[PATCH v2 05/11] kasan: docs: update boot parameters section

From: Andrey Konovalov
Date: Fri Mar 12 2021 - 09:28:16 EST


Update the "Boot parameters" section in KASAN documentation:

- Mention panic_on_warn.
- Mention kasan_multi_shot and its interaction with panic_on_warn.
- Clarify kasan.fault=panic interaction with panic_on_warn.
- A readability clean-up.

Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
Documentation/dev-tools/kasan.rst | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index cd12c890b888..1189be9b4cb5 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -174,10 +174,16 @@ call_rcu() and workqueue queuing.
Boot parameters
~~~~~~~~~~~~~~~

+KASAN is affected by the generic ``panic_on_warn`` command line parameter.
+When it is enabled, KASAN panics the kernel after printing a bug report.
+
+By default, KASAN prints a bug report only for the first invalid memory access.
+With ``kasan_multi_shot``, KASAN prints a report on every invalid access. This
+effectively disables ``panic_on_warn`` for KASAN reports.
+
Hardware tag-based KASAN mode (see the section about various modes below) is
intended for use in production as a security mitigation. Therefore, it supports
-boot parameters that allow to disable KASAN competely or otherwise control
-particular KASAN features.
+boot parameters that allow disabling KASAN or controlling its features.

- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``).

@@ -185,8 +191,8 @@ particular KASAN features.
traces collection (default: ``on``).

- ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN
- report or also panic the kernel (default: ``report``). Note, that tag
- checking gets disabled after the first reported bug.
+ report or also panic the kernel (default: ``report``). The panic happens even
+ if ``kasan_multi_shot`` is enabled.

Implementation details
----------------------
--
2.31.0.rc2.261.g7f71774620-goog