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[llvm-objcopy] Fix bug in how segment alignment was being handled
Just aligning segment offsets to segment alignment is incorrect and also wastes more space than is needed. The requirement is that p_offset == p_addr modulo p_align *not* that p_offset == 0 modulo p_align. Generally speaking we've been using p_addr == 0 modulo p_align. In fact yaml2obj can't even produce a valid situation which causes llvm-objcopy to produce incorrect results because alignment and offset were both inherited from the sections the program header covers. This change fixes this bad behavior in llvm-objcopy. Differential Revision: https://reviews.llvm.org/D39132 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317284 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jake Ehrlich
parent
6d06c89303
commit
89fd072604
40
test/tools/llvm-objcopy/check-addr-offset-align-binary.test
Normal file
40
test/tools/llvm-objcopy/check-addr-offset-align-binary.test
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@ -0,0 +1,40 @@
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# RUN: yaml2obj %s -o %t
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# RUN: llvm-objcopy -O binary %t %t2
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# RUN: od -t x1 %t2 | FileCheck %s
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!ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_EXEC
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Machine: EM_X86_64
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x1000
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AddressAlign: 0x0000000000001000
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Content: "c3c3c3c3"
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- Name: .data
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC ]
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Address: 0x1008
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AddressAlign: 0x0000000000000008
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Content: "3232"
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_X, PF_R ]
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VAddr: 0x1000
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PAddr: 0x1000
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Align: 0x1000
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Sections:
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- Section: .text
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- Type: PT_LOAD
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Flags: [ PF_R, PF_W ]
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VAddr: 0x1008
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PAddr: 0x1008
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Align: 0x1000
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Sections:
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- Section: .data
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# CHECK: 0000000 c3 c3 c3 c3 00 00 00 00 32 32
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67
test/tools/llvm-objcopy/check-addr-offset-align.test
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67
test/tools/llvm-objcopy/check-addr-offset-align.test
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@ -0,0 +1,67 @@
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# RUN: yaml2obj %s -o %t
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# RUN: llvm-objcopy %t %t2
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# RUN: llvm-readobj -program-headers %t2 | FileCheck %s
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!ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_EXEC
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Machine: EM_X86_64
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x1000
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AddressAlign: 0x0000000000001000
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Content: "c3c3c3c3"
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- Name: .data
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC ]
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Address: 0x1008
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AddressAlign: 0x0000000000000008
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Content: "3232"
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_X, PF_R ]
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VAddr: 0x1000
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PAddr: 0x1000
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Align: 0x1000
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Sections:
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- Section: .text
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- Type: PT_LOAD
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Flags: [ PF_R, PF_W ]
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VAddr: 0x1008
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PAddr: 0x1008
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Align: 0x1000
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Sections:
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- Section: .data
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#CHECK: ProgramHeaders [
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#CHECK-NEXT: ProgramHeader {
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#CHECK-NEXT: Type: PT_LOAD
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#CHECK-NEXT: Offset: 0x1000
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#CHECK-NEXT: VirtualAddress: 0x1000
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#CHECK-NEXT: PhysicalAddress: 0x1000
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#CHECK-NEXT: FileSize: 4
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#CHECK-NEXT: MemSize: 4
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#CHECK-NEXT: Flags [
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#CHECK-NEXT: PF_R
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#CHECK-NEXT: PF_X
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#CHECK-NEXT: ]
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#CHECK-NEXT: Alignment: 4096
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#CHECK-NEXT: }
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#CHECK-NEXT: ProgramHeader {
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#CHECK-NEXT: Type: PT_LOAD
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#CHECK-NEXT: Offset: 0x1008
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#CHECK-NEXT: VirtualAddress: 0x1008
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#CHECK-NEXT: PhysicalAddress: 0x1008
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#CHECK-NEXT: FileSize: 2
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#CHECK-NEXT: MemSize: 2
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#CHECK-NEXT: Flags [
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#CHECK-NEXT: PF_R
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#CHECK-NEXT: PF_W
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#CHECK-NEXT: ]
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#CHECK-NEXT: Alignment: 4096
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#CHECK-NEXT: }
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#CHECK-NEXT:]
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@ -685,6 +685,19 @@ template <class ELFT> void ELFObject<ELFT>::sortSections() {
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CompareSections);
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}
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static uint64_t alignToAddr(uint64_t Offset, uint64_t Addr, uint64_t Align) {
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// Calculate Diff such that (Offset + Diff) & -Align == Addr & -Align.
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if (Align == 0)
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Align = 1;
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auto Diff =
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static_cast<int64_t>(Addr % Align) - static_cast<int64_t>(Offset % Align);
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// We only want to add to Offset, however, so if Diff < 0 we can add Align and
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// (Offset + Diff) & -Align == Addr & -Align will still hold.
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if (Diff < 0)
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Diff += Align;
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return Offset + Diff;
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}
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template <class ELFT> void ELFObject<ELFT>::assignOffsets() {
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// We need a temporary list of segments that has a special order to it
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// so that we know that anytime ->ParentSegment is set that segment has
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@ -728,7 +741,7 @@ template <class ELFT> void ELFObject<ELFT>::assignOffsets() {
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Segment->Offset =
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Parent->Offset + Segment->OriginalOffset - Parent->OriginalOffset;
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} else {
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Offset = alignTo(Offset, Segment->Align == 0 ? 1 : Segment->Align);
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Offset = alignToAddr(Offset, Segment->VAddr, Segment->Align);
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Segment->Offset = Offset;
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}
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Offset = std::max(Offset, Segment->Offset + Segment->FileSize);
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@ -829,8 +842,9 @@ template <class ELFT> void BinaryObject<ELFT>::finalize() {
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uint64_t Offset = 0;
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for (auto &Segment : this->Segments) {
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if (Segment->Type == PT_LOAD && Segment->firstSection() != nullptr) {
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Offset = alignTo(Offset, Segment->Align);
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if (Segment->Type == llvm::ELF::PT_LOAD &&
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Segment->firstSection() != nullptr) {
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Offset = alignToAddr(Offset, Segment->VAddr, Segment->Align);
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Segment->Offset = Offset;
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Offset += Segment->FileSize;
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}
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