Self-driving truck startup Einride raises $113M PIPE ahead of public debut
人 民 网 版 权 所 有 ，未 经 书 面 授 权 禁 止 使 用
，这一点在Line官方版本下载中也有详细论述
Author(s): Oliver A. Dicks, Solveig S. Aamlid, Alannah M. Hallas, Joerg Rottler
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