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 <ryabinin.a.a@gmail.com>,
kasan-dev@googlegroups.com,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org,
Evgenii Stepanov <eugenis@google.com>,
linux-kernel@vger.kernel.org,
Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH v2 33/34] kasan: documentation updates
Date: Mon, 6 Dec 2021 22:44:10 +0100 [thread overview]
Message-ID: <e6d60d5748b8e1907be8f26ac20944c41119bf0e.1638825394.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1638825394.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:[~2021-12-06 21:47 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 21:22 [PATCH v2 00/34] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS andrey.konovalov
2021-12-06 21:22 ` [PATCH v2 01/34] kasan, page_alloc: deduplicate should_skip_kasan_poison andrey.konovalov
2021-12-06 21:31 ` [PATCH v2 02/34] kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages andrey.konovalov
2021-12-06 21:31 ` [PATCH v2 03/34] kasan, page_alloc: merge kasan_free_pages into free_pages_prepare andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 04/34] kasan, page_alloc: simplify kasan_poison_pages call site andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 05/34] kasan, page_alloc: init memory of skipped pages on free andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 06/34] kasan: drop skip_kasan_poison variable in free_pages_prepare andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 07/34] mm: clarify __GFP_ZEROTAGS comment andrey.konovalov
2021-12-07 17:33 ` Andrey Konovalov
2021-12-06 21:43 ` [PATCH v2 08/34] kasan: only apply __GFP_ZEROTAGS when memory is zeroed andrey.konovalov
2021-12-10 17:48 ` Catalin Marinas
2021-12-13 21:57 ` Andrey Konovalov
2021-12-06 21:43 ` [PATCH v2 09/34] kasan, page_alloc: refactor init checks in post_alloc_hook andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 10/34] kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 11/34] kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 12/34] kasan, page_alloc: move SetPageSkipKASanPoison " andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 13/34] kasan, page_alloc: move kernel_init_free_pages " andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 14/34] kasan, page_alloc: simplify kasan_unpoison_pages call site andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 15/34] kasan: clean up metadata byte definitions andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 16/34] kasan: define KASAN_VMALLOC_INVALID for SW_TAGS andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 17/34] kasan, x86, arm64, s390: rename functions for modules shadow andrey.konovalov
2021-12-10 17:55 ` Catalin Marinas
2021-12-06 21:43 ` [PATCH v2 18/34] kasan, vmalloc: drop outdated VM_KASAN comment andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 19/34] kasan: reorder vmalloc hooks andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 20/34] kasan: add wrappers for " andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 21/34] kasan, vmalloc: reset tags in vmalloc functions andrey.konovalov
2021-12-06 21:43 ` [PATCH v2 22/34] kasan, fork: don't tag stacks allocated with vmalloc andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 23/34] kasan, vmalloc: add vmalloc support to SW_TAGS andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 24/34] kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged andrey.konovalov
2021-12-06 21:48 ` Andrey Konovalov
2021-12-13 15:17 ` Vincenzo Frascino
2021-12-13 21:57 ` Andrey Konovalov
2021-12-06 21:44 ` [PATCH v2 25/34] kasan, vmalloc: don't unpoison VM_ALLOC pages before mapping andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 26/34] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 27/34] kasan, page_alloc: allow skipping memory init " andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 28/34] kasan, vmalloc: add vmalloc support to HW_TAGS andrey.konovalov
2021-12-06 21:49 ` Andrey Konovalov
2021-12-13 15:34 ` Vincenzo Frascino
2021-12-13 21:57 ` Andrey Konovalov
2021-12-06 21:44 ` [PATCH v2 29/34] kasan: mark kasan_arg_stacktrace as __initdata andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 30/34] kasan: simplify kasan_init_hw_tags andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 31/34] kasan: add kasan.vmalloc command line flag andrey.konovalov
2021-12-06 21:44 ` [PATCH v2 32/34] arm64: select KASAN_VMALLOC for SW/HW_TAGS modes andrey.konovalov
2021-12-10 18:04 ` Catalin Marinas
2021-12-06 21:44 ` andrey.konovalov [this message]
2021-12-06 21:44 ` [PATCH v2 34/34] kasan: improve vmalloc tests andrey.konovalov
2021-12-07 19:46 ` [PATCH v2 00/34] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS Andrey Konovalov
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