From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [PATCH v8 02/14] x86/cet/ibt: User-mode indirect branch tracking support Date: Tue, 13 Aug 2019 13:53:47 -0700 Message-ID: <20190813205359.12196-3-yu-cheng.yu@intel.com> References: <20190813205359.12196-1-yu-cheng.yu@intel.com> Return-path: In-Reply-To: <20190813205359.12196-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit Cc: Yu-cheng Yu List-Id: linux-api@vger.kernel.org Add user-mode indirect branch tracking enabling/disabling and supporting routines. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/cet.h | 6 ++++ arch/x86/include/asm/disabled-features.h | 8 ++++- arch/x86/kernel/cet.c | 36 +++++++++++++++++++ arch/x86/kernel/cpu/common.c | 17 +++++++++ .../arch/x86/include/asm/disabled-features.h | 8 ++++- 5 files changed, 73 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h index 2df357dffd24..2561efe081ad 100644 --- a/arch/x86/include/asm/cet.h +++ b/arch/x86/include/asm/cet.h @@ -16,6 +16,8 @@ struct cet_status { unsigned long shstk_size; unsigned int locked:1; unsigned int shstk_enabled:1; + unsigned int ibt_enabled:1; + unsigned int ibt_bitmap_used:1; }; #ifdef CONFIG_X86_INTEL_CET @@ -27,6 +29,8 @@ void cet_disable_shstk(void); void cet_disable_free_shstk(struct task_struct *p); int cet_restore_signal(bool ia32, struct sc_ext *sc); int cet_setup_signal(bool ia32, unsigned long rstor, struct sc_ext *sc); +int cet_setup_ibt(void); +void cet_disable_ibt(void); #else static inline int prctl_cet(int option, unsigned long arg2) { return -EINVAL; } static inline int cet_setup_shstk(void) { return -EINVAL; } @@ -37,6 +41,8 @@ static inline void cet_disable_free_shstk(struct task_struct *p) {} static inline int cet_restore_signal(bool ia32, struct sc_ext *sc) { return -EINVAL; } static inline int cet_setup_signal(bool ia32, unsigned long rstor, struct sc_ext *sc) { return -EINVAL; } +static inline int cet_setup_ibt(void) { return -EINVAL; } +static inline void cet_disable_ibt(void) {} #endif #define cpu_x86_cet_enabled() \ diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h index 06323ebed643..fc7d3d5a1bf4 100644 --- a/arch/x86/include/asm/disabled-features.h +++ b/arch/x86/include/asm/disabled-features.h @@ -68,6 +68,12 @@ #define DISABLE_SHSTK (1<<(X86_FEATURE_SHSTK & 31)) #endif +#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER +#define DISABLE_IBT 0 +#else +#define DISABLE_IBT (1<<(X86_FEATURE_IBT & 31)) +#endif + /* * Make sure to add features to the correct mask */ @@ -89,7 +95,7 @@ #define DISABLED_MASK15 0 #define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP|DISABLE_SHSTK) #define DISABLED_MASK17 0 -#define DISABLED_MASK18 0 +#define DISABLED_MASK18 (DISABLE_IBT) #define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 19) #endif /* _ASM_X86_DISABLED_FEATURES_H */ diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c index e4e20d6ab07b..505a69f476e1 100644 --- a/arch/x86/kernel/cet.c +++ b/arch/x86/kernel/cet.c @@ -13,6 +13,8 @@ #include #include #include +#include +#include #include #include #include @@ -325,3 +327,37 @@ int cet_setup_signal(bool ia32, unsigned long rstor_addr, struct sc_ext *sc_ext) modify_fpu_regs_end(); return 0; } + +int cet_setup_ibt(void) +{ + u64 r; + + if (!cpu_feature_enabled(X86_FEATURE_IBT)) + return -EOPNOTSUPP; + + modify_fpu_regs_begin(); + rdmsrl(MSR_IA32_U_CET, r); + r |= (MSR_IA32_CET_ENDBR_EN | MSR_IA32_CET_NO_TRACK_EN); + wrmsrl(MSR_IA32_U_CET, r); + modify_fpu_regs_end(); + + current->thread.cet.ibt_enabled = 1; + return 0; +} + +void cet_disable_ibt(void) +{ + u64 r; + + if (!cpu_feature_enabled(X86_FEATURE_IBT)) + return; + + modify_fpu_regs_begin(); + rdmsrl(MSR_IA32_U_CET, r); + r &= ~(MSR_IA32_CET_ENDBR_EN | MSR_IA32_CET_LEG_IW_EN | + MSR_IA32_CET_NO_TRACK_EN | MSR_IA32_CET_BITMAP_MASK); + wrmsrl(MSR_IA32_U_CET, r); + modify_fpu_regs_end(); + + current->thread.cet.ibt_enabled = 0; +} diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index d3addbd3f4d4..092979715d16 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -512,6 +512,23 @@ static __init int setup_disable_shstk(char *s) __setup("no_cet_shstk", setup_disable_shstk); #endif +#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER +static __init int setup_disable_ibt(char *s) +{ + /* require an exact match without trailing characters */ + if (s[0] != '\0') + return 0; + + if (!boot_cpu_has(X86_FEATURE_IBT)) + return 1; + + setup_clear_cpu_cap(X86_FEATURE_IBT); + pr_info("x86: 'no_cet_ibt' specified, disabling Branch Tracking\n"); + return 1; +} +__setup("no_cet_ibt", setup_disable_ibt); +#endif + /* * Some CPU features depend on higher CPUID levels, which may not always * be available due to CPUID level capping or broken virtualization diff --git a/tools/arch/x86/include/asm/disabled-features.h b/tools/arch/x86/include/asm/disabled-features.h index 06323ebed643..fc7d3d5a1bf4 100644 --- a/tools/arch/x86/include/asm/disabled-features.h +++ b/tools/arch/x86/include/asm/disabled-features.h @@ -68,6 +68,12 @@ #define DISABLE_SHSTK (1<<(X86_FEATURE_SHSTK & 31)) #endif +#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER +#define DISABLE_IBT 0 +#else +#define DISABLE_IBT (1<<(X86_FEATURE_IBT & 31)) +#endif + /* * Make sure to add features to the correct mask */ @@ -89,7 +95,7 @@ #define DISABLED_MASK15 0 #define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP|DISABLE_SHSTK) #define DISABLED_MASK17 0 -#define DISABLED_MASK18 0 +#define DISABLED_MASK18 (DISABLE_IBT) #define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 19) #endif /* _ASM_X86_DISABLED_FEATURES_H */ -- 2.17.1