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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-08-31 01:00:33 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-08-31 01:00:33 +0300 |
commit | 0a096f240aa1992ddac65f8e704f7b0c0795fe1c (patch) | |
tree | 04c64aca17b94b0862214e09784fc23b413df578 /Documentation/userspace-api/spec_ctrl.rst | |
parent | 7d6e3fa87e732ec1e7761bf325c0907685c8571b (diff) | |
parent | b7fe54f6c2d437082dcbecfbd832f38edd9caaf4 (diff) | |
download | linux-0a096f240aa1992ddac65f8e704f7b0c0795fe1c.tar.xz |
Merge tag 'x86-cpu-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cache flush updates from Thomas Gleixner:
"A reworked version of the opt-in L1D flush mechanism.
This is a stop gap for potential future speculation related hardware
vulnerabilities and a mechanism for truly security paranoid
applications.
It allows a task to request that the L1D cache is flushed when the
kernel switches to a different mm. This can be requested via prctl().
Changes vs the previous versions:
- Get rid of the software flush fallback
- Make the handling consistent with other mitigations
- Kill the task when it ends up on a SMT enabled core which defeats
the purpose of L1D flushing obviously"
* tag 'x86-cpu-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Documentation: Add L1D flushing Documentation
x86, prctl: Hook L1D flushing in via prctl
x86/mm: Prepare for opt-in based L1D flush in switch_mm()
x86/process: Make room for TIF_SPEC_L1D_FLUSH
sched: Add task_work callback for paranoid L1D flush
x86/mm: Refactor cond_ibpb() to support other use cases
x86/smp: Add a per-cpu view of SMT state
Diffstat (limited to 'Documentation/userspace-api/spec_ctrl.rst')
-rw-r--r-- | Documentation/userspace-api/spec_ctrl.rst | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/userspace-api/spec_ctrl.rst b/Documentation/userspace-api/spec_ctrl.rst index 7ddd8f667459..5e8ed9eef9aa 100644 --- a/Documentation/userspace-api/spec_ctrl.rst +++ b/Documentation/userspace-api/spec_ctrl.rst @@ -106,3 +106,11 @@ Speculation misfeature controls * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_ENABLE, 0, 0); * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_DISABLE, 0, 0); * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_FORCE_DISABLE, 0, 0); + +- PR_SPEC_L1D_FLUSH: Flush L1D Cache on context switch out of the task + (works only when tasks run on non SMT cores) + + Invocations: + * prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_L1D_FLUSH, 0, 0, 0); + * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_L1D_FLUSH, PR_SPEC_ENABLE, 0, 0); + * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_L1D_FLUSH, PR_SPEC_DISABLE, 0, 0); |