From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 0184A6B0664 for ; Fri, 11 May 2018 10:36:36 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id z16-v6so1921883pgv.16 for ; Fri, 11 May 2018 07:36:35 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id c21-v6sor848638pgn.162.2018.05.11.07.36.34 for (Google Transport Security); Fri, 11 May 2018 07:36:35 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20180511143248.112484-1-dvyukov@google.com> References: <20180511143248.112484-1-dvyukov@google.com> From: Dmitry Vyukov Date: Fri, 11 May 2018 16:36:13 +0200 Message-ID: Subject: Re: [PATCH v2] arm: port KCOV to arm Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Russell King - ARM Linux , Mark Rutland , Abbott Liu , Catalin Marinas , Linux-MM , Andrew Morton Cc: Dmitry Vyukov , Koguchi Takuo , Linux ARM , syzkaller On Fri, May 11, 2018 at 4:32 PM, Dmitry Vyukov wrote: > KCOV is code coverage collection facility used, in particular, by syzkaller > system call fuzzer. There is some interest in using syzkaller on arm devices. > So port KCOV to arm. > > On implementation level this merely declares that KCOV is supported and > disables instrumentation of 3 special cases. Reasons for disabling are > commented in code. > > Tested with qemu-system-arm/vexpress-a15. > > Signed-off-by: Dmitry Vyukov > Cc: Russell King > Cc: Mark Rutland > Cc: Abbott Liu > Cc: Catalin Marinas > Cc: Koguchi Takuo > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-mm@kvack.org > Cc: syzkaller@googlegroups.com > > --- > > Changes since v1: > - remove disable of instrumentation for arch/arm/mm/fault.c > - disable instrumentation of arch/arm/kvm/hyp/* > - resort ARCH_HAS_KCOV alphabetically Andrew, this is for MM tree because this depends on the following patches in MM tree: kcov: prefault the kcov_area kcov: ensure irq code sees a valid area sched/core / kcov: avoid kcov_area during task switch > --- > arch/arm/Kconfig | 3 ++- > arch/arm/boot/compressed/Makefile | 3 +++ > arch/arm/kvm/hyp/Makefile | 8 ++++++++ > arch/arm/vdso/Makefile | 3 +++ > 4 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 3493f840e89c..34591796c36f 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -8,9 +8,10 @@ config ARM > select ARCH_HAS_DEVMEM_IS_ALLOWED > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FORTIFY_SOURCE > + select ARCH_HAS_KCOV > select ARCH_HAS_PTE_SPECIAL if ARM_LPAE > - select ARCH_HAS_SET_MEMORY > select ARCH_HAS_PHYS_TO_DMA > + select ARCH_HAS_SET_MEMORY > select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL > select ARCH_HAS_STRICT_MODULE_RWX if MMU > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile > index 6a4e7341ecd3..5f5f081e4879 100644 > --- a/arch/arm/boot/compressed/Makefile > +++ b/arch/arm/boot/compressed/Makefile > @@ -25,6 +25,9 @@ endif > > GCOV_PROFILE := n > > +# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. > +KCOV_INSTRUMENT := n > + > # > # Architecture dependencies > # > diff --git a/arch/arm/kvm/hyp/Makefile b/arch/arm/kvm/hyp/Makefile > index 7fc0638f263a..d2b5ec9c4b92 100644 > --- a/arch/arm/kvm/hyp/Makefile > +++ b/arch/arm/kvm/hyp/Makefile > @@ -23,3 +23,11 @@ obj-$(CONFIG_KVM_ARM_HOST) += hyp-entry.o > obj-$(CONFIG_KVM_ARM_HOST) += switch.o > CFLAGS_switch.o += $(CFLAGS_ARMV7VE) > obj-$(CONFIG_KVM_ARM_HOST) += s2-setup.o > + > +# KVM code is run at a different exception code with a different map, so > +# compiler instrumentation that inserts callbacks or checks into the code may > +# cause crashes. Just disable it. > +GCOV_PROFILE := n > +KASAN_SANITIZE := n > +UBSAN_SANITIZE := n > +KCOV_INSTRUMENT := n > diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile > index bb4118213fee..f4efff9d3afb 100644 > --- a/arch/arm/vdso/Makefile > +++ b/arch/arm/vdso/Makefile > @@ -30,6 +30,9 @@ CFLAGS_vgettimeofday.o = -O2 > # Disable gcov profiling for VDSO code > GCOV_PROFILE := n > > +# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. > +KCOV_INSTRUMENT := n > + > # Force dependency > $(obj)/vdso.o : $(obj)/vdso.so > > -- > 2.17.0.441.gb46fe60e1d-goog >