@ -23,6 +23,17 @@
 
 #define GDB_MULTI_ARCH 1
 
+/* ABI variants that we know about.  If you add to this enum, please
+   update the table of names in sh-tdep.c.  */
+enum sh_abi
+{
+  SH_ABI_UNKNOWN = 0,
+  SH_ABI_LINUX,
+  SH_ABI_NETBSD_ELF,
+
+  SH_ABI_INVALID	/* Keep this last.  */
+};
+
 /* Information that is dependent on the processor variant. */
 
 struct gdbarch_tdep
@@ -56,6 +67,9 @@
     int ARGLAST_REGNUM;
     int FLOAT_ARGLAST_REGNUM;
     int RETURN_REGNUM;
+
+    enum sh_abi sh_abi;		/* OS/ABI of the inferior */
+    const char *abi_name;	/* Name of the above */
   };
 
 /* Registers common to all the SH variants. */
@@ -81,4 +95,3 @@
 #define LITTLE_REMOTE_BREAKPOINT { 0x20, 0xc3 } /* Used in remote.c */
 
 /*#define NOP   {0x20, 0x0b}*/ /* Who uses this???*/
-