RISC-V: Clarify the addends of pc-relative access.
[deliverable/binutils-gdb.git] / bfd / elfnn-riscv.c
index eef1e800221ac25a2435b0370b8d03e4cc1d21dd..f206708a9f356eb119589228c8c68a048ed2c89c 100644 (file)
@@ -1739,25 +1739,41 @@ perform_relocation (const reloc_howto_type *howto,
 
 typedef struct
 {
+  /* PC value.  */
   bfd_vma address;
+  /* Relocation value with addend.  */
   bfd_vma value;
+  /* Original reloc type.  */
+  int type;
 } riscv_pcrel_hi_reloc;
 
 typedef struct riscv_pcrel_lo_reloc
 {
+  /* PC value of auipc.  */
+  bfd_vma address;
+  /* Internal relocation.  */
+  const Elf_Internal_Rela *reloc;
+  /* Record the following information helps to resolve the %pcrel
+     which cross different input section.  For now we build a hash
+     for pcrel at the start of riscv_elf_relocate_section, and then
+     free the hash at the end.  But riscv_elf_relocate_section only
+     handles an input section at a time, so that means we can only
+     resolve the %pcrel_hi and %pcrel_lo which are in the same input
+     section.  Otherwise, we will report dangerous relocation errors
+     for those %pcrel which are not in the same input section.  */
   asection *input_section;
   struct bfd_link_info *info;
   reloc_howto_type *howto;
-  const Elf_Internal_Rela *reloc;
-  bfd_vma addr;
-  const char *name;
   bfd_byte *contents;
+  /* The next riscv_pcrel_lo_reloc.  */
   struct riscv_pcrel_lo_reloc *next;
 } riscv_pcrel_lo_reloc;
 
 typedef struct
 {
+  /* Hash table for riscv_pcrel_hi_reloc.  */
   htab_t hi_relocs;
+  /* Linked list for riscv_pcrel_lo_reloc.  */
   riscv_pcrel_lo_reloc *lo_relocs;
 } riscv_pcrel_relocs;
 
@@ -1805,8 +1821,7 @@ riscv_zero_pcrel_hi_reloc (Elf_Internal_Rela *rel,
                           bfd_vma pc,
                           bfd_vma addr,
                           bfd_byte *contents,
-                          const reloc_howto_type *howto,
-                          bfd *input_bfd ATTRIBUTE_UNUSED)
+                          const reloc_howto_type *howto)
 {
   /* We may need to reference low addreses in PC-relative modes even when the
      PC is far away from these addresses.  For example, undefweak references
@@ -1839,11 +1854,14 @@ riscv_zero_pcrel_hi_reloc (Elf_Internal_Rela *rel,
 }
 
 static bool
-riscv_record_pcrel_hi_reloc (riscv_pcrel_relocs *p, bfd_vma addr,
-                            bfd_vma value, bool absolute)
+riscv_record_pcrel_hi_reloc (riscv_pcrel_relocs *p,
+                            bfd_vma addr,
+                            bfd_vma value,
+                            int type,
+                            bool absolute)
 {
   bfd_vma offset = absolute ? value : value - addr;
-  riscv_pcrel_hi_reloc entry = {addr, offset};
+  riscv_pcrel_hi_reloc entry = {addr, offset, type};
   riscv_pcrel_hi_reloc **slot =
     (riscv_pcrel_hi_reloc **) htab_find_slot (p->hi_relocs, &entry, INSERT);
 
@@ -1857,20 +1875,19 @@ riscv_record_pcrel_hi_reloc (riscv_pcrel_relocs *p, bfd_vma addr,
 
 static bool
 riscv_record_pcrel_lo_reloc (riscv_pcrel_relocs *p,
+                            bfd_vma addr,
+                            const Elf_Internal_Rela *reloc,
                             asection *input_section,
                             struct bfd_link_info *info,
                             reloc_howto_type *howto,
-                            const Elf_Internal_Rela *reloc,
-                            bfd_vma addr,
-                            const char *name,
                             bfd_byte *contents)
 {
   riscv_pcrel_lo_reloc *entry;
   entry = (riscv_pcrel_lo_reloc *) bfd_malloc (sizeof (riscv_pcrel_lo_reloc));
   if (entry == NULL)
     return false;
-  *entry = (riscv_pcrel_lo_reloc) {input_section, info, howto, reloc, addr,
-                                  name, contents, p->lo_relocs};
+  *entry = (riscv_pcrel_lo_reloc) {addr, reloc, input_section, info,
+                                  howto, contents, p->lo_relocs};
   p->lo_relocs = entry;
   return true;
 }
@@ -1884,26 +1901,34 @@ riscv_resolve_pcrel_lo_relocs (riscv_pcrel_relocs *p)
     {
       bfd *input_bfd = r->input_section->owner;
 
-      riscv_pcrel_hi_reloc search = {r->addr, 0};
+      riscv_pcrel_hi_reloc search = {r->address, 0, 0};
       riscv_pcrel_hi_reloc *entry = htab_find (p->hi_relocs, &search);
-      if (entry == NULL
-         /* Check the overflow when adding reloc addend.  */
-         || (RISCV_CONST_HIGH_PART (entry->value)
-             != RISCV_CONST_HIGH_PART (entry->value + r->reloc->r_addend)))
+      /* There may be a risk if the %pcrel_lo with addend refers to
+        an IFUNC symbol.  The %pcrel_hi has been relocated to plt,
+        so the corresponding %pcrel_lo with addend looks wrong.  */
+      char *string = NULL;
+      if (entry == NULL)
+       string = _("%pcrel_lo missing matching %pcrel_hi");
+      else if (entry->type == R_RISCV_GOT_HI20
+              && r->reloc->r_addend != 0)
+       string = _("%pcrel_lo with addend isn't allowed for R_RISCV_GOT_HI20");
+      else if (RISCV_CONST_HIGH_PART (entry->value)
+              != RISCV_CONST_HIGH_PART (entry->value + r->reloc->r_addend))
        {
-         char *string;
-         if (entry == NULL)
-           string = _("%pcrel_lo missing matching %pcrel_hi");
-         else if (asprintf (&string,
-                            _("%%pcrel_lo overflow with an addend, the "
-                              "value of %%pcrel_hi is 0x%" PRIx64 " without "
-                              "any addend, but may be 0x%" PRIx64 " after "
-                              "adding the %%pcrel_lo addend"),
-                            (int64_t) RISCV_CONST_HIGH_PART (entry->value),
-                            (int64_t) RISCV_CONST_HIGH_PART
+         /* Check the overflow when adding reloc addend.  */
+         if (asprintf (&string,
+                       _("%%pcrel_lo overflow with an addend, the "
+                         "value of %%pcrel_hi is 0x%" PRIx64 " without "
+                         "any addend, but may be 0x%" PRIx64 " after "
+                         "adding the %%pcrel_lo addend"),
+                       (int64_t) RISCV_CONST_HIGH_PART (entry->value),
+                       (int64_t) RISCV_CONST_HIGH_PART
                                (entry->value + r->reloc->r_addend)) == -1)
            string = _("%pcrel_lo overflow with an addend");
+       }
 
+      if (string != NULL)
+       {
          (*r->info->callbacks->reloc_dangerous)
            (r->info, string, input_bfd, r->input_section, r->reloc->r_offset);
          return true;
@@ -2225,12 +2250,9 @@ riscv_elf_relocate_section (bfd *output_bfd,
                relocation = base_got->output_section->vma
                             + base_got->output_offset + off;
 
-               r_type = ELFNN_R_TYPE (rel->r_info);
-               howto = riscv_elf_rtype_to_howto (input_bfd, r_type);
-               if (howto == NULL)
-                 r = bfd_reloc_notsupported;
-               else if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
-                                                      relocation, false))
+               if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
+                                                 relocation, r_type,
+                                                 false))
                  r = bfd_reloc_overflow;
                goto do_relocation;
 
@@ -2242,12 +2264,9 @@ riscv_elf_relocate_section (bfd *output_bfd,
                goto do_relocation;
 
              case R_RISCV_PCREL_HI20:
-               r_type = ELFNN_R_TYPE (rel->r_info);
-               howto = riscv_elf_rtype_to_howto (input_bfd, r_type);
-               if (howto == NULL)
-                 r = bfd_reloc_notsupported;
-               else if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
-                                                      relocation, false))
+               if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
+                                                 relocation, r_type,
+                                                 false))
                  r = bfd_reloc_overflow;
                goto do_relocation;
 
@@ -2384,21 +2403,29 @@ riscv_elf_relocate_section (bfd *output_bfd,
                  local_got_offsets[r_symndx] |= 1;
                }
            }
-         relocation = sec_addr (htab->elf.sgot) + off;
-         absolute = riscv_zero_pcrel_hi_reloc (rel,
-                                               info,
-                                               pc,
-                                               relocation,
-                                               contents,
-                                               howto,
-                                               input_bfd);
-         r_type = ELFNN_R_TYPE (rel->r_info);
-         howto = riscv_elf_rtype_to_howto (input_bfd, r_type);
-         if (howto == NULL)
-           r = bfd_reloc_notsupported;
-         else if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
-                                                relocation, absolute))
-           r = bfd_reloc_overflow;
+
+         if (rel->r_addend != 0)
+           {
+             msg = _("The addend isn't allowed for R_RISCV_GOT_HI20");
+             r = bfd_reloc_dangerous;
+           }
+         else
+           {
+             /* Address of got entry.  */
+             relocation = sec_addr (htab->elf.sgot) + off;
+             absolute = riscv_zero_pcrel_hi_reloc (rel, info, pc,
+                                                   relocation, contents,
+                                                   howto);
+             /* Update howto if relocation is changed.  */
+             howto = riscv_elf_rtype_to_howto (input_bfd,
+                                               ELFNN_R_TYPE (rel->r_info));
+             if (howto == NULL)
+               r = bfd_reloc_notsupported;
+             else if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
+                                                    relocation, r_type,
+                                                    absolute))
+               r = bfd_reloc_overflow;
+           }
          break;
 
        case R_RISCV_ADD8:
@@ -2499,20 +2526,16 @@ riscv_elf_relocate_section (bfd *output_bfd,
          }
 
        case R_RISCV_PCREL_HI20:
-         absolute = riscv_zero_pcrel_hi_reloc (rel,
-                                               info,
-                                               pc,
-                                               relocation,
-                                               contents,
-                                               howto,
-                                               input_bfd);
-         r_type = ELFNN_R_TYPE (rel->r_info);
-         howto = riscv_elf_rtype_to_howto (input_bfd, r_type);
+         absolute = riscv_zero_pcrel_hi_reloc (rel, info, pc, relocation,
+                                               contents, howto);
+         /* Update howto if relocation is changed.  */
+         howto = riscv_elf_rtype_to_howto (input_bfd,
+                                           ELFNN_R_TYPE (rel->r_info));
          if (howto == NULL)
            r = bfd_reloc_notsupported;
          else if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
                                                 relocation + rel->r_addend,
-                                                absolute))
+                                                r_type, absolute))
            r = bfd_reloc_overflow;
          break;
 
@@ -2532,8 +2555,8 @@ riscv_elf_relocate_section (bfd *output_bfd,
              break;
            }
 
-         if (riscv_record_pcrel_lo_reloc (&pcrel_relocs, input_section, info,
-                                          howto, rel, relocation, name,
+         if (riscv_record_pcrel_lo_reloc (&pcrel_relocs, relocation, rel,
+                                          input_section, info, howto,
                                           contents))
            continue;
          r = bfd_reloc_overflow;
@@ -2726,7 +2749,8 @@ riscv_elf_relocate_section (bfd *output_bfd,
          BFD_ASSERT (off < (bfd_vma) -2);
          relocation = sec_addr (htab->elf.sgot) + off + (is_ie ? ie_off : 0);
          if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
-                                           relocation, false))
+                                           relocation, r_type,
+                                           false))
            r = bfd_reloc_overflow;
          unresolved_reloc = false;
          break;
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