src/os_cpu/linux_x86/vm/os_linux_x86.cpp

rev 7905 : 8074552:  SafeFetch32 and SafeFetchN do not work in error handling
Summary: handle SafeFetch faults in secondary signal handlers
Contributed-by: Thomas Stuefe

*** 120,129 ****
--- 120,133 ----
  
  address os::Linux::ucontext_get_pc(ucontext_t * uc) {
    return (address)uc->uc_mcontext.gregs[REG_PC];
  }
  
+ void os::Linux::ucontext_set_pc(ucontext_t * uc, address pc) {
+   uc->uc_mcontext.gregs[REG_PC] = (intptr_t)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) {
*** 277,287 ****
    //%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
--- 281,291 ----
    //%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)) {
!       os::Linux::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
        return 1;
      }
  
  #ifndef AMD64
      // Halt if SI_KERNEL before more crashes get misdiagnosed as Java bugs
*** 512,522 ****
  
    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)) {
--- 516,526 ----
  
    if (stub != NULL) {
      // save all thread context in case we need to restore it
      if (thread != NULL) thread->set_saved_exception_pc(pc);
  
!     os::Linux::ucontext_set_pc(uc, stub);
      return true;
    }
  
    // signal-chaining
    if (os::Linux::chained_handler(sig, info, ucVoid)) {