Re: [PATCH]: Linker trampoline generation for HC11/HC12

[Stephane Carrez <stcarrez at nerim dot fr>]

Hi!

> Committed but not yet used (it needs the bfd part).
>
>     Stephane
>
> 2003-04-19  Stephane Carrez  <stcarrez at nerim dot fr>
>
>     * emultempl/m68hc1xelf.em: New file to generate far trampolines on
>     68HC11 and 68HC12.
>     (LDEMUL_BEFORE_ALLOCATION): Override to gather the trampolines to
>     generate.
>     (LDEMUL_FINISH): Override to generate the trampolines after gc and
>     linker relaxation.
>     (LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS): Override to create the
>     stub file for trampolines.
>     (PARSE_AND_LIST_OPTIONS, PARSE_AND_LIST_LONGOPTS): New options
>     --no-trampoline and --bank-window to control the memory bank window.
Oops... forgot the patch below...

Index: emultempl/m68hc1xelf.em
===================================================================
RCS file: emultempl/m68hc1xelf.em
diff -N emultempl/m68hc1xelf.em
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ emultempl/m68hc1xelf.em	19 Apr 2003 08:00:55 -0000
@@ -0,0 +1,391 @@
+# This shell script emits a C file. -*- C -*-
+#   Copyright 1991, 1993, 1994, 1997, 1999, 2000, 2001, 2002, 2003
+#   Free Software Foundation, Inc.
+#
+# This file is part of GLD, the Gnu Linker.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+#
+
+# This file is sourced from elf32.em, and defines extra m68hc12-elf
+# and m68hc11-elf specific routines.  It is used to generate the
+# HC11/HC12 trampolines to call a far function by using a normal 'jsr/bsr'.
+#
+# - The HC11/HC12 relocations are checked to see if there is a
+#   R_M68HC11_16 relocation to a symbol marked with STO_M68HC12_FAR.
+#   This relocation cannot be made on the symbol but must be made on
+#   its trampoline
+#   The trampolines to generate are collected during this pass
+#   (See elf32_m68hc11_size_stubs)
+#
+# - The trampolines are generated in a ".tramp" section.  The generation
+#   takes care of HC11 and HC12 specificities.
+#   (See elf32_m68hc11_build_stubs)
+#
+# - During relocation the R_M68HC11_16 relocation to the far symbols
+#   are redirected to the trampoline that was generated.
+#
+# Copied from hppaelf and adapted for M68HC11/M68HC12 specific needs.
+#
+cat >>e${EMULATION_NAME}.c <<EOF
+
+#include "ldctor.h"
+#include "elf32-m68hc1x.h"
+
+static void m68hc11elf_create_output_section_statements PARAMS ((void));
+static asection *m68hc11elf_add_stub_section
+  PARAMS ((const char *, asection *));
+static void gld${EMULATION_NAME}_finish PARAMS ((void));
+static void m68hc11_elf_${EMULATION_NAME}_before_allocation PARAMS ((void));
+
+
+/* Fake input file for stubs.  */
+static lang_input_statement_type *stub_file;
+
+/* By default the HC11/HC12 trampolines to call a far function using
+   a normal 'bsr' and 'jsr' convention are generated during the link.
+   The --no-trampoline option prevents that.  */
+static int no_trampoline = 0;
+
+/* Name of memory bank window in the MEMORY description.
+   This is set by --bank-window option.  */
+static const char* bank_window_name = 0;
+
+static void
+m68hc11_elf_${EMULATION_NAME}_before_allocation ()
+{
+  lang_memory_region_type* region;
+  int ret;
+
+  gld${EMULATION_NAME}_before_allocation ();
+
+  /* If generating a relocatable output file, then we don't
+     have to generate the trampolines.  */
+  if (link_info.relocateable)
+    return;
+
+  ret = elf32_m68hc11_setup_section_lists (output_bfd, &link_info);
+  if (ret != 0 && no_trampoline == 0)
+    {
+      if (ret < 0)
+	{
+	  einfo ("%X%P: can not size stub section: %E\n");
+	  return;
+	}
+
+      /* Call into the BFD backend to do the real work.  */
+      if (!elf32_m68hc11_size_stubs (output_bfd,
+                                     stub_file->the_bfd,
+                                     &link_info,
+                                     &m68hc11elf_add_stub_section))
+	{
+	  einfo ("%X%P: can not size stub section: %E\n");
+	  return;
+	}
+    }
+
+  if (bank_window_name == 0)
+    return;
+
+  /* The 'bank_window_name' memory region is a special region that describes
+     the memory bank window to access to paged memory.  For 68HC12
+     this is fixed and should be:
+
+     window (rx) : ORIGIN = 0x8000, LENGTH = 16K
+
+     But for 68HC11 this is board specific.  The definition of such
+     memory region allows to control how this paged memory is accessed.  */
+  region = lang_memory_region_lookup (bank_window_name);
+
+  /* Check the length to see if it was defined in the script.  */
+  if (region->length != 0)
+    {
+      struct m68hc11_page_info *pinfo;
+      unsigned i;
+
+      /* Get default values  */
+      m68hc11_elf_get_bank_parameters (&link_info);
+      pinfo = &m68hc11_elf_hash_table (&link_info)->pinfo;
+
+      /* And override them with the region definition.  */
+      pinfo->bank_size = region->length;
+      pinfo->bank_shift = 0;
+      for (i = pinfo->bank_size; i != 0; i >>= 1)
+        pinfo->bank_shift++;
+      pinfo->bank_shift--;
+      pinfo->bank_size = 1L << pinfo->bank_shift;
+      pinfo->bank_mask = (1 << pinfo->bank_shift) - 1;
+      pinfo->bank_physical = region->origin;
+      pinfo->bank_physical_end = region->origin + pinfo->bank_size;
+
+      if (pinfo->bank_size != region->length)
+        {
+          einfo (_("warning: the size of the 'window' memory region "
+                   "is not a power of 2\n"));
+          einfo (_("warning: its size %d is truncated to %d\n"),
+                 region->length, pinfo->bank_size);
+        }
+    }
+}
+
+/* This is called before the input files are opened.  We create a new
+   fake input file to hold the stub sections.  */
+
+static void
+m68hc11elf_create_output_section_statements ()
+{
+  stub_file = lang_add_input_file ("linker stubs",
+				   lang_input_file_is_fake_enum,
+				   NULL);
+  stub_file->the_bfd = bfd_create ("linker stubs", output_bfd);
+  if (stub_file->the_bfd == NULL
+      || !bfd_set_arch_mach (stub_file->the_bfd,
+                             bfd_get_arch (output_bfd),
+                             bfd_get_mach (output_bfd)))
+    {
+      einfo ("%X%P: can not create BFD %E\n");
+      return;
+    }
+
+  ldlang_add_file (stub_file);
+}
+
+
+struct hook_stub_info
+{
+  lang_statement_list_type add;
+  asection *input_section;
+};
+
+/* Traverse the linker tree to find the spot where the stub goes.  */
+
+static bfd_boolean hook_in_stub
+  PARAMS ((struct hook_stub_info *, lang_statement_union_type **));
+
+static bfd_boolean
+hook_in_stub (info, lp)
+     struct hook_stub_info *info;
+     lang_statement_union_type **lp;
+{
+  lang_statement_union_type *l;
+  bfd_boolean ret;
+
+  for (; (l = *lp) != NULL; lp = &l->header.next)
+    {
+      switch (l->header.type)
+	{
+	case lang_constructors_statement_enum:
+	  ret = hook_in_stub (info, &constructor_list.head);
+	  if (ret)
+	    return ret;
+	  break;
+
+	case lang_output_section_statement_enum:
+	  ret = hook_in_stub (info,
+			      &l->output_section_statement.children.head);
+	  if (ret)
+	    return ret;
+	  break;
+
+	case lang_wild_statement_enum:
+	  ret = hook_in_stub (info, &l->wild_statement.children.head);
+	  if (ret)
+	    return ret;
+	  break;
+
+	case lang_group_statement_enum:
+	  ret = hook_in_stub (info, &l->group_statement.children.head);
+	  if (ret)
+	    return ret;
+	  break;
+
+	case lang_input_section_enum:
+	  if (l->input_section.section == info->input_section
+              || strcmp (bfd_get_section_name (output_section,
+                                               l->input_section.section),
+                         bfd_get_section_name (output_section,
+                                               info->input_section)) == 0)
+	    {
+	      /* We've found our section.  Insert the stub immediately
+		 before its associated input section.  */
+	      *lp = info->add.head;
+	      *(info->add.tail) = l;
+	      return TRUE;
+	    }
+	  break;
+
+	case lang_data_statement_enum:
+	case lang_reloc_statement_enum:
+	case lang_object_symbols_statement_enum:
+	case lang_output_statement_enum:
+	case lang_target_statement_enum:
+	case lang_input_statement_enum:
+	case lang_assignment_statement_enum:
+	case lang_padding_statement_enum:
+	case lang_address_statement_enum:
+	case lang_fill_statement_enum:
+	  break;
+
+	default:
+	  FAIL ();
+	  break;
+	}
+    }
+  return FALSE;
+}
+
+
+/* Call-back for elf32_m68hc11_size_stubs.  */
+
+/* Create a new stub section, and arrange for it to be linked
+   immediately before INPUT_SECTION.  */
+
+static asection *
+m68hc11elf_add_stub_section (stub_sec_name, tramp_section)
+     const char *stub_sec_name;
+     asection *tramp_section;
+{
+  asection *stub_sec;
+  flagword flags;
+  asection *output_section;
+  const char *secname;
+  lang_output_section_statement_type *os;
+  struct hook_stub_info info;
+  
+  stub_sec = bfd_make_section_anyway (stub_file->the_bfd, stub_sec_name);
+  if (stub_sec == NULL)
+    goto err_ret;
+
+  flags = (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE
+	   | SEC_HAS_CONTENTS | SEC_RELOC | SEC_IN_MEMORY | SEC_KEEP);
+  if (!bfd_set_section_flags (stub_file->the_bfd, stub_sec, flags))
+    goto err_ret;
+
+  output_section = tramp_section->output_section;
+  secname = bfd_get_section_name (output_section->owner, output_section);
+  os = lang_output_section_find (secname);
+
+  /* Try to put the new section at the same place as an existing
+     .tramp section.  Such .tramp section exists in most cases and
+     contains the trampoline code.  This way we put the generated trampoline
+     at the correct place.  */
+  info.input_section = tramp_section;
+  lang_list_init (&info.add);
+  lang_add_section (&info.add, stub_sec, os, stub_file);
+
+  if (info.add.head == NULL)
+    goto err_ret;
+
+  if (hook_in_stub (&info, &os->children.head))
+    return stub_sec;
+
+ err_ret:
+  einfo ("%X%P: can not make stub section: %E\n");
+  return NULL;
+}
+
+/* Final emulation specific call.  For the 68HC12 we use this opportunity
+   to build linker stubs.  */
+
+static void
+gld${EMULATION_NAME}_finish ()
+{
+  /* Now build the linker stubs.  */
+  if (stub_file->the_bfd->sections != NULL)
+    {
+      /* Call again the trampoline analyzer to initialize the trampoline
+         stubs with the correct symbol addresses.  Since there could have
+         been relaxation, the symbol addresses that were found during
+         first call may no longer be correct.  */
+      if (!elf32_m68hc11_size_stubs (output_bfd,
+                                     stub_file->the_bfd,
+                                     &link_info, 0))
+	{
+	  einfo ("%X%P: can not size stub section: %E\n");
+	  return;
+	}
+      if (!elf32_m68hc11_build_stubs (output_bfd, &link_info))
+	einfo ("%X%P: can not build stubs: %E\n");
+    }
+}
+
+
+/* Avoid processing the fake stub_file in vercheck, stat_needed and
+   check_needed routines.  */
+
+static void m68hc11_for_each_input_file_wrapper
+  PARAMS ((lang_input_statement_type *));
+static void m68hc11_lang_for_each_input_file
+  PARAMS ((void (*) (lang_input_statement_type *)));
+
+static void (*real_func) PARAMS ((lang_input_statement_type *));
+
+static void m68hc11_for_each_input_file_wrapper (l)
+     lang_input_statement_type *l;
+{
+  if (l != stub_file)
+    (*real_func) (l);
+}
+
+static void
+m68hc11_lang_for_each_input_file (func)
+     void (*func) PARAMS ((lang_input_statement_type *));
+{
+  real_func = func;
+  lang_for_each_input_file (&m68hc11_for_each_input_file_wrapper);
+}
+
+#define lang_for_each_input_file m68hc11_lang_for_each_input_file
+
+EOF
+
+# Define some shell vars to insert bits of code into the standard elf
+# parse_args and list_options functions.
+#
+PARSE_AND_LIST_PROLOGUE='
+#define OPTION_NO_TRAMPOLINE            300
+#define OPTION_BANK_WINDOW              301
+'
+
+# The options are repeated below so that no abbreviations are allowed.
+# Otherwise -s matches stub-group-size
+PARSE_AND_LIST_LONGOPTS='
+  { "no-trampoline", no_argument, NULL, OPTION_NO_TRAMPOLINE },
+  { "bank-window",   required_argument, NULL, OPTION_BANK_WINDOW },
+'
+
+PARSE_AND_LIST_OPTIONS='
+  fprintf (file, _(""
+"  --no-trampoline         Do not generate the far trampolines used to call\n"
+"                          a far function using 'jsr' or 'bsr'.\n"
+"  --bank-window NAME      Specify the name of the memory region describing\n"
+"                          the layout of the memory bank window.\n"
+		   ));
+'
+
+PARSE_AND_LIST_ARGS_CASES='
+    case OPTION_NO_TRAMPOLINE:
+      no_trampoline = 1;
+      break;
+    case OPTION_BANK_WINDOW:
+      bank_window_name = optarg;
+      break;
+'
+
+# Put these extra m68hc11elf routines in ld_${EMULATION_NAME}_emulation
+#
+LDEMUL_BEFORE_ALLOCATION=m68hc11_elf_${EMULATION_NAME}_before_allocation
+LDEMUL_FINISH=gld${EMULATION_NAME}_finish
+LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS=m68hc11elf_create_output_section_statements