The key is the test TST_SEL_RET on line 682. It compares the RPL of the return CS selector (saved on the stack by the original CALL) against the current CPL. If RPL == CPL, the PLA returns 0x000 (continue) and LD_DESCRIPTOR finishes normally -- same-privilege return. If RPL CPL, the caller is returning to a less-privileged ring, so the PLA redirects to 0x686 (RETF_OUTER_LEV) -- the cross-privilege path that must also restore the caller's stack. If RPL
西方国家用了数百年时间建立这套制度——土地登记、公司注册、破产法、抵押制度等看似枯燥的法律基础设施，正是资本主义运行的前提。没有它们，再多资产也只是“沉睡资产”。
。Line官方版本下载是该领域的重要参考
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