The following commit has been merged into the x86/splitlock branch of tip: Commit-ID: ebca17707e38f2050b188d837bd4646b29a1b0c2 Gitweb: https://git.kernel.org/tip/ebca17707e38f2050b188d837bd4646b29a1b0c2 Author: Fenghua Yu <fenghua.yu@xxxxxxxxx> AuthorDate: Mon, 22 Mar 2021 13:53:25 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Sun, 28 Mar 2021 22:52:16 +02:00 Documentation/admin-guide: Change doc for split_lock_detect parameter Since #DB for bus lock detect changes the split_lock_detect parameter, update the documentation for the changes. Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx> Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210322135325.682257-4-fenghua.yu@xxxxxxxxx --- Documentation/admin-guide/kernel-parameters.txt | 22 +++++++++++----- 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 0454572..aef927c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5100,27 +5100,37 @@ spia_peddr= split_lock_detect= - [X86] Enable split lock detection + [X86] Enable split lock detection or bus lock detection When enabled (and if hardware support is present), atomic instructions that access data across cache line - boundaries will result in an alignment check exception. + boundaries will result in an alignment check exception + for split lock detection or a debug exception for + bus lock detection. off - not enabled - warn - the kernel will emit rate limited warnings + warn - the kernel will emit rate-limited warnings about applications triggering the #AC - exception. This mode is the default on CPUs - that supports split lock detection. + exception or the #DB exception. This mode is + the default on CPUs that support split lock + detection or bus lock detection. Default + behavior is by #AC if both features are + enabled in hardware. fatal - the kernel will send SIGBUS to applications - that trigger the #AC exception. + that trigger the #AC exception or the #DB + exception. Default behavior is by #AC if + both features are enabled in hardware. If an #AC exception is hit in the kernel or in firmware (i.e. not while executing in user mode) the kernel will oops in either "warn" or "fatal" mode. + #DB exception for bus lock is triggered only when + CPL > 0. + srbds= [X86,INTEL] Control the Special Register Buffer Data Sampling (SRBDS) mitigation.
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