Merging r325653 with test fixups:

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r325653 | sdardis | 2018-02-21 00:06:53 +0000 (Wed, 21 Feb 2018) | 31 lines

[mips] Spectre variant two mitigation for MIPSR2

This patch provides mitigation for CVE-2017-5715, Spectre variant two,
which affects the P5600 and P6600. It implements the LLVM part of
-mindirect-jump=hazard. It is _not_ enabled by default for the P5600.

The migitation strategy suggested by MIPS for these processors is to use
hazard barrier instructions. 'jalr.hb' and 'jr.hb' are hazard
barrier variants of the 'jalr' and 'jr' instructions respectively.

These instructions impede the execution of instruction stream until
architecturally defined hazards (changes to the instruction stream,
privileged registers which may affect execution) are cleared. These
instructions in MIPS' designs are not speculated past.

These instructions are used with the attribute +use-indirect-jump-hazard
when branching indirectly and for indirect function calls.

These instructions are defined by the MIPS32R2 ISA, so this mitigation
method is not compatible with processors which implement an earlier
revision of the MIPS ISA.

Performance benchmarking of this option with -fpic and lld using
-z hazardplt shows a difference of overall 10%~ time increase
for the LLVM testsuite. Certain benchmarks such as methcall show a
substantially larger increase in time due to their nature.

Reviewers: atanasyan, zoran.jovanovic

Differential Revision: https://reviews.llvm.org/D43486

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@329798 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Simon Dardis

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

@@ -5136,6 +5136,7 @@ unsigned MipsAsmParser::checkTargetMatchPredicate(MCInst &Inst) {
   // It also applies for registers Rt and Rs of microMIPSr6 jalrc.hb instruction
   // and registers Rd and Base for microMIPS lwp instruction
   case Mips::JALR_HB:
+  case Mips::JALR_HB64:
   case Mips::JALRC_HB_MMR6:
   case Mips::JALRC_MMR6:
     if (Inst.getOperand(0).getReg() == Inst.getOperand(1).getReg())

lib/Target/Mips/MicroMips32r6InstrInfo.td

@@ -1886,6 +1886,12 @@ let AddedComplexity = 41 in {
 
 def TAILCALL_MMR6 : TailCall<BC_MMR6, brtarget26_mm>, ISA_MICROMIPS32R6;
 
+def TAILCALLREG_MMR6  : TailCallReg<JRC16_MM, GPR32Opnd>, ISA_MICROMIPS32R6;
+
+def PseudoIndirectBranch_MMR6 : PseudoIndirectBranchBase<JRC16_MMR6,
+                                                         GPR32Opnd>,
+                                ISA_MICROMIPS32R6;
+
 def : MipsPat<(MipsTailCall (iPTR tglobaladdr:$dst)),
               (TAILCALL_MMR6 tglobaladdr:$dst)>, ISA_MICROMIPS32R6;
 

lib/Target/Mips/MicroMipsInstrInfo.td

@@ -1003,6 +1003,12 @@ let DecoderNamespace = "MicroMips", Predicates = [InMicroMips] in {
 
 def TAILCALL_MM : TailCall<J_MM, jmptarget_mm>, ISA_MIPS1_NOT_32R6_64R6;
 
+def TAILCALLREG_MM  : TailCallReg<JRC16_MM, GPR32Opnd>,
+                      ISA_MICROMIPS32_NOT_MIPS32R6;
+
+def PseudoIndirectBranch_MM : PseudoIndirectBranchBase<JR_MM, GPR32Opnd>,
+                              ISA_MICROMIPS32_NOT_MIPS32R6;
+
 let DecoderNamespace = "MicroMips" in {
   def RDHWR_MM : MMRel, R6MMR6Rel, ReadHardware<GPR32Opnd, HWRegsOpnd>,
                  RDHWR_FM_MM, ISA_MICROMIPS32_NOT_MIPS32R6;

lib/Target/Mips/Mips.td

@@ -193,6 +193,10 @@ def FeatureMT : SubtargetFeature<"mt", "HasMT", "true", "Mips MT ASE">;
 def FeatureLongCalls : SubtargetFeature<"long-calls", "UseLongCalls", "true",
                                         "Disable use of the jal instruction">;
 
+def FeatureUseIndirectJumpsHazard : SubtargetFeature<"use-indirect-jump-hazard",
+                                                    "UseIndirectJumpsHazard",
+                                                    "true", "Use indirect jump"
+                        " guards to prevent certain speculation based attacks">;
 //===----------------------------------------------------------------------===//
 // Mips processors supported.
 //===----------------------------------------------------------------------===//

lib/Target/Mips/Mips32r6InstrInfo.td

@@ -1036,3 +1036,42 @@ def : MipsPat<(select i32:$cond, immz, i32:$f),
               (SELEQZ i32:$f, i32:$cond)>,
               ISA_MIPS32R6;
 }
+
+// Pseudo instructions
+let isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1, hasDelaySlot = 1,
+    hasExtraSrcRegAllocReq = 1, isCTI = 1, Defs = [AT] in {
+  class TailCallRegR6<Instruction JumpInst, Register RT, RegisterOperand RO> :
+    PseudoSE<(outs), (ins RO:$rs), [(MipsTailCall RO:$rs)], II_JR>,
+    PseudoInstExpansion<(JumpInst RT:$rt, RO:$rs)>;
+}
+
+class PseudoIndirectBranchBaseR6<Instruction JumpInst, Register RT,
+                                 RegisterOperand RO> :
+    MipsPseudo<(outs), (ins RO:$rs), [(brind RO:$rs)],
+               II_IndirectBranchPseudo>,
+    PseudoInstExpansion<(JumpInst RT:$rt, RO:$rs)> {
+  let isTerminator=1;
+  let isBarrier=1;
+  let hasDelaySlot = 1;
+  let isBranch = 1;
+  let isIndirectBranch = 1;
+  bit isCTI = 1;
+}
+
+
+let AdditionalPredicates = [NotInMips16Mode, NotInMicroMips,
+                            NoIndirectJumpGuards] in {
+  def TAILCALLR6REG : TailCallRegR6<JALR, ZERO, GPR32Opnd>, ISA_MIPS32R6;
+  def PseudoIndirectBranchR6 : PseudoIndirectBranchBaseR6<JALR, ZERO,
+                                                          GPR32Opnd>,
+                               ISA_MIPS32R6;
+}
+
+let AdditionalPredicates = [NotInMips16Mode, NotInMicroMips,
+                            UseIndirectJumpsHazard] in {
+  def TAILCALLHBR6REG : TailCallReg<JR_HB_R6, GPR32Opnd>, ISA_MIPS32R6;
+  def PseudoIndrectHazardBranchR6 : PseudoIndirectBranchBase<JR_HB_R6,
+                                                             GPR32Opnd>,
+                                    ISA_MIPS32R6;
+}
+

lib/Target/Mips/Mips64InstrInfo.td

@@ -240,13 +240,32 @@ let isCodeGenOnly = 1 in {
   def BGTZ64 : CBranchZero<"bgtz", brtarget, setgt, GPR64Opnd>, BGEZ_FM<7, 0>;
   def BLEZ64 : CBranchZero<"blez", brtarget, setle, GPR64Opnd>, BGEZ_FM<6, 0>;
   def BLTZ64 : CBranchZero<"bltz", brtarget, setlt, GPR64Opnd>, BGEZ_FM<1, 0>;
-  def JALR64Pseudo : JumpLinkRegPseudo<GPR64Opnd, JALR, RA, GPR32Opnd>;
+  let AdditionalPredicates = [NoIndirectJumpGuards] in
+    def JALR64Pseudo : JumpLinkRegPseudo<GPR64Opnd, JALR, RA, GPR32Opnd>;
 }
+let AdditionalPredicates = [NotInMicroMips],
+    DecoderNamespace = "Mips64" in {
+  def JR_HB64 : JR_HB_DESC<GPR64Opnd>, JR_HB_ENC, ISA_MIPS32_NOT_32R6_64R6;
+  def JALR_HB64 : JALR_HB_DESC<GPR64Opnd>, JALR_HB_ENC, ISA_MIPS32R2;
+}
+def PseudoReturn64 : PseudoReturnBase<GPR64Opnd>;
 
-def TAILCALLREG64 : TailCallReg<GPR64Opnd>;
+let AdditionalPredicates = [NotInMips16Mode, NotInMicroMips,
+                            NoIndirectJumpGuards] in {
+  def TAILCALLREG64 : TailCallReg<JR64, GPR64Opnd>, ISA_MIPS3_NOT_32R6_64R6,
+                      PTR_64;
+  def PseudoIndirectBranch64 : PseudoIndirectBranchBase<JR64, GPR64Opnd>,
+                               ISA_MIPS3_NOT_32R6_64R6;
+}
 
-def PseudoReturn64 : PseudoReturnBase<GPR64Opnd>;
-def PseudoIndirectBranch64 : PseudoIndirectBranchBase<GPR64Opnd>;
+let AdditionalPredicates = [NotInMips16Mode, NotInMicroMips,
+                            UseIndirectJumpsHazard] in {
+  def TAILCALLREGHB64 : TailCallReg<JR_HB64, GPR64Opnd>,
+                        ISA_MIPS32R2_NOT_32R6_64R6, PTR_64;
+  def PseudoIndirectHazardBranch64 : PseudoIndirectBranchBase<JR_HB64,
+                                                              GPR64Opnd>,
+                                     ISA_MIPS32R2_NOT_32R6_64R6;
+}
 
 /// Multiply and Divide Instructions.
 let AdditionalPredicates = [NotInMicroMips] in {
@@ -536,6 +555,10 @@ def DMTC2 : MTC3OP<"dmtc2", COP2Opnd, GPR64Opnd, II_DMTC2>, MFC3OP_FM<0x12, 5>,
             ISA_MIPS3;
 }
 
+
+let AdditionalPredicates = [UseIndirectJumpsHazard] in
+  def JALRHB64Pseudo : JumpLinkRegPseudo<GPR64Opnd, JALR_HB64, RA_64>;
+
 //===----------------------------------------------------------------------===//
 //  Arbitrary patterns that map to one or more instructions
 //===----------------------------------------------------------------------===//
@@ -843,7 +866,8 @@ let AdditionalPredicates = [NotInMicroMips] in {
   def : MipsInstAlias<"dext $rt, $rs, $pos, $size",
                       (DEXTU GPR64Opnd:$rt, GPR64Opnd:$rs, uimm5_plus32:$pos,
                              uimm5_plus1:$size), 0>, ISA_MIPS64R2;
-
+  def : MipsInstAlias<"jalr.hb $rs", (JALR_HB64 RA_64, GPR64Opnd:$rs), 1>,
+        ISA_MIPS64;
 // Two operand (implicit 0 selector) versions:
   def : MipsInstAlias<"dmtc0 $rt, $rd",
                       (DMTC0 COP0Opnd:$rd, GPR64Opnd:$rt, 0), 0>;

lib/Target/Mips/Mips64r6InstrInfo.td

@@ -104,6 +104,16 @@ class JIC64_DESC : JMP_IDX_COMPACT_DESC_BASE<"jic", jmpoffset16, GPR64Opnd,
 
 class LL64_R6_DESC : LL_R6_DESC_BASE<"ll", GPR32Opnd, mem_simm9, II_LL>;
 class SC64_R6_DESC : SC_R6_DESC_BASE<"sc", GPR32Opnd, II_SC>;
+
+class JR_HB64_R6_DESC : JR_HB_DESC_BASE<"jr.hb", GPR64Opnd> {
+  bit isBranch = 1;
+  bit isIndirectBranch = 1;
+  bit hasDelaySlot = 1;
+  bit isTerminator=1;
+  bit isBarrier=1;
+  bit isCTI = 1;
+  InstrItinClass Itinerary = II_JR_HB;
+}
 //===----------------------------------------------------------------------===//
 //
 // Instruction Definitions
@@ -136,6 +146,7 @@ def SCD_R6 : SCD_R6_ENC, SCD_R6_DESC, ISA_MIPS32R6;
 let DecoderNamespace = "Mips32r6_64r6_GP64" in {
   def SELEQZ64 : SELEQZ_ENC, SELEQZ64_DESC, ISA_MIPS32R6, GPR_64;
   def SELNEZ64 : SELNEZ_ENC, SELNEZ64_DESC, ISA_MIPS32R6, GPR_64;
+  def JR_HB64_R6 : JR_HB_R6_ENC, JR_HB64_R6_DESC, ISA_MIPS32R6;
 }
 let AdditionalPredicates = [NotInMicroMips],
     DecoderNamespace = "Mips32r6_64r6_PTR64" in {
@@ -277,3 +288,22 @@ def : MipsPat<(select (i32 (setne i32:$cond, immz)), immz, i64:$f),
 def : MipsPat<(select (i32 (seteq i32:$cond, immz)), immz, i64:$f),
               (SELNEZ64 i64:$f, (SLL64_32 i32:$cond))>,
               ISA_MIPS64R6;
+
+// Pseudo instructions
+
+let AdditionalPredicates = [NotInMips16Mode, NotInMicroMips,
+                            NoIndirectJumpGuards] in {
+  def TAILCALL64R6REG : TailCallRegR6<JALR64, ZERO_64, GPR64Opnd>, ISA_MIPS64R6;
+  def PseudoIndirectBranch64R6 : PseudoIndirectBranchBaseR6<JALR64, ZERO_64,
+                                                            GPR64Opnd>,
+                                 ISA_MIPS64R6;
+}
+
+let AdditionalPredicates = [NotInMips16Mode, NotInMicroMips,
+                            UseIndirectJumpsHazard] in {
+  def TAILCALLHB64R6REG : TailCallReg<JR_HB64_R6, GPR64Opnd>,
+                          ISA_MIPS64R6;
+  def PseudoIndrectHazardBranch64R6 : PseudoIndirectBranchBase<JR_HB64_R6,
+                                                                 GPR64Opnd>,
+                                      ISA_MIPS64R6;
+}

lib/Target/Mips/MipsDSPInstrFormats.td

@@ -53,7 +53,7 @@ class DSPInst<string opstr = "">
 
 class PseudoDSP<dag outs, dag ins, list<dag> pattern,
                 InstrItinClass itin = IIPseudo>
-    : MipsPseudo<outs, ins, pattern, itin>, PredicateControl {
+    : MipsPseudo<outs, ins, pattern, itin> {
   let InsnPredicates = [HasDSP];
 }
 

lib/Target/Mips/MipsInstrFormats.td

@@ -128,15 +128,15 @@ class InstSE<dag outs, dag ins, string asmstr, list<dag> pattern,
 // Mips Pseudo Instructions Format
 class MipsPseudo<dag outs, dag ins, list<dag> pattern,
                  InstrItinClass itin = IIPseudo> :
-  MipsInst<outs, ins, "", pattern, itin, Pseudo> {
+  MipsInst<outs, ins, "", pattern, itin, Pseudo>, PredicateControl {
   let isCodeGenOnly = 1;
   let isPseudo = 1;
 }
 
 // Mips32/64 Pseudo Instruction Format
 class PseudoSE<dag outs, dag ins, list<dag> pattern,
                InstrItinClass itin = IIPseudo> :
-  MipsPseudo<outs, ins, pattern, itin>, PredicateControl {
+  MipsPseudo<outs, ins, pattern, itin> {
   let EncodingPredicates = [HasStdEnc];
 }
 

lib/Target/Mips/MipsInstrInfo.cpp

@@ -298,7 +298,6 @@ unsigned MipsInstrInfo::getEquivalentCompactForm(
     case Mips::JR:
     case Mips::PseudoReturn:
     case Mips::PseudoIndirectBranch:
-    case Mips::TAILCALLREG:
       canUseShortMicroMipsCTI = true;
       break;
     }
@@ -377,18 +376,18 @@ unsigned MipsInstrInfo::getEquivalentCompactForm(
     // For MIPSR6, the instruction 'jic' can be used for these cases. Some
     // tools will accept 'jrc reg' as an alias for 'jic 0, $reg'.
     case Mips::JR:
+    case Mips::PseudoIndirectBranchR6:
     case Mips::PseudoReturn:
-    case Mips::PseudoIndirectBranch:
-    case Mips::TAILCALLREG:
+    case Mips::TAILCALLR6REG:
       if (canUseShortMicroMipsCTI)
         return Mips::JRC16_MM;
       return Mips::JIC;
     case Mips::JALRPseudo:
       return Mips::JIALC;
     case Mips::JR64:
+    case Mips::PseudoIndirectBranch64R6:
     case Mips::PseudoReturn64:
-    case Mips::PseudoIndirectBranch64:
-    case Mips::TAILCALLREG64:
+    case Mips::TAILCALL64R6REG:
       return Mips::JIC64;
     case Mips::JALR64Pseudo:
       return Mips::JIALC64;
@@ -617,6 +616,18 @@ bool MipsInstrInfo::verifyInstruction(const MachineInstr &MI,
       return verifyInsExtInstruction(MI, ErrInfo, 0, 32, 32, 64, 32, 64);
     case Mips::DEXTU:
       return verifyInsExtInstruction(MI, ErrInfo, 32, 64, 0, 32, 32, 64);
+    case Mips::TAILCALLREG:
+    case Mips::PseudoIndirectBranch:
+    case Mips::JR:
+    case Mips::JR64:
+    case Mips::JALR:
+    case Mips::JALR64:
+    case Mips::JALRPseudo:
+      if (!Subtarget.useIndirectJumpsHazard())
+        return true;
+
+      ErrInfo = "invalid instruction when using jump guards!";
+      return false;
     default:
       return true;
   }