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    • Vineet Gupta's avatar
      ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc" · 5b242828
      Vineet Gupta authored
      
      
      ARCompact TRAP_S insn used for breakpoints, commits before exception is
      taken (updating architectural PC). So ptregs->ret contains next-PC and
      not the breakpoint PC itself. This is different from other restartable
      exceptions such as TLB Miss where ptregs->ret has exact faulting PC.
      gdb needs to know exact-PC hence ARC ptrace GETREGSET provides for
      @stop_pc which returns ptregs->ret vs. EFA depending on the
      situation.
      
      However, writing stop_pc (SETREGSET request), which updates ptregs->ret
      doesn't makes sense stop_pc doesn't always correspond to that reg as
      described above.
      
      This was not an issue so far since user_regs->ret / user_regs->stop_pc
      had same value and both writing to ptregs->ret was OK, needless, but NOT
      broken, hence not observed.
      
      With gdb "jump", they diverge, and user_regs->ret updating ptregs is
      overwritten immediately with stop_pc, which this patch fixes.
      
      Reported-by: default avatarAnton Kolesov <akolesov@synopsys.com>
      Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
      5b242828