[Qemu-devel] [Bug 1757363] Re: infinite loop due to improper deal with "eret" on mips32

[philmd]

** Tags added: mips

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https://bugs.launchpad.net/bugs/1757363

Title:
  infinite loop due to improper deal with "eret" on mips32

Status in QEMU:
  New

Bug description:
  1.qemu 2.9.1 release on the official web build with tcg
  2.cmd: qemu-system-mips -kernel kernelfile
  3. host: ubuntu 16.04.1 with linux kernel 4.6.2 x86_64
     guest: mips bigendian 32bit (tplink firmware)

  
  detail:

  static inline void exception_return(CPUMIPSState *env)
  {
      debug_pre_eret(env);
      if (env->CP0_Status & (1 << CP0St_ERL)) {
          set_pc(env, env->CP0_ErrorEPC);
          env->CP0_Status &= ~(1 << CP0St_ERL);
      } else {
          set_pc(env, env->CP0_EPC);
          env->CP0_Status &= ~(1 << CP0St_EXL);====================> ISSUE????
      }
      compute_hflags(env);
      debug_post_eret(env);
  }

  void helper_eret(CPUMIPSState *env)
  {
      exception_return(env);
      env->lladdr = 1;
  }

  
  In the Issue Line, there is no check CP0_Status whether int is disabled 
(should not enter int routine),
  that result in the cpu can not jump out the int routine.

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