[DebugInfo/DWARF] - Test invalid CFI opcodes properly and refine related CFIProgram::parse code.

There are following issues with `CFIProgram::parse` code:

1) Invalid CFI opcodes were never tested. And currently a test would fail
when the `LLVM_ENABLE_ABI_BREAKING_CHECKS` is enabled. It happens because
the `DataExtractor::Cursor C` remains unchecked when the
"Invalid extended CFI opcode" error is reported:

```
.eh_frame section at offset 0x1128 address 0x0:
Program aborted due to an unhandled Error:
Error value was Success. (Note: Success values must still be checked prior to being destroyed).
```

2) It is impossible to reach the "Invalid primary CFI opcode" error with the current code.
There are 3 possible primary opcode values and all of them are handled. Hence this error
should be replaced with llvm_unreachable.

3) Errors currently reported are upper-case.

This patch refines the code in the `CFIProgram::parse` method to fix all issues mentioned
and adds unit tests for all possible invalid extended CFI opcodes.

Differential revision: https://reviews.llvm.org/D82868

lib/DebugInfo/DWARF/DWARFDebugFrame.cpp

@@ -39,18 +39,15 @@ Error CFIProgram::parse(DWARFDataExtractor Data, uint64_t *Offset,
   DataExtractor::Cursor C(*Offset);
   while (C && C.tell() < EndOffset) {
     uint8_t Opcode = Data.getRelocatedValue(C, 1);
-    // Some instructions have a primary opcode encoded in the top bits.
+    if (!C)
-    uint8_t Primary = Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK;
+      break;
 
-    if (Primary) {
+    // Some instructions have a primary opcode encoded in the top bits.
+    if (uint8_t Primary = Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK) {
       // If it's a primary opcode, the first operand is encoded in the bottom
       // bits of the opcode itself.
       uint64_t Op1 = Opcode & DWARF_CFI_PRIMARY_OPERAND_MASK;
       switch (Primary) {
-      default:
-        return createStringError(errc::illegal_byte_sequence,
-                                 "Invalid primary CFI opcode 0x%" PRIx8,
-                                 Primary);
       case DW_CFA_advance_loc:
       case DW_CFA_restore:
         addInstruction(Primary, Op1);
@@ -58,14 +55,17 @@ Error CFIProgram::parse(DWARFDataExtractor Data, uint64_t *Offset,
       case DW_CFA_offset:
         addInstruction(Primary, Op1, Data.getULEB128(C));
         break;
+      default:
+        llvm_unreachable("invalid primary CFI opcode");
       }
-    } else {
+      continue;
+    }
+
     // Extended opcode - its value is Opcode itself.
     switch (Opcode) {
     default:
       return createStringError(errc::illegal_byte_sequence,
-                                 "Invalid extended CFI opcode 0x%" PRIx8,
+                               "invalid extended CFI opcode 0x%" PRIx8, Opcode);
-                                 Opcode);
     case DW_CFA_nop:
     case DW_CFA_remember_state:
     case DW_CFA_restore_state:
@@ -157,7 +157,6 @@ Error CFIProgram::parse(DWARFDataExtractor Data, uint64_t *Offset,
     }
     }
   }
-  }
 
   *Offset = C.tell();
   return C.takeError();

unittests/DebugInfo/DWARF/DWARFDebugFrameTest.cpp

@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/BinaryFormat/Dwarf.h"
@@ -120,65 +121,116 @@ TEST(DWARFDebugFrame, DumpEH64FDE) {
                    "cie=1111ab9a000c pc=4444abcdabcd...5555bcdebcde");
 }
 
-// Here we test how truncated Call Frame Instructions are parsed.
+static Error parseCFI(dwarf::CIE &C, ArrayRef<uint8_t> Instructions,
-TEST(DWARFDebugFrame, ParseTruncatedCFITest) {
-  auto ParseCFI = [](dwarf::CIE &C, ArrayRef<uint8_t> Instructions,
                       Optional<uint64_t> Size = None) {
   DWARFDataExtractor Data(Instructions, /*IsLittleEndian=*/true,
                           /*AddressSize=*/8);
   uint64_t Offset = 0;
   const uint64_t EndOffset = Size ? *Size : (uint64_t)Instructions.size();
   return C.cfis().parse(Data, &Offset, EndOffset);
-  };
+}
+
+TEST(DWARFDebugFrame, InvalidCFIOpcodesTest) {
+  llvm::DenseSet<uint8_t> ValidExtendedOpcodes = {
+      dwarf::DW_CFA_nop,
+      dwarf::DW_CFA_advance_loc,
+      dwarf::DW_CFA_offset,
+      dwarf::DW_CFA_restore,
+      dwarf::DW_CFA_set_loc,
+      dwarf::DW_CFA_advance_loc1,
+      dwarf::DW_CFA_advance_loc2,
+      dwarf::DW_CFA_advance_loc4,
+      dwarf::DW_CFA_offset_extended,
+      dwarf::DW_CFA_restore_extended,
+      dwarf::DW_CFA_undefined,
+      dwarf::DW_CFA_same_value,
+      dwarf::DW_CFA_register,
+      dwarf::DW_CFA_remember_state,
+      dwarf::DW_CFA_restore_state,
+      dwarf::DW_CFA_def_cfa,
+      dwarf::DW_CFA_def_cfa_register,
+      dwarf::DW_CFA_def_cfa_offset,
+      dwarf::DW_CFA_def_cfa_expression,
+      dwarf::DW_CFA_expression,
+      dwarf::DW_CFA_offset_extended_sf,
+      dwarf::DW_CFA_def_cfa_sf,
+      dwarf::DW_CFA_def_cfa_offset_sf,
+      dwarf::DW_CFA_val_offset,
+      dwarf::DW_CFA_val_offset_sf,
+      dwarf::DW_CFA_val_expression,
+      dwarf::DW_CFA_MIPS_advance_loc8,
+      dwarf::DW_CFA_GNU_window_save,
+      dwarf::DW_CFA_AARCH64_negate_ra_state,
+      dwarf::DW_CFA_GNU_args_size};
 
   dwarf::CIE TestCIE = createCIE(/*IsDWARF64=*/false,
                                  /*Offset=*/0x0,
                                  /*Length=*/0xff);
 
+  // See DWARF standard v3, section 7.23: low 6 bits are used to encode an
+  // extended opcode.
+  for (uint8_t Code = 0; Code <= 63; ++Code) {
+    if (ValidExtendedOpcodes.count(Code))
+      continue;
+
+    EXPECT_THAT_ERROR(parseCFI(TestCIE, Code),
+                      FailedWithMessage(("invalid extended CFI opcode 0x" +
+                                         Twine::utohexstr(Code))
+                                            .str()
+                                            .c_str()));
+  }
+}
+
+// Here we test how truncated Call Frame Instructions are parsed.
+TEST(DWARFDebugFrame, ParseTruncatedCFITest) {
+  dwarf::CIE TestCIE = createCIE(/*IsDWARF64=*/false,
+                                 /*Offset=*/0x0,
+                                 /*Length=*/0xff);
+
   // Having an empty instructions list is fine.
-  EXPECT_THAT_ERROR(ParseCFI(TestCIE, {}), Succeeded());
+  EXPECT_THAT_ERROR(parseCFI(TestCIE, {}), Succeeded());
 
   // Unable to read an opcode, because the instructions list is empty, but we
   // say to the parser that it is not.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {}, /*Size=*/1),
+      parseCFI(TestCIE, {}, /*Size=*/1),
       FailedWithMessage(
           "unexpected end of data at offset 0x0 while reading [0x0, 0x1)"));
 
   // Unable to read a truncated DW_CFA_offset instruction.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_offset}),
+      parseCFI(TestCIE, {dwarf::DW_CFA_offset}),
       FailedWithMessage("unable to decode LEB128 at offset 0x00000001: "
                         "malformed uleb128, extends past end"));
 
   // Unable to read a truncated DW_CFA_set_loc instruction.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_set_loc}),
+      parseCFI(TestCIE, {dwarf::DW_CFA_set_loc}),
       FailedWithMessage(
           "unexpected end of data at offset 0x1 while reading [0x1, 0x9)"));
 
   // Unable to read a truncated DW_CFA_advance_loc1 instruction.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_advance_loc1}),
+      parseCFI(TestCIE, {dwarf::DW_CFA_advance_loc1}),
       FailedWithMessage(
           "unexpected end of data at offset 0x1 while reading [0x1, 0x2)"));
 
   // Unable to read a truncated DW_CFA_advance_loc2 instruction.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_advance_loc2}),
+      parseCFI(TestCIE, {dwarf::DW_CFA_advance_loc2}),
       FailedWithMessage(
           "unexpected end of data at offset 0x1 while reading [0x1, 0x3)"));
 
   // Unable to read a truncated DW_CFA_advance_loc4 instruction.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_advance_loc4}),
+      parseCFI(TestCIE, {dwarf::DW_CFA_advance_loc4}),
       FailedWithMessage(
           "unexpected end of data at offset 0x1 while reading [0x1, 0x5)"));
 
   // A test for an instruction with a single ULEB128 operand.
   auto CheckOp_ULEB128 = [&](uint8_t Inst) {
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, Inst),
+        parseCFI(TestCIE, Inst),
         FailedWithMessage("unable to decode LEB128 at offset 0x00000001: "
                           "malformed uleb128, extends past end"));
   };
@@ -191,19 +243,19 @@ TEST(DWARFDebugFrame, ParseTruncatedCFITest) {
 
   // Unable to read a truncated DW_CFA_def_cfa_offset_sf instruction.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_offset_sf}),
+      parseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_offset_sf}),
       FailedWithMessage("unable to decode LEB128 at offset 0x00000001: "
                         "malformed sleb128, extends past end"));
 
   // A test for an instruction with two ULEB128 operands.
   auto CheckOp_ULEB128_ULEB128 = [&](uint8_t Inst) {
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, Inst),
+        parseCFI(TestCIE, Inst),
         FailedWithMessage("unable to decode LEB128 at offset 0x00000001: "
                           "malformed uleb128, extends past end"));
 
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, {Inst, /*Op1=*/0}),
+        parseCFI(TestCIE, {Inst, /*Op1=*/0}),
         FailedWithMessage("unable to decode LEB128 at offset 0x00000002: "
                           "malformed uleb128, extends past end"));
   };
@@ -215,12 +267,12 @@ TEST(DWARFDebugFrame, ParseTruncatedCFITest) {
   // A test for an instruction with two operands: ULEB128, SLEB128.
   auto CheckOp_ULEB128_SLEB128 = [&](uint8_t Inst) {
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, Inst),
+        parseCFI(TestCIE, Inst),
         FailedWithMessage("unable to decode LEB128 at offset 0x00000001: "
                           "malformed uleb128, extends past end"));
 
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, {Inst, /*Op1=*/0}),
+        parseCFI(TestCIE, {Inst, /*Op1=*/0}),
         FailedWithMessage("unable to decode LEB128 at offset 0x00000002: "
                           "malformed sleb128, extends past end"));
   };
@@ -231,16 +283,16 @@ TEST(DWARFDebugFrame, ParseTruncatedCFITest) {
 
   // Unable to read a truncated DW_CFA_def_cfa_expression instruction.
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_expression}),
+      parseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_expression}),
       FailedWithMessage("unable to decode LEB128 at offset 0x00000001: "
                         "malformed uleb128, extends past end"));
   EXPECT_THAT_ERROR(
-      ParseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_expression,
+      parseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_expression,
                          /*expression length=*/0x1}),
       FailedWithMessage(
           "unexpected end of data at offset 0x2 while reading [0x2, 0x3)"));
   // The DW_CFA_def_cfa_expression can contain a zero length expression.
-  EXPECT_THAT_ERROR(ParseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_expression,
+  EXPECT_THAT_ERROR(parseCFI(TestCIE, {dwarf::DW_CFA_def_cfa_expression,
                                        /*ExprLen=*/0}),
                     Succeeded());
 
@@ -248,19 +300,19 @@ TEST(DWARFDebugFrame, ParseTruncatedCFITest) {
   // (ULEB128) and expression bytes.
   auto CheckOp_ULEB128_Expr = [&](uint8_t Inst) {
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, {Inst}),
+        parseCFI(TestCIE, {Inst}),
         FailedWithMessage("unable to decode LEB128 at offset 0x00000001: "
                           "malformed uleb128, extends past end"));
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, {Inst, /*Op1=*/0}),
+        parseCFI(TestCIE, {Inst, /*Op1=*/0}),
         FailedWithMessage("unable to decode LEB128 at offset 0x00000002: "
                           "malformed uleb128, extends past end"));
     // A zero length expression is fine
-    EXPECT_THAT_ERROR(ParseCFI(TestCIE, {Inst,
+    EXPECT_THAT_ERROR(parseCFI(TestCIE, {Inst,
                                          /*Op1=*/0, /*ExprLen=*/0}),
                       Succeeded());
     EXPECT_THAT_ERROR(
-        ParseCFI(TestCIE, {Inst,
+        parseCFI(TestCIE, {Inst,
                            /*Op1=*/0, /*ExprLen=*/1}),
         FailedWithMessage(
             "unexpected end of data at offset 0x3 while reading [0x3, 0x4)"));