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Tue, 15 Sep 2026 03:22:32 +0000 Message-ID: Date: Mon, 14 Sep 2026 20:22:30 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 7/7] selftests/x86: Add a userspace test for LASS enforcement Content-Language: en-US To: Binbin Wu CC: , , Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Shuah Khan , Peter Zijlstra , "Chang S . 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>> + >> + if (!is_lass_active()) >> + ksft_exit_skip("LASS is not enabled\n"); >> + >> + ksft_set_plan(TOTAL_TESTS); >> + >> + sethandler(SIGSEGV, fault_handler, 0); >> + /* Only to report a #SS; LASS shouldn't cause one here. */ >> + sethandler(SIGBUS, fault_handler, 0); > > So the purpose is that if there is an unexpected #SS, fails the test instead of > killing it, right? > Sorry, I missed this question earlier. Yes, the goal is to catch the SIGBUS and report a failure. I think it isn't worth keeping in the first place. My initial plan was to trigger an LASS violation #SS. But, it turned out to be much harder to trigger. I'll probably remove it because it creates a distraction. >> + >> + ksft_print_msg("Accessing the kernel address 0x%lx from userspace\n", >> + (unsigned long)KERNEL_ADDR); >> + test_kernel_read(); >> + test_kernel_write(); >> + test_kernel_fetch(); >> + >> + clearhandler(SIGBUS); >> + clearhandler(SIGSEGV); >> + >> + ksft_finished(); >> +} >