[BOLT] Abort on out-of-section symbols in GOT

bolt/include/bolt/Core/BinaryContext.h

@@ -911,7 +911,8 @@ class BinaryContext {
   /// of \p Flags.
   MCSymbol *registerNameAtAddress(StringRef Name, uint64_t Address,
                                   uint64_t Size, uint16_t Alignment,
-                                  unsigned Flags = 0);
+                                  unsigned Flags = 0,
+                                  BinarySection *Section = NULL);
 
   /// Return BinaryData registered at a given \p Address or nullptr if no
   /// global symbol was registered at the location.

bolt/lib/Core/BinaryContext.cpp

@@ -1056,18 +1056,28 @@ void BinaryContext::adjustCodePadding() {
 MCSymbol *BinaryContext::registerNameAtAddress(StringRef Name, uint64_t Address,
                                                uint64_t Size,
                                                uint16_t Alignment,
-                                               unsigned Flags) {
+                                               unsigned Flags,
+                                               BinarySection *Section) {
   // Register the name with MCContext.
   MCSymbol *Symbol = Ctx->getOrCreateSymbol(Name);
+  BinaryData *BD;
+
+  // Register out of section symbols only in GlobalSymbols map
+  if (Section && Section->getEndAddress() == Address) {
+    BD = new BinaryData(*Symbol, Address, Size, Alignment ? Alignment : 1,
+                        *Section, Flags);
+    GlobalSymbols[Name] = BD;
+    return Symbol;
+  }
 
   auto GAI = BinaryDataMap.find(Address);
-  BinaryData *BD;
   if (GAI == BinaryDataMap.end()) {
     ErrorOr<BinarySection &> SectionOrErr = getSectionForAddress(Address);
-    BinarySection &Section =
-        SectionOrErr ? SectionOrErr.get() : absoluteSection();
+    BinarySection &SectionRef = Section        ? *Section
+                                : SectionOrErr ? SectionOrErr.get()
+                                               : absoluteSection();
     BD = new BinaryData(*Symbol, Address, Size, Alignment ? Alignment : 1,
-                        Section, Flags);
+                        SectionRef, Flags);
     GAI = BinaryDataMap.emplace(Address, BD).first;
     GlobalSymbols[Name] = BD;
     updateObjectNesting(GAI);
@@ -1402,7 +1412,7 @@ void BinaryContext::postProcessSymbolTable() {
     if ((BD->getName().starts_with("SYMBOLat") ||
          BD->getName().starts_with("DATAat")) &&
         !BD->getParent() && !BD->getSize() && !BD->isAbsolute() &&
-        BD->getSection()) {
+        BD->getSection().getSize()) {
       this->errs() << "BOLT-WARNING: zero-sized top level symbol: " << *BD
                    << "\n";
       Valid = false;

bolt/lib/Rewrite/RewriteInstance.cpp

@@ -955,13 +955,13 @@ void RewriteInstance::discoverFileObjects() {
     uint64_t SymbolSize = ELFSymbolRef(Symbol).getSize();
     uint64_t SymbolAlignment = Symbol.getAlignment();
 
-    auto registerName = [&](uint64_t FinalSize) {
+    auto registerName = [&](uint64_t FinalSize, BinarySection *Section = NULL) {
       // Register names even if it's not a function, e.g. for an entry point.
       BC->registerNameAtAddress(UniqueName, SymbolAddress, FinalSize,
-                                SymbolAlignment, SymbolFlags);
+                                SymbolAlignment, SymbolFlags, Section);
       if (!AlternativeName.empty())
         BC->registerNameAtAddress(AlternativeName, SymbolAddress, FinalSize,
-                                  SymbolAlignment, SymbolFlags);
+                                  SymbolAlignment, SymbolFlags, Section);
     };
 
     section_iterator Section =
@@ -986,12 +986,25 @@ void RewriteInstance::discoverFileObjects() {
                       << " for function\n");
 
     if (SymbolAddress == Section->getAddress() + Section->getSize()) {
+      ErrorOr<BinarySection &> SectionOrError =
+          BC->getSectionForAddress(Section->getAddress());
+
+      // Skip symbols from invalid sections
+      if (!SectionOrError) {
+        BC->errs() << "BOLT-WARNING: " << UniqueName << " (0x"
+                   << Twine::utohexstr(SymbolAddress)
+                   << ") does not have any section\n";
+        continue;
+      }
+
       assert(SymbolSize == 0 &&
              "unexpect non-zero sized symbol at end of section");
-      LLVM_DEBUG(
-          dbgs()
-          << "BOLT-DEBUG: rejecting as symbol points to end of its section\n");
-      registerName(SymbolSize);
+      LLVM_DEBUG({
+        dbgs() << "BOLT-DEBUG: rejecting as symbol " << UniqueName
+               << " points to end of " << SectionOrError->getName()
+               << " section\n";
+      });
+      registerName(SymbolSize, &SectionOrError.get());
       continue;
     }
 
@@ -2614,6 +2627,30 @@ void RewriteInstance::handleRelocation(const SectionRef &RelocatedSection,
     }
   }
 
+  if (Relocation::isGOT(RType) && !Relocation::isTLS(RType)) {
+    auto exitOnGotEndSymol = [&](StringRef Name) {
+      BC->errs() << "BOLT-ERROR: GOT table contains currently unsupported "
+                    "section end symbol "
+                 << Name << "\n";
+      exit(1);
+    };
+
+    if (SymbolIter != InputFile->symbol_end() && ReferencedSection) {
+      if (cantFail(SymbolIter->getAddress()) ==
+          ReferencedSection->getEndAddress())
+        exitOnGotEndSymol(cantFail(SymbolIter->getName()));
+    } else {
+      // If no section and symbol are provided by relocation, try to find the
+      // symbol by its name, including the possibility that the symbol is local.
+      BinaryData *BD = BC->getBinaryDataByName(SymbolName);
+      if (!BD && NR.getUniquifiedNameCount(SymbolName) == 1)
+        BD = BC->getBinaryDataByName(NR.getUniqueName(SymbolName, 1));
+
+      if ((BD && BD->getAddress() == BD->getSection().getEndAddress()))
+        exitOnGotEndSymol(BD->getName());
+    }
+  }
+
   if (!ReferencedSection)
     ReferencedSection = BC->getSectionForAddress(SymbolAddress);
 

bolt/test/AArch64/Inputs/got_end_of_section_symbol.lld_script

@@ -0,0 +1,6 @@
+SECTIONS {
+  PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x400000)); . = SEGMENT_START("text-segment", 0x400000) + SIZEOF_HEADERS;
+  .data : { *(.data)  *(.array) }
+  .text : { *(.text) }
+  .got  : { *(.got) *(.igot) }
+}

bolt/test/AArch64/got_end_of_section_symbol.s

@@ -0,0 +1,28 @@
+# RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown \
+# RUN:   %s -o %t.o
+# RUN: %clang %cflags  -nostartfiles -nodefaultlibs -static -Wl,--no-relax \
+# RUN:   -Wl,-q -Wl,-T %S/Inputs/got_end_of_section_symbol.lld_script  \
+# RUN:   %t.o -o %t.exe
+# RUN: not llvm-bolt %t.exe -o %t.bolt 2>&1 | FileCheck %s
+
+# CHECK: BOLT-ERROR: GOT table contains currently unsupported section end
+# CHECK-SAME: symbol array_end
+
+.section .array, "a", @progbits
+.globl array_start
+.globl array_end
+array_start:
+  .word 0
+array_end:
+
+.section .text
+.globl _start
+.type _start, %function
+_start:
+  adrp x1, #:got:array_start
+  ldr x1, [x1, #:got_lo12:array_start]
+  adrp x0, #:got:array_end
+  ldr x0, [x0, #:got_lo12:array_end]
+  adrp x2, #:got:_start
+  ldr x2, [x2, #:got_lo12:_start]
+  ret

bolt/test/X86/section-end-sym.s

@@ -1,15 +1,15 @@
 ## Check that BOLT doesn't consider end-of-section symbols (e.g., _etext) as
 ## functions.
 
-# REQUIRES: x86_64-linux, asserts
+# REQUIRES: system-linux, asserts
 
 # RUN: llvm-mc -filetype=obj -triple x86_64-unknown-linux %s -o %t.o
 # RUN: ld.lld %t.o -o %t.exe -q
 # RUN: llvm-bolt %t.exe -o %t.null --print-cfg --debug-only=bolt 2>&1 \
 # RUN:   | FileCheck %s
 
 # CHECK: considering symbol etext for function
-# CHECK-NEXT: rejecting as symbol points to end of its section
+# CHECK-NEXT: rejecting as symbol etext points to end of .text section
 # CHECK-NOT: Binary Function "etext{{.*}}" after building cfg