RFR: 8266749: AArch64: Backtracing broken on PAC enabled systems [v5]

Andrew Haley aph at openjdk.java.net
Fri May 28 08:20:13 UTC 2021 

On Thu, 27 May 2021 16:19:57 GMT, Alan Hayward <github.com+4146708+a74nh at openjdk.org> wrote:

>> On PAC systems, native code may sign return addresses before saving
>> them to the stack. We must ensure we strip the any signed bits in
>> order to walk the stack.
>> Add extra asserts in places where we do not expect saved return
>> addresses to be signed.
>> 
>> On non-PAC systems, all PAC instructions are treated as NOPs.
>> 
>> On Apple, use the provided ptrauth interface instead of asm
>> as the compiler may optimise further.
>> 
>> Fedora 33 compiles all distro packages using PAC. Running the distro
>> provided OpenJDK-latest in GDB on a PAC system:
>> 
>> Thread 2 "java" hit Breakpoint 1, 0x0000fffff68d7fe4 in init_globals() ()
>>    from /usr/lib/jvm/java-16-openjdk-16.0.1.0.9-1.rolling.fc33.aarch64-fastdebug/lib/server/libjvm.so
>> (gdb) call (int)pns($sp, $fp, $pc)
>> 
>> "Executing pns"
>> Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
>> V  [libjvm.so+0xe26fe4]  init_globals()+0x10
>> C  0x006ffffff74750c4
>> C  0x0042fffff6a7f84c
>> C  0x0037fffff7fa0954
>> C  0x0030fffff7fa4540
>> C  0x0078fffff7d980c8
>> 
>> OpenJDK with this patch at the same breakpoint:
>> 
>> (gdb) call (int)pns($sp, $fp, $pc)
>> "Executing pns"
>> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
>> V  [libjvm.so+0x189c47c]  Threads::create_vm(JavaVMInitArgs*, bool*)+0x27c
>> V  [libjvm.so+0xf527a0]  JNI_CreateJavaVM+0xc0
>> C  [libjli.so+0x3860]  JavaMain+0x7c
>> C  [libjli.so+0x732c]  ThreadJavaMain+0xc
>> C  [libpthread.so.0+0x80c8]  start_thread+0xd8
>> 
>> OpenJDK with this patch breakpointed at pd_hotspot_signal_handler:
>> 
>> "Executing pns"
>> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
>> V  [libjvm.so+0x148a730]  PosixSignals::pd_hotspot_signal_handler(int, siginfo_t*, ucontext_t*, JavaThread*)+0x0
>> C  [linux-vdso.so.1+0x80c]  __kernel_rt_sigreturn+0x0
>> J 53 c1 jdk.internal.org.objectweb.asm.SymbolTable.addConstantUtf8(Ljava/lang/String;)I java.base (98 bytes) @ 0x0000ffffe159cc3c [0x0000ffffe159cb40+0x00000000000000fc]
>> j  jdk.internal.org.objectweb.asm.SymbolTable.setMajorVersionAndClassName(ILjava/lang/String;)I+12 java.base
>> j  jdk.internal.org.objectweb.asm.ClassWriter.visit(IILjava/lang/String;Ljava/lang/String;Ljava/lang/String;[Ljava/lang/String;)V+20 java.base
>> j  java.lang.invoke.InvokerBytecodeGenerator.classFilePrologue()Ljdk/internal/org/objectweb/asm/ClassWriter;+30 java.base
>> j  java.lang.invoke.InvokerBytecodeGenerator.generateCustomizedCodeBytes()[B+1 java.base
>> j  java.lang.invoke.InvokerBytecodeGenerator.generateCustomizedCode(Ljava/lang/invoke/LambdaForm;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/MemberName;+27 java.base
>> j  java.lang.invoke.LambdaForm.compileToBytecode()V+69 java.base
>> j  java.lang.invoke.DirectMethodHandle.makePreparedLambdaForm(Ljava/lang/invoke/MethodType;I)Ljava/lang/invoke/LambdaForm;+792 java.base
>> j  java.lang.invoke.DirectMethodHandle.preparedLambdaForm(Ljava/lang/invoke/MethodType;I)Ljava/lang/invoke/LambdaForm;+17 java.base
>> j  java.lang.invoke.DirectMethodHandle.preparedLambdaForm(Ljava/lang/invoke/MemberName;Z)Ljava/lang/invoke/LambdaForm;+163 java.base
>> j  java.lang.invoke.DirectMethodHandle.preparedLambdaForm(Ljava/lang/invoke/MemberName;)Ljava/lang/invoke/LambdaForm;+2 java.base
>> j  java.lang.invoke.DirectMethodHandle.make(BLjava/lang/Class;Ljava/lang/invoke/MemberName;Ljava/lang/Class;)Ljava/lang/invoke/DirectMethodHandle;+159 java.base
>> j  java.lang.invoke.MethodHandles$Lookup.getDirectMethodCommon(BLjava/lang/Class;Ljava/lang/invoke/MemberName;ZZLjava/lang/invoke/MethodHandles$Lookup;)Ljava/lang/invoke/MethodHandle;+210 java.base
>> j  java.lang.invoke.MethodHandles$Lookup.getDirectMethodNoSecurityManager(BLjava/lang/Class;Ljava/lang/invoke/MemberName;Ljava/lang/invoke/MethodHandles$Lookup;)Ljava/lang/invoke/MethodHandle;+14 java.base
>> j  java.lang.invoke.MethodHandles$Lookup.getDirectMethodForConstant(BLjava/lang/Class;Ljava/lang/invoke/MemberName;)Ljava/lang/invoke/MethodHandle;+31 java.base
>> j  java.lang.invoke.MethodHandles$Lookup.linkMethodHandleConstant(BLjava/lang/Class;Ljava/lang/String;Ljava/lang/Object;)Ljava/lang/invoke/MethodHandle;+153 java.base
>> j  java.lang.invoke.MethodHandleNatives.linkMethodHandleConstant(Ljava/lang/Class;ILjava/lang/Class;Ljava/lang/String;Ljava/lang/Object;)Ljava/lang/invoke/MethodHandle;+38 java.base
>> v  ~StubRoutines::call_stub
>> V  [libjvm.so+0xe20118]  JavaCalls::call_helper(JavaValue*, methodHandle const&, JavaCallArguments*, Thread*)+0x5c8
>> V  [libjvm.so+0xe20f64]  JavaCalls::call_static(JavaValue*, Klass*, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x284
>> V  [libjvm.so+0x184b778]  SystemDictionary::link_method_handle_constant(Klass*, int, Klass*, Symbol*, Symbol*, Thread*)+0x398
>> V  [libjvm.so+0xa1f104]  ConstantPool::resolve_constant_at_impl(constantPoolHandle const&, int, int, bool*, Thread*)+0xca0
>> V  [libjvm.so+0xa1fb6c]  ConstantPool::copy_bootstrap_arguments_at_impl(constantPoolHandle const&, int, int, int, objArrayHandle, int, bool, Handle, Thread*)+0x3fc
>> V  [libjvm.so+0x6bef6c]  BootstrapInfo::resolve_args(Thread*)+0xcbc
>> V  [libjvm.so+0x6c1538]  BootstrapInfo::resolve_bsm(Thread*)+0x1194
>> V  [libjvm.so+0x184d300]  SystemDictionary::invoke_bootstrap_method(BootstrapInfo&, Thread*)+0x30
>> V  [libjvm.so+0x120450c]  LinkResolver::resolve_dynamic_call(CallInfo&, BootstrapInfo&, Thread*)+0x2c
>> V  [libjvm.so+0x1204b1c]  LinkResolver::resolve_invokedynamic(CallInfo&, constantPoolHandle const&, int, Thread*)+0x1bc
>> V  [libjvm.so+0xe0ecc4]  InterpreterRuntime::resolve_invokedynamic(JavaThread*)+0x190
>> V  [libjvm.so+0xe123a0]  InterpreterRuntime::resolve_from_cache(JavaThread*, Bytecodes::Code)+0x160
>> j  jdk.internal.module.ModulePath.explodedPackages(Ljava/nio/file/Path;)Ljava/util/Set;+5 java.base
>> j  jdk.internal.module.ModulePath.lambda$readExplodedModule$9(Ljava/nio/file/Path;)Ljava/util/Set;+2 java.base
>> j  jdk.internal.module.ModulePath$$Lambda$2+0x000000010003bbe0.get()Ljava/lang/Object;+8 java.base
>> j  jdk.internal.module.ModuleInfo.doRead(Ljava/io/DataInput;)Ljdk/internal/module/ModuleInfo$Attributes;+762 java.base
>> j  jdk.internal.module.ModuleInfo.read(Ljava/io/InputStream;Ljava/util/function/Supplier;)Ljdk/internal/module/ModuleInfo$Attributes;+16 java.base
>> j  jdk.internal.module.ModulePath.readExplodedModule(Ljava/nio/file/Path;)Ljava/lang/module/ModuleReference;+35 java.base
>> j  jdk.internal.module.ModulePath.readModule(Ljava/nio/file/Path;Ljava/nio/file/attribute/BasicFileAttributes;)Ljava/lang/module/ModuleReference;+11 java.base
>> j  jdk.internal.module.ModulePath.scanDirectory(Ljava/nio/file/Path;)Ljava/util/Map;+69 java.base
>> j  jdk.internal.module.ModulePath.scan(Ljava/nio/file/Path;)Ljava/util/Map;+60 java.base
>> j  jdk.internal.module.ModulePath.scanNextEntry()V+23 java.base
>> j  jdk.internal.module.ModulePath.find(Ljava/lang/String;)Ljava/util/Optional;+36 java.base
>> j  jdk.internal.module.SystemModuleFinders$1.lambda$find$0(Ljava/lang/module/ModuleFinder;Ljava/lang/String;)Ljava/util/Optional;+2 java.base
>> j  jdk.internal.module.SystemModuleFinders$1$$Lambda$1+0x0000000100033b00.run()Ljava/lang/Object;+8 java.base
>> j  java.security.AccessController.executePrivileged(Ljava/security/PrivilegedAction;Ljava/security/AccessControlContext;Ljava/lang/Class;)Ljava/lang/Object;+29 java.base
>> j  java.security.AccessController.doPrivileged(Ljava/security/PrivilegedAction;)Ljava/lang/Object;+5 java.base
>> j  jdk.internal.module.SystemModuleFinders$1.find(Ljava/lang/String;)Ljava/util/Optional;+12 java.base
>> j  jdk.internal.module.ModuleBootstrap.boot2()Ljava/lang/ModuleLayer;+304 java.base
>> j  jdk.internal.module.ModuleBootstrap.boot()Ljava/lang/ModuleLayer;+64 java.base
>> j  java.lang.System.initPhase2(ZZ)I+0 java.base
>> v  ~StubRoutines::call_stub
>> V  [libjvm.so+0xe20118]  JavaCalls::call_helper(JavaValue*, methodHandle const&, JavaCallArguments*, Thread*)+0x5c8
>> V  [libjvm.so+0xe20f64]  JavaCalls::call_static(JavaValue*, Klass*, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x284
>> V  [libjvm.so+0x189c7bc]  Threads::create_vm(JavaVMInitArgs*, bool*)+0x5bc
>> V  [libjvm.so+0xf527a0]  JNI_CreateJavaVM+0xc0
>> C  [libjli.so+0x3860]  JavaMain+0x7c
>> C  [libjli.so+0x732c]  ThreadJavaMain+0xc
>> C  [libpthread.so.0+0x80c8]  start_thread+0xd8
>
> Alan Hayward has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add sender_pc_raw()
>   
>   Change-Id: I865170d4462c2ff3a67cbee992eadad4810efebf
>   CustomizedGitHooks: yes

OK, that's much better.

-------------

Marked as reviewed by aph (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4029

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