linux-kernel - [PATCH v11 4/6] kasan: Document support on 32-bit powerpc

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Message-Id: <20210319144058.772525-5-dja@axtens.net>
Date:   Sat, 20 Mar 2021 01:40:56 +1100
From:   Daniel Axtens <dja@...ens.net>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linuxppc-dev@...ts.ozlabs.org, kasan-dev@...glegroups.com,
        christophe.leroy@...roup.eu, aneesh.kumar@...ux.ibm.com,
        bsingharora@...il.com
Cc:     Daniel Axtens <dja@...ens.net>
Subject: [PATCH v11 4/6] kasan: Document support on 32-bit powerpc

KASAN is supported on 32-bit powerpc and the docs should reflect this.

Suggested-by: Christophe Leroy <christophe.leroy@...roup.eu>
Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
Signed-off-by: Daniel Axtens <dja@...ens.net>
---
 Documentation/dev-tools/kasan.rst |  8 ++++++--
 Documentation/powerpc/kasan.txt   | 12 ++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/powerpc/kasan.txt

diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index a8c3e0cff88d..2cfd5d9068c0 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -36,7 +36,8 @@ Both software KASAN modes work with SLUB and SLAB memory allocators,
 while the hardware tag-based KASAN currently only supports SLUB.
 
 Currently, generic KASAN is supported for the x86_64, arm, arm64, xtensa, s390,
-and riscv architectures, and tag-based KASAN modes are supported only for arm64.
+and riscv architectures. It is also supported on 32-bit powerpc kernels.
+Tag-based KASAN modes are supported only for arm64.
 
 Usage
 -----
@@ -334,7 +335,10 @@ 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.
+riscv, s390, and 32-bit powerpc.
+
+It is optional, except on 32-bit powerpc kernels with module support,
+where it is required.
 
 This works by hooking into vmalloc and vmap and dynamically
 allocating real shadow memory to back the mappings.
diff --git a/Documentation/powerpc/kasan.txt b/Documentation/powerpc/kasan.txt
new file mode 100644
index 000000000000..26bb0e8bb18c
--- /dev/null
+++ b/Documentation/powerpc/kasan.txt
@@ -0,0 +1,12 @@
+KASAN is supported on powerpc on 32-bit only.
+
+32 bit support
+==============
+
+KASAN is supported on both hash and nohash MMUs on 32-bit.
+
+The shadow area sits at the top of the kernel virtual memory space above the
+fixmap area and occupies one eighth of the total kernel virtual memory space.
+
+Instrumentation of the vmalloc area is optional, unless built with modules,
+in which case it is required.
-- 
2.27.0