diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0027-x86-Introduce-barrier_nospec.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0027-x86-Introduce-barrier_nospec.patch | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0027-x86-Introduce-barrier_nospec.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0027-x86-Introduce-barrier_nospec.patch new file mode 100644 index 00000000..9b3ea121 --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0027-x86-Introduce-barrier_nospec.patch @@ -0,0 +1,70 @@ +From 13c25ff312ecc09941828ec112a11c40debbfef1 Mon Sep 17 00:00:00 2001 +From: Dan Williams <dan.j.williams@intel.com> +Date: Mon, 29 Jan 2018 17:02:33 -0800 +Subject: [PATCH 27/42] x86: Introduce barrier_nospec + +(cherry picked from commit b3d7ad85b80bbc404635dca80f5b129f6242bc7a) + +Rename the open coded form of this instruction sequence from +rdtsc_ordered() into a generic barrier primitive, barrier_nospec(). + +One of the mitigations for Spectre variant1 vulnerabilities is to fence +speculative execution after successfully validating a bounds check. I.e. +force the result of a bounds check to resolve in the instruction pipeline +to ensure speculative execution honors that result before potentially +operating on out-of-bounds data. + +No functional changes. + +Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> +Suggested-by: Andi Kleen <ak@linux.intel.com> +Suggested-by: Ingo Molnar <mingo@redhat.com> +Signed-off-by: Dan Williams <dan.j.williams@intel.com> +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +Cc: linux-arch@vger.kernel.org +Cc: Tom Lendacky <thomas.lendacky@amd.com> +Cc: Kees Cook <keescook@chromium.org> +Cc: kernel-hardening@lists.openwall.com +Cc: gregkh@linuxfoundation.org +Cc: Al Viro <viro@zeniv.linux.org.uk> +Cc: alan@linux.intel.com +Link: https://lkml.kernel.org/r/151727415361.33451.9049453007262764675.stgit@dwillia2-desk3.amr.corp.intel.com +Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + arch/x86/include/asm/barrier.h | 4 ++++ + arch/x86/include/asm/msr.h | 3 +-- + 2 files changed, 5 insertions(+), 2 deletions(-) + +diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h +index ca22173..8575903 100644 +--- a/arch/x86/include/asm/barrier.h ++++ b/arch/x86/include/asm/barrier.h +@@ -47,6 +47,10 @@ static inline unsigned long array_index_mask_nospec(unsigned long index, + /* Override the default implementation from linux/nospec.h. */ + #define array_index_mask_nospec array_index_mask_nospec + ++/* Prevent speculative execution past this barrier. */ ++#define barrier_nospec() alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, \ ++ "lfence", X86_FEATURE_LFENCE_RDTSC) ++ + #ifdef CONFIG_X86_PPRO_FENCE + #define dma_rmb() rmb() + #else +diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h +index b5fee97..ed35b91 100644 +--- a/arch/x86/include/asm/msr.h ++++ b/arch/x86/include/asm/msr.h +@@ -188,8 +188,7 @@ static __always_inline unsigned long long rdtsc_ordered(void) + * that some other imaginary CPU is updating continuously with a + * time stamp. + */ +- alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, +- "lfence", X86_FEATURE_LFENCE_RDTSC); ++ barrier_nospec(); + return rdtsc(); + } + +-- +2.7.4 + |