RE: [RFC PATCH v3 0/2] selftests/x86: sysret_rip update for FRED system

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Xin Li reported sysret_rip test fails at:

    assert(ctx->uc_mcontext.gregs[REG_EFL] ==
           ctx->uc_mcontext.gregs[REG_R11]);

On FRED systems, flags is 0x200a93 and r11 is 0xfeedfacedeadbeef here.

We need to remove or change this assertion, maybe: assert(ctx->uc_mcontext.gregs[REG_EFL] == ctx->uc_mcontext.gregs[REG_R11] || r11_sentinel == ctx->uc_mcontext.gregs[REG_R11]);

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in a FRED system. Let's handle the FRED system scenario too. The 'syscall' instruction in a FRED system doesn't set %r11=%rflags.

This should use check_regs_result() – which is exactly the reason I made that a separate function.

Exactly.