From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Move the "Boot parameters" section in KASAN documentation next to the section that describes KASAN build options. No content changes. Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> --- Documentation/dev-tools/kasan.rst | 82 +++++++++++++++---------------- 1 file changed, 41 insertions(+), 41 deletions(-) diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index 2ed0b77d1db6..1772fd457fed 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -94,6 +94,47 @@ To include alloc and free stack traces of affected slab objects into reports, enable ``CONFIG_STACKTRACE``. To include alloc and free stack traces of affected physical pages, enable ``CONFIG_PAGE_OWNER`` and boot with ``page_owner=on``. +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. + +Alternatively, independent of ``panic_on_warn``, the ``kasan.fault=`` boot +parameter can be used to control panic and reporting behaviour: + +- ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN + report or also panic the kernel (default: ``report``). The panic happens even + if ``kasan_multi_shot`` is enabled. + +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 +additional boot parameters that allow disabling KASAN or controlling features: + +- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). + +- ``kasan.mode=sync``, ``=async`` or ``=asymm`` controls whether KASAN + is configured in synchronous, asynchronous or asymmetric mode of + execution (default: ``sync``). + Synchronous mode: a bad access is detected immediately when a tag + check fault occurs. + Asynchronous mode: a bad access detection is delayed. When a tag check + fault occurs, the information is stored in hardware (in the TFSR_EL1 + register for arm64). The kernel periodically checks the hardware and + only reports tag faults during these checks. + Asymmetric mode: a bad access is detected synchronously on reads and + asynchronously on writes. + +- ``kasan.vmalloc=off`` or ``=on`` disables or enables tagging of vmalloc + allocations (default: ``on``). + +- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack + traces collection (default: ``on``). + Error reports ~~~~~~~~~~~~~ @@ -208,47 +249,6 @@ traces point to places in code that interacted with the object but that are not directly present in the bad access stack trace. Currently, this includes 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. - -Alternatively, independent of ``panic_on_warn``, the ``kasan.fault=`` boot -parameter can be used to control panic and reporting behaviour: - -- ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN - report or also panic the kernel (default: ``report``). The panic happens even - if ``kasan_multi_shot`` is enabled. - -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 -additional boot parameters that allow disabling KASAN or controlling features: - -- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). - -- ``kasan.mode=sync``, ``=async`` or ``=asymm`` controls whether KASAN - is configured in synchronous, asynchronous or asymmetric mode of - execution (default: ``sync``). - Synchronous mode: a bad access is detected immediately when a tag - check fault occurs. - Asynchronous mode: a bad access detection is delayed. When a tag check - fault occurs, the information is stored in hardware (in the TFSR_EL1 - register for arm64). The kernel periodically checks the hardware and - only reports tag faults during these checks. - Asymmetric mode: a bad access is detected synchronously on reads and - asynchronously on writes. - -- ``kasan.vmalloc=off`` or ``=on`` disables or enables tagging of vmalloc - allocations (default: ``on``). - -- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack - traces collection (default: ``on``). - Implementation details ---------------------- -- 2.25.1
