diff options
Diffstat (limited to 'bolt')
| -rw-r--r-- | bolt/include/bolt/Core/BinaryFunction.h | 4 | ||||
| -rw-r--r-- | bolt/lib/Core/BinaryFunction.cpp | 12 | ||||
| -rw-r--r-- | bolt/lib/Rewrite/LinuxKernelRewriter.cpp | 31 | ||||
| -rw-r--r-- | bolt/test/X86/linux-alt-instruction.s | 49 |
4 files changed, 88 insertions, 8 deletions
diff --git a/bolt/include/bolt/Core/BinaryFunction.h b/bolt/include/bolt/Core/BinaryFunction.h index 3c64158..1048e50 100644 --- a/bolt/include/bolt/Core/BinaryFunction.h +++ b/bolt/include/bolt/Core/BinaryFunction.h @@ -930,6 +930,10 @@ public: return const_cast<BinaryFunction *>(this)->getInstructionAtOffset(Offset); } + /// When the function is in disassembled state, return an instruction that + /// contains the \p Offset. + MCInst *getInstructionContainingOffset(uint64_t Offset); + std::optional<MCInst> disassembleInstructionAtOffset(uint64_t Offset) const; /// Return offset for the first instruction. If there is data at the diff --git a/bolt/lib/Core/BinaryFunction.cpp b/bolt/lib/Core/BinaryFunction.cpp index 5d33aa6..21c4995 100644 --- a/bolt/lib/Core/BinaryFunction.cpp +++ b/bolt/lib/Core/BinaryFunction.cpp @@ -4472,6 +4472,18 @@ MCInst *BinaryFunction::getInstructionAtOffset(uint64_t Offset) { } } +MCInst *BinaryFunction::getInstructionContainingOffset(uint64_t Offset) { + assert(CurrentState == State::Disassembled && "Wrong function state"); + + if (Offset > Size) + return nullptr; + + auto II = Instructions.upper_bound(Offset); + assert(II != Instructions.begin() && "First instruction not at offset 0"); + --II; + return &II->second; +} + void BinaryFunction::printLoopInfo(raw_ostream &OS) const { if (!opts::shouldPrint(*this)) return; diff --git a/bolt/lib/Rewrite/LinuxKernelRewriter.cpp b/bolt/lib/Rewrite/LinuxKernelRewriter.cpp index aa18e79..03b414b 100644 --- a/bolt/lib/Rewrite/LinuxKernelRewriter.cpp +++ b/bolt/lib/Rewrite/LinuxKernelRewriter.cpp @@ -295,9 +295,6 @@ public: if (Error E = processSMPLocks()) return E; - if (Error E = readORCTables()) - return E; - if (Error E = readStaticCalls()) return E; @@ -313,6 +310,11 @@ public: if (Error E = readAltInstructions()) return E; + // Some ORC entries could be linked to alternative instruction + // sequences. Hence, we read ORC after .altinstructions. + if (Error E = readORCTables()) + return E; + if (Error E = readPCIFixupTable()) return E; @@ -563,11 +565,28 @@ Error LinuxKernelRewriter::readORCTables() { if (!BF->hasInstructions()) continue; - MCInst *Inst = BF->getInstructionAtOffset(IP - BF->getAddress()); - if (!Inst) + const uint64_t Offset = IP - BF->getAddress(); + MCInst *Inst = BF->getInstructionAtOffset(Offset); + if (!Inst) { + // Check if there is an alternative instruction(s) at this IP. Multiple + // alternative instructions can take a place of a single original + // instruction and each alternative can have a separate ORC entry. + // Since ORC table is shared between all alternative sequences, there's + // a requirement that only one (out of many) sequences can have an + // instruction from the ORC table to avoid ambiguities/conflicts. + // + // For now, we have limited support for alternatives. I.e. we still print + // functions with them, but will not change the code in the output binary. + // As such, we can ignore alternative ORC entries. They will be preserved + // in the binary, but will not get printed in the instruction stream. + Inst = BF->getInstructionContainingOffset(Offset); + if (Inst || BC.MIB->hasAnnotation(*Inst, "AltInst")) + continue; + return createStringError( errc::executable_format_error, "no instruction at address 0x%" PRIx64 " in .orc_unwind_ip", IP); + } // Some addresses will have two entries associated with them. The first // one being a "weak" section terminator. Since we ignore the terminator, @@ -1440,7 +1459,7 @@ Error LinuxKernelRewriter::tryReadAltInstructions(uint32_t AltInstFeatureSize, AltBF->setIgnored(); } - if (!BF || !BC.shouldEmit(*BF)) + if (!BF || !BF->hasInstructions()) continue; if (OrgInstAddress + OrgSize > BF->getAddress() + BF->getSize()) diff --git a/bolt/test/X86/linux-alt-instruction.s b/bolt/test/X86/linux-alt-instruction.s index dc1b12a2..fe3abbf 100644 --- a/bolt/test/X86/linux-alt-instruction.s +++ b/bolt/test/X86/linux-alt-instruction.s @@ -38,7 +38,7 @@ # RUN: llvm-bolt %t.exe --print-cfg -o %t.fs4.out | FileCheck %s # CHECK: BOLT-INFO: Linux kernel binary detected -# CHECK: BOLT-INFO: parsed 2 alternative instruction entries +# CHECK: BOLT-INFO: parsed 3 alternative instruction entries .text .globl _start @@ -50,10 +50,12 @@ _start: # CHECK: rdtsc # CHECK-SAME: AltInst: 1 # CHECK-SAME: AltInst2: 2 +# CHECK-SAME: AltInst3: 3 nop # CHECK-NEXT: nop # CHECK-SAME: AltInst: 1 # CHECK-SAME: AltInst2: 2 +# CHECK-SAME: AltInst3: 3 nop nop .L1: @@ -66,6 +68,9 @@ _start: rdtsc .A1: rdtscp +.A2: + pushf + pop %rax .Ae: ## Alternative instruction info. @@ -92,11 +97,51 @@ _start: .word 0x3b # feature flags .endif .byte .L1 - .L0 # org size - .byte .Ae - .A1 # alt size + .byte .A2 - .A1 # alt size .ifdef PADLEN .byte 0 .endif + .long .L0 - . # org instruction + .long .A2 - . # alt instruction +.ifdef FEATURE_SIZE_4 + .long 0x110 # feature flags +.else + .word 0x110 # feature flags +.endif + .byte .L1 - .L0 # org size + .byte .Ae - .A2 # alt size +.ifdef PADLEN + .byte 0 +.endif + +## ORC unwind for "pushf; pop %rax" alternative sequence. + .section .orc_unwind,"a",@progbits + .align 4 + .section .orc_unwind_ip,"a",@progbits + .align 4 + + .section .orc_unwind + .2byte 8 + .2byte 0 + .2byte 0x205 + .section .orc_unwind_ip + .long _start - . + + .section .orc_unwind + .2byte 16 + .2byte 0 + .2byte 0x205 + .section .orc_unwind_ip + .long .L0 + 1 - . + + .section .orc_unwind + .2byte 8 + .2byte 0 + .2byte 0x205 + .section .orc_unwind_ip + .long .L0 + 2 - . + ## Fake Linux Kernel sections. .section __ksymtab,"a",@progbits .section __ksymtab_gpl,"a",@progbits |