From: andrey.konovalov@linux.dev
To: Marco Elver <elver@google.com>,
Alexander Potapenko <glider@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Peter Collingbourne <pcc@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
kasan-dev@googlegroups.com,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
Evgenii Stepanov <eugenis@google.com>,
linux-kernel@vger.kernel.org,
Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH 30/31] kasan: documentation updates
Date: Tue, 30 Nov 2021 23:08:25 +0100 [thread overview]
Message-ID: <0525538d5a3a57c831f4e2442824768af56109ff.1638308023.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1638308023.git.andreyknvl@google.com>
From: Andrey Konovalov <andreyknvl@google.com>
Update KASAN documentation:
- Bump Clang version requirement for HW_TAGS as ARM64_MTE depends on
AS_HAS_LSE_ATOMICS as of commit 2decad92f4731 ("arm64: mte: Ensure
TIF_MTE_ASYNC_FAULT is set atomically"), which requires Clang 12.
- Add description of the new kasan.vmalloc command line flag.
- Mention that SW_TAGS and HW_TAGS modes now support vmalloc tagging.
- Explicitly say that the "Shadow memory" section is only applicable
to software KASAN modes.
- Mention that shadow-based KASAN_VMALLOC is supported on arm64.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
Documentation/dev-tools/kasan.rst | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index 8089c559d339..7614a1fc30fa 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -30,7 +30,7 @@ Software tag-based KASAN mode is only supported in Clang.
The hardware KASAN mode (#3) relies on hardware to perform the checks but
still requires a compiler version that supports memory tagging instructions.
-This mode is supported in GCC 10+ and Clang 11+.
+This mode is supported in GCC 10+ and Clang 12+.
Both software KASAN modes work with SLUB and SLAB memory allocators,
while the hardware tag-based KASAN currently only supports SLUB.
@@ -206,6 +206,9 @@ additional boot parameters that allow disabling KASAN or controlling features:
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``).
@@ -279,8 +282,8 @@ Software tag-based KASAN uses 0xFF as a match-all pointer tag (accesses through
pointers with the 0xFF pointer tag are not checked). The value 0xFE is currently
reserved to tag freed memory regions.
-Software tag-based KASAN currently only supports tagging of slab and page_alloc
-memory.
+Software tag-based KASAN currently only supports tagging of slab, page_alloc,
+and vmalloc memory.
Hardware tag-based KASAN
~~~~~~~~~~~~~~~~~~~~~~~~
@@ -303,8 +306,8 @@ Hardware tag-based KASAN uses 0xFF as a match-all pointer tag (accesses through
pointers with the 0xFF pointer tag are not checked). The value 0xFE is currently
reserved to tag freed memory regions.
-Hardware tag-based KASAN currently only supports tagging of slab and page_alloc
-memory.
+Hardware tag-based KASAN currently only supports tagging of slab, page_alloc,
+and VM_ALLOC-based vmalloc memory.
If the hardware does not support MTE (pre ARMv8.5), hardware tag-based KASAN
will not be enabled. In this case, all KASAN boot parameters are ignored.
@@ -319,6 +322,8 @@ checking gets disabled.
Shadow memory
-------------
+The contents of this section are only applicable to software KASAN modes.
+
The kernel maps memory in several different parts of the address space.
The range of kernel virtual addresses is large: there is not enough real
memory to support a real shadow region for every address that could be
@@ -349,7 +354,7 @@ CONFIG_KASAN_VMALLOC
With ``CONFIG_KASAN_VMALLOC``, KASAN can cover vmalloc space at the
cost of greater memory usage. Currently, this is supported on x86,
-riscv, s390, and powerpc.
+arm64, riscv, s390, and powerpc.
This works by hooking into vmalloc and vmap and dynamically
allocating real shadow memory to back the mappings.
--
2.25.1
next prev parent reply other threads:[~2021-11-30 22:13 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 21:39 [PATCH 00/31] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS andrey.konovalov
2021-11-30 21:39 ` [PATCH 01/31] kasan, page_alloc: deduplicate should_skip_kasan_poison andrey.konovalov
2021-11-30 21:39 ` [PATCH 02/31] kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages andrey.konovalov
2021-12-02 15:24 ` Alexander Potapenko
2021-11-30 21:39 ` [PATCH 03/31] kasan, page_alloc: merge kasan_free_pages into free_pages_prepare andrey.konovalov
2021-12-02 15:32 ` Alexander Potapenko
2021-11-30 21:39 ` [PATCH 04/31] kasan, page_alloc: simplify kasan_poison_pages call site andrey.konovalov
2021-12-01 14:09 ` Marco Elver
2021-12-06 21:07 ` Andrey Konovalov
2021-11-30 21:39 ` [PATCH 05/31] kasan, page_alloc: init memory of skipped pages on free andrey.konovalov
2021-11-30 21:41 ` [PATCH 06/31] mm: clarify __GFP_ZEROTAGS comment andrey.konovalov
2021-11-30 21:41 ` [PATCH 07/31] kasan: only apply __GFP_ZEROTAGS when memory is zeroed andrey.konovalov
2021-12-02 15:40 ` Alexander Potapenko
2021-11-30 21:41 ` [PATCH 08/31] kasan, page_alloc: refactor init checks in post_alloc_hook andrey.konovalov
2021-12-02 16:13 ` Alexander Potapenko
2021-12-06 21:09 ` Andrey Konovalov
2021-12-16 10:59 ` Alexander Potapenko
2021-11-30 21:42 ` [PATCH 09/31] kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook andrey.konovalov
2021-11-30 21:52 ` [PATCH 10/31] kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook andrey.konovalov
2021-11-30 22:05 ` [PATCH 11/31] kasan, page_alloc: move SetPageSkipKASanPoison " andrey.konovalov
2021-11-30 22:05 ` [PATCH 12/31] kasan, page_alloc: move kernel_init_free_pages " andrey.konovalov
2021-11-30 22:05 ` [PATCH 13/31] kasan, page_alloc: simplify kasan_unpoison_pages call site andrey.konovalov
2021-11-30 22:06 ` [PATCH 14/31] kasan: clean up metadata byte definitions andrey.konovalov
2021-11-30 22:06 ` [PATCH 15/31] kasan: define KASAN_VMALLOC_INVALID for SW_TAGS andrey.konovalov
2021-11-30 22:06 ` [PATCH 16/31] kasan, x86, arm64, s390: rename functions for modules shadow andrey.konovalov
2021-11-30 22:06 ` [PATCH 17/31] kasan, vmalloc: drop outdated VM_KASAN comment andrey.konovalov
2021-11-30 22:07 ` [PATCH 18/31] kasan: reorder vmalloc hooks andrey.konovalov
2021-11-30 22:07 ` [PATCH 20/31] kasan, vmalloc: reset tags in vmalloc functions andrey.konovalov
2021-12-02 14:17 ` Marco Elver
2021-12-06 21:08 ` Andrey Konovalov
2021-11-30 22:07 ` [PATCH 19/31] kasan: add wrappers for vmalloc hooks andrey.konovalov
2021-11-30 22:07 ` [PATCH 21/31] kasan, fork: don't tag stacks allocated with vmalloc andrey.konovalov
2021-12-02 14:27 ` Marco Elver
2021-12-06 21:08 ` Andrey Konovalov
2021-11-30 22:07 ` [PATCH 22/31] kasan, vmalloc: add vmalloc support to SW_TAGS andrey.konovalov
2021-11-30 22:07 ` [PATCH 23/31] kasan, arm64: allow KASAN_VMALLOC with SW_TAGS andrey.konovalov
2021-12-03 12:37 ` Marco Elver
2021-12-06 21:10 ` Andrey Konovalov
2021-11-30 22:07 ` [PATCH 24/31] kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged andrey.konovalov
2021-12-03 12:42 ` Marco Elver
2021-12-06 21:12 ` Andrey Konovalov
2021-11-30 22:08 ` [PATCH 25/31] kasan, vmalloc: don't unpoison VM_ALLOC pages before mapping andrey.konovalov
2021-11-30 22:08 ` [PATCH 26/31] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS andrey.konovalov
2021-11-30 22:08 ` [PATCH 27/31] kasan, vmalloc: add vmalloc support to HW_TAGS andrey.konovalov
2021-12-03 12:41 ` Marco Elver
2021-12-06 21:12 ` Andrey Konovalov
2021-11-30 22:08 ` [PATCH 28/31] kasan: add kasan.vmalloc command line flag andrey.konovalov
2021-12-03 12:09 ` Marco Elver
2021-12-06 21:09 ` Andrey Konovalov
2021-11-30 22:08 ` [PATCH 29/31] kasan, arm64: allow KASAN_VMALLOC with HW_TAGS andrey.konovalov
2021-12-01 11:35 ` Marco Elver
2021-12-06 21:10 ` Andrey Konovalov
2021-12-03 12:40 ` Marco Elver
2021-12-06 21:10 ` Andrey Konovalov
2021-11-30 22:08 ` andrey.konovalov [this message]
2021-11-30 22:08 ` [PATCH 31/31] kasan: improve vmalloc tests andrey.konovalov
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