Merge tag 'x86-splitlock-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel...

[platform/kernel/linux-starfive.git] / Documentation / admin-guide / kernel-parameters.txt

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index dd5947a..0136cdf 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5111,27 +5111,37 @@
        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.