This is a note to let you know that I've just added the patch titled
x86: Introduce barrier_nospec
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-introduce-barrier_nospec.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Feb 8 03:32:24 CET 2018
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Date: Mon, 29 Jan 2018 17:02:33 -0800
Subject: x86: Introduce barrier_nospec
From: Dan Williams <dan.j.williams@xxxxxxxxx>
(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@xxxxxxxxxxxxxxxxxxxx>
Suggested-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Suggested-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: kernel-hardening@xxxxxxxxxxxxxxxxxx
Cc: gregkh@xxxxxxxxxxxxxxxxxxx
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: alan@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/151727415361.33451.9049453007262764675.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/barrier.h | 4 ++++
arch/x86/include/asm/msr.h | 3 +--
2 files changed, 5 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -47,6 +47,10 @@ static inline unsigned long array_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
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -188,8 +188,7 @@ static __always_inline unsigned long lon
* 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();
}
Patches currently in stable-queue which might be from dan.j.williams@xxxxxxxxx are
queue-4.9/kvm-vmx-allow-direct-access-to-msr_ia32_spec_ctrl.patch
queue-4.9/kvm-x86-add-ibpb-support.patch
queue-4.9/kvm-svm-allow-direct-access-to-msr_ia32_spec_ctrl.patch
queue-4.9/x86-paravirt-remove-noreplace-paravirt-cmdline-option.patch
queue-4.9/documentation-document-array_index_nospec.patch
queue-4.9/x86-usercopy-replace-open-coded-stac-clac-with-__uaccess_-begin-end.patch
queue-4.9/kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch
queue-4.9/vfs-fdtable-prevent-bounds-check-bypass-via-speculative-execution.patch
queue-4.9/x86-uaccess-use-__uaccess_begin_nospec-and-uaccess_try_nospec.patch
queue-4.9/x86-implement-array_index_mask_nospec.patch
queue-4.9/array_index_nospec-sanitize-speculative-array-de-references.patch
queue-4.9/kvm-vmx-make-indirect-call-speculation-safe.patch
queue-4.9/x86-kvm-update-spectre-v1-mitigation.patch
queue-4.9/x86-get_user-use-pointer-masking-to-limit-speculation.patch
queue-4.9/x86-syscall-sanitize-syscall-table-de-references-under-speculation.patch
queue-4.9/x86-spectre-report-get_user-mitigation-for-spectre_v1.patch
queue-4.9/x86-introduce-barrier_nospec.patch
queue-4.9/kvm-vmx-emulate-msr_ia32_arch_capabilities.patch
queue-4.9/x86-introduce-__uaccess_begin_nospec-and-uaccess_try_nospec.patch
queue-4.9/nl80211-sanitize-array-index-in-parse_txq_params.patch