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PATCH: Automatically apply an address offset when linking between XGATE and M68HC1x cores.


Hi,

Users of XGATE and M68HC1x Binutils have requested that the linker apply an appropriate offset for one another, when linking between the two cores. This offset is only applied when the address is within "shared RAM". If the address falls outside this area, no offset is applied and a warning is emitted.

Thanks,
Sean Keys


Attachment: changelog-m68hc1x-ld.txt
Description: Text document

diff --git a/bfd/elf32-m68hc1x.c b/bfd/elf32-m68hc1x.c
index d862c9f..ae34184 100644
--- a/bfd/elf32-m68hc1x.c
+++ b/bfd/elf32-m68hc1x.c
@@ -948,6 +948,8 @@ elf32_m68hc11_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
       bfd_vma insn_addr;
       bfd_vma insn_page;
       bfd_boolean is_far = FALSE;
+      bfd_boolean is_xgate_symbol = FALSE;
+      bfd_boolean is_section_symbol = FALSE;
       struct elf_link_hash_entry *h;
       bfd_vma val;
 
@@ -972,6 +974,8 @@ elf32_m68hc11_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
 			+ sec->output_offset
 			+ sym->st_value);
 	  is_far = (sym && (sym->st_other & STO_M68HC12_FAR));
+	  is_xgate_symbol = (sym && (sym->st_target_internal));
+	  is_section_symbol =   ELF_ST_TYPE (sym->st_info) & STT_SECTION;
 	}
       else
 	{
@@ -983,6 +987,7 @@ elf32_m68hc11_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
 				   warned);
 
 	  is_far = (h && (h->other & STO_M68HC12_FAR));
+	  is_xgate_symbol = (h && (h->target_internal));
 	}
 
       if (sec != NULL && discarded_section (sec))
@@ -1122,6 +1127,39 @@ elf32_m68hc11_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
 
           insn_page = m68hc11_phys_page (pinfo, insn_addr);
 
+         /* If we are linking an S12 instruction against an XGATE symbol, we
+            need to change the offset of the symbol value so that it's correct from the
+            S12's perspective. */
+          if (is_xgate_symbol)
+          {
+            /* The ram in the global space is mapped to 0x2000 in the 16-bit
+               address space for S12 and 0xE000 in the 16-bit address space
+               for XGATE.  */
+            if (relocation >= 0xE000)
+              {
+                /* We offset the address by the difference
+                   between these two mappings.  */
+                relocation -= 0xC000;
+                break;
+              }
+            else
+              {
+                const char* msg;
+                char* buf;
+
+                msg = _("XGATE address (%lx) is not within shared RAM"
+                    "(0xE000-0xFFFF), therefore you must manually offset "
+                    "the address, and possibly manage the page, in your "
+                    "code.");
+                buf = alloca (strlen (msg) + 128);
+                sprintf (buf, msg, phys_addr);
+                if (!((*info->callbacks->warning) (info, buf, name, input_bfd,
+                    input_section, insn_addr)))
+                  return FALSE;
+                break;
+              }
+          }
+
           if (m68hc11_addr_is_banked (pinfo, relocation + rel->r_addend)
               && m68hc11_addr_is_banked (pinfo, insn_addr)
               && phys_page != insn_page)
@@ -1169,6 +1207,45 @@ elf32_m68hc11_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
           break;
         }
 
+      /* If we are linking an XGATE instruction against an S12 symbol, we
+         need to change the offset of the symbol value so that it's correct from the
+         XGATE's perspective.  */
+      if (!strcmp (howto->name, "R_XGATE_IMM8_LO")
+          || !strcmp (howto->name, "R_XGATE_IMM8_HI"))
+        {
+          /* We can only offset S12 addresses that lie within the non-paged
+             area of RAM.  */
+          if (!is_xgate_symbol && !is_section_symbol)
+            {
+              /* The ram in the global space is mapped to 0x2000 and stops at
+                 0x4000 in the 16-bit address space for S12 and 0xE000 in the
+                 16-bit address space for XGATE.  */
+              if (relocation >= 0x2000 && relocation < 0x4000)
+                 /* We offset the address by the difference
+                   between these two mappings.  */
+                relocation += 0xC000;
+              else
+                {
+                  const char* msg;
+                  char* buf;
+
+                  /* Get virtual address of instruction having the relocation.  */
+                  insn_addr = input_section->output_section->vma
+                      + input_section->output_offset + rel->r_offset;
+
+                  msg = _("S12 address (%lx) is not within shared RAM"
+                      "(0x2000-0x4000), therefore you must manually "
+                      "offset the address in your code");
+                  buf = alloca (strlen (msg) + 128);
+                  sprintf (buf, msg, phys_addr);
+                  if (!((*info->callbacks->warning) (info, buf, name, input_bfd,
+                      input_section, insn_addr)))
+                    return FALSE;
+                  break;
+                }
+            }
+        }
+
       if (r_type != R_M68HC11_NONE)
         {
           if ((r_type == R_M68HC12_PCREL_9) || (r_type == R_M68HC12_PCREL_10))

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