[LLD][ELF] - Set DF_STATIC_TLS flag for X64 target

[grimar]

Summary

This is the same as D57749, but for x64 target.

"ELF Handling For Thread-Local Storage" p41 says (https://www.akkadia.org/drepper/tls.pdf):
R_X86_64_GOTTPOFF relocation is used for IE TLS models.
Hence if linker sees this relocation we should add DF_STATIC_TLS flag.
This is the relocation which FreeBSD was interested in initially I think (https://reviews.freebsd.org/D19072)

For LE model (p49), the R_X86_64_TPOFF32 is used.
But linkers do not allow to use it for DSO, for example, LLD would report:
"error: relocation R_X86_64_TPOFF32 cannot be used against symbol var; recompile with -fPIC"
So seems we only want to catch the R_X86_64_GOTTPOFF?

[grimar]

Will update. Forgot about the other test cases. Sorry.

[grimar]

• Updated the tests.

[ruiu]

LGTM

test/ELF/x86_64-static-tls-model.s

1 ↗

(On Diff #185559)

We use x86-64 instead of x86_64 as a prefix for test files.

[pcc]

ELF/Arch/X86_64.cpp

84 ↗

(On Diff #185559)

Should this be done in scanRelocs? Then I believe that HasStaticTlsModel would not need to be atomic.

[grimar]

ELF/Arch/X86_64.cpp

84 ↗

(On Diff #185559)

I suggested this in comments for D57749:
https://reviews.llvm.org/D57749?id=185294#inline-511460

Rui seems to prefer to have atomic. I have no strong feeling about what is better.
Both approaches have own pros and cons.

lld/trunk/ELF/Arch/X86_64.cpp

 template <class ELFT>
 int X86_64<ELFT>::getTlsGdRelaxSkip(RelType Type) const {
   return 2;
 }
 
 template <class ELFT>
 RelExpr X86_64<ELFT>::getRelExpr(RelType Type, const Symbol &S,
                                  const uint8_t *Loc) const {
+  if (Type == R_X86_64_GOTTPOFF)
+    Config->HasStaticTlsModel = true;
+
   switch (Type) {
   case R_X86_64_8:
   case R_X86_64_16:
   case R_X86_64_32:
   case R_X86_64_32S:
   case R_X86_64_64:
   case R_X86_64_DTPOFF32:
   case R_X86_64_DTPOFF64:

lld/trunk/test/ELF/tls-dynamic.s

 
 // CHECK:      Sections [
 // CHECK:          Name: .got (
 // CHECK-NEXT:     Type: SHT_PROGBITS
 // CHECK-NEXT:     Flags [
 // CHECK-NEXT:       SHF_ALLOC
 // CHECK-NEXT:       SHF_WRITE
 // CHECK-NEXT:     ]
-// CHECK-NEXT:     Address: 0x30D0
+// CHECK-NEXT:     Address: 0x30E0
 // CHECK-NEXT:     Offset:
 // CHECK-NEXT:     Size: 40
 
 // CHECK:      Relocations [
 // CHECK:        Section ({{.+}}) .rela.dyn {
-// CHECK-NEXT:     0x30D0 R_X86_64_DTPMOD64 - 0x0
-// CHECK-NEXT:     0x30E0 R_X86_64_DTPMOD64 c 0x0
-// CHECK-NEXT:     0x30E8 R_X86_64_DTPOFF64 c 0x0
-// CHECK-NEXT:     0x30F0 R_X86_64_TPOFF64 c 0x0
+// CHECK-NEXT:     0x30E0 R_X86_64_DTPMOD64 - 0x0
+// CHECK-NEXT:     0x30F0 R_X86_64_DTPMOD64 c 0x0
+// CHECK-NEXT:     0x30F8 R_X86_64_DTPOFF64 c 0x0
+// CHECK-NEXT:     0x3100 R_X86_64_TPOFF64 c 0x0
 // CHECK-NEXT:   }
 
-// 4297 = (0x20D0 + -4) - (0x1000 + 3) // PC relative offset to got entry.
-// 4285 = (0x20D0 + -4) - (0x100c + 3) // PC relative offset to got entry.
-// 4267 = (0x20E0 + -4) - (0x102e + 3) // PC relative offset to got entry.
-// 4263 = (0x20F0 + -4) - (0x1042 + 3) // PC relative offset to got entry.
+// 8409 = (0x30E0 + -4) - (0x1000 + 3) // PC relative offset to got entry.
+// 8397 = (0x30F0 + -4) - (0x100c + 3) // PC relative offset to got entry.
+// 8379 = (0x30F8 + -4) - (0x102e + 3) // PC relative offset to got entry.
+// 8375 = (0x3100 + -4) - (0x1042 + 3) // PC relative offset to got entry.
 
 // DIS:      Disassembly of section .text:
 // DIS-NEXT: .text:
-// DIS-NEXT:     1000: {{.+}} leaq    8393(%rip), %rdi
+// DIS-NEXT:     1000: {{.+}} leaq    8409(%rip), %rdi
 // DIS-NEXT:     1007: {{.+}} callq
-// DIS-NEXT:     100c: {{.+}} leaq    8381(%rip), %rdi
+// DIS-NEXT:     100c: {{.+}} leaq    8397(%rip), %rdi
 // DIS-NEXT:     1013: {{.+}} callq
 // DIS-NEXT:     1018: {{.+}} leaq    (%rax), %rcx
 // DIS-NEXT:     101f: {{.+}} leaq    4(%rax), %rcx
 // DIS-NEXT:     1026: 04 00
 // DIS-NEXT:     1028: 00 00
 // DIS-NEXT:     102a: 00 00
 // DIS-NEXT:     102c: 00 00
-// DIS-NEXT:     102e: {{.+}} leaq    8363(%rip), %rdi
+// DIS-NEXT:     102e: {{.+}} leaq    8379(%rip), %rdi
 // DIS-NEXT:     1035: {{.+}} callq
 // DIS-NEXT:     103b: {{.+}} leaq    (%rax), %rcx
-// DIS-NEXT:     1042: {{.+}} movq    8359(%rip), %rax
+// DIS-NEXT:     1042: {{.+}} movq    8375(%rip), %rax
 // DIS-NEXT:     1049: {{.+}} movq    %fs:(%rax), %rax
 // DIS-NEXT:     104d: {{.+}} movabsq $0, %rax
 // DIS-NEXT:     1057: {{.+}} movabsq $4, %rax
 // DIS-NEXT:     1061: {{.+}} movabsq $0, %rax

lld/trunk/test/ELF/tls-got.s

 // CHECK:      Index: 8
 // CHECK-NEXT: Name: .got
 // CHECK-NEXT: Type: SHT_PROGBITS
 // CHECK-NEXT: Flags [
 // CHECK-NEXT:   SHF_ALLOC
 // CHECK-NEXT:   SHF_WRITE
 // CHECK-NEXT: ]
 // CHECK-NEXT: Address: [[ADDR:.*]]
-// CHECK-NEXT: Offset: 0x20B0
+// CHECK-NEXT: Offset: 0x20C0
 // CHECK-NEXT: Size: 16
 // CHECK-NEXT: Link: 0
 // CHECK-NEXT: Info: 0
 // CHECK-NEXT: AddressAlignment: 8
 // CHECK-NEXT: EntrySize: 0
 // CHECK-NEXT: }
 
 // CHECK:      Relocations [
 // CHECK-NEXT:   Section (4) .rela.dyn {
-// CHECK-NEXT:     0x2020B8 R_X86_64_TPOFF64 tls0 0x0
-// CHECK-NEXT:     0x2020B0 R_X86_64_TPOFF64 tls1 0x0
+// CHECK-NEXT:     0x2020C8 R_X86_64_TPOFF64 tls0 0x0
+// CHECK-NEXT:     [[ADDR]] R_X86_64_TPOFF64 tls1 0x0
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
 
-//0x201000 + 4265 + 7 = 0x2020B0
-//0x20100A + 4263 + 7 = 0x2020B8
-//0x201014 + 4253 + 7 = 0x2020B8
+//0x201000 + 4281 + 7 = 0x2020C0
+//0x20100A + 4279 + 7 = 0x2020C8
+//0x201014 + 4269 + 7 = 0x2020C8
 //DISASM:      Disassembly of section .text:
 //DISASM-NEXT: main:
-//DISASM-NEXT: 201000: 48 8b 05 a9 10 00 00 movq 4265(%rip), %rax
-//DISASM-NEXT: 201007: 64 8b 00 movl %fs:(%rax), %eax
-//DISASM-NEXT: 20100a: 48 8b 05 a7 10 00 00 movq 4263(%rip), %rax
-//DISASM-NEXT: 201011: 64 8b 00 movl %fs:(%rax), %eax
-//DISASM-NEXT: 201014: 48 8b 05 9d 10 00 00 movq 4253(%rip), %rax
-//DISASM-NEXT: 20101b: 64 8b 00 movl %fs:(%rax), %eax
-//DISASM-NEXT: 20101e: c3 retq
+//DISASM-NEXT: 201000: {{.*}} movq 4281(%rip), %rax
+//DISASM-NEXT: 201007: {{.*}} movl %fs:(%rax), %eax
+//DISASM-NEXT: 20100a: {{.*}} movq 4279(%rip), %rax
+//DISASM-NEXT: 201011: {{.*}} movl %fs:(%rax), %eax
+//DISASM-NEXT: 201014: {{.*}} movq 4269(%rip), %rax
+//DISASM-NEXT: 20101b: {{.*}} movl %fs:(%rax), %eax
+//DISASM-NEXT: 20101e: {{.*}} retq
 
 .section .tdata,"awT",@progbits
 
 .text
  .globl main
  .align 16, 0x90
  .type main,@function
 main:
  movq tls1@GOTTPOFF(%rip), %rax
  movl %fs:0(%rax), %eax
  movq tls0@GOTTPOFF(%rip), %rax
  movl %fs:0(%rax), %eax
  movq tls0@GOTTPOFF(%rip), %rax
  movl %fs:0(%rax), %eax
  ret

lld/trunk/test/ELF/tls-initial-exec-local.s

 // REQUIRES: x86
 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 // RUN: ld.lld --hash-style=sysv -shared %t.o -o %t
 // RUN: llvm-readobj -r -s %t | FileCheck %s
 // RUN: llvm-objdump -d %t | FileCheck --check-prefix=DISASM %s
 
 // CHECK:      Name: .got
 // CHECK-NEXT: Type: SHT_PROGBITS
 // CHECK-NEXT: Flags [
 // CHECK-NEXT:   SHF_ALLOC (0x2)
 // CHECK-NEXT:   SHF_WRITE (0x1)
 // CHECK-NEXT: ]
-// CHECK-NEXT: Address: 0x2090
+// CHECK-NEXT: Address: 0x20A0
 
 // CHECK:      Relocations [
 // CHECK-NEXT:   Section ({{.*}}) .rela.dyn {
-// CHECK-NEXT:     0x2090 R_X86_64_TPOFF64 - 0x0
-// CHECK-NEXT:     0x2098 R_X86_64_TPOFF64 - 0x4
+// CHECK-NEXT:     0x20A0 R_X86_64_TPOFF64 - 0x0
+// CHECK-NEXT:     0x20A8 R_X86_64_TPOFF64 - 0x4
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
 
-// 0x1007 + 4233 = 0x2090
-// 0x100e + 4234 = 0x2098
+// 0x1007 + 4249 = 0x20A0
+// 0x100e + 4250 = 0x20A8
 // DISASM:      Disassembly of section .text:
 // DISASM-NEXT: .text:
-// DISASM-NEXT:  1000: {{.*}} addq      4233(%rip), %rax
-// DISASM-NEXT:  1007: {{.*}} addq      4234(%rip), %rax
+// DISASM-NEXT:  1000: {{.*}} addq 4249(%rip), %rax
+// DISASM-NEXT:  1007: {{.*}} addq 4250(%rip), %rax
 
         addq    foo@GOTTPOFF(%rip), %rax
         addq    bar@GOTTPOFF(%rip), %rax
 
         .section        .tbss,"awT",@nobits
 foo:
         .long 0
 bar:
         .long 0

lld/trunk/test/ELF/x86-64-static-tls-model.s

+# REQUIRES: x86
+
+## In this test R_X86_64_GOTTPOFF is a IE relocation (static TLS model),
+## test check we add STATIC_TLS flag.
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: ld.lld %t.o -o %t1 -shared
+# RUN: llvm-readobj -dynamic-table %t1 | FileCheck %s
+
+# CHECK: DynamicSection [
+# CHECK: FLAGS STATIC_TLS
+
+.section ".tdata", "awT", @progbits
+.globl var
+var:
+
+movq var@GOTTPOFF(%rip), %rax # R_X86_64_GOTTPOFF
+movl %fs:0(%rax), %eax