/* * Copyright (c) 2023 Ian Marco Moffett and the Osmora Team. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of Hyra nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include #include #include #include #include __MODULE_NAME("spectre"); __KERNEL_META("$Hyra$: spectre.c, Ian Marco Moffett, " "Spectre mitigation support"); #if __SPECTRE_MITIGATION == 1 /* * Returns true if Indirect Branch Restricted Speculation (IBRS) * is supported. */ __naked bool __can_mitigate_spectre(void); /* * Returns EXIT_FAILURE if not supported, returns * EXIT_SUCCESS if mitigation is now active. * * This function will be NULL if spectre mitigation isn't enabled; * therefore it is wise to verify to prevent access violations and * undefined behaviour. * * This behaviour is governed by the __SPECTRE_MITIGATION define * * TODO: Try to enable others, not just IBRS */ __weak int try_spectre_mitigate(void) { uint64_t tmp; if (!__can_mitigate_spectre()) { KINFO("IBRS not supported; spectre mitigation NOT enabled\n"); return EXIT_FAILURE; } KINFO("IBRS supported; spectre mitigation enabled\n"); tmp = rdmsr(IA32_SPEC_CTL); tmp |= __BIT(0); /* IBRS */ wrmsr(IA32_SPEC_CTL, tmp); return EXIT_SUCCESS; } #endif /* __SPECTRE_MITIGATION == 1 */