From: andrey.konovalov@linux.dev
To: Mark Rutland <mark.rutland@arm.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>,
Marco Elver <elver@google.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
kasan-dev@googlegroups.com,
Catalin Marinas <catalin.marinas@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH 1/2] arm64: kasan: do not instrument stacktrace.c
Date: Sun, 22 May 2022 01:50:58 +0200 [thread overview]
Message-ID: <697e015e22ea78b021c2546f390ad5d773f3af86.1653177005.git.andreyknvl@google.com> (raw)
From: Andrey Konovalov <andreyknvl@google.com>
Disable KASAN instrumentation of arch/arm64/kernel/stacktrace.c.
This speeds up Generic KASAN by 5-20%.
As a side-effect, KASAN is now unable to detect bugs in the stack trace
collection code. This is taken as an acceptable downside.
Also replace READ_ONCE_NOCHECK() with READ_ONCE() in stacktrace.c.
As the file is now not instrumented, there is no need to use the
NOCHECK version of READ_ONCE().
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
arch/arm64/kernel/Makefile | 3 +++
arch/arm64/kernel/stacktrace.c | 4 ++--
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index fa7981d0d917..da8cf6905c76 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -14,6 +14,9 @@ CFLAGS_REMOVE_return_address.o = $(CC_FLAGS_FTRACE)
CFLAGS_REMOVE_syscall.o = -fstack-protector -fstack-protector-strong
CFLAGS_syscall.o += -fno-stack-protector
+# Do not instrument to improve performance.
+KASAN_SANITIZE_stacktrace.o := n
+
# It's not safe to invoke KCOV when portions of the kernel environment aren't
# available or are out-of-sync with HW state. Since `noinstr` doesn't always
# inhibit KCOV instrumentation, disable it for the entire compilation unit.
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index e4103e085681..33e96ae4b15f 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -110,8 +110,8 @@ static int notrace unwind_frame(struct task_struct *tsk,
* Record this frame record's values and location. The prev_fp and
* prev_type are only meaningful to the next unwind_frame() invocation.
*/
- frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
- frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
+ frame->fp = READ_ONCE(*(unsigned long *)(fp));
+ frame->pc = READ_ONCE(*(unsigned long *)(fp + 8));
frame->prev_fp = fp;
frame->prev_type = info.type;
--
2.25.1
next reply other threads:[~2022-05-21 23:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-21 23:50 andrey.konovalov [this message]
2022-05-21 23:50 ` [PATCH 2/2] arm64: stacktrace: use non-atomic __set_bit andrey.konovalov
2022-05-23 11:34 ` Mark Rutland
2022-05-23 11:33 ` [PATCH 1/2] arm64: kasan: do not instrument stacktrace.c Mark Rutland
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