[PPC64] Add support for initial-exec TLS model

[syzaara]

Summary

This patch adds the relocations needed support the initial-exec TLS model:
R_PPC64_GOT_TPREL16_HA
R_PPC64_GOT_TPREL16_LO_DS
R_PPC64_GOT_TPREL16_DS
R_PPC64_GOT_TPREL16_HI
R_PPC64_TLS

[ruiu]

LGTM

lld/ELF/Arch/PPC64.cpp

PPC64::PPC64() {
   GotPltEntrySize = 8;
   GotBaseSymInGotPlt = false;
   GotBaseSymOff = 0x8000;
   GotHeaderEntriesNum = 1;
   GotPltHeaderEntriesNum = 2;
   PltHeaderSize = 60;
   NeedsThunks = true;
 
+  TlsGotRel = R_PPC64_TPREL64;
+
   // We need 64K pages (at least under glibc/Linux, the loader won't
   // set different permissions on a finer granularity than that).
   DefaultMaxPageSize = 65536;
 
   // The PPC64 ELF ABI v1 spec, says:
   //
   //   It is normally desirable to put segments with different characteristics
   //   in separate 256 Mbyte portions of the address space, to give the
case R_PPC64_TOC:
     return R_PPC_TOC;
   case R_PPC64_REL24:
     return R_PPC_CALL_PLT;
   case R_PPC64_REL16_LO:
   case R_PPC64_REL16_HA:
   case R_PPC64_REL32:
   case R_PPC64_REL64:
     return R_PC;
+  case R_PPC64_TLS:
+    return R_HINT;
+  case R_PPC64_GOT_TPREL16_HA:
+  case R_PPC64_GOT_TPREL16_LO_DS:
+  case R_PPC64_GOT_TPREL16_DS:
+  case R_PPC64_GOT_TPREL16_HI:
+    return R_GOT_OFF;
   default:
     return R_ABS;
   }
 }
 
 void PPC64::writeGotHeader(uint8_t *Buf) const {
   write64(Buf, getPPC64TocBase());
 }

 }
 
 static std::pair<RelType, uint64_t> toAddr16Rel(RelType Type, uint64_t Val) {
   uint64_t V = Val - PPC64TocOffset;
   switch (Type) {
   case R_PPC64_TOC16:
     return {R_PPC64_ADDR16, V};
   case R_PPC64_TOC16_DS:
+  case R_PPC64_GOT_TPREL16_DS:
     return {R_PPC64_ADDR16_DS, V};
+  case R_PPC64_GOT_TPREL16_HA:
   case R_PPC64_TOC16_HA:
     return {R_PPC64_ADDR16_HA, V};
   case R_PPC64_TOC16_HI:
+  case R_PPC64_GOT_TPREL16_HI:
     return {R_PPC64_ADDR16_HI, V};
   case R_PPC64_TOC16_LO:
     return {R_PPC64_ADDR16_LO, V};
   case R_PPC64_TOC16_LO_DS:
+  case R_PPC64_GOT_TPREL16_LO_DS:
     return {R_PPC64_ADDR16_LO_DS, V};
   default:
     return {Type, Val};
   }
 }
 
 void PPC64::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
   // For a TOC-relative relocation, proceed in terms of the corresponding

lld/test/ELF/Inputs/ppc64-tls.s

+  .text
+  .abiversion 2
+  .type a,@object # @a
+  .type b,@object # @a
+  .type c,@object # @a
+  .section  .tdata,"awT",@progbits
+  .globl  a
+a:
+  .long 10                      # 0xa
+  .size a, 4
+
+  .globl  b
+b:
+  .long 10                      # 0xa
+  .size b, 4
+
+  .globl  c
+c:
+  .long 10                      # 0xa
+  .size c, 4

lld/test/ELF/ppc64-initial-exec-tls.s

+// REQUIRES: ppc
+
+// RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %p/Inputs/ppc64-tls.s -o %t2.o
+// RUN: ld.lld -shared %t2.o -o %t2.so
+// RUN: ld.lld -dynamic-linker /lib64/ld64.so.2 %t.o %t2.so -o %t
+// RUN: llvm-readelf -relocations --wide %t.o | FileCheck --check-prefix=InputRelocs %s
+// RUN: llvm-readelf -relocations --wide %t | FileCheck --check-prefix=OutputRelocs %s
+// RUN: llvm-objdump --section-headers %t | FileCheck --check-prefix=CheckGot %s
+// RUN: llvm-objdump -D %t | FileCheck --check-prefix=Dis %s
+
+// RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %p/Inputs/ppc64-tls.s -o %t2.o
+// RUN: ld.lld -shared %t2.o -o %t2.so
+// RUN: ld.lld -dynamic-linker /lib64/ld64.so.2 %t.o %t2.so -o %t
+// RUN: llvm-readelf -relocations --wide %t.o | FileCheck --check-prefix=InputRelocs %s
+// RUN: llvm-readelf -relocations --wide %t | FileCheck --check-prefix=OutputRelocs %s
+// RUN: llvm-objdump --section-headers %t | FileCheck --check-prefix=CheckGot %s
+// RUN: llvm-objdump -D %t | FileCheck --check-prefix=Dis %s
+
+  .text
+  .abiversion 2
+  .file "intial_exec.c"
+  .globl  test_initial_exec                    # -- Begin function test_initial_exec
+  .p2align  4
+  .type test_initial_exec,@function
+test_initial_exec:                                   # @test_initial_exec
+.Lfunc_begin0:
+.Lfunc_gep0:
+  addis 2, 12, .TOC.-.Lfunc_gep0@ha
+  addi 2, 2, .TOC.-.Lfunc_gep0@l
+.Lfunc_lep0:
+  .localentry test_initial_exec, .Lfunc_lep0-.Lfunc_gep0
+# %bb.0:                                # %entry
+  li 3, 0
+  stw 3, -12(1)
+  addis 3, 2, a@got@tprel@ha
+  ld 3, a@got@tprel@l(3)
+  lwzx 4, 3, a@tls
+  extsw 3, 4
+  blr
+
+
+test_hi:
+.Lfunc_gep1:
+  addis 2, 12, .TOC.-.Lfunc_gep1@ha
+  addi  2, 2,  .TOC.-.Lfunc_gep1@l
+.Lfunc_lep1:
+  .localentry test2, .Lfunc_lep1-.Lfunc_gep1
+  addis 3, 0, b@got@tprel@h
+  blr
+
+test_ds:
+.Lfunc_gep2:
+  addis 2, 12, .TOC.-.Lfunc_gep2@ha
+  addi 2, 2, .TOC.-.Lfunc_gep2@l
+.Lfunc_lep2:
+  .localentry test16, .Lfunc_lep2-.Lfunc_gep2
+  addi 3, 0, c@got@tprel
+  blr
+
+// Verify that the input has every initial-exec tls relocation type.
+// InputRelocs: Relocation section '.rela.text'
+// InputRelocs: R_PPC64_GOT_TPREL16_HA {{0+}} a + 0
+// InputRelocs: R_PPC64_GOT_TPREL16_LO_DS {{0+}} a + 0
+// InputRelocs: R_PPC64_TLS {{0+}} a + 0
+// InputRelocs: R_PPC64_GOT_TPREL16_HI {{0+}} b + 0
+// InputRelocs: R_PPC64_GOT_TPREL16_DS {{0+}} c + 0
+
+// There is a got entry for each tls variable that is accessed with the
+// initial-exec model to be filled in by the dynamic linker.
+// OutputRelocs: Relocation section '.rela.dyn' at offset 0x{{[0-9a-f]+}} contains 3 entries:
+// OutputRelocs: R_PPC64_TPREL64  {{0+}}  a + 0
+// OutputRelocs: R_PPC64_TPREL64  {{0+}}  b + 0
+// OutputRelocs: R_PPC64_TPREL64  {{0+}}  c + 0
+
+// Check that the got has 4 entires. (1 for the TOC and 3 entries for TLS
+// variables). Also verify the address so we can check
+// the offsets we calculated for each relocation type.
+// CheckGot: got          00000020 00000000100200c0
+
+// GOT stats at 0x100200c0, so TOC will be 0x100280c0
+
+// We are building the address of the first TLS got entry which contains the
+// offset of the tls variable relative to the thread pointer.
+// 0x100200c8 (got[1]).
+// #ha(a@got@tprel) --> (0x100200c8 - 0x100280c0 + 0x8000) >> 16 = 0
+// #lo(a@got@tprel)) --> (0x100200c8 - 0x100280c0) & 0xFFFF =  -7ff8 = -32760
+// Dis:  test_initial_exec:
+// Dis:    addis 3, 2, 0
+// Dis:    ld 3, -32760(3)
+// Dis:    lwzx 4, 3, 13
+
+// Second TLS got entry starts at got[2] 0x100200d0
+// #hi(b@got@tprel) --> (0x100200d0 - 0x100280c0) >> 16 = -1
+// Dis: test_hi:
+// Dis:   lis 3, -1
+
+// Third TLS got entry starts at got[3] 0x100200d8.
+// c@got@tprel--> (0x100200d8. -  0x100280c0) = -0x7fe8 = 32744
+// Dis: test_ds:
+// Dis:   li 3, -32744