[4/4] RISC-V: Initial ld.bfd support for TLSDESC.

Message ID 20230817180852.121628-6-ishitatsuyuki@gmail.com
State New
Headers
Series RISC-V: Implement TLS Descriptors. |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_binutils_check--master-aarch64 success Testing passed
linaro-tcwg-bot/tcwg_binutils_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_binutils_build--master-aarch64 success Testing passed
linaro-tcwg-bot/tcwg_binutils_check--master-arm success Testing passed

Commit Message

Tatsuyuki Ishi Aug. 17, 2023, 6:08 p.m. UTC
  Only relocation handling for now; relaxation is not implemented yet.
---
 bfd/elfnn-riscv.c                          | 91 +++++++++++++++++++---
 ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp |  2 +
 2 files changed, 84 insertions(+), 9 deletions(-)
  

Patch

diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
index 38883134828..a55bee7af52 100644
--- a/bfd/elfnn-riscv.c
+++ b/bfd/elfnn-riscv.c
@@ -166,6 +166,7 @@  struct riscv_elf_link_hash_entry
 #define GOT_TLS_GD	2
 #define GOT_TLS_IE	4
 #define GOT_TLS_LE	8
+#define GOT_TLSDESC	16
   char tls_type;
 };
 
@@ -303,6 +304,7 @@  riscv_is_insn_reloc (const reloc_howto_type *howto)
 #define GOT_ENTRY_SIZE RISCV_ELF_WORD_BYTES
 #define TLS_GD_GOT_ENTRY_SIZE (RISCV_ELF_WORD_BYTES * 2)
 #define TLS_IE_GOT_ENTRY_SIZE RISCV_ELF_WORD_BYTES
+#define TLSDESC_GOT_ENTRY_SIZE (RISCV_ELF_WORD_BYTES * 2)
 /* Reserve two entries of GOTPLT for ld.so, one is used for PLT resolver,
    the other is used for link map.  Other targets also reserve one more
    entry used for runtime profile?  */
@@ -858,6 +860,12 @@  riscv_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	    return false;
 	  break;
 
+	  case R_RISCV_TLSDESC_HI20:
+	    if (!riscv_elf_record_got_reference (abfd, info, h, r_symndx)
+		|| !riscv_elf_record_tls_type (abfd, h, r_symndx, GOT_TLSDESC))
+	      return false;
+	  break;
+
 	case R_RISCV_CALL:
 	case R_RISCV_CALL_PLT:
 	  /* These symbol requires a procedure linkage table entry.
@@ -1316,7 +1324,7 @@  allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
       s = htab->elf.sgot;
       h->got.offset = s->size;
       dyn = htab->elf.dynamic_sections_created;
-      if (tls_type & (GOT_TLS_GD | GOT_TLS_IE))
+      if (tls_type & (GOT_TLS_GD | GOT_TLS_IE | GOT_TLSDESC))
 	{
 	  int indx = 0;
 	  bool need_reloc = false;
@@ -1337,6 +1345,14 @@  allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	      if (need_reloc)
 		htab->elf.srelgot->size += sizeof (ElfNN_External_Rela);
 	    }
+
+	  /* TLSDESC needs one dynamic reloc and four GOT slots.  */
+	  if (tls_type & GOT_TLSDESC)
+	    {
+	      s->size += TLSDESC_GOT_ENTRY_SIZE;
+	      /* TLSDESC always use dynamic relocs.  */
+	      htab->elf.srelgot->size += sizeof (ElfNN_External_Rela);
+	    }
 	}
       else
 	{
@@ -1564,7 +1580,7 @@  riscv_elf_size_dynamic_sections (bfd *output_bfd, struct bfd_link_info *info)
 	  if (*local_got > 0)
 	    {
 	      *local_got = s->size;
-	      if (*local_tls_type & (GOT_TLS_GD | GOT_TLS_IE))
+	      if (*local_tls_type & (GOT_TLS_GD | GOT_TLS_IE | GOT_TLSDESC))
 		{
 		  if (*local_tls_type & GOT_TLS_GD)
 		    {
@@ -1578,6 +1594,11 @@  riscv_elf_size_dynamic_sections (bfd *output_bfd, struct bfd_link_info *info)
 		      if (bfd_link_dll (info))
 			srel->size += sizeof (ElfNN_External_Rela);
 		    }
+		  if (*local_tls_type & GOT_TLSDESC)
+		    {
+		      s->size += TLSDESC_GOT_ENTRY_SIZE;
+		      srel->size += sizeof (ElfNN_External_Rela);
+		    }
 		}
 	      else
 		{
@@ -1728,6 +1749,17 @@  tpoff (struct bfd_link_info *info, bfd_vma address)
   return address - elf_hash_table (info)->tls_sec->vma - TP_OFFSET;
 }
 
+/* Return the relocation value for a static TLSDESC relocation.  */
+
+static bfd_vma
+tlsdescoff (struct bfd_link_info *info, bfd_vma address)
+{
+  /* If tls_sec is NULL, we should have signalled an error already.  */
+  if (elf_hash_table (info)->tls_sec == NULL)
+    return 0;
+  return address - elf_hash_table (info)->tls_sec->vma;
+}
+
 /* Return the global pointer's value, or 0 if it is not in use.  */
 
 static bfd_vma
@@ -1764,6 +1796,7 @@  perform_relocation (const reloc_howto_type *howto,
     case R_RISCV_GOT_HI20:
     case R_RISCV_TLS_GOT_HI20:
     case R_RISCV_TLS_GD_HI20:
+    case R_RISCV_TLSDESC_HI20:
       if (ARCH_SIZE > 32 && !VALID_UTYPE_IMM (RISCV_CONST_HIGH_PART (value)))
 	return bfd_reloc_overflow;
       value = ENCODE_UTYPE_IMM (RISCV_CONST_HIGH_PART (value));
@@ -1774,6 +1807,8 @@  perform_relocation (const reloc_howto_type *howto,
     case R_RISCV_TPREL_LO12_I:
     case R_RISCV_TPREL_I:
     case R_RISCV_PCREL_LO12_I:
+    case R_RISCV_TLSDESC_LOAD_LO12:
+    case R_RISCV_TLSDESC_ADD_LO12:
       value = ENCODE_ITYPE_IMM (value);
       break;
 
@@ -2195,8 +2230,8 @@  riscv_elf_relocate_section (bfd *output_bfd,
       bfd_vma relocation;
       bfd_reloc_status_type r = bfd_reloc_ok;
       const char *name = NULL;
-      bfd_vma off, ie_off;
-      bool unresolved_reloc, is_ie = false;
+      bfd_vma off, ie_off, desc_off;
+      bool unresolved_reloc, is_ie = false, is_desc = false;
       bfd_vma pc = sec_addr (input_section) + rel->r_offset;
       int r_type = ELFNN_R_TYPE (rel->r_info), tls_type;
       reloc_howto_type *howto = riscv_elf_rtype_to_howto (input_bfd, r_type);
@@ -2499,6 +2534,7 @@  riscv_elf_relocate_section (bfd *output_bfd,
 	case R_RISCV_NONE:
 	case R_RISCV_RELAX:
 	case R_RISCV_TPREL_ADD:
+	case R_RISCV_TLSDESC_CALL:
 	case R_RISCV_COPY:
 	case R_RISCV_JUMP_SLOT:
 	case R_RISCV_RELATIVE:
@@ -2820,6 +2856,15 @@  riscv_elf_relocate_section (bfd *output_bfd,
 	  relocation = dtpoff (info, relocation);
 	  break;
 
+	case R_RISCV_TLSDESC_LOAD_LO12:
+	case R_RISCV_TLSDESC_ADD_LO12:
+	  if (riscv_record_pcrel_lo_reloc (&pcrel_relocs, relocation, rel,
+					   input_section, info, howto,
+					   contents))
+	      continue;
+	  r = bfd_reloc_overflow;
+	  break;
+
 	case R_RISCV_32:
 	  /* Non ABS symbol should be blocked in check_relocs.  */
 	  if (ARCH_SIZE > 32)
@@ -2885,11 +2930,16 @@  riscv_elf_relocate_section (bfd *output_bfd,
 	    }
 	  break;
 
+	case R_RISCV_TLSDESC_HI20:
+	  is_desc = true;
+	  goto tls;
+
 	case R_RISCV_TLS_GOT_HI20:
 	  is_ie = true;
-	  /* Fall through.  */
+	  goto tls;
 
 	case R_RISCV_TLS_GD_HI20:
+	tls:
 	  if (h != NULL)
 	    {
 	      off = h->got.offset;
@@ -2902,12 +2952,16 @@  riscv_elf_relocate_section (bfd *output_bfd,
 	    }
 
 	  tls_type = _bfd_riscv_elf_tls_type (input_bfd, h, r_symndx);
-	  BFD_ASSERT (tls_type & (GOT_TLS_IE | GOT_TLS_GD));
+	  BFD_ASSERT (tls_type & (GOT_TLS_IE | GOT_TLS_GD | GOT_TLSDESC));
 	  /* If this symbol is referenced by both GD and IE TLS, the IE
 	     reference's GOT slot follows the GD reference's slots.  */
 	  ie_off = 0;
 	  if ((tls_type & GOT_TLS_GD) && (tls_type & GOT_TLS_IE))
-	    ie_off = TLS_GD_GOT_ENTRY_SIZE;
+	    ie_off += TLS_GD_GOT_ENTRY_SIZE;
+
+	  desc_off = ie_off;
+	  if (tls_type & GOT_TLS_IE)
+	    desc_off += TLS_IE_GOT_ENTRY_SIZE;
 
 	  if ((off & 1) != 0)
 	    off &= ~1;
@@ -2989,10 +3043,29 @@  riscv_elf_relocate_section (bfd *output_bfd,
 				  htab->elf.sgot->contents + off + ie_off);
 		    }
 		}
+
+	      if (tls_type & GOT_TLSDESC)
+		{
+		  /* TLSDESC is always handled by the dynamic linker and always need
+		   * a relocation.  */
+		  bfd_put_NN (output_bfd, 0,
+			      htab->elf.sgot->contents + off + desc_off);
+		  outrel.r_offset = sec_addr (htab->elf.sgot)
+				    + off + desc_off;
+		  outrel.r_addend = 0;
+		  if (indx == 0)
+		    outrel.r_addend = tlsdescoff (info, relocation);
+		  outrel.r_info = ELFNN_R_INFO (indx, R_RISCV_TLSDESC);
+		  riscv_elf_append_rela (output_bfd, htab->elf.srelgot, &outrel);
+		}
 	    }
 
 	  BFD_ASSERT (off < (bfd_vma) -2);
-	  relocation = sec_addr (htab->elf.sgot) + off + (is_ie ? ie_off : 0);
+	  relocation = sec_addr (htab->elf.sgot) + off;
+	  if (is_ie)
+	    relocation += ie_off;
+	  else if (is_desc)
+	    relocation += desc_off;
 	  if (!riscv_record_pcrel_hi_reloc (&pcrel_relocs, pc,
 					    relocation, r_type,
 					    false))
@@ -3212,7 +3285,7 @@  riscv_elf_finish_dynamic_symbol (bfd *output_bfd,
     }
 
   if (h->got.offset != (bfd_vma) -1
-      && !(riscv_elf_hash_entry (h)->tls_type & (GOT_TLS_GD | GOT_TLS_IE))
+      && !(riscv_elf_hash_entry (h)->tls_type & (GOT_TLS_GD | GOT_TLS_IE | GOT_TLSDESC))
       && !UNDEFWEAK_NO_DYNAMIC_RELOC (info, h))
     {
       asection *sgot;
diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
index 947a266ba72..e09c25486a5 100644
--- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
+++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
@@ -317,4 +317,6 @@  if [istarget "riscv*-*-*"] {
     run_dump_test "pcrel-reloc-rel-pie"
     run_dump_test "pcrel-reloc-abs-nopie"
     run_dump_test "pcrel-reloc-abs-pie"
+
+    run_dump_test "tlsdesc"
 }