[llvm] r317284 - [llvm-objcopy] Fix bug in how segment alignment was being handled
Jake Ehrlich via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 2 16:24:04 PDT 2017
Author: jakehehrlich
Date: Thu Nov 2 16:24:04 2017
New Revision: 317284
URL: http://llvm.org/viewvc/llvm-project?rev=317284&view=rev
Log:
[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
Added:
llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align-binary.test
llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align.test
Modified:
llvm/trunk/tools/llvm-objcopy/Object.cpp
Added: llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align-binary.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align-binary.test?rev=317284&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align-binary.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align-binary.test Thu Nov 2 16:24:04 2017
@@ -0,0 +1,40 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy -O binary %t %t2
+# RUN: od -t x1 %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 ]
+ Address: 0x1000
+ AddressAlign: 0x0000000000001000
+ Content: "c3c3c3c3"
+ - Name: .data
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC ]
+ Address: 0x1008
+ AddressAlign: 0x0000000000000008
+ Content: "3232"
+ProgramHeaders:
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ VAddr: 0x1000
+ PAddr: 0x1000
+ Align: 0x1000
+ Sections:
+ - Section: .text
+ - Type: PT_LOAD
+ Flags: [ PF_R, PF_W ]
+ VAddr: 0x1008
+ PAddr: 0x1008
+ Align: 0x1000
+ Sections:
+ - Section: .data
+
+# CHECK: 0000000 c3 c3 c3 c3 00 00 00 00 32 32
Added: llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align.test?rev=317284&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/check-addr-offset-align.test Thu Nov 2 16:24:04 2017
@@ -0,0 +1,67 @@
+# 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 ]
+ Address: 0x1000
+ AddressAlign: 0x0000000000001000
+ Content: "c3c3c3c3"
+ - Name: .data
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC ]
+ Address: 0x1008
+ AddressAlign: 0x0000000000000008
+ Content: "3232"
+ProgramHeaders:
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ VAddr: 0x1000
+ PAddr: 0x1000
+ Align: 0x1000
+ Sections:
+ - Section: .text
+ - Type: PT_LOAD
+ Flags: [ PF_R, PF_W ]
+ VAddr: 0x1008
+ PAddr: 0x1008
+ Align: 0x1000
+ Sections:
+ - Section: .data
+
+#CHECK: ProgramHeaders [
+#CHECK-NEXT: ProgramHeader {
+#CHECK-NEXT: Type: PT_LOAD
+#CHECK-NEXT: Offset: 0x1000
+#CHECK-NEXT: VirtualAddress: 0x1000
+#CHECK-NEXT: PhysicalAddress: 0x1000
+#CHECK-NEXT: FileSize: 4
+#CHECK-NEXT: MemSize: 4
+#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: 0x1008
+#CHECK-NEXT: VirtualAddress: 0x1008
+#CHECK-NEXT: PhysicalAddress: 0x1008
+#CHECK-NEXT: FileSize: 2
+#CHECK-NEXT: MemSize: 2
+#CHECK-NEXT: Flags [
+#CHECK-NEXT: PF_R
+#CHECK-NEXT: PF_W
+#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=317284&r1=317283&r2=317284&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/Object.cpp (original)
+++ llvm/trunk/tools/llvm-objcopy/Object.cpp Thu Nov 2 16:24:04 2017
@@ -685,6 +685,19 @@ template <class ELFT> void ELFObject<ELF
CompareSections);
}
+static uint64_t alignToAddr(uint64_t Offset, uint64_t Addr, uint64_t Align) {
+ // Calculate Diff such that (Offset + Diff) & -Align == Addr & -Align.
+ if (Align == 0)
+ Align = 1;
+ auto Diff =
+ static_cast<int64_t>(Addr % Align) - static_cast<int64_t>(Offset % Align);
+ // We only want to add to Offset, however, so if Diff < 0 we can add Align and
+ // (Offset + Diff) & -Align == Addr & -Align will still hold.
+ if (Diff < 0)
+ Diff += Align;
+ return Offset + Diff;
+}
+
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
@@ -728,7 +741,7 @@ template <class ELFT> void ELFObject<ELF
Segment->Offset =
Parent->Offset + Segment->OriginalOffset - Parent->OriginalOffset;
} else {
- Offset = alignTo(Offset, Segment->Align == 0 ? 1 : Segment->Align);
+ Offset = alignToAddr(Offset, Segment->VAddr, Segment->Align);
Segment->Offset = Offset;
}
Offset = std::max(Offset, Segment->Offset + Segment->FileSize);
@@ -829,8 +842,9 @@ template <class ELFT> void BinaryObject<
uint64_t Offset = 0;
for (auto &Segment : this->Segments) {
- if (Segment->Type == PT_LOAD && Segment->firstSection() != nullptr) {
- Offset = alignTo(Offset, Segment->Align);
+ if (Segment->Type == llvm::ELF::PT_LOAD &&
+ Segment->firstSection() != nullptr) {
+ Offset = alignToAddr(Offset, Segment->VAddr, Segment->Align);
Segment->Offset = Offset;
Offset += Segment->FileSize;
}
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