[cfi-verify] Abort on unsupported targets

[jgalenson]

Summary

As suggested in the review for r337007, this makes cfi-verify abort on unsupported targets instead of producing incorrect results. It also updates the design document to reflect this.

Note that I'm not sure if 32-bit x86 is supported. We don't seem to have any tests for it, but I tried a toy example and it worked, so I left it there. What do you think?

[vlad.tsyrklevich]

I think leaving x86 in there is reasonable.

llvm/trunk/docs/CFIVerify.rst

 
 Other Design Notes
 ~~~~~~~~~~~~~~~~~~
 
 Only machine code sections that are marked as executable will be subject to this
 analysis. Non-executable sections do not require analysis as any execution
 present in these sections has already violated the control flow integrity.
 
-Suitable extensions may be made at a later date to include anaylsis for indirect
+Suitable extensions may be made at a later date to include analysis for indirect
 control flow operations across DSO boundaries. Currently, these CFI features are
 only experimental with an unstable ABI, making them unsuitable for analysis.
+
+The tool currently only supports the x86, x86_64, and AArch64 architectures.

llvm/trunk/test/tools/llvm-cfi-verify/Unsupported/arm-protected-lineinfo.s

+# RUN: llvm-mc %s -filetype obj -triple armv7a-- -o %t.o
+# RUN: not llvm-cfi-verify %t.o 2>&1 | FileCheck %s
+
+# CHECK: Could not initialise disassembler: Unsupported architecture.
+
+# Source (tiny.cc):
+#   int a() { return 42; }
+#   int b() { return 137; }
+#   int main(int argc, char** argv) {
+#     int(*ptr)();
+#     if (argc == 1)
+#       ptr = &a;
+#     else
+#       ptr = &b;
+#     return ptr();
+#   }
+  .text
+  .syntax unified
+  .eabi_attribute 67, "2.09"
+  .eabi_attribute 6, 2
+  .eabi_attribute 8, 1
+  .eabi_attribute 9, 1
+  .eabi_attribute 34, 1
+  .eabi_attribute 15, 1
+  .eabi_attribute 16, 1
+  .eabi_attribute 17, 2
+  .eabi_attribute 20, 1
+  .eabi_attribute 21, 1
+  .eabi_attribute 23, 3
+  .eabi_attribute 24, 1
+  .eabi_attribute 25, 1
+  .eabi_attribute 38, 1
+  .eabi_attribute 18, 4
+  .eabi_attribute 26, 2
+  .eabi_attribute 14, 0
+  .file "ld-temp.o"
+  .p2align  2
+  .type _Z1av.cfi,%function
+  .code 32
+_Z1av.cfi:
+.Lfunc_begin0:
+  .file 1 "tiny.cc"
+  .loc  1 1 0
+  .fnstart
+  .cfi_sections .debug_frame
+  .cfi_startproc
+  .loc  1 1 11 prologue_end
+  mov r0, #42
+  bx  lr
+.Ltmp0:
+.Lfunc_end0:
+  .size _Z1av.cfi, .Lfunc_end0-_Z1av.cfi
+  .cfi_endproc
+  .cantunwind
+  .fnend
+
+  .p2align  2
+  .type _Z1bv.cfi,%function
+  .code 32
+_Z1bv.cfi:
+.Lfunc_begin1:
+  .loc  1 2 0
+  .fnstart
+  .cfi_startproc
+  .loc  1 2 11 prologue_end
+  mov r0, #137
+  bx  lr
+.Ltmp1:
+.Lfunc_end1:
+  .size _Z1bv.cfi, .Lfunc_end1-_Z1bv.cfi
+  .cfi_endproc
+  .cantunwind
+  .fnend
+
+  .p2align  2
+  .type main,%function
+  .code 32
+main:
+.Lfunc_begin2:
+  .loc  1 3 0
+  .fnstart
+  .cfi_startproc
+  .save {r11, lr}
+  push  {r11, lr}
+  .cfi_def_cfa_offset 8
+  .cfi_offset lr, -4
+  .cfi_offset r11, -8
+  .setfp  r11, sp
+  mov r11, sp
+  .cfi_def_cfa_register r11
+  .pad  #16
+  sub sp, sp, #16
+  mov r2, #0
+  str r2, [r11, #-4]
+  str r0, [sp, #8]
+  str r1, [sp, #4]
+.Ltmp2:
+  .loc  1 5 7 prologue_end
+  ldr r0, [sp, #8]
+  cmp r0, #1
+  bne .LBB2_2
+  b .LBB2_1
+.LBB2_1:
+  .loc  1 6 9
+  ldr r0, .LCPI2_0
+.LPC2_0:
+  add r0, pc, r0
+  str r0, [sp]
+  .loc  1 6 5 is_stmt 0
+  b .LBB2_3
+.LBB2_2:
+  .loc  1 8 9 is_stmt 1
+  ldr r0, .LCPI2_1
+.LPC2_1:
+  add r0, pc, r0
+  str r0, [sp]
+  b .LBB2_3
+.LBB2_3:
+  .loc  1 9 10
+  ldr r1, [sp]
+  ldr r0, .LCPI2_2
+.LPC2_2:
+  add r0, pc, r0
+  sub r0, r1, r0
+  ror r0, r0, #2
+  cmp r0, #2
+  blo .LBB2_5
+  b .LBB2_4
+.LBB2_4:
+  .inst 0xe7ffdefe
+.LBB2_5:
+  mov lr, pc
+  bx  r1
+  .loc  1 9 3 is_stmt 0
+  mov sp, r11
+  pop {r11, lr}
+  bx  lr
+.Ltmp3:
+  .p2align  2
+  .loc  1 0 3
+.LCPI2_0:
+  .long _Z1av-(.LPC2_0+8)
+.LCPI2_1:
+  .long _Z1bv-(.LPC2_1+8)
+.LCPI2_2:
+  .long .L.cfi.jumptable-(.LPC2_2+8)
+.Lfunc_end2:
+  .size main, .Lfunc_end2-main
+  .cfi_endproc
+  .fnend
+
+  .p2align  2
+  .type .L.cfi.jumptable,%function
+  .code 32
+.L.cfi.jumptable:
+.Lfunc_begin3:
+  .fnstart
+  .cfi_startproc
+  @APP
+  b _Z1av.cfi
+  b _Z1bv.cfi
+
+  @NO_APP
+.Lfunc_end3:
+  .size .L.cfi.jumptable, .Lfunc_end3-.L.cfi.jumptable
+  .cfi_endproc
+  .cantunwind
+  .fnend
+
+  .type .L__unnamed_1,%object
+  .section  .rodata,"a",%progbits
+.L__unnamed_1:
+  .size .L__unnamed_1, 0
+
+  .section  .debug_str,"MS",%progbits,1
+.Linfo_string0:
+  .asciz  "clang version 7.0.0 (trunk 336681) (llvm/trunk 336683)"
+.Linfo_string1:
+  .asciz  "tiny.cc"
+.Linfo_string2:
+  .asciz  ""
+  .section  .debug_abbrev,"",%progbits
+  .byte 1
+  .byte 17
+  .byte 0
+  .byte 37
+  .byte 14
+  .byte 19
+  .byte 5
+  .byte 3
+  .byte 14
+  .byte 16
+  .byte 23
+  .byte 27
+  .byte 14
+  .byte 17
+  .byte 1
+  .byte 18
+  .byte 6
+  .byte 0
+  .byte 0
+  .byte 0
+  .section  .debug_info,"",%progbits
+.Lcu_begin0:
+  .long 34
+  .short  4
+  .long .debug_abbrev
+  .byte 4
+  .byte 1
+  .long .Linfo_string0
+  .short  4
+  .long .Linfo_string1
+  .long .Lline_table_start0
+  .long .Linfo_string2
+  .long .Lfunc_begin0
+  .long .Lfunc_end2-.Lfunc_begin0
+  .section  .debug_ranges,"",%progbits
+  .section  .debug_macinfo,"",%progbits
+  .byte 0
+
+  .globl  __typeid__ZTSFivE_global_addr
+  .hidden __typeid__ZTSFivE_global_addr
+.set __typeid__ZTSFivE_global_addr, .L.cfi.jumptable
+  .size __typeid__ZTSFivE_global_addr, 1
+  .type _Z1av,%function
+.set _Z1av, .L.cfi.jumptable
+  .type _Z1bv,%function
+.set _Z1bv, .L.cfi.jumptable+4
+  .ident  "clang version 7.0.0 (trunk 336681) (llvm/trunk 336683)"
+  .section  ".note.GNU-stack","",%progbits
+  .section  .debug_line,"",%progbits
+.Lline_table_start0:

llvm/trunk/test/tools/llvm-cfi-verify/Unsupported/lit.local.cfg

+if not 'ARM' in config.root.targets:
+    config.unsupported = True

llvm/trunk/tools/llvm-cfi-verify/lib/FileAnalysis.cpp

Expected<FileAnalysis> FileAnalysis::Create(StringRef Filename) {
   // Construct the object and allow it to take ownership of the binary.
   object::OwningBinary<object::Binary> Binary = std::move(BinaryOrErr.get());
   FileAnalysis Analysis(std::move(Binary));
 
   Analysis.Object = dyn_cast<object::ObjectFile>(Analysis.Binary.getBinary());
   if (!Analysis.Object)
     return make_error<UnsupportedDisassembly>("Failed to cast object");
 
+  switch (Analysis.Object->getArch()) {
+    case Triple::x86:
+    case Triple::x86_64:
+    case Triple::aarch64:
+    case Triple::aarch64_be:
+      break;
+    default:
+      return make_error<UnsupportedDisassembly>("Unsupported architecture.");
+  }
+
   Analysis.ObjectTriple = Analysis.Object->makeTriple();
   Analysis.Features = Analysis.Object->getFeatures();
 
   // Init the rest of the object.
   if (auto InitResponse = Analysis.initialiseDisassemblyMembers())
     return std::move(InitResponse);
 
   if (auto SectionParseResponse = Analysis.parseCodeSections())