[lld] r353437 - Fix a bug in R_X86_64_PC{8,16} relocation handling.

[Shoaib Meenai via llvm-commits]

Should this be merged to 8.0?

On 2/7/19, 10:12 AM, "llvm-commits on behalf of Rui Ueyama via llvm-commits" <llvm-commits-bounces at lists.llvm.org on behalf of llvm-commits at lists.llvm.org> wrote:

    Author: ruiu
    Date: Thu Feb  7 10:12:57 2019
    New Revision: 353437
    
    URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D353437-26view-3Drev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=SsIV4bxzRk5xcqIODXUWMAKgrjALt2jgK-8molEY6ik&s=cXPyCTPqI-n63UfUmlWURBOeqMLYWXWNr7J7MBI2A9k&e=
    Log:
    Fix a bug in R_X86_64_PC{8,16} relocation handling.
    
    R_X86_64_PC{8,16} relocations are sign-extended, so when we check
    for relocation overflow, we had to use checkInt instead of checkUInt.
    I confirmed that GNU linkers create the same output for the test case.
    
    Added:
        lld/trunk/test/ELF/Inputs/x86-64-pcrel.s
    Modified:
        lld/trunk/ELF/Arch/X86_64.cpp
        lld/trunk/test/ELF/x86-64-pcrel.s
    
    Modified: lld/trunk/ELF/Arch/X86_64.cpp
    URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_lld_trunk_ELF_Arch_X86-5F64.cpp-3Frev-3D353437-26r1-3D353436-26r2-3D353437-26view-3Ddiff&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=SsIV4bxzRk5xcqIODXUWMAKgrjALt2jgK-8molEY6ik&s=1z6MXm9dyJ34rii6Pnpfo2Z6p1hjqOVNa5a6HMGyHKs&e=
    ==============================================================================
    --- lld/trunk/ELF/Arch/X86_64.cpp (original)
    +++ lld/trunk/ELF/Arch/X86_64.cpp Thu Feb  7 10:12:57 2019
    @@ -324,15 +324,21 @@ template <class ELFT>
     void X86_64<ELFT>::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
       switch (Type) {
       case R_X86_64_8:
    -  case R_X86_64_PC8:
         checkUInt(Loc, Val, 8, Type);
         *Loc = Val;
         break;
    +  case R_X86_64_PC8:
    +    checkInt(Loc, Val, 8, Type);
    +    *Loc = Val;
    +    break;
       case R_X86_64_16:
    -  case R_X86_64_PC16:
         checkUInt(Loc, Val, 16, Type);
         write16le(Loc, Val);
         break;
    +  case R_X86_64_PC16:
    +    checkInt(Loc, Val, 16, Type);
    +    write16le(Loc, Val);
    +    break;
       case R_X86_64_32:
         checkUInt(Loc, Val, 32, Type);
         write32le(Loc, Val);
    
    Added: lld/trunk/test/ELF/Inputs/x86-64-pcrel.s
    URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_lld_trunk_test_ELF_Inputs_x86-2D64-2Dpcrel.s-3Frev-3D353437-26view-3Dauto&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=SsIV4bxzRk5xcqIODXUWMAKgrjALt2jgK-8molEY6ik&s=SSJnKLh-SoIbbcSN6izHhnGL8HVY9OQ0-DjTN8xdCaM&e=
    ==============================================================================
    --- lld/trunk/test/ELF/Inputs/x86-64-pcrel.s (added)
    +++ lld/trunk/test/ELF/Inputs/x86-64-pcrel.s Thu Feb  7 10:12:57 2019
    @@ -0,0 +1,8 @@
    +.globl foo
    +foo:
    +
    +.word _start - foo
    +.fill 14,1,0xcc
    +
    +.byte _start - foo
    +.fill 15,1,0xcc
    
    Modified: lld/trunk/test/ELF/x86-64-pcrel.s
    URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_lld_trunk_test_ELF_x86-2D64-2Dpcrel.s-3Frev-3D353437-26r1-3D353436-26r2-3D353437-26view-3Ddiff&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=SsIV4bxzRk5xcqIODXUWMAKgrjALt2jgK-8molEY6ik&s=KwH6YCrVh-2BtX_A9zDtFgiZ15ayv1TbU-56rwu-XO0&e=
    ==============================================================================
    --- lld/trunk/test/ELF/x86-64-pcrel.s (original)
    +++ lld/trunk/test/ELF/x86-64-pcrel.s Thu Feb  7 10:12:57 2019
    @@ -3,13 +3,15 @@
     // This is a test for R_X86_64_PC8 and R_X86_64_PC16.
     
     // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t1.o
    -// RUN: echo '.globl foo; foo:' | llvm-mc -filetype=obj -triple=x86_64-pc-linux - -o %t2.o
    +// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/x86-64-pcrel.s -o %t2.o
     // RUN: ld.lld -o %t.exe %t1.o %t2.o
     // RUN: llvm-objdump -s %t.exe | FileCheck %s
     
    -// CHECK: Contents of section .text:
    -// CHECK: 2000cccc cccccccc cccccccc cccccccc
    -// CHECK: 20cccccc cccccccc cccccccc cccccccc
    +// CHECK:      Contents of section .text:
    +// CHECK-NEXT: 2000cccc cccccccc cccccccc cccccccc
    +// CHECK-NEXT: 20cccccc cccccccc cccccccc cccccccc
    +// CHECK-NEXT: e0ffcccc cccccccc cccccccc cccccccc
    +// CHECK-NEXT: e0cccccc cccccccc cccccccc cccccccc
     
     .globl _start
     _start:
    
    
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