jdk8-mips64-public/hotspot: src/os_cpu/linux_x86/vm/os_linux

src/os_cpu/linux_x86/vm/os_linux_x86.cpp@899ecf76b570 (annotated)

src/os_cpu/linux_x86/vm/os_linux_x86.cpp

Wed, 25 Sep 2013 13:58:13 +0200

author: dsimms
date: Wed, 25 Sep 2013 13:58:13 +0200
changeset 5781: 899ecf76b570
parent 5426: af21010d1062
child 6198: 55fb97c4c58d
permissions: -rw-r--r--

8023956: Provide a work-around to broken Linux 32 bit "Exec Shield" using CS for NX emulation (crashing with SI_KERNEL)
Summary: Execute some code at a high virtual address value, and keep mapped
Reviewed-by: coleenp, zgu

 /*
  * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 // no precompiled headers
 #include "asm/macroAssembler.hpp"
 #include "classfile/classLoader.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "code/icBuffer.hpp"
 #include "code/vtableStubs.hpp"
 #include "interpreter/interpreter.hpp"
 #include "jvm_linux.h"
 #include "memory/allocation.inline.hpp"
 #include "mutex_linux.inline.hpp"
 #include "os_share_linux.hpp"
 #include "prims/jniFastGetField.hpp"
 #include "prims/jvm.h"
 #include "prims/jvm_misc.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/extendedPC.hpp"
 #include "runtime/frame.inline.hpp"
 #include "runtime/interfaceSupport.hpp"
 #include "runtime/java.hpp"
 #include "runtime/javaCalls.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/osThread.hpp"
 #include "runtime/sharedRuntime.hpp"
 #include "runtime/stubRoutines.hpp"
 #include "runtime/thread.inline.hpp"
 #include "runtime/timer.hpp"
 #include "utilities/events.hpp"
 #include "utilities/vmError.hpp"
 // put OS-includes here
 # include <sys/types.h>
 # include <sys/mman.h>
 # include <pthread.h>
 # include <signal.h>
 # include <errno.h>
 # include <dlfcn.h>
 # include <stdlib.h>
 # include <stdio.h>
 # include <unistd.h>
 # include <sys/resource.h>
 # include <pthread.h>
 # include <sys/stat.h>
 # include <sys/time.h>
 # include <sys/utsname.h>
 # include <sys/socket.h>
 # include <sys/wait.h>
 # include <pwd.h>
 # include <poll.h>
 # include <ucontext.h>
 # include <fpu_control.h>
 #ifdef AMD64
 #define REG_SP REG_RSP
 #define REG_PC REG_RIP
 #define REG_FP REG_RBP
 #define SPELL_REG_SP "rsp"
 #define SPELL_REG_FP "rbp"
 #else
 #define REG_SP REG_UESP
 #define REG_PC REG_EIP
 #define REG_FP REG_EBP
 #define SPELL_REG_SP "esp"
 #define SPELL_REG_FP "ebp"
 #endif // AMD64
 address os::current_stack_pointer() {
 #ifdef SPARC_WORKS
   register void *esp;
   __asm__("mov %%"SPELL_REG_SP", %0":"=r"(esp));
   return (address) ((char*)esp + sizeof(long)*2);
 #elif defined(__clang__)
   intptr_t* esp;
   __asm__ __volatile__ ("mov %%"SPELL_REG_SP", %0":"=r"(esp):);
   return (address) esp;
 #else
   register void *esp __asm__ (SPELL_REG_SP);
   return (address) esp;
 #endif
 }
 char* os::non_memory_address_word() {
   // Must never look like an address returned by reserve_memory,
   // even in its subfields (as defined by the CPU immediate fields,
   // if the CPU splits constants across multiple instructions).
   return (char*) -1;
 }
 void os::initialize_thread(Thread* thr) {
 // Nothing to do.
 }
 address os::Linux::ucontext_get_pc(ucontext_t * uc) {
   return (address)uc->uc_mcontext.gregs[REG_PC];
 }
 intptr_t* os::Linux::ucontext_get_sp(ucontext_t * uc) {
   return (intptr_t*)uc->uc_mcontext.gregs[REG_SP];
 }
 intptr_t* os::Linux::ucontext_get_fp(ucontext_t * uc) {
   return (intptr_t*)uc->uc_mcontext.gregs[REG_FP];
 }
 // For Forte Analyzer AsyncGetCallTrace profiling support - thread
 // is currently interrupted by SIGPROF.
 // os::Solaris::fetch_frame_from_ucontext() tries to skip nested signal
 // frames. Currently we don't do that on Linux, so it's the same as
 // os::fetch_frame_from_context().
 ExtendedPC os::Linux::fetch_frame_from_ucontext(Thread* thread,
   ucontext_t* uc, intptr_t** ret_sp, intptr_t** ret_fp) {
   assert(thread != NULL, "just checking");
   assert(ret_sp != NULL, "just checking");
   assert(ret_fp != NULL, "just checking");
   return os::fetch_frame_from_context(uc, ret_sp, ret_fp);
 }
 ExtendedPC os::fetch_frame_from_context(void* ucVoid,
                     intptr_t** ret_sp, intptr_t** ret_fp) {
   ExtendedPC  epc;
   ucontext_t* uc = (ucontext_t*)ucVoid;
   if (uc != NULL) {
     epc = ExtendedPC(os::Linux::ucontext_get_pc(uc));
     if (ret_sp) *ret_sp = os::Linux::ucontext_get_sp(uc);
     if (ret_fp) *ret_fp = os::Linux::ucontext_get_fp(uc);
   } else {
     // construct empty ExtendedPC for return value checking
     epc = ExtendedPC(NULL);
     if (ret_sp) *ret_sp = (intptr_t *)NULL;
     if (ret_fp) *ret_fp = (intptr_t *)NULL;
   }
   return epc;
 }
 frame os::fetch_frame_from_context(void* ucVoid) {
   intptr_t* sp;
   intptr_t* fp;
   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
   return frame(sp, fp, epc.pc());
 }
 // By default, gcc always save frame pointer (%ebp/%rbp) on stack. It may get
 // turned off by -fomit-frame-pointer,
 frame os::get_sender_for_C_frame(frame* fr) {
   return frame(fr->sender_sp(), fr->link(), fr->sender_pc());
 }
 intptr_t* _get_previous_fp() {
 #ifdef SPARC_WORKS
   register intptr_t **ebp;
   __asm__("mov %%"SPELL_REG_FP", %0":"=r"(ebp));
 #elif defined(__clang__)
   intptr_t **ebp;
   __asm__ __volatile__ ("mov %%"SPELL_REG_FP", %0":"=r"(ebp):);
 #else
   register intptr_t **ebp __asm__ (SPELL_REG_FP);
 #endif
   return (intptr_t*) *ebp;   // we want what it points to.
 }
 frame os::current_frame() {
   intptr_t* fp = _get_previous_fp();
   frame myframe((intptr_t*)os::current_stack_pointer(),
                 (intptr_t*)fp,
                 CAST_FROM_FN_PTR(address, os::current_frame));
   if (os::is_first_C_frame(&myframe)) {
     // stack is not walkable
     return frame();
   } else {
     return os::get_sender_for_C_frame(&myframe);
   }
 }
 // Utility functions
 // From IA32 System Programming Guide
 enum {
   trap_page_fault = 0xE
 };
 extern "C" JNIEXPORT int
 JVM_handle_linux_signal(int sig,
                         siginfo_t* info,
                         void* ucVoid,
                         int abort_if_unrecognized) {
   ucontext_t* uc = (ucontext_t*) ucVoid;
   Thread* t = ThreadLocalStorage::get_thread_slow();
   // Must do this before SignalHandlerMark, if crash protection installed we will longjmp away
   // (no destructors can be run)
   os::WatcherThreadCrashProtection::check_crash_protection(sig, t);
   SignalHandlerMark shm(t);
   // Note: it's not uncommon that JNI code uses signal/sigset to install
   // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
   // or have a SIGILL handler when detecting CPU type). When that happens,
   // JVM_handle_linux_signal() might be invoked with junk info/ucVoid. To
   // avoid unnecessary crash when libjsig is not preloaded, try handle signals
   // that do not require siginfo/ucontext first.
   if (sig == SIGPIPE || sig == SIGXFSZ) {
     // allow chained handler to go first
     if (os::Linux::chained_handler(sig, info, ucVoid)) {
       return true;
     } else {
       if (PrintMiscellaneous && (WizardMode || Verbose)) {
         char buf[64];
         warning("Ignoring %s - see bugs 4229104 or 646499219",
                 os::exception_name(sig, buf, sizeof(buf)));
       }
       return true;
     }
   }
   JavaThread* thread = NULL;
   VMThread* vmthread = NULL;
   if (os::Linux::signal_handlers_are_installed) {
     if (t != NULL ){
       if(t->is_Java_thread()) {
         thread = (JavaThread*)t;
       }
       else if(t->is_VM_thread()){
         vmthread = (VMThread *)t;
       }
     }
   }
 /*
   NOTE: does not seem to work on linux.
   if (info == NULL || info->si_code <= 0 || info->si_code == SI_NOINFO) {
     // can't decode this kind of signal
     info = NULL;
   } else {
     assert(sig == info->si_signo, "bad siginfo");
   }
 */
   // decide if this trap can be handled by a stub
   address stub = NULL;
   address pc          = NULL;
   //%note os_trap_1
   if (info != NULL && uc != NULL && thread != NULL) {
     pc = (address) os::Linux::ucontext_get_pc(uc);
     if (StubRoutines::is_safefetch_fault(pc)) {
       uc->uc_mcontext.gregs[REG_PC] = intptr_t(StubRoutines::continuation_for_safefetch_fault(pc));
       return 1;
     }
 #ifndef AMD64
     // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
     // This can happen in any running code (currently more frequently in
     // interpreter code but has been seen in compiled code)
     if (sig == SIGSEGV && info->si_addr == 0 && info->si_code == SI_KERNEL) {
       fatal("An irrecoverable SI_KERNEL SIGSEGV has occurred due "
             "to unstable signal handling in this distribution.");
     }
 #endif // AMD64
     // Handle ALL stack overflow variations here
     if (sig == SIGSEGV) {
       address addr = (address) info->si_addr;
       // check if fault address is within thread stack
       if (addr < thread->stack_base() &&
           addr >= thread->stack_base() - thread->stack_size()) {
         // stack overflow
         if (thread->in_stack_yellow_zone(addr)) {
           thread->disable_stack_yellow_zone();
           if (thread->thread_state() == _thread_in_Java) {
             // Throw a stack overflow exception.  Guard pages will be reenabled
             // while unwinding the stack.
             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
           } else {
             // Thread was in the vm or native code.  Return and try to finish.
             return 1;
           }
         } else if (thread->in_stack_red_zone(addr)) {
           // Fatal red zone violation.  Disable the guard pages and fall through
           // to handle_unexpected_exception way down below.
           thread->disable_stack_red_zone();
           tty->print_raw_cr("An irrecoverable stack overflow has occurred.");
           // This is a likely cause, but hard to verify. Let's just print
           // it as a hint.
           tty->print_raw_cr("Please check if any of your loaded .so files has "
                             "enabled executable stack (see man page execstack(8))");
         } else {
           // Accessing stack address below sp may cause SEGV if current
           // thread has MAP_GROWSDOWN stack. This should only happen when
           // current thread was created by user code with MAP_GROWSDOWN flag
           // and then attached to VM. See notes in os_linux.cpp.
           if (thread->osthread()->expanding_stack() == 0) {
              thread->osthread()->set_expanding_stack();
              if (os::Linux::manually_expand_stack(thread, addr)) {
                thread->osthread()->clear_expanding_stack();
                return 1;
              }
              thread->osthread()->clear_expanding_stack();
           } else {
              fatal("recursive segv. expanding stack.");
           }
         }
       }
     }
     if (thread->thread_state() == _thread_in_Java) {
       // Java thread running in Java code => find exception handler if any
       // a fault inside compiled code, the interpreter, or a stub
       if (sig == SIGSEGV && os::is_poll_address((address)info->si_addr)) {
         stub = SharedRuntime::get_poll_stub(pc);
       } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
         // BugId 4454115: A read from a MappedByteBuffer can fault
         // here if the underlying file has been truncated.
         // Do not crash the VM in such a case.
         CodeBlob* cb = CodeCache::find_blob_unsafe(pc);
         nmethod* nm = (cb != NULL && cb->is_nmethod()) ? (nmethod*)cb : NULL;
         if (nm != NULL && nm->has_unsafe_access()) {
           stub = StubRoutines::handler_for_unsafe_access();
         }
       }
       else
 #ifdef AMD64
       if (sig == SIGFPE  &&
           (info->si_code == FPE_INTDIV || info->si_code == FPE_FLTDIV)) {
         stub =
           SharedRuntime::
           continuation_for_implicit_exception(thread,
                                               pc,
                                               SharedRuntime::
                                               IMPLICIT_DIVIDE_BY_ZERO);
 #else
       if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
         // HACK: si_code does not work on linux 2.2.12-20!!!
         int op = pc[0];
         if (op == 0xDB) {
           // FIST
           // TODO: The encoding of D2I in i486.ad can cause an exception
           // prior to the fist instruction if there was an invalid operation
           // pending. We want to dismiss that exception. From the win_32
           // side it also seems that if it really was the fist causing
           // the exception that we do the d2i by hand with different
           // rounding. Seems kind of weird.
           // NOTE: that we take the exception at the NEXT floating point instruction.
           assert(pc[0] == 0xDB, "not a FIST opcode");
           assert(pc[1] == 0x14, "not a FIST opcode");
           assert(pc[2] == 0x24, "not a FIST opcode");
           return true;
         } else if (op == 0xF7) {
           // IDIV
           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_DIVIDE_BY_ZERO);
         } else {
           // TODO: handle more cases if we are using other x86 instructions
           //   that can generate SIGFPE signal on linux.
           tty->print_cr("unknown opcode 0x%X with SIGFPE.", op);
           fatal("please update this code.");
         }
 #endif // AMD64
       } else if (sig == SIGSEGV &&
                !MacroAssembler::needs_explicit_null_check((intptr_t)info->si_addr)) {
           // Determination of interpreter/vtable stub/compiled code null exception
           stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
       }
     } else if (thread->thread_state() == _thread_in_vm &&
                sig == SIGBUS && /* info->si_code == BUS_OBJERR && */
                thread->doing_unsafe_access()) {
         stub = StubRoutines::handler_for_unsafe_access();
     }
     // jni_fast_Get<Primitive>Field can trap at certain pc's if a GC kicks in
     // and the heap gets shrunk before the field access.
     if ((sig == SIGSEGV) || (sig == SIGBUS)) {
       address addr = JNI_FastGetField::find_slowcase_pc(pc);
       if (addr != (address)-1) {
         stub = addr;
       }
     }
     // Check to see if we caught the safepoint code in the
     // process of write protecting the memory serialization page.
     // It write enables the page immediately after protecting it
     // so we can just return to retry the write.
     if ((sig == SIGSEGV) &&
         os::is_memory_serialize_page(thread, (address) info->si_addr)) {
       // Block current thread until the memory serialize page permission restored.
       os::block_on_serialize_page_trap();
       return true;
     }
   }
 #ifndef AMD64
   // Execution protection violation
   //
   // This should be kept as the last step in the triage.  We don't
   // have a dedicated trap number for a no-execute fault, so be
   // conservative and allow other handlers the first shot.
   //
   // Note: We don't test that info->si_code == SEGV_ACCERR here.
   // this si_code is so generic that it is almost meaningless; and
   // the si_code for this condition may change in the future.
   // Furthermore, a false-positive should be harmless.
   if (UnguardOnExecutionViolation > 0 &&
       (sig == SIGSEGV || sig == SIGBUS) &&
       uc->uc_mcontext.gregs[REG_TRAPNO] == trap_page_fault) {
     int page_size = os::vm_page_size();
     address addr = (address) info->si_addr;
     address pc = os::Linux::ucontext_get_pc(uc);
     // Make sure the pc and the faulting address are sane.
     //
     // If an instruction spans a page boundary, and the page containing
     // the beginning of the instruction is executable but the following
     // page is not, the pc and the faulting address might be slightly
     // different - we still want to unguard the 2nd page in this case.
     //
     // 15 bytes seems to be a (very) safe value for max instruction size.
     bool pc_is_near_addr =
       (pointer_delta((void*) addr, (void*) pc, sizeof(char)) < 15);
     bool instr_spans_page_boundary =
       (align_size_down((intptr_t) pc ^ (intptr_t) addr,
                        (intptr_t) page_size) > 0);
     if (pc == addr || (pc_is_near_addr && instr_spans_page_boundary)) {
       static volatile address last_addr =
         (address) os::non_memory_address_word();
       // In conservative mode, don't unguard unless the address is in the VM
       if (addr != last_addr &&
           (UnguardOnExecutionViolation > 1 || os::address_is_in_vm(addr))) {
         // Set memory to RWX and retry
         address page_start =
           (address) align_size_down((intptr_t) addr, (intptr_t) page_size);
         bool res = os::protect_memory((char*) page_start, page_size,
                                       os::MEM_PROT_RWX);
         if (PrintMiscellaneous && Verbose) {
           char buf[256];
           jio_snprintf(buf, sizeof(buf), "Execution protection violation "
                        "at " INTPTR_FORMAT
                        ", unguarding " INTPTR_FORMAT ": %s, errno=%d", addr,
                        page_start, (res ? "success" : "failed"), errno);
           tty->print_raw_cr(buf);
         }
         stub = pc;
         // Set last_addr so if we fault again at the same address, we don't end
         // up in an endless loop.
         //
         // There are two potential complications here.  Two threads trapping at
         // the same address at the same time could cause one of the threads to
         // think it already unguarded, and abort the VM.  Likely very rare.
         //
         // The other race involves two threads alternately trapping at
         // different addresses and failing to unguard the page, resulting in
         // an endless loop.  This condition is probably even more unlikely than
         // the first.
         //
         // Although both cases could be avoided by using locks or thread local
         // last_addr, these solutions are unnecessary complication: this
         // handler is a best-effort safety net, not a complete solution.  It is
         // disabled by default and should only be used as a workaround in case
         // we missed any no-execute-unsafe VM code.
         last_addr = addr;
       }
     }
   }
 #endif // !AMD64
   if (stub != NULL) {
     // save all thread context in case we need to restore it
     if (thread != NULL) thread->set_saved_exception_pc(pc);
     uc->uc_mcontext.gregs[REG_PC] = (greg_t)stub;
     return true;
   }
   // signal-chaining
   if (os::Linux::chained_handler(sig, info, ucVoid)) {
      return true;
   }
   if (!abort_if_unrecognized) {
     // caller wants another chance, so give it to him
     return false;
   }
   if (pc == NULL && uc != NULL) {
     pc = os::Linux::ucontext_get_pc(uc);
   }
   // unmask current signal
   sigset_t newset;
   sigemptyset(&newset);
   sigaddset(&newset, sig);
   sigprocmask(SIG_UNBLOCK, &newset, NULL);
   VMError err(t, sig, pc, info, ucVoid);
   err.report_and_die();
   ShouldNotReachHere();
 }
 void os::Linux::init_thread_fpu_state(void) {
 #ifndef AMD64
   // set fpu to 53 bit precision
   set_fpu_control_word(0x27f);
 #endif // !AMD64
 }
 int os::Linux::get_fpu_control_word(void) {
 #ifdef AMD64
   return 0;
 #else
   int fpu_control;
   _FPU_GETCW(fpu_control);
   return fpu_control & 0xffff;
 #endif // AMD64
 }
 void os::Linux::set_fpu_control_word(int fpu_control) {
 #ifndef AMD64
   _FPU_SETCW(fpu_control);
 #endif // !AMD64
 }
 // Check that the linux kernel version is 2.4 or higher since earlier
 // versions do not support SSE without patches.
 bool os::supports_sse() {
 #ifdef AMD64
   return true;
 #else
   struct utsname uts;
   if( uname(&uts) != 0 ) return false; // uname fails?
   char *minor_string;
   int major = strtol(uts.release,&minor_string,10);
   int minor = strtol(minor_string+1,NULL,10);
   bool result = (major > 2 || (major==2 && minor >= 4));
 #ifndef PRODUCT
   if (PrintMiscellaneous && Verbose) {
     tty->print("OS version is %d.%d, which %s support SSE/SSE2\n",
                major,minor, result ? "DOES" : "does NOT");
   }
 #endif
   return result;
 #endif // AMD64
 }
 bool os::is_allocatable(size_t bytes) {
 #ifdef AMD64
   // unused on amd64?
   return true;
 #else
   if (bytes < 2 * G) {
     return true;
   }
   char* addr = reserve_memory(bytes, NULL);
   if (addr != NULL) {
     release_memory(addr, bytes);
   }
   return addr != NULL;
 #endif // AMD64
 }
 ////////////////////////////////////////////////////////////////////////////////
 // thread stack
 #ifdef AMD64
 size_t os::Linux::min_stack_allowed  = 64 * K;
 // amd64: pthread on amd64 is always in floating stack mode
 bool os::Linux::supports_variable_stack_size() {  return true; }
 #else
 size_t os::Linux::min_stack_allowed  =  (48 DEBUG_ONLY(+4))*K;
 #ifdef __GNUC__
 #define GET_GS() ({int gs; __asm__ volatile("movw %%gs, %w0":"=q"(gs)); gs&0xffff;})
 #endif
 // Test if pthread library can support variable thread stack size. LinuxThreads
 // in fixed stack mode allocates 2M fixed slot for each thread. LinuxThreads
 // in floating stack mode and NPTL support variable stack size.
 bool os::Linux::supports_variable_stack_size() {
   if (os::Linux::is_NPTL()) {
      // NPTL, yes
      return true;
   } else {
     // Note: We can't control default stack size when creating a thread.
     // If we use non-default stack size (pthread_attr_setstacksize), both
     // floating stack and non-floating stack LinuxThreads will return the
     // same value. This makes it impossible to implement this function by
     // detecting thread stack size directly.
     //
     // An alternative approach is to check %gs. Fixed-stack LinuxThreads
     // do not use %gs, so its value is 0. Floating-stack LinuxThreads use
     // %gs (either as LDT selector or GDT selector, depending on kernel)
     // to access thread specific data.
     //
     // Note that %gs is a reserved glibc register since early 2001, so
     // applications are not allowed to change its value (Ulrich Drepper from
     // Redhat confirmed that all known offenders have been modified to use
     // either %fs or TSD). In the worst case scenario, when VM is embedded in
     // a native application that plays with %gs, we might see non-zero %gs
     // even LinuxThreads is running in fixed stack mode. As the result, we'll
     // return true and skip _thread_safety_check(), so we may not be able to
     // detect stack-heap collisions. But otherwise it's harmless.
     //
 #ifdef __GNUC__
     return (GET_GS() != 0);
 #else
     return false;
 #endif
   }
 }
 #endif // AMD64
 // return default stack size for thr_type
 size_t os::Linux::default_stack_size(os::ThreadType thr_type) {
   // default stack size (compiler thread needs larger stack)
 #ifdef AMD64
   size_t s = (thr_type == os::compiler_thread ? 4 * M : 1 * M);
 #else
   size_t s = (thr_type == os::compiler_thread ? 2 * M : 512 * K);
 #endif // AMD64
   return s;
 }
 size_t os::Linux::default_guard_size(os::ThreadType thr_type) {
   // Creating guard page is very expensive. Java thread has HotSpot
   // guard page, only enable glibc guard page for non-Java threads.
   return (thr_type == java_thread ? 0 : page_size());
 }
 // Java thread:
 //
 //   Low memory addresses
 //    +------------------------+
 //    |                        |\  JavaThread created by VM does not have glibc
 //    |    glibc guard page    | - guard, attached Java thread usually has
 //    |                        |/  1 page glibc guard.
 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
 //    |                        |\
 //    |  HotSpot Guard Pages   | - red and yellow pages
 //    |                        |/
 //    +------------------------+ JavaThread::stack_yellow_zone_base()
 //    |                        |\
 //    |      Normal Stack      | -
 //    |                        |/
 // P2 +------------------------+ Thread::stack_base()
 //
 // Non-Java thread:
 //
 //   Low memory addresses
 //    +------------------------+
 //    |                        |\
 //    |  glibc guard page      | - usually 1 page
 //    |                        |/
 // P1 +------------------------+ Thread::stack_base() - Thread::stack_size()
 //    |                        |\
 //    |      Normal Stack      | -
 //    |                        |/
 // P2 +------------------------+ Thread::stack_base()
 //
 // ** P1 (aka bottom) and size ( P2 = P1 - size) are the address and stack size returned from
 //    pthread_attr_getstack()
 static void current_stack_region(address * bottom, size_t * size) {
   if (os::Linux::is_initial_thread()) {
      // initial thread needs special handling because pthread_getattr_np()
      // may return bogus value.
      *bottom = os::Linux::initial_thread_stack_bottom();
      *size   = os::Linux::initial_thread_stack_size();
   } else {
      pthread_attr_t attr;
      int rslt = pthread_getattr_np(pthread_self(), &attr);
      // JVM needs to know exact stack location, abort if it fails
      if (rslt != 0) {
        if (rslt == ENOMEM) {
          vm_exit_out_of_memory(0, OOM_MMAP_ERROR, "pthread_getattr_np");
        } else {
          fatal(err_msg("pthread_getattr_np failed with errno = %d", rslt));
        }
      }
      if (pthread_attr_getstack(&attr, (void **)bottom, size) != 0) {
          fatal("Can not locate current stack attributes!");
      }
      pthread_attr_destroy(&attr);
   }
   assert(os::current_stack_pointer() >= *bottom &&
          os::current_stack_pointer() < *bottom + *size, "just checking");
 }
 address os::current_stack_base() {
   address bottom;
   size_t size;
   current_stack_region(&bottom, &size);
   return (bottom + size);
 }
 size_t os::current_stack_size() {
   // stack size includes normal stack and HotSpot guard pages
   address bottom;
   size_t size;
   current_stack_region(&bottom, &size);
   return size;
 }
 /////////////////////////////////////////////////////////////////////////////
 // helper functions for fatal error handler
 void os::print_context(outputStream *st, void *context) {
   if (context == NULL) return;
   ucontext_t *uc = (ucontext_t*)context;
   st->print_cr("Registers:");
 #ifdef AMD64
   st->print(  "RAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RAX]);
   st->print(", RBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBX]);
   st->print(", RCX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RCX]);
   st->print(", RDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDX]);
   st->cr();
   st->print(  "RSP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSP]);
   st->print(", RBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RBP]);
   st->print(", RSI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RSI]);
   st->print(", RDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RDI]);
   st->cr();
   st->print(  "R8 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R8]);
   st->print(", R9 =" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R9]);
   st->print(", R10=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R10]);
   st->print(", R11=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R11]);
   st->cr();
   st->print(  "R12=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R12]);
   st->print(", R13=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R13]);
   st->print(", R14=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R14]);
   st->print(", R15=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_R15]);
   st->cr();
   st->print(  "RIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_RIP]);
   st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
   st->print(", CSGSFS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_CSGSFS]);
   st->print(", ERR=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ERR]);
   st->cr();
   st->print("  TRAPNO=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_TRAPNO]);
 #else
   st->print(  "EAX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EAX]);
   st->print(", EBX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBX]);
   st->print(", ECX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ECX]);
   st->print(", EDX=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDX]);
   st->cr();
   st->print(  "ESP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_UESP]);
   st->print(", EBP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EBP]);
   st->print(", ESI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_ESI]);
   st->print(", EDI=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EDI]);
   st->cr();
   st->print(  "EIP=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EIP]);
   st->print(", EFLAGS=" INTPTR_FORMAT, uc->uc_mcontext.gregs[REG_EFL]);
   st->print(", CR2=" INTPTR_FORMAT, uc->uc_mcontext.cr2);
 #endif // AMD64
   st->cr();
   st->cr();
   intptr_t *sp = (intptr_t *)os::Linux::ucontext_get_sp(uc);
   st->print_cr("Top of Stack: (sp=" PTR_FORMAT ")", sp);
   print_hex_dump(st, (address)sp, (address)(sp + 8*sizeof(intptr_t)), sizeof(intptr_t));
   st->cr();
   // Note: it may be unsafe to inspect memory near pc. For example, pc may
   // point to garbage if entry point in an nmethod is corrupted. Leave
   // this at the end, and hope for the best.
   address pc = os::Linux::ucontext_get_pc(uc);
   st->print_cr("Instructions: (pc=" PTR_FORMAT ")", pc);
   print_hex_dump(st, pc - 32, pc + 32, sizeof(char));
 }
 void os::print_register_info(outputStream *st, void *context) {
   if (context == NULL) return;
   ucontext_t *uc = (ucontext_t*)context;
   st->print_cr("Register to memory mapping:");
   st->cr();
   // this is horrendously verbose but the layout of the registers in the
   // context does not match how we defined our abstract Register set, so
   // we can't just iterate through the gregs area
   // this is only for the "general purpose" registers
 #ifdef AMD64
   st->print("RAX="); print_location(st, uc->uc_mcontext.gregs[REG_RAX]);
   st->print("RBX="); print_location(st, uc->uc_mcontext.gregs[REG_RBX]);
   st->print("RCX="); print_location(st, uc->uc_mcontext.gregs[REG_RCX]);
   st->print("RDX="); print_location(st, uc->uc_mcontext.gregs[REG_RDX]);
   st->print("RSP="); print_location(st, uc->uc_mcontext.gregs[REG_RSP]);
   st->print("RBP="); print_location(st, uc->uc_mcontext.gregs[REG_RBP]);
   st->print("RSI="); print_location(st, uc->uc_mcontext.gregs[REG_RSI]);
   st->print("RDI="); print_location(st, uc->uc_mcontext.gregs[REG_RDI]);
   st->print("R8 ="); print_location(st, uc->uc_mcontext.gregs[REG_R8]);
   st->print("R9 ="); print_location(st, uc->uc_mcontext.gregs[REG_R9]);
   st->print("R10="); print_location(st, uc->uc_mcontext.gregs[REG_R10]);
   st->print("R11="); print_location(st, uc->uc_mcontext.gregs[REG_R11]);
   st->print("R12="); print_location(st, uc->uc_mcontext.gregs[REG_R12]);
   st->print("R13="); print_location(st, uc->uc_mcontext.gregs[REG_R13]);
   st->print("R14="); print_location(st, uc->uc_mcontext.gregs[REG_R14]);
   st->print("R15="); print_location(st, uc->uc_mcontext.gregs[REG_R15]);
 #else
   st->print("EAX="); print_location(st, uc->uc_mcontext.gregs[REG_EAX]);
   st->print("EBX="); print_location(st, uc->uc_mcontext.gregs[REG_EBX]);
   st->print("ECX="); print_location(st, uc->uc_mcontext.gregs[REG_ECX]);
   st->print("EDX="); print_location(st, uc->uc_mcontext.gregs[REG_EDX]);
   st->print("ESP="); print_location(st, uc->uc_mcontext.gregs[REG_ESP]);
   st->print("EBP="); print_location(st, uc->uc_mcontext.gregs[REG_EBP]);
   st->print("ESI="); print_location(st, uc->uc_mcontext.gregs[REG_ESI]);
   st->print("EDI="); print_location(st, uc->uc_mcontext.gregs[REG_EDI]);
 #endif // AMD64
   st->cr();
 }
 void os::setup_fpu() {
 #ifndef AMD64
   address fpu_cntrl = StubRoutines::addr_fpu_cntrl_wrd_std();
   __asm__ volatile (  "fldcw (%0)" :
                       : "r" (fpu_cntrl) : "memory");
 #endif // !AMD64
 }
 #ifndef PRODUCT
 void os::verify_stack_alignment() {
 #ifdef AMD64
   assert(((intptr_t)os::current_stack_pointer() & (StackAlignmentInBytes-1)) == 0, "incorrect stack alignment");
 #endif
 }
 #endif
 /*
  * IA32 only: execute code at a high address in case buggy NX emulation is present. I.e. avoid CS limit
  * updates (JDK-8023956).
  */
 void os::workaround_expand_exec_shield_cs_limit() {
 #if defined(IA32)
   size_t page_size = os::vm_page_size();
   /*
    * Take the highest VA the OS will give us and exec
    *
    * Although using -(pagesz) as mmap hint works on newer kernel as you would
    * think, older variants affected by this work-around don't (search forward only).
    *
    * On the affected distributions, we understand the memory layout to be:
    *
    *   TASK_LIMIT= 3G, main stack base close to TASK_LIMT.
    *
    * A few pages south main stack will do it.
    *
    * If we are embedded in an app other than launcher (initial != main stack),
    * we don't have much control or understanding of the address space, just let it slide.
    */
   char* hint = (char*) (Linux::initial_thread_stack_bottom() -
                         ((StackYellowPages + StackRedPages + 1) * page_size));
   char* codebuf = os::reserve_memory(page_size, hint);
   if ( (codebuf == NULL) || (!os::commit_memory(codebuf, page_size, true)) ) {
     return; // No matter, we tried, best effort.
   }
   if (PrintMiscellaneous && (Verbose || WizardMode)) {
      tty->print_cr("[CS limit NX emulation work-around, exec code at: %p]", codebuf);
   }
   // Some code to exec: the 'ret' instruction
   codebuf[0] = 0xC3;
   // Call the code in the codebuf
   __asm__ volatile("call *%0" : : "r"(codebuf));
   // keep the page mapped so CS limit isn't reduced.
 #endif
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/os_cpu/linux_x86/vm/os_linux_x86.cpp@899ecf76b570 (annotated)

src/os_cpu/linux_x86/vm/os_linux_x86.cpp