[xray] Add llvm-xray extract support for 32 bit ARM

Summary:
XRay works on 32-bit ARM but extract didn't support it.

See also another previous attempt in D77858.

Reviewers: MaskRay, dberris, johnislarry

Subscribers: kristof.beyls, hiraditya, danielkiss, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80185

llvm/lib/XRay/InstrumentationMap.cpp

@@ -61,6 +61,7 @@ loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
   if ((!ObjFile.getBinary()->isELF() && !ObjFile.getBinary()->isMachO()) ||
       !(ObjFile.getBinary()->getArch() == Triple::x86_64 ||
         ObjFile.getBinary()->getArch() == Triple::ppc64le ||
+        ObjFile.getBinary()->getArch() == Triple::arm ||
         ObjFile.getBinary()->getArch() == Triple::aarch64))
     return make_error<StringError>(
         "File format not supported (only does ELF and Mach-O little endian "
@@ -115,7 +116,14 @@ loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
 
     for (const object::SectionRef &Section : Sections) {
       for (const object::RelocationRef &Reloc : Section.relocations()) {
-        if (SupportsRelocation && SupportsRelocation(Reloc.getType())) {
+        if (ObjFile.getBinary()->getArch() == Triple::arm) {
+          if (SupportsRelocation && SupportsRelocation(Reloc.getType())) {
+            Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
+            if (!ValueOrErr)
+              return ValueOrErr.takeError();
+            Relocs.insert({Reloc.getOffset(), Resolver(Reloc, *ValueOrErr, 0)});
+          }
+        } else if (SupportsRelocation && SupportsRelocation(Reloc.getType())) {
           auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend();
           auto A = AddendOrErr ? *AddendOrErr : 0;
           Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
@@ -133,12 +141,13 @@ loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
 
   // Copy the instrumentation map data into the Sleds data structure.
   auto C = Contents.bytes_begin();
-  static constexpr size_t ELF64SledEntrySize = 32;
+  bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit();
+  size_t ELFSledEntrySize = Is32Bit ? 16 : 32;
 
-  if ((C - Contents.bytes_end()) % ELF64SledEntrySize != 0)
+  if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0)
     return make_error<StringError>(
         Twine("Instrumentation map entries not evenly divisible by size of "
-              "an XRay sled entry in ELF64."),
+              "an XRay sled entry."),
         std::make_error_code(std::errc::executable_format_error));
 
   auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) {
@@ -151,20 +160,26 @@ loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
     return Address;
   };
 
-  const int WordSize = 8;
+  const int WordSize = Is32Bit ? 4 : 8;
   int32_t FuncId = 1;
   uint64_t CurFn = 0;
-  for (; C != Contents.bytes_end(); C += ELF64SledEntrySize) {
+  for (; C != Contents.bytes_end(); C += ELFSledEntrySize) {
     DataExtractor Extractor(
-        StringRef(reinterpret_cast<const char *>(C), ELF64SledEntrySize), true,
+        StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true,
         8);
     Sleds.push_back({});
     auto &Entry = Sleds.back();
     uint64_t OffsetPtr = 0;
     uint64_t AddrOff = OffsetPtr;
-    Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr));
+    if (Is32Bit)
+      Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr));
+    else
+      Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr));
     uint64_t FuncOff = OffsetPtr;
-    Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr));
+    if (Is32Bit)
+      Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr));
+    else
+      Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr));
     auto Kind = Extractor.getU8(&OffsetPtr);
     static constexpr SledEntry::FunctionKinds Kinds[] = {
         SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT,

llvm/test/tools/llvm-xray/ARM/extract-instrmap.test

@@ -0,0 +1,150 @@
+## This test makes sure we can extract the instrumentation map from an
+## XRay-instrumented PIE file.
+
+## Generated from the following source:
+## __attribute__((xray_always_instrument)) void foo() {}
+## __attribute__((xray_always_instrument)) void bar() {}
+## __attribute__((xray_always_instrument)) void jar() {}
+## Built with the following arguments:
+## -target armv7a-linux-androideabi -nostdlib -fxray-instrument -fPIC -shared
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS32
+  Data:            ELFDATA2LSB
+  Type:            ET_DYN
+  Machine:         EM_ARM
+  Flags:           [ EF_ARM_SOFT_FLOAT, EF_ARM_EABI_VER5 ]
+  Entry:           0x00000000000012B0
+ProgramHeaders:
+  - Type:            PT_LOAD
+    Flags:           [ PF_R ]
+    Sections:
+      - Section:         .rel.dyn
+    Align:           0x0000000000001000
+  - Type:            PT_LOAD
+    Flags:           [ PF_X, PF_R ]
+    Sections:
+      - Section:         .text
+    VAddr:           0x00000000000012B0
+    Align:           0x0000000000001000
+  - Type:            PT_LOAD
+    Flags:           [ PF_W, PF_R ]
+    Sections:
+      - Section:         xray_instr_map
+      - Section:         xray_fn_idx
+    VAddr:           0x00000000000033CC
+    Align:           0x0000000000001000
+Sections:
+  - Name:            .rel.dyn
+    Type:            SHT_REL
+    Flags:           [ SHF_ALLOC ]
+    Address:         0x0000000000000200
+    Link:            .dynsym
+    AddressAlign:    0x0000000000000004
+    Relocations:
+      - Offset:          0x00000000000033CC
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x00000000000033DC
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x00000000000033EC
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x00000000000033FC
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x000000000000340C
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x000000000000341C
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x0000000000003430
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x0000000000003434
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x0000000000003438
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x000000000000343C
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x0000000000003440
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x0000000000003444
+        Type:            R_ARM_RELATIVE
+      - Offset:          0x00000000000033F0
+        Symbol:          _Z3barv
+        Type:            R_ARM_ABS32
+      - Offset:          0x0000000000003400
+        Symbol:          _Z3barv
+        Type:            R_ARM_ABS32
+      - Offset:          0x00000000000033D0
+        Symbol:          _Z3foov
+        Type:            R_ARM_ABS32
+      - Offset:          0x00000000000033E0
+        Symbol:          _Z3foov
+        Type:            R_ARM_ABS32
+      - Offset:          0x0000000000003410
+        Symbol:          _Z3jarv
+        Type:            R_ARM_ABS32
+      - Offset:          0x0000000000003420
+        Symbol:          _Z3jarv
+        Type:            R_ARM_ABS32
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x00000000000012B0
+    AddressAlign:    0x0000000000000004
+    Size:            180
+  - Name:            xray_instr_map
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC, SHF_LINK_ORDER ]
+    Address:         0x00000000000033CC
+    Link:            .text
+    AddressAlign:    0x0000000000000001
+    Content:         B0120000000000000001000000000000CC120000000000000101000000000000EC120000000000000001000000000000081300000000000001010000000000002813000000000000000100000000000044130000000000000101000000000000
+  - Name:            xray_fn_idx
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC, SHF_LINK_ORDER ]
+    Address:         0x0000000000003430
+    Link:            .text
+    AddressAlign:    0x0000000000000008
+    Content:         CC330000EC330000EC3300000C3400000C3400002C340000
+DynamicSymbols:
+  - Name:            _Z3barv
+    Type:            STT_FUNC
+    Section:         .text
+    Binding:         STB_GLOBAL
+    Value:           0x00000000000012EC
+    Size:            0x000000000000003C
+  - Name:            _Z3foov
+    Type:            STT_FUNC
+    Section:         .text
+    Binding:         STB_GLOBAL
+    Value:           0x00000000000012B0
+    Size:            0x000000000000003C
+  - Name:            _Z3jarv
+    Type:            STT_FUNC
+    Section:         .text
+    Binding:         STB_GLOBAL
+    Value:           0x0000000000001328
+    Size:            0x000000000000003C
+...
+
+# RUN: yaml2obj %s -o %t.so
+# RUN: llvm-xray extract %t.so -s | FileCheck %s
+
+# CHECK:      ---
+# CHECK-NEXT: - { id: 1, address: 0x00000000000012B0, function: 0x00000000000012B0, kind: function-enter, always-instrument: true, function-name: 'foo()' }
+# CHECK-NEXT: - { id: 1, address: 0x00000000000012CC, function: 0x00000000000012B0, kind: function-exit, always-instrument: true, function-name: 'foo()' }
+# CHECK-NEXT: - { id: 2, address: 0x00000000000012EC, function: 0x00000000000012EC, kind: function-enter, always-instrument: true, function-name: 'bar()' }
+# CHECK-NEXT: - { id: 2, address: 0x0000000000001308, function: 0x00000000000012EC, kind: function-exit, always-instrument: true, function-name: 'bar()' }
+# CHECK-NEXT: - { id: 3, address: 0x0000000000001328, function: 0x0000000000001328, kind: function-enter, always-instrument: true, function-name: 'jar()' }
+# CHECK-NEXT: - { id: 3, address: 0x0000000000001344, function: 0x0000000000001328, kind: function-exit, always-instrument: true, function-name: 'jar()' }
+# CHECK-NEXT: ...
+
+# RUN: llvm-xray extract -s --no-demangle %t.so | FileCheck --check-prefix=MANGLED %s
+
+# MANGLED:      ---
+# MANGLED-NEXT: - { id: 1, address: 0x00000000000012B0, function: 0x00000000000012B0, kind: function-enter, always-instrument: true, function-name: _Z3foov }
+# MANGLED-NEXT: - { id: 1, address: 0x00000000000012CC, function: 0x00000000000012B0, kind: function-exit, always-instrument: true, function-name: _Z3foov }
+# MANGLED-NEXT: - { id: 2, address: 0x00000000000012EC, function: 0x00000000000012EC, kind: function-enter, always-instrument: true, function-name: _Z3barv }
+# MANGLED-NEXT: - { id: 2, address: 0x0000000000001308, function: 0x00000000000012EC, kind: function-exit, always-instrument: true, function-name: _Z3barv }
+# MANGLED-NEXT: - { id: 3, address: 0x0000000000001328, function: 0x0000000000001328, kind: function-enter, always-instrument: true, function-name: _Z3jarv }
+# MANGLED-NEXT: - { id: 3, address: 0x0000000000001344, function: 0x0000000000001328, kind: function-exit, always-instrument: true, function-name: _Z3jarv }
+# MANGLED-NEXT: ...

llvm/test/tools/llvm-xray/X86/bad-instrmap-sizes.txt

@@ -1,3 +1,3 @@
 ; RUN: not llvm-xray extract %S/Inputs/elf64-badentrysizes.bin 2>&1 | FileCheck %s
 ; CHECK: llvm-xray: Cannot extract instrumentation map from '{{.*}}elf64-badentrysizes.bin'.
-; CHECK-NEXT: Instrumentation map entries not evenly divisible by size of an XRay sled entry in ELF64.
+; CHECK-NEXT: Instrumentation map entries not evenly divisible by size of an XRay sled entry.

llvm/test/tools/llvm-xray/X86/unsupported-elf32.txt

@@ -1,3 +1,3 @@
 ; RUN: not llvm-xray extract %S/Inputs/elf32-noxray.bin 2>&1 | FileCheck %s
 ; CHECK: llvm-xray: Cannot extract instrumentation map from '{{.*}}elf32-noxray.bin'.
-; CHECK-NEXT: File format not supported (only does ELF and Mach-O little endian 64-bit).
+; CHECK-NEXT: File format not supported.  Supports: AArch64/ARM/ppc64le/x86-64.