| Message ID | 697e015e22ea78b021c2546f390ad5d773f3af86.1653177005.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] arm64: kasan: do not instrument stacktrace.c | expand |
On Sun, May 22, 2022 at 01:50:58AM +0200, andrey.konovalov@linux.dev wrote: > 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 Can we make that a little more descriptive? e.g. # When KASAN is enabled, a stacktrace is recorded for every alloc/free, which # can significantly impact performance. Avoid instrumenting the stacktrace code # to minimize this impact. KASAN_SANITIZE_stacktrace.o := n With that: Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > + > # 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 >
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;