[RuntimeDyld] Fix debug section relocation (pr20457)

Summary:
Debug info sections, (or non-SHF_ALLOC sections in general) should be
linked as if their load address was zero to emulate the behavior of the
static linker.

This bug was discovered because it was breaking lldb expression evaluation on
linux.

Reviewers: lhames

Subscribers: aprantl, eugene, clayborg, lldb-commits, llvm-commits

Differential Revision: https://reviews.llvm.org/D32899

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303239 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index e9a4b71c903d391be75cf809062de67817c3ee62..ab86e5d6a0fd70cfc485ccb437fecd2a3cbfdc83 100644 (file)
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -705,7 +705,7 @@ RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
   unsigned PaddingSize = 0;
   unsigned StubBufSize = 0;
-  bool IsRequired = isRequiredForExecution(Section) || ProcessAllSections;
+  bool IsRequired = isRequiredForExecution(Section);
   bool IsVirtual = Section.isVirtual();
   bool IsZeroInit = isZeroInit(Section);
   bool IsReadOnly = isReadOnlyData(Section);
@@ -745,8 +745,8 @@ RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
     Alignment = std::max(Alignment, getStubAlignment());
 
   // Some sections, such as debug info, don't need to be loaded for execution.
-  // Leave those where they are.
-  if (IsRequired) {
+  // Process those only if explicitly requested.
+  if (IsRequired || ProcessAllSections) {
     Allocate = DataSize + PaddingSize + StubBufSize;
     if (!Allocate)
       Allocate = 1;
@@ -790,6 +790,10 @@ RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
   Sections.push_back(
       SectionEntry(Name, Addr, DataSize, Allocate, (uintptr_t)pData));
 
+  // Debug info sections are linked as if their load address was zero
+  if (!IsRequired)
+    Sections.back().setLoadAddress(0);
+
   if (Checker)
     Checker->registerSection(Obj.getFileName(), SectionID);
 

diff --git a/test/ExecutionEngine/RuntimeDyld/X86/ELF_x86-64_debug_frame.s b/test/ExecutionEngine/RuntimeDyld/X86/ELF_x86-64_debug_frame.s
new file mode 100644 (file)
index 0000000..8f907a6
--- /dev/null
+++ b/test/ExecutionEngine/RuntimeDyld/X86/ELF_x86-64_debug_frame.s
@@ -0,0 +1,20 @@
+# RUN: llvm-mc -triple=x86_64-pc-linux -filetype=obj -o %T/ELF_x86-64_debug_frame.o %s
+# RUN: llvm-rtdyld -triple=x86_64-pc-linux -verify -check=%s %T/ELF_x86-64_debug_frame.o
+
+        .text
+        .file   "debug_frame_test.c"
+        .align  16, 0x90
+        .type   foo,@function
+foo:
+        .cfi_startproc
+        retq
+.Ltmp0:
+        .size   foo, .Ltmp0-foo
+        .cfi_endproc
+        .cfi_sections .debug_frame
+
+# Check that .debug_frame is mapped to 0.
+# rtdyld-check: section_addr(ELF_x86-64_debug_frame.o, .debug_frame) = 0
+
+# Check that The relocated FDE's CIE offset also points to zero.
+# rtdyld-check: *{4}(section_addr(ELF_x86-64_debug_frame.o, .debug_frame) + 0x1C) = 0