lkml.org 
[lkml]   [2022]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.19 0149/1157] arm64: kasan: do not instrument stacktrace.c
    Date
    From: Andrey Konovalov <andreyknvl@google.com>

    [ Upstream commit 802b91118d11227b527153849ea761b280691373 ]

    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>
    Acked-by: Mark Rutland <mark.rutland@arm.com>
    Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    Link: https://lore.kernel.org/r/c4c944a2a905e949760fbeb29258185087171708.1653317461.git.andreyknvl@google.com
    Signed-off-by: Will Deacon <will@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/arm64/kernel/Makefile | 5 +++++
    arch/arm64/kernel/stacktrace.c | 4 ++--
    2 files changed, 7 insertions(+), 2 deletions(-)

    diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
    index fa7981d0d917..7075a9c6a4a6 100644
    --- a/arch/arm64/kernel/Makefile
    +++ b/arch/arm64/kernel/Makefile
    @@ -14,6 +14,11 @@ CFLAGS_REMOVE_return_address.o = $(CC_FLAGS_FTRACE)
    CFLAGS_REMOVE_syscall.o = -fstack-protector -fstack-protector-strong
    CFLAGS_syscall.o += -fno-stack-protector

    +# When KASAN is enabled, a stack trace is recorded for every alloc/free, which
    +# can significantly impact performance. Avoid instrumenting the stack trace
    +# collection code to minimize this impact.
    +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 0467cb79f080..c246e8d9f95b 100644
    --- a/arch/arm64/kernel/stacktrace.c
    +++ b/arch/arm64/kernel/stacktrace.c
    @@ -124,8 +124,8 @@ static int notrace unwind_next(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_next() invocation.
    */
    - state->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
    - state->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
    + state->fp = READ_ONCE(*(unsigned long *)(fp));
    + state->pc = READ_ONCE(*(unsigned long *)(fp + 8));
    state->prev_fp = fp;
    state->prev_type = info.type;

    --
    2.35.1


    \
     
     \ /
      Last update: 2022-08-16 00:39    [W:4.016 / U:23.256 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site