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

[Shankar Easwaran]

LGTM.

On 2/10/2015 8:18 PM, Will Newton wrote:
> 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
>
>


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