[lld] r268525 - [ELF][MIPS] R_MIPS_GOT_DISP, R_MIPS_GOT_PAGE, R_MIPS_GOT_OFST relocations support

Simon Atanasyan via llvm-commits llvm-commits at lists.llvm.org
Wed May 4 10:47:11 PDT 2016


Author: atanasyan
Date: Wed May  4 12:47:11 2016
New Revision: 268525

URL: http://llvm.org/viewvc/llvm-project?rev=268525&view=rev
Log:
[ELF][MIPS] R_MIPS_GOT_DISP, R_MIPS_GOT_PAGE, R_MIPS_GOT_OFST relocations support

These relocations introduced by MIPS N64 ABI. R_MIPS_GOT_DISP references
GOT entry with full symbol's address, R_MIPS_GOT_PAGE creates GOT entry
with address of memory page which includes symbol's address,
R_MIPS_GOT_OFST used together with R_MIPS_GOT_PAGE. This relocation
calculates offset from beginning of memory page to the symbol address.

Added:
    lld/trunk/test/ELF/mips-64-got.s
Modified:
    lld/trunk/ELF/Target.cpp

Modified: lld/trunk/ELF/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=268525&r1=268524&r2=268525&view=diff
==============================================================================
--- lld/trunk/ELF/Target.cpp (original)
+++ lld/trunk/ELF/Target.cpp Wed May  4 12:47:11 2016
@@ -1252,6 +1252,7 @@ RelExpr MipsTargetInfo<ELFT>::getRelExpr
     return R_PLT;
   case R_MIPS_HI16:
   case R_MIPS_LO16:
+  case R_MIPS_GOT_OFST:
     // MIPS _gp_disp designates offset between start of function and 'gp'
     // pointer into GOT. __gnu_local_gp is equal to the current value of
     // the 'gp'. Therefore any relocations against them do not require
@@ -1268,12 +1269,16 @@ RelExpr MipsTargetInfo<ELFT>::getRelExpr
   case R_MIPS_PCLO16:
     return R_PC;
   case R_MIPS_GOT16:
-  case R_MIPS_CALL16:
     if (S.isLocal())
       return R_MIPS_GOT_LOCAL;
+  // fallthrough
+  case R_MIPS_CALL16:
+  case R_MIPS_GOT_DISP:
     if (!S.isPreemptible())
       return R_MIPS_GOT;
     return R_GOT_OFF;
+  case R_MIPS_GOT_PAGE:
+    return R_MIPS_GOT_LOCAL;
   }
 }
 
@@ -1451,10 +1456,13 @@ void MipsTargetInfo<ELFT>::relocateOne(u
     write32<E>(Loc, (Instr & ~0x3ffffff) | (Val >> 2));
     break;
   }
+  case R_MIPS_GOT_DISP:
+  case R_MIPS_GOT_PAGE:
   case R_MIPS_GOT16:
     checkInt<16>(Val, Type);
   // fallthrough
   case R_MIPS_CALL16:
+  case R_MIPS_GOT_OFST:
     writeMipsLo16<E>(Loc, Val);
     break;
   case R_MIPS_GPREL16: {
@@ -1515,7 +1523,7 @@ void MipsTargetInfo<ELFT>::relocateOne(u
 
 template <class ELFT>
 bool MipsTargetInfo<ELFT>::usesOnlyLowPageBits(uint32_t Type) const {
-  return Type == R_MIPS_LO16;
+  return Type == R_MIPS_LO16 || Type == R_MIPS_GOT_OFST;
 }
 }
 }

Added: lld/trunk/test/ELF/mips-64-got.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips-64-got.s?rev=268525&view=auto
==============================================================================
--- lld/trunk/test/ELF/mips-64-got.s (added)
+++ lld/trunk/test/ELF/mips-64-got.s Wed May  4 12:47:11 2016
@@ -0,0 +1,80 @@
+# Check MIPS N64 ABI GOT relocations
+
+# RUN: llvm-mc -filetype=obj -triple=mips64-unknown-linux \
+# RUN:         %p/Inputs/mips-pic.s -o %t.so.o
+# RUN: llvm-mc -filetype=obj -triple=mips64-unknown-linux %s -o %t.exe.o
+# RUN: ld.lld %t.so.o -shared -o %t.so
+# RUN: ld.lld %t.exe.o %t.so -o %t.exe
+# RUN: llvm-objdump -d -t %t.exe | FileCheck %s
+# RUN: llvm-readobj -r -mips-plt-got %t.exe | FileCheck -check-prefix=GOT %s
+
+# REQUIRES: mips
+
+# CHECK:      __start:
+
+# CHECK-NEXT:    20000:   df 82 80 20   ld      $2, -32736($gp)
+# CHECK-NEXT:    20004:   64 42 00 14   daddiu  $2,  $2, 20
+# CHECK-NEXT:    20008:   24 42 80 30   addiu   $2,  $2, -32720
+# CHECK-NEXT:    2000c:   24 42 80 28   addiu   $2,  $2, -32728
+
+# CHECK: 0000000000020014   .text   00000000 foo
+# CHECK: 0000000000037ff0   .got    00000000 .hidden _gp
+# CHECK: 0000000000020000   .text   00000000 __start
+# CHECK: 0000000000020010   .text   00000000 bar
+
+# GOT:      Relocations [
+# GOT-NEXT: ]
+# GOT-NEXT: Primary GOT {
+# GOT-NEXT:   Canonical gp value: 0x37FF0
+# GOT-NEXT:   Reserved entries [
+# GOT-NEXT:     Entry {
+# GOT-NEXT:       Address: 0x30000
+# GOT-NEXT:       Access: -32752
+# GOT-NEXT:       Initial: 0x0
+# GOT-NEXT:       Purpose: Lazy resolver
+# GOT-NEXT:     }
+# GOT-NEXT:     Entry {
+# GOT-NEXT:       Address: 0x30008
+# GOT-NEXT:       Access: -32744
+# GOT-NEXT:       Initial: 0x8000000000000000
+# GOT-NEXT:       Purpose: Module pointer (GNU extension)
+# GOT-NEXT:     }
+# GOT-NEXT:   ]
+# GOT-NEXT:   Local entries [
+# GOT-NEXT:     Entry {
+# GOT-NEXT:       Address: 0x30010
+# GOT-NEXT:       Access: -32736
+# GOT-NEXT:       Initial: 0x20000
+# GOT-NEXT:     }
+# GOT-NEXT:     Entry {
+# GOT-NEXT:       Address: 0x30018
+# GOT-NEXT:       Access: -32728
+# GOT-NEXT:       Initial: 0x20010
+# GOT-NEXT:     }
+# GOT-NEXT:   ]
+# GOT-NEXT:   Global entries [
+# GOT-NEXT:     Entry {
+# GOT-NEXT:       Address: 0x30020
+# GOT-NEXT:       Access: -32720
+# GOT-NEXT:       Initial: 0x0
+# GOT-NEXT:       Value: 0x0
+# GOT-NEXT:       Type: Function
+# GOT-NEXT:       Section: Undefined
+# GOT-NEXT:       Name: foo1a
+# GOT-NEXT:     }
+# GOT-NEXT:   ]
+# GOT-NEXT:   Number of TLS and multi-GOT entries: 0
+# GOT-NEXT: }
+
+  .text
+  .global  __start, bar
+__start:
+  ld      $v0,%got_page(foo)($gp)             # R_MIPS_GOT_PAGE
+  daddiu  $v0,$v0,%got_ofst(foo)              # R_MIPS_GOT_OFST
+  addiu   $v0,$v0,%got_disp(foo1a)            # R_MIPS_GOT_DISP
+  addiu   $v0,$v0,%got_disp(bar)              # R_MIPS_GOT_DISP
+
+bar:
+  nop
+foo:
+  nop




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