x86/cfi: Document the "cfi=" bootparam options

The kernel-parameters.txt didn't have a section for the cfi= options.
Add it.

Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20250904034656.3670313-3-kees@kernel.org

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 747a55abf4946bb9efe320f0f62fdcd1560b0a71..8bbffbb334ab95e6a22a4963aab9c3a7e182cf7f 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -608,6 +608,23 @@
        ccw_timeout_log [S390]
                        See Documentation/arch/s390/common_io.rst for details.
 
+       cfi=            [X86-64] Set Control Flow Integrity checking features
+                       when CONFIG_FINEIBT is enabled.
+                       Format: feature[,feature...]
+                       Default: auto
+
+                       auto:     Use FineIBT if IBT available, otherwise kCFI.
+                                 Under FineIBT, enable "paranoid" mode when
+                                 FRED is not available.
+                       off:      Turn off CFI checking.
+                       kcfi:     Use kCFI (disable FineIBT).
+                       fineibt:  Use FineIBT (even if IBT not available).
+                       norand:   Do not re-randomize CFI hashes.
+                       paranoid: Add caller hash checking under FineIBT.
+                       bhi:      Enable register poisoning to stop speculation
+                                 across FineIBT. (Disabled by default.)
+                       warn:     Do not enforce CFI checking: warn only.
+
        cgroup_disable= [KNL] Disable a particular controller or optional feature
                        Format: {name of the controller(s) or feature(s) to disable}
                        The effects of cgroup_disable=foo are: