From c0a0aecd54098269a4b50a1f07517ee24b007124 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 20 Jul 2018 10:53:06 +0100 Subject: [PATCH] arm64: ssbd: Restore mitigation status on CPU resume BugLink: https://bugs.launchpad.net/bugs/1787993 CVE-2018-3639 (arm64) commit 647d0519b53f440a55df163de21c52a8205431cc upstream. On a system where firmware can dynamically change the state of the mitigation, the CPU will always come up with the mitigation enabled, including when coming back from suspend. If the user has requested "no mitigation" via a command line option, let's enforce it by calling into the firmware again to disable it. Similarily, for a resume from hibernate, the mitigation could have been disabled by the boot kernel. Let's ensure that it is set back on in that case. Acked-by: Will Deacon Reviewed-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman (cherry picked from commit c5c89bb4deb8e1f0eed0968f37dfa936f6b5e4c1 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git / linux-4.14.y) Signed-off-by: Paolo Pisati Acked-by: Stefan Bader Acked-by: Kleber Sacilotto de Souza Signed-off-by: Kleber Sacilotto de Souza --- arch/arm64/include/asm/cpufeature.h | 6 ++++++ arch/arm64/kernel/cpu_errata.c | 2 +- arch/arm64/kernel/hibernate.c | 11 +++++++++++ arch/arm64/kernel/suspend.c | 8 ++++++++ 4 files changed, 26 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 9a6fa29062c2..3666cdf28164 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -323,6 +323,12 @@ static inline int arm64_get_ssbd_state(void) #endif } +#ifdef CONFIG_ARM64_SSBD +void arm64_set_ssbd_mitigation(bool state); +#else +static inline void arm64_set_ssbd_mitigation(bool state) {} +#endif + #endif /* __ASSEMBLY__ */ #endif diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 012dab9d9a01..eccdb28b4a39 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -299,7 +299,7 @@ void __init arm64_enable_wa2_handling(struct alt_instr *alt, *updptr = cpu_to_le32(aarch64_insn_gen_nop()); } -static void arm64_set_ssbd_mitigation(bool state) +void arm64_set_ssbd_mitigation(bool state) { switch (psci_ops.conduit) { case PSCI_CONDUIT_HVC: diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c index 3009b8b80f08..f76c02f28ae5 100644 --- a/arch/arm64/kernel/hibernate.c +++ b/arch/arm64/kernel/hibernate.c @@ -314,6 +314,17 @@ int swsusp_arch_suspend(void) sleep_cpu = -EINVAL; __cpu_suspend_exit(); + + /* + * Just in case the boot kernel did turn the SSBD + * mitigation off behind our back, let's set the state + * to what we expect it to be. + */ + switch (arm64_get_ssbd_state()) { + case ARM64_SSBD_FORCE_ENABLE: + case ARM64_SSBD_KERNEL: + arm64_set_ssbd_mitigation(true); + } } local_daif_restore(flags); diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c index a307b9e13392..70c283368b64 100644 --- a/arch/arm64/kernel/suspend.c +++ b/arch/arm64/kernel/suspend.c @@ -62,6 +62,14 @@ void notrace __cpu_suspend_exit(void) */ if (hw_breakpoint_restore) hw_breakpoint_restore(cpu); + + /* + * On resume, firmware implementing dynamic mitigation will + * have turned the mitigation on. If the user has forcefully + * disabled it, make sure their wishes are obeyed. + */ + if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) + arm64_set_ssbd_mitigation(false); } /* -- 2.39.2