linux-kernel - [PATCH v7 3/7] ARM: Disable instrumentation for some code

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Message-Id: <20200117224839.23531-4-f.fainelli@gmail.com>
Date:   Fri, 17 Jan 2020 14:48:35 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Abbott Liu <liuwenliang@...wei.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list@...adcom.com, glider@...gle.com,
        dvyukov@...gle.com, corbet@....net, linux@...linux.org.uk,
        christoffer.dall@....com, marc.zyngier@....com, arnd@...db.de,
        nico@...xnic.net, vladimir.murzin@....com, keescook@...omium.org,
        jinb.park7@...il.com, alexandre.belloni@...tlin.com,
        ard.biesheuvel@...aro.org, daniel.lezcano@...aro.org,
        pombredanne@...b.com, rob@...dley.net, gregkh@...uxfoundation.org,
        akpm@...ux-foundation.org, mark.rutland@....com,
        catalin.marinas@....com, yamada.masahiro@...ionext.com,
        tglx@...utronix.de, thgarnie@...gle.com, dhowells@...hat.com,
        geert@...ux-m68k.org, andre.przywara@....com,
        julien.thierry@....com, drjones@...hat.com, philip@....systems,
        mhocko@...e.com, kirill.shutemov@...ux.intel.com,
        kasan-dev@...glegroups.com, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
        ryabinin.a.a@...il.com
Subject: [PATCH v7 3/7] ARM: Disable instrumentation for some code

From: Andrey Ryabinin <aryabinin@...tuozzo.com>

Disable instrumentation for arch/arm/boot/compressed/* and
arch/arm/vdso/* because that code would not linkd with kernel image.

Disable instrumentation for arch/arm/kvm/hyp/*. See commit a6cdf1c08cbf
("kvm: arm64: Disable compiler instrumentation for hypervisor code") for
more details.

Disable instrumentation for arch/arm/mm/physaddr.c. See commit
ec6d06efb0ba ("arm64: Add support for CONFIG_DEBUG_VIRTUAL") for more
details.

Disable kasan check in the function unwind_pop_register because it does
not matter that kasan checks failed when unwind_pop_register read stack
memory of task.

Reported-by: Florian Fainelli <f.fainelli@...il.com>
Reported-by: Marc Zyngier <marc.zyngier@....com>
Tested-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Abbott Liu <liuwenliang@...wei.com>
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 arch/arm/boot/compressed/Makefile | 1 +
 arch/arm/kernel/unwind.c          | 6 +++++-
 arch/arm/mm/Makefile              | 1 +
 arch/arm/vdso/Makefile            | 2 ++
 4 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index a1e883c5e5c4..83991a0447fa 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -24,6 +24,7 @@ OBJS		+= hyp-stub.o
 endif
 
 GCOV_PROFILE		:= n
+KASAN_SANITIZE		:= n
 
 # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
 KCOV_INSTRUMENT		:= n
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 4574e6aea0a5..f73601416f90 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -236,7 +236,11 @@ static int unwind_pop_register(struct unwind_ctrl_block *ctrl,
 		if (*vsp >= (unsigned long *)ctrl->sp_high)
 			return -URC_FAILURE;
 
-	ctrl->vrs[reg] = *(*vsp)++;
+	/* Use READ_ONCE_NOCHECK here to avoid this memory access
+	 * from being tracked by KASAN.
+	 */
+	ctrl->vrs[reg] = READ_ONCE_NOCHECK(*(*vsp));
+	(*vsp)++;
 	return URC_OK;
 }
 
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 7cb1699fbfc4..432302911d6e 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -16,6 +16,7 @@ endif
 obj-$(CONFIG_ARM_PTDUMP_CORE)	+= dump.o
 obj-$(CONFIG_ARM_PTDUMP_DEBUGFS)	+= ptdump_debugfs.o
 obj-$(CONFIG_MODULES)		+= proc-syms.o
+KASAN_SANITIZE_physaddr.o	:= n
 obj-$(CONFIG_DEBUG_VIRTUAL)	+= physaddr.o
 
 obj-$(CONFIG_ALIGNMENT_TRAP)	+= alignment.o
diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
index 0fda344beb0b..1f76a5ff6e49 100644
--- a/arch/arm/vdso/Makefile
+++ b/arch/arm/vdso/Makefile
@@ -42,6 +42,8 @@ GCOV_PROFILE := n
 # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
 KCOV_INSTRUMENT := n
 
+KASAN_SANITIZE := n
+
 # Force dependency
 $(obj)/vdso.o : $(obj)/vdso.so
 
-- 
2.17.1