lkml.org 
[lkml]   [2020]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH 1/4] kselftests/arm64: add a basic Pointer Authentication test
From
Date
Hi Boyan,

On 8/28/20 6:46 PM, Boyan Karatotev wrote:
> PAuth signs and verifies return addresses on the stack. It does so by
> inserting a Pointer Authentication code (PAC) into some of the unused top
> bits of an address. This is achieved by adding paciasp/autiasp instructions
> at the beginning and end of a function.
>
> This feature is partially backwards compatible with earlier versions of the
> ARM architecture. To coerce the compiler into emitting fully backwards
> compatible code the main file is compiled to target an earlier ARM version.
> This allows the tests to check for the feature and print meaningful error
> messages instead of crashing.
>
> Add a test to verify that corrupting the return address results in a
> SIGSEGV on return.
>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
> ---
> tools/testing/selftests/arm64/Makefile | 2 +-
> .../testing/selftests/arm64/pauth/.gitignore | 1 +
> tools/testing/selftests/arm64/pauth/Makefile | 22 ++++++++++++
> tools/testing/selftests/arm64/pauth/helper.h | 10 ++++++
> tools/testing/selftests/arm64/pauth/pac.c | 32 +++++++++++++++++
> .../selftests/arm64/pauth/pac_corruptor.S | 36 +++++++++++++++++++
> 6 files changed, 102 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/arm64/pauth/.gitignore
> create mode 100644 tools/testing/selftests/arm64/pauth/Makefile
> create mode 100644 tools/testing/selftests/arm64/pauth/helper.h
> create mode 100644 tools/testing/selftests/arm64/pauth/pac.c
> create mode 100644 tools/testing/selftests/arm64/pauth/pac_corruptor.S
>
> diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
> index 93b567d23c8b..525506fd97b9 100644
> --- a/tools/testing/selftests/arm64/Makefile
> +++ b/tools/testing/selftests/arm64/Makefile
> @@ -4,7 +4,7 @@
> ARCH ?= $(shell uname -m 2>/dev/null || echo not)
>
> ifneq (,$(filter $(ARCH),aarch64 arm64))
> -ARM64_SUBTARGETS ?= tags signal
> +ARM64_SUBTARGETS ?= tags signal pauth
> else
> ARM64_SUBTARGETS :=
> endif
> diff --git a/tools/testing/selftests/arm64/pauth/.gitignore b/tools/testing/selftests/arm64/pauth/.gitignore
> new file mode 100644
> index 000000000000..b557c916720a
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/pauth/.gitignore
> @@ -0,0 +1 @@
> +pac
> diff --git a/tools/testing/selftests/arm64/pauth/Makefile b/tools/testing/selftests/arm64/pauth/Makefile
> new file mode 100644
> index 000000000000..785c775e5e41
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/pauth/Makefile
> @@ -0,0 +1,22 @@
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2020 ARM Limited
> +
> +CFLAGS += -mbranch-protection=pac-ret

There is no CFLAGS validation present which may give error with non
supported compiler.

Can you add a check something like,

+#check if the compiler works well
+pauth_cc_support := $(shell if ($(CC) $(CFLAGS) -march=armv8.3-a -E -x
c /dev/null -o /dev/null 2>&1) then echo "1"; fi)
+
+ifeq ($(pauth_cc_support),1)
TEST_GEN_PROGS := pac
TEST_GEN_FILES := pac_corruptor.o
+endif

include ../../lib.mk

+ifeq ($(pauth_cc_support),1)
# pac* and aut* instructions are not available on architectures berfore
# ARMv8.3. Therefore target ARMv8.3 wherever they are used directly
$(OUTPUT)/pac_corruptor.o: pac_corruptor.S
@@ -19,4 +25,4 @@ $(OUTPUT)/pac_corruptor.o: pac_corruptor.S
# run on earlier targets and print a meaningful error messages
$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o
$(CC) $^ -o $@ $(CFLAGS) -march=armv8.2-a
-
+endif
> +
> +TEST_GEN_PROGS := pac
> +TEST_GEN_FILES := pac_corruptor.o
> +
> +include ../../lib.mk
> +
> +# pac* and aut* instructions are not available on architectures berfore
> +# ARMv8.3. Therefore target ARMv8.3 wherever they are used directly
> +$(OUTPUT)/pac_corruptor.o: pac_corruptor.S
> + $(CC) -c $^ -o $@ $(CFLAGS) -march=armv8.3-a
> +
> +# when -mbranch-protection is enabled and the target architecture is ARMv8.3 or
> +# greater, gcc emits pac* instructions which are not in HINT NOP space,
> +# preventing the tests from occurring at all. Compile for ARMv8.2 so tests can
> +# run on earlier targets and print a meaningful error messages
> +$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o
> + $(CC) $^ -o $@ $(CFLAGS) -march=armv8.2-a
> +
> diff --git a/tools/testing/selftests/arm64/pauth/helper.h b/tools/testing/selftests/arm64/pauth/helper.h
> new file mode 100644
> index 000000000000..f777f88acf0a
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/pauth/helper.h
> @@ -0,0 +1,10 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2020 ARM Limited */
> +
> +#ifndef _HELPER_H_
> +#define _HELPER_H_
> +
> +void pac_corruptor(void);
> +
> +#endif
> +

Please delete extra line at end of file here and other places too.

Other changes look fine for me. After the suggested changes please free
to add,
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@arm.com>

Thanks,
Amit Daniel


> diff --git a/tools/testing/selftests/arm64/pauth/pac.c b/tools/testing/selftests/arm64/pauth/pac.c
> new file mode 100644
> index 000000000000..ed445050f621
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/pauth/pac.c
> @@ -0,0 +1,32 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2020 ARM Limited
> +
> +#include <sys/auxv.h>
> +#include <signal.h>
> +
>

\
 
 \ /
  Last update: 2020-08-31 10:07    [W:0.182 / U:0.252 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site