[lldb] Fix m_hwp_regs size for ppc64le

[nikic]

Summary

The size of the m_hwp_regs array should match the default value of m_max_hwp_supported. This ensures that no out-of-bounds accesses occur, even if the array is accessed prior to a call to ReadHardwareDebugInfo().

Fixes https://github.com/llvm/llvm-project/issues/54520, see also there for additional background.

lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_ppc64le.h

lldb::addr_t hit_addr;  // Address at which last watchpoint trigger
                             // exception occurred.
     lldb::addr_t real_addr; // Address value that should cause target to stop.
     uint32_t control;       // Breakpoint/watchpoint control value.
     uint32_t refcount;      // Serves as enable/disable and reference counter.
     long slot;              // Saves the value returned from PTRACE_SETHWDEBUG.
     int mode;               // Defines if watchpoint is read/write/access.
   };
 
-  std::array<DREG, 4> m_hwp_regs;
+  std::array<DREG, 16> m_hwp_regs;
 
   // 16 is just a maximum value, query hardware for actual watchpoint count
   uint32_t m_max_hwp_supported = 16;
   uint32_t m_max_hbp_supported = 16;
   bool m_refresh_hwdebug_info = true;
 };
 
 } // namespace process_linux
 } // namespace lldb_private
 
 #endif // #ifndef lldb_NativeRegisterContextLinux_ppc64le_h
 
 #endif // defined(__powerpc64__)