[llvm] r313682 - Reland "[llvm-objcopy] Add support for nested and overlapping segments"
Jake Ehrlich via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 19 14:37:35 PDT 2017
Author: jakehehrlich
Date: Tue Sep 19 14:37:35 2017
New Revision: 313682
URL: http://llvm.org/viewvc/llvm-project?rev=313682&view=rev
Log:
Reland "[llvm-objcopy] Add support for nested and overlapping segments"
I didn't initialize a pointer to be nullptr that I needed to.
This change adds support for nested and even overlapping segments. This means
that PT_PHDR, PT_GNU_RELRO, PT_TLS, and PT_DYNAMIC can be supported properly.
Differential Revision: https://reviews.llvm.org/D36558
Added:
llvm/trunk/test/tools/llvm-objcopy/adjacent-segments.test
llvm/trunk/test/tools/llvm-objcopy/identical-segments.test
llvm/trunk/test/tools/llvm-objcopy/overlap-chain.test
llvm/trunk/test/tools/llvm-objcopy/pt-phdr.test
llvm/trunk/test/tools/llvm-objcopy/triple-overlap.test
Modified:
llvm/trunk/tools/llvm-objcopy/Object.cpp
llvm/trunk/tools/llvm-objcopy/Object.h
Added: llvm/trunk/test/tools/llvm-objcopy/adjacent-segments.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/adjacent-segments.test?rev=313682&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/adjacent-segments.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/adjacent-segments.test Tue Sep 19 14:37:35 2017
@@ -0,0 +1,62 @@
+# This test tests that if two non-overlapping segments are right next to each
+# other no problems arise.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy %t %t2
+# RUN: llvm-readobj --program-headers %t2 | FileCheck %s
+
+!ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .text
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 24
+ - Name: .text2
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x10
+ Size: 16
+ProgramHeaders:
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text2
+
+#CHECK: ProgramHeaders [
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x1000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 24
+#CHECK-NEXT: MemSize: 24
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x1020
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 16
+#CHECK-NEXT: MemSize: 16
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 16
+#CHECK-NEXT: }
+#CHECK-NEXT:]
Added: llvm/trunk/test/tools/llvm-objcopy/identical-segments.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/identical-segments.test?rev=313682&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/identical-segments.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/identical-segments.test Tue Sep 19 14:37:35 2017
@@ -0,0 +1,82 @@
+# This test tests that if two possible parent segments have the same offset that
+# they're disambiguated based on their original index. This ensures that cycles
+# do not occur.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy %t %t2
+# RUN: llvm-readobj --program-headers %t2 | FileCheck %s
+
+!ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .text
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text2
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ProgramHeaders:
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text2
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text
+ - Section: .text2
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text
+ - Section: .text2
+
+#CHECK: ProgramHeaders [
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x2000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 4096
+#CHECK-NEXT: MemSize: 4096
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x1000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 8192
+#CHECK-NEXT: MemSize: 8192
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x1000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 8192
+#CHECK-NEXT: MemSize: 8192
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT:]
Added: llvm/trunk/test/tools/llvm-objcopy/overlap-chain.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/overlap-chain.test?rev=313682&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/overlap-chain.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/overlap-chain.test Tue Sep 19 14:37:35 2017
@@ -0,0 +1,117 @@
+# This test tests how ParentSegment is set for Segments. In particular this test
+# tests that if a chain of parents forms, the offsets are chosen for parents
+# first despite the order of the list. It also tests multiple branches of the
+# code that assigns parents.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy %t %t2
+# RUN: llvm-readobj -program-headers %t2 | FileCheck %s
+
+!ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .text
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text2
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text3
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text4
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text5
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ProgramHeaders:
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text
+ - Section: .text2
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text4
+ - Section: .text5
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text3
+ - Section: .text4
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text2
+ - Section: .text3
+
+#CHECK: ProgramHeaders [
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x1000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 8192
+#CHECK-NEXT: MemSize: 8192
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x4000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 8192
+#CHECK-NEXT: MemSize: 8192
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x3000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 8192
+#CHECK-NEXT: MemSize: 8192
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x2000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 8192
+#CHECK-NEXT: MemSize: 8192
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT:]
Added: llvm/trunk/test/tools/llvm-objcopy/pt-phdr.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/pt-phdr.test?rev=313682&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/pt-phdr.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/pt-phdr.test Tue Sep 19 14:37:35 2017
@@ -0,0 +1,71 @@
+# This test simply tests a simple but common real world example of overlapping
+# segments.
+
+# RUN: llvm-objcopy %p/Inputs/pt-phdr.elf %t
+# RUN: llvm-readobj -program-headers %t | FileCheck %s
+
+#CHECK: ProgramHeaders [
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_PHDR
+#CHECK-NEXT: Offset: 0x40
+#CHECK-NEXT: VirtualAddress: 0x200040
+#CHECK-NEXT: PhysicalAddress: 0x200040
+#CHECK-NEXT: FileSize: 280
+#CHECK-NEXT: MemSize: 280
+#CHECK-NEXT: Flags [
+#CHECK-NEXT: PF_R
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 8
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD
+#CHECK-NEXT: Offset: 0x0
+#CHECK-NEXT: VirtualAddress: 0x200000
+#CHECK-NEXT: PhysicalAddress: 0x200000
+#CHECK-NEXT: FileSize: 344
+#CHECK-NEXT: MemSize: 344
+#CHECK-NEXT: Flags [
+#CHECK-NEXT: PF_R
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD
+#CHECK-NEXT: Offset: 0x1000
+#CHECK-NEXT: VirtualAddress: 0x201000
+#CHECK-NEXT: PhysicalAddress: 0x201000
+#CHECK-NEXT: FileSize: 1
+#CHECK-NEXT: MemSize: 1
+#CHECK-NEXT: Flags [
+#CHECK-NEXT: PF_R
+#CHECK-NEXT: PF_X
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD
+#CHECK-NEXT: Offset: 0x2000
+#CHECK-NEXT: VirtualAddress: 0x202000
+#CHECK-NEXT: PhysicalAddress: 0x202000
+#CHECK-NEXT: FileSize: 14
+#CHECK-NEXT: MemSize: 14
+#CHECK-NEXT: Flags [
+#CHECK-NEXT: PF_R
+#CHECK-NEXT: PF_W
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_GNU_STACK (0x6474E551)
+#CHECK-NEXT: Offset: 0x0
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 0
+#CHECK-NEXT: MemSize: 0
+#CHECK-NEXT: Flags [
+#CHECK-NEXT: PF_R
+#CHECK-NEXT: PF_W
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 0
+#CHECK-NEXT: }
+#CHECK-NEXT:]
Added: llvm/trunk/test/tools/llvm-objcopy/triple-overlap.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/triple-overlap.test?rev=313682&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/triple-overlap.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/triple-overlap.test Tue Sep 19 14:37:35 2017
@@ -0,0 +1,123 @@
+# This test tests that each segment is assigned a canonical parent segment.
+# Importantly if two segments could be the parent segment of a segment this test
+# should cover the case where a new parent replaces the old parent and the case
+# where an old parent is not replaced by a new parent.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy %t %t2
+# RUN: llvm-readobj --program-headers %t2 | FileCheck %s
+
+!ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .text
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text2
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text3
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text4
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ - Name: .text5
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ AddressAlign: 0x1000
+ Size: 4096
+ProgramHeaders:
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text4
+ - Section: .text5
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text3
+ - Section: .text4
+ - Section: .text5
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text
+ - Section: .text2
+ - Section: .text3
+ - Section: .text4
+ - Section: .text5
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ Sections:
+ - Section: .text2
+ - Section: .text3
+ - Section: .text4
+ - Section: .text5
+
+#CHECK: ProgramHeaders [
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x4000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 8192
+#CHECK-NEXT: MemSize: 8192
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x3000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 12288
+#CHECK-NEXT: MemSize: 12288
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x1000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 20480
+#CHECK-NEXT: MemSize: 20480
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD (0x1)
+#CHECK-NEXT: Offset: 0x2000
+#CHECK-NEXT: VirtualAddress: 0x0
+#CHECK-NEXT: PhysicalAddress: 0x0
+#CHECK-NEXT: FileSize: 16384
+#CHECK-NEXT: MemSize: 16384
+#CHECK-NEXT: Flags [ (0x5)
+#CHECK-NEXT: PF_R (0x4)
+#CHECK-NEXT: PF_X (0x1)
+#CHECK-NEXT: ]
+#CHECK-NEXT: Alignment: 4096
+#CHECK-NEXT: }
+#CHECK-NEXT:]
Modified: llvm/trunk/tools/llvm-objcopy/Object.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/Object.cpp?rev=313682&r1=313681&r2=313682&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/Object.cpp (original)
+++ llvm/trunk/tools/llvm-objcopy/Object.cpp Tue Sep 19 14:37:35 2017
@@ -240,6 +240,15 @@ static bool sectionWithinSegment(const S
Segment.Offset + Segment.FileSize >= Section.OriginalOffset + SecSize;
}
+// Returns true IFF a segment's original offset is inside of another segment's
+// range.
+static bool segmentOverlapsSegment(const Segment &Child,
+ const Segment &Parent) {
+
+ return Parent.OriginalOffset <= Child.OriginalOffset &&
+ Parent.OriginalOffset + Parent.FileSize > Child.OriginalOffset;
+}
+
template <class ELFT>
void Object<ELFT>::readProgramHeaders(const ELFFile<ELFT> &ElfFile) {
uint32_t Index = 0;
@@ -268,6 +277,30 @@ void Object<ELFT>::readProgramHeaders(co
}
}
}
+ // Now we do an O(n^2) loop through the segments in order to match up
+ // segments.
+ for (auto &Child : Segments) {
+ for (auto &Parent : Segments) {
+ // Every segment will overlap with itself but we don't want a segment to
+ // be it's own parent so we avoid that situation.
+ if (&Child != &Parent && segmentOverlapsSegment(*Child, *Parent)) {
+ // We want a canonical "most parental" segment but this requires
+ // inspecting the ParentSegment.
+ if (Child->ParentSegment != nullptr) {
+ if (Child->ParentSegment->OriginalOffset > Parent->OriginalOffset) {
+ Child->ParentSegment = Parent.get();
+ } else if (Child->ParentSegment->Index > Parent->Index) {
+ // They must have equal OriginalOffsets so we need to disambiguate.
+ // To decide which is the parent we'll choose the one with the
+ // higher index.
+ Child->ParentSegment = Parent.get();
+ }
+ } else {
+ Child->ParentSegment = Parent.get();
+ }
+ }
+ }
+ }
}
template <class ELFT>
@@ -497,13 +530,30 @@ template <class ELFT> void ELFObject<ELF
}
template <class ELFT> void ELFObject<ELFT>::assignOffsets() {
+ // We need a temporary list of segments that has a special order to it
+ // so that we know that anytime ->ParentSegment is set that segment has
+ // already had it's offset properly set.
+ std::vector<Segment *> OrderedSegments;
+ for (auto &Segment : this->Segments)
+ OrderedSegments.push_back(Segment.get());
+ auto CompareSegments = [](const Segment *A, const Segment *B) {
+ // Any segment without a parent segment should come before a segment
+ // that has a parent segment.
+ if (A->OriginalOffset < B->OriginalOffset)
+ return true;
+ if (A->OriginalOffset > B->OriginalOffset)
+ return false;
+ return A->Index < B->Index;
+ };
+ std::stable_sort(std::begin(OrderedSegments), std::end(OrderedSegments),
+ CompareSegments);
// The size of ELF + program headers will not change so it is ok to assume
// that the first offset of the first segment is a good place to start
// outputting sections. This covers both the standard case and the PT_PHDR
// case.
uint64_t Offset;
- if (!this->Segments.empty()) {
- Offset = this->Segments[0]->Offset;
+ if (!OrderedSegments.empty()) {
+ Offset = OrderedSegments[0]->Offset;
} else {
Offset = sizeof(Elf_Ehdr);
}
@@ -512,10 +562,20 @@ template <class ELFT> void ELFObject<ELF
// then it's acceptable, but not ideal, to simply move it to after the
// segments. So we can simply layout segments one after the other accounting
// for alignment.
- for (auto &Segment : this->Segments) {
- Offset = alignTo(Offset, Segment->Align);
- Segment->Offset = Offset;
- Offset += Segment->FileSize;
+ for (auto &Segment : OrderedSegments) {
+ // We assume that segments have been ordered by OriginalOffset and Index
+ // such that a parent segment will always come before a child segment in
+ // OrderedSegments. This means that the Offset of the ParentSegment should
+ // already be set and we can set our offset relative to it.
+ if (Segment->ParentSegment != nullptr) {
+ auto Parent = Segment->ParentSegment;
+ Segment->Offset =
+ Parent->Offset + Segment->OriginalOffset - Parent->OriginalOffset;
+ } else {
+ Offset = alignTo(Offset, Segment->Align == 0 ? 1 : Segment->Align);
+ Segment->Offset = Offset;
+ Offset += Segment->FileSize;
+ }
}
// Now the offset of every segment has been set we can assign the offsets
// of each section. For sections that are covered by a segment we should use
Modified: llvm/trunk/tools/llvm-objcopy/Object.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/Object.h?rev=313682&r1=313681&r2=313682&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/Object.h (original)
+++ llvm/trunk/tools/llvm-objcopy/Object.h Tue Sep 19 14:37:35 2017
@@ -72,6 +72,7 @@ public:
uint64_t VAddr;
uint64_t OriginalOffset;
+ Segment *ParentSegment = nullptr;
Segment(llvm::ArrayRef<uint8_t> Data) : Contents(Data) {}
void finalize();
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