+ kasan-arm64-dont-instrument-functions-that-enable-kasan.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: kasan, arm64: don't instrument functions that enable kasan
has been added to the -mm tree.  Its filename is
     kasan-arm64-dont-instrument-functions-that-enable-kasan.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/kasan-arm64-dont-instrument-functions-that-enable-kasan.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/kasan-arm64-dont-instrument-functions-that-enable-kasan.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Andrey Konovalov <andreyknvl@google.com>
Subject: kasan, arm64: don't instrument functions that enable kasan

This patch prepares Software Tag-Based KASAN for stack tagging support.

With stack tagging enabled, KASAN tags stack variable in each function in
its prologue.  In start_kernel() stack variables get tagged before KASAN
is enabled via setup_arch()->kasan_init().  As the result the tags for
start_kernel()'s stack variables end up in the temporary shadow memory. 
Later when KASAN gets enabled, switched to normal shadow, and starts
checking tags, this leads to false-positive reports, as proper tags are
missing in normal shadow.

Disable KASAN instrumentation for start_kernel().  Also disable it for
arm64's setup_arch() as a precaution (it doesn't have any stack variables
right now).

Link: http://lkml.kernel.org/r/55d432671a92e931ab8234b03dc36b14d4c21bfb.1596199677.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Elena Petrova <lenaptr@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Walter Wu <walter-zh.wu@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm64/kernel/setup.c |    2 +-
 init/main.c               |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/arch/arm64/kernel/setup.c~kasan-arm64-dont-instrument-functions-that-enable-kasan
+++ a/arch/arm64/kernel/setup.c
@@ -276,7 +276,7 @@ arch_initcall(reserve_memblock_reserved_
 
 u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
 
-void __init setup_arch(char **cmdline_p)
+void __init __no_sanitize_address setup_arch(char **cmdline_p)
 {
 	init_mm.start_code = (unsigned long) _text;
 	init_mm.end_code   = (unsigned long) _etext;
--- a/init/main.c~kasan-arm64-dont-instrument-functions-that-enable-kasan
+++ a/init/main.c
@@ -827,7 +827,7 @@ void __init __weak arch_call_rest_init(v
 	rest_init();
 }
 
-asmlinkage __visible void __init start_kernel(void)
+asmlinkage __visible __no_sanitize_address void __init start_kernel(void)
 {
 	char *command_line;
 	char *after_dashes;
_

Patches currently in -mm which might be from andreyknvl@google.com are

kasan-dont-tag-stacks-allocated-with-pagealloc.patch
kasan-arm64-dont-instrument-functions-that-enable-kasan.patch
kasan-allow-enabling-stack-tagging-for-tag-based-mode.patch
kasan-adjust-kasan_stack_oob-for-tag-based-mode.patch