[PATCH] D79038: [objdump][ELF] Handle sections not contained in PT_LOAD segments

[LemonBoy via Phabricator via llvm-commits]

LemonBoy created this revision.
LemonBoy added reviewers: MaskRay, jakehehrlich.
Herald added subscribers: llvm-commits, emaste.
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Herald added a reviewer: alexshap.
Herald added a reviewer: rupprecht.
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In D71035 <https://reviews.llvm.org/D71035> the LMA calculation was changed to more closely match the behaviour of GNU
tools. The code assumed that every parent section would be a PT_LOAD one, but it's possible
to create legal ELF binaries where this rule doesn't hold anymore.

Handle this case by using the same equation used by GNU objdump, the fix allows objdump
to create correctly-sized raw binaries now.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D79038

Files:
  llvm/test/tools/llvm-objcopy/ELF/binary-paddr.test
  llvm/tools/llvm-objcopy/ELF/Object.cpp


Index: llvm/tools/llvm-objcopy/ELF/Object.cpp
===================================================================
--- llvm/tools/llvm-objcopy/ELF/Object.cpp
+++ llvm/tools/llvm-objcopy/ELF/Object.cpp
@@ -2258,9 +2258,14 @@
   // skipped.
   uint64_t MinAddr = UINT64_MAX;
   for (SectionBase &Sec : Obj.allocSections()) {
-    if (Sec.ParentSegment != nullptr)
-      Sec.Addr =
-          Sec.Offset - Sec.ParentSegment->Offset + Sec.ParentSegment->PAddr;
+    if (Sec.ParentSegment != nullptr) {
+      if (Sec.ParentSegment->Type == PT_LOAD)
+        Sec.Addr =
+            Sec.Offset - Sec.ParentSegment->Offset + Sec.ParentSegment->PAddr;
+      else
+        Sec.Addr =
+            Sec.Addr - Sec.ParentSegment->PAddr + Sec.ParentSegment->VAddr;
+    }
     MinAddr = std::min(MinAddr, Sec.Addr);
   }
 
Index: llvm/test/tools/llvm-objcopy/ELF/binary-paddr.test
===================================================================
--- llvm/test/tools/llvm-objcopy/ELF/binary-paddr.test
+++ llvm/test/tools/llvm-objcopy/ELF/binary-paddr.test
@@ -129,3 +129,47 @@
     VAddr: 0x3000
     Sections:
       - Section: .data
+
+## Check that the LMA is correctly calculated for sections not contained in a
+## PT_LOAD segment.
+
+# RUN: yaml2obj --docnum=4 %s -o %t4
+# RUN: llvm-objcopy -O binary %t4 %t4.out
+# RUN: od -A x -t x2 %t4.out | FileCheck %s --check-prefix=CHECK4 --ignore-case
+# RUN: wc -c %t4.out | FileCheck %s --check-prefix=SIZE4
+
+# CHECK4:      9090 9090 9090 90c3
+# SIZE4:       8
+
+--- !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:         0x8000
+    AddressAlign:    0x8
+    Content:         90909090909090C3
+  - Name:            .bss
+    Type:            SHT_NOBITS
+    Flags:           [ SHF_ALLOC, SHF_WRITE ]
+    Address:         0x8008
+    AddressAlign:    0x1
+    Size:            0x4
+ProgramHeaders:
+  - Type: PT_LOAD
+    Flags: [ PF_R, PF_X ]
+    VAddr: 0x8000
+    Sections:
+      - Section: .text
+  - Type: PT_GNU_STACK
+    Flags: [ PF_R, PF_W ]
+    VAddr: 0x0000
+    FileSize: 0x0000
+    Align: 0x0000
+    # The huge size makes this phdr a parent of .bss
+    MemSize: 0x1000000


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