[PATCH v2][lld] ELF/AArch64: Add support for checking for ABS32 overflow

[Will Newton]

On 2 February 2015 at 17:31, Will Newton <will.newton at linaro.org> wrote:
> On 28 January 2015 at 15:21, Will Newton <will.newton at linaro.org> wrote:
>> Add support for checking overflow when applying a R_AARCH64_ABS32
>> relocation and add a test to ensure it behaves correctly.
>> ---
>>  .../ELF/AArch64/AArch64RelocationHandler.cpp       | 19 ++++++--
>>  test/elf/AArch64/rel-abs32-overflow.test           | 53 ++++++++++++++++++++++
>>  2 files changed, 67 insertions(+), 5 deletions(-)
>>  create mode 100644 test/elf/AArch64/rel-abs32-overflow.test
>>
>> Changes in v2:
>>  - Make withingSignedUnisgnedRange static
>>  - Implement range check with isIntN and isUIntN
>
> Ping?

Ping?

>> diff --git a/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp b/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp
>> index 924836d..878b2ad 100644
>> --- a/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp
>> +++ b/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp
>> @@ -10,12 +10,18 @@
>>  #include "AArch64TargetHandler.h"
>>  #include "AArch64LinkingContext.h"
>>  #include "llvm/Support/Debug.h"
>> +#include "llvm/Support/MathExtras.h"
>>
>>  using namespace lld;
>>  using namespace elf;
>>
>>  #define PAGE(X) ((X) & ~0x0FFFL)
>>
>> +/// \brief Check X is in the interval (-2^(bits-1), 2^bits]
>> +static bool withinSignedUnsignedRange(int64_t X, int bits) {
>> +  return isIntN(bits - 1, X) || isUIntN(bits, X);
>> +}
>> +
>>  /// \brief R_AARCH64_ABS64 - word64: S + A
>>  static void relocR_AARCH64_ABS64(uint8_t *location, uint64_t P, uint64_t S,
>>                                   int64_t A) {
>> @@ -41,9 +47,11 @@ static void relocR_AARCH64_PREL32(uint8_t *location, uint64_t P, uint64_t S,
>>  }
>>
>>  /// \brief R_AARCH64_ABS32 - word32:  S + A
>> -static void relocR_AARCH64_ABS32(uint8_t *location, uint64_t P, uint64_t S,
>> -                                 int64_t A) {
>> -  int32_t result = (int32_t)(S + A);
>> +static std::error_code relocR_AARCH64_ABS32(uint8_t *location, uint64_t P,
>> +                                            uint64_t S, int64_t A) {
>> +  int64_t result = S + A;
>> +  if (!withinSignedUnsignedRange(result, 32))
>> +    return make_out_of_range_reloc_error();
>>    DEBUG_WITH_TYPE(
>>        "AArch64", llvm::dbgs() << "\t\tHandle " << LLVM_FUNCTION_NAME << " -";
>>        llvm::dbgs() << " S: 0x" << Twine::utohexstr(S);
>> @@ -53,6 +61,7 @@ static void relocR_AARCH64_ABS32(uint8_t *location, uint64_t P, uint64_t S,
>>    *reinterpret_cast<llvm::support::ulittle32_t *>(location) =
>>        result |
>>        (int32_t) * reinterpret_cast<llvm::support::little32_t *>(location);
>> +  return std::error_code();
>>  }
>>
>>  /// \brief R_AARCH64_ADR_PREL_PG_HI21 - Page(S+A) - Page(P)
>> @@ -385,8 +394,8 @@ std::error_code AArch64TargetRelocationHandler::applyRelocation(
>>                            ref.addend());
>>      break;
>>    case R_AARCH64_ABS32:
>> -    relocR_AARCH64_ABS32(location, relocVAddress, targetVAddress, ref.addend());
>> -    break;
>> +    return relocR_AARCH64_ABS32(location, relocVAddress, targetVAddress,
>> +                                ref.addend());
>>    // Runtime only relocations. Ignore here.
>>    case R_AARCH64_RELATIVE:
>>    case R_AARCH64_IRELATIVE:
>> diff --git a/test/elf/AArch64/rel-abs32-overflow.test b/test/elf/AArch64/rel-abs32-overflow.test
>> new file mode 100644
>> index 0000000..be65ebc
>> --- /dev/null
>> +++ b/test/elf/AArch64/rel-abs32-overflow.test
>> @@ -0,0 +1,53 @@
>> +# Check handling of R_AARCH64_ABS32 relocation overflow.
>> +# RUN: yaml2obj -format=elf %s > %t-obj
>> +# RUN: not lld -flavor gnu -target arm64 -o %t-exe %t-obj 2>&1 | FileCheck %s
>> +
>> +# CHECK: Relocation out of range in file {{.*}}: reference from data1+0 to data2+34359738369 of type 258 (R_AARCH64_ABS32)
>> +# CHECK: Relocation out of range in file {{.*}}: reference from data2+0 to data1+34359738369 of type 258 (R_AARCH64_ABS32)
>> +
>> +!ELF
>> +FileHeader: !FileHeader
>> +  Class: ELFCLASS64
>> +  Data: ELFDATA2LSB
>> +  Type: ET_REL
>> +  Machine: EM_AARCH64
>> +
>> +Sections:
>> +- Name: .text
>> +  Type: SHT_PROGBITS
>> +  Content: "00000000"
>> +  AddressAlign: 16
>> +  Flags: [SHF_ALLOC, SHF_EXECINSTR]
>> +- Name: .data
>> +  Type: SHT_PROGBITS
>> +  Content: "0000000000000000"
>> +  AddressAlign: 16
>> +  Flags: [SHF_ALLOC, SHF_WRITE]
>> +
>> +- Name: .rela.data
>> +  Type: SHT_RELA
>> +  Info: .data
>> +  AddressAlign: 8
>> +  Relocations:
>> +    - Offset: 0x0
>> +      Symbol: data2
>> +      Type: R_AARCH64_ABS32
>> +      Addend: 0x800000001
>> +    - Offset: 0x4
>> +      Symbol: data1
>> +      Type: R_AARCH64_ABS32
>> +      Addend: 0x800000001
>> +
>> +Symbols:
>> +  Global:
>> +    - Name: _start
>> +      Section: .text
>> +      Value: 0x0
>> +      Size: 4
>> +    - Name: data1
>> +      Section: .data
>> +      Size: 4
>> +    - Name: data2
>> +      Section: .data
>> +      Value: 0x4
>> +      Size: 4
>> --
>> 2.1.0
>>
>
>
>
> --
> Will Newton
> Toolchain Working Group, Linaro



-- 
Will Newton
Toolchain Working Group, Linaro