Subject: Re: [PATCH v3 02/11] kselftest: arm64: adds first test and common utils

From: Cristian Marussi <[email-masked]>
Date: Wed, 7 Aug 2019 16:42:45 +0100

Hi

On 02/08/2019 18:02, Cristian Marussi wrote:
> Added some arm64/signal specific boilerplate and utility code to help
> further testcase development.
> 
> A simple testcase and related helpers are also introduced in this commit:
> mangle_pstate_invalid_compat_toggle is a simple mangle testcase which
> messes with the ucontext_t from within the sig_handler, trying to toggle
> PSTATE state bits to switch the system between 32bit/64bit execution state.
> Expects SIGSEGV on test PASS.
> 
> Signed-off-by: Cristian Marussi <[email-masked]>
> ---
> A few fixes:
> - test_arm64_signals.sh runner script generation has been reviewed in order to
>   be safe against the .gitignore
> - using kselftest.h officially provided defines for tests' return values
> - removed SAFE_WRITE()/dump_uc()
> - looking for si_code==SEGV_ACCERR on SEGV test cases to better understand if
>   the sigfault had been directly triggered by Kernel
> ---
>  tools/testing/selftests/arm64/Makefile        |   2 +-
>  .../testing/selftests/arm64/signal/.gitignore |   6 +
>  tools/testing/selftests/arm64/signal/Makefile |  88 ++++++
>  tools/testing/selftests/arm64/signal/README   |  59 ++++
>  .../arm64/signal/test_arm64_signals.src_shell |  55 ++++
>  .../selftests/arm64/signal/test_signals.c     |  26 ++
>  .../selftests/arm64/signal/test_signals.h     | 137 +++++++++
>  .../arm64/signal/test_signals_utils.c         | 261 ++++++++++++++++++
>  .../arm64/signal/test_signals_utils.h         |  13 +
>  .../arm64/signal/testcases/.gitignore         |   1 +
>  .../mangle_pstate_invalid_compat_toggle.c     |  25 ++
>  .../arm64/signal/testcases/testcases.c        | 150 ++++++++++
>  .../arm64/signal/testcases/testcases.h        |  83 ++++++
>  13 files changed, 905 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/arm64/signal/.gitignore
>  create mode 100644 tools/testing/selftests/arm64/signal/Makefile
>  create mode 100644 tools/testing/selftests/arm64/signal/README
>  create mode 100755 tools/testing/selftests/arm64/signal/test_arm64_signals.src_shell
>  create mode 100644 tools/testing/selftests/arm64/signal/test_signals.c
>  create mode 100644 tools/testing/selftests/arm64/signal/test_signals.h
>  create mode 100644 tools/testing/selftests/arm64/signal/test_signals_utils.c
>  create mode 100644 tools/testing/selftests/arm64/signal/test_signals_utils.h
>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/.gitignore
>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c
>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/testcases.c
>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/testcases.h
> 

I discovered an additional issue with this patch while building
some additional SVE related arm64/signal testcases (ofr a different patch series),
which is related to the logic of the helper get_header() that is flawed under some
specific conditions (not exposed by the test-cases included in this series).

A fix like the one below will go into V4, once reviews have settled.

diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.c b/tools/testing/selftests/arm64/signal/testcases/testcases.c
index a59785092e1f..0727b3987bbd 100644
--- a/tools/testing/selftests/arm64/signal/testcases/testcases.c
+++ b/tools/testing/selftests/arm64/signal/testcases/testcases.c
@@ -10,9 +10,16 @@ struct _aarch64_ctx *get_header(struct _aarch64_ctx *head, uint32_t magic,
                return found;
 
        do {
+               /*
+                * account for the fact that:
+                * - we could be in search of the terminator itself
+                * - a terminator should anyway terminate the loop
+                */
                if (head->magic == magic) {
                        found = head;
                        break;
+               } else if (!head->magic) {
+                       break;
                }
                offs += head->size;
                head = GET_RESV_NEXT_HEAD(head);

Cheers

Cristian

> diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
> index 03a0d4f71218..af59dc74e0dc 100644
> --- a/tools/testing/selftests/arm64/Makefile
> +++ b/tools/testing/selftests/arm64/Makefile
> @@ -6,7 +6,7 @@ ARCH ?= $(shell uname -m)
>  ARCH := $(shell echo $(ARCH) | sed -e s/aarch64/arm64/)
>  
>  ifeq ("x$(ARCH)", "xarm64")
> -SUBDIRS :=
> +SUBDIRS := signal
>  else
>  SUBDIRS :=
>  endif
> diff --git a/tools/testing/selftests/arm64/signal/.gitignore b/tools/testing/selftests/arm64/signal/.gitignore
> new file mode 100644
> index 000000000000..434f65c15f03
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/.gitignore
> @@ -0,0 +1,6 @@
> +# Helper script's internal testcases list (TPROGS) is regenerated
> +# each time by Makefile on standalone (non KSFT driven) runs.
> +# Committing such list creates a dependency between testcases
> +# patches such that they are no more easily revertable. Just ignore.
> +test_arm64_signals.src_shell
> +test_arm64_signals.sh
> diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile
> new file mode 100644
> index 000000000000..8c8d08be4b0d
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/Makefile
> @@ -0,0 +1,88 @@
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2019 ARM Limited
> +
> +# Supports also standalone invokation out of KSFT-tree
> +# Compile standalone and run on your device with:
> +#
> +#  $ make -C tools/testing/selftests/arm64/signal INSTALL_PATH=<your-dir> install
> +#
> +# Run standalone on device with:
> +#
> +#  $ <your-device-instdir>/test_arm64_signals.sh [-k|-v]
> +#
> +# If INSTALL_PATH= is NOT provided it will default to ./install
> +
> +# A proper top_srcdir is needed both by KSFT(lib.mk)
> +# and standalone builds
> +top_srcdir = ../../../../..
> +
> +CFLAGS += -std=gnu99 -I. -I$(top_srcdir)/tools/testing/selftests/
> +SRCS := $(filter-out testcases/testcases.c,$(wildcard testcases/*.c))
> +PROGS := $(patsubst %.c,%,$(SRCS))
> +
> +# Guessing as best as we can where the Kernel headers
> +# could have been installed depending on ENV config and
> +# type of invocation.
> +ifeq ($(KBUILD_OUTPUT),)
> +khdr_dir = $(top_srcdir)/usr/include
> +else
> +ifeq (0,$(MAKELEVEL))
> +khdr_dir = $(KBUILD_OUTPUT)/usr/include
> +else
> +# the KSFT preferred location when KBUILD_OUTPUT is set
> +khdr_dir = $(KBUILD_OUTPUT)/kselftest/usr/include
> +endif
> +endif
> +
> +CFLAGS += -I$(khdr_dir)
> +
> +# Standalone run
> +ifeq (0,$(MAKELEVEL))
> +CC := $(CROSS_COMPILE)gcc
> +RUNNER_SRC = test_arm64_signals.src_shell
> +RUNNER = test_arm64_signals.sh
> +INSTALL_PATH ?= install/
> +
> +all: $(RUNNER)
> +
> +$(RUNNER): $(PROGS)
> +	cp $(RUNNER_SRC) $(RUNNER)
> +	sed -i -e 's#PROGS=.*#PROGS="$(PROGS)"#' $@
> +
> +install: all
> +	mkdir -p $(INSTALL_PATH)/testcases
> +	cp $(PROGS) $(INSTALL_PATH)/testcases
> +	cp $(RUNNER) $(INSTALL_PATH)/
> +
> +.PHONY clean:
> +	rm -f $(PROGS)
> +# KSFT run
> +else
> +# Generated binaries to be installed by top KSFT script
> +TEST_GEN_PROGS := $(notdir $(PROGS))
> +
> +# Get Kernel headers installed and use them.
> +KSFT_KHDR_INSTALL := 1
> +
> +# This include mk will also mangle the TEST_GEN_PROGS list
> +# to account for any OUTPUT target-dirs optionally provided
> +# by the toplevel makefile
> +include ../../lib.mk
> +
> +$(TEST_GEN_PROGS): $(PROGS)
> +	cp $(PROGS) $(OUTPUT)/
> +
> +clean:
> +	$(CLEAN)
> +	rm -f $(PROGS)
> +endif
> +
> +# Common test-unit targets to build common-layout test-cases executables
> +# Needs secondary expansion to properly include the testcase c-file in pre-reqs
> +.SECONDEXPANSION:
> +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h
> +	@if [ ! -d $(khdr_dir) ]; then \
> +		echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \
> +		echo "===>  Are you sure Kernel Headers have been installed properly ?\n"; \
> +	fi
> +	$(CC) $(CFLAGS) $^ -o $@
> diff --git a/tools/testing/selftests/arm64/signal/README b/tools/testing/selftests/arm64/signal/README
> new file mode 100644
> index 000000000000..53f005f7910a
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/README
> @@ -0,0 +1,59 @@
> +KSelfTest arm64/signal/
> +=======================
> +
> +Signals Tests
> ++++++++++++++
> +
> +- Tests are built around a common main compilation unit: such shared main
> +  enforces a standard sequence of operations needed to perform a single
> +  signal-test (setup/trigger/run/result/cleanup)
> +
> +- The above mentioned ops are configurable on a test-by-test basis: each test
> +  is described (and configured) using the descriptor signals.h::struct tdescr
> +
> +- Each signal testcase is compiled into its own executable: a separate
> +  executable is used for each test since many tests complete successfully
> +  by receiving some kind of fatal signal from the Kernel, so it's safer
> +  to run each test unit in its own standalone process, so as to start each
> +  test from a clean slate.
> +
> +- New tests can be simply defined in testcases/ dir providing a proper struct
> +  tdescr overriding all the defaults we wish to change (as of now providing a
> +  custom run method is mandatory though)
> +
> +- Signals' test-cases hereafter defined belong currently to two
> +  principal families:
> +
> +  - 'mangle_' tests: a real signal (SIGUSR1) is raised and used as a trigger
> +    and then the test case code messes-up with the sigframe ucontext_t from
> +    inside the sighandler itself.
> +
> +  - 'fake_sigreturn_' tests: a brand new custom artificial sigframe structure
> +    is placed on the stack and a sigreturn syscall is called to simulate a
> +    real signal return. This kind of tests does not use a trigger usually and
> +    they are just fired using some simple included assembly trampoline code.
> +
> + - Most of these tests are successfully passing if the process gets killed by
> +   some fatal signal: usually SIGSEGV or SIGBUS. Since while writing this
> +   kind of tests it is extremely easy in fact to end-up injecting other
> +   unrelated SEGV bugs in the testcases, it becomes extremely tricky to
> +   be really sure that the tests are really addressing what they are meant
> +   to address and they are not instead falling apart due to unplanned bugs
> +   in the test code.
> +   In order to alleviate the misery of the life of such test-developer, a few
> +   helpers are provided:
> +
> +   - a couple of ASSERT_BAD/GOOD_CONTEXT() macros to easily parse a ucontext_t
> +     and verify if it is indeed GOOD or BAD (depending on what we were
> +     expecting), using the same logic/perspective as in the arm64 Kernel signals
> +     routines.
> +
> +   - a sanity mechanism to be used in 'fake_sigreturn_'-alike tests: enabled by
> +     default it takes care to verify that the test-execution had at least
> +     successfully progressed up to the stage of triggering the fake sigreturn
> +     call.
> +
> +  In both cases test results are expected in terms of:
> +   - some fatal signal sent by the Kernel to the test process
> +  or
> +  - analyzing some final regs state
> diff --git a/tools/testing/selftests/arm64/signal/test_arm64_signals.src_shell b/tools/testing/selftests/arm64/signal/test_arm64_signals.src_shell
> new file mode 100755
> index 000000000000..163e941e2997
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/test_arm64_signals.src_shell
> @@ -0,0 +1,55 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2019 ARM Limited
> +
> +ret=0
> +keep_on_fail=0
> +err_out="2> /dev/null"
> +
> +usage() {
> +	echo "Usage: `basename $0` [-v] [-k]"
> +	exit 1
> +}
> +
> +# avoiding getopt to avoid compatibility issues on targets
> +# with limited resources
> +while [ $# -gt 0 ]
> +do
> +	case $1 in
> +		"-k")
> +			keep_on_fail=1
> +			;;
> +		"-v")
> +			err_out=
> +			;;
> +		*)
> +			usage
> +			;;
> +	esac
> +	shift
> +done
> +
> +TPROGS=
> +
> +tot=$(echo $TPROGS | wc -w)
> +
> +# Tests are expected in testcases/ subdir inside the installation path
> +workdir="`dirname $0 2>/dev/null`"
> +[ -n $workdir ] && cd $workdir
> +
> +passed=0
> +run=0
> +for test in $TPROGS
> +do
> +	run=$((run + 1))
> +	eval ./$test $err_out
> +	if [ $? != 0 ]; then
> +		[ $keep_on_fail = 0 ] && echo "===>>> FAILED:: $test <<<===" && ret=1 && break
> +	else
> +		passed=$((passed + 1))
> +	fi
> +done
> +
> +echo "==>> PASSED: $passed/$run on $tot available tests."
> +
> +exit $ret
> diff --git a/tools/testing/selftests/arm64/signal/test_signals.c b/tools/testing/selftests/arm64/signal/test_signals.c
> new file mode 100644
> index 000000000000..3447d7011aec
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/test_signals.c
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2019 ARM Limited */
> +
> +#include <kselftest.h>
> +
> +#include "test_signals.h"
> +#include "test_signals_utils.h"
> +
> +struct tdescr *current;
> +extern struct tdescr tde;
> +
> +int main(int argc, char *argv[])
> +{
> +	current = &tde;
> +
> +	ksft_print_msg("%s :: %s - SIG_TRIG:%d  SIG_OK:%d -- current:%p\n",
> +		       current->name, current->descr, current->sig_trig,
> +		       current->sig_ok, current);
> +	if (test_setup(current)) {
> +		if (test_run(current))
> +			test_result(current);
> +		test_cleanup(current);
> +	}
> +
> +	return current->pass ? KSFT_PASS : KSFT_FAIL;
> +}
> diff --git a/tools/testing/selftests/arm64/signal/test_signals.h b/tools/testing/selftests/arm64/signal/test_signals.h
> new file mode 100644
> index 000000000000..85db3ac44b32
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/test_signals.h
> @@ -0,0 +1,137 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2019 ARM Limited */
> +
> +#ifndef __TEST_SIGNALS_H__
> +#define __TEST_SIGNALS_H__
> +
> +#include <assert.h>
> +#include <stdbool.h>
> +#include <signal.h>
> +#include <ucontext.h>
> +#include <stdint.h>
> +
> +/*
> + * Using ARCH specific and sanitized Kernel headers installed by KSFT
> + * framework since we asked for it by setting flag KSFT_KHDR_INSTALL
> + * in our Makefile.
> + */
> +#include <asm/ptrace.h>
> +#include <asm/hwcap.h>
> +
> +/* pasted from include/linux/stringify.h */
> +#define __stringify_1(x...)	#x
> +#define __stringify(x...)	__stringify_1(x)
> +
> +/*
> + * Reads a sysreg using the, possibly provided, S3_ encoding in order to
> + * avoid inject any dependency on the used toolchain regarding possibly
> + * still unsupported ARMv8 extensions.
> + *
> + * Using a standard mnemonic here to indicate the specific sysreg (like SSBS)
> + * would introduce a compile-time dependency on possibly unsupported ARMv8
> + * Extensions: you could end-up failing to build the test depending on the
> + * available toolchain.
> + * This is undesirable since some tests, even if specifically targeted at some
> + * ARMv8 Extensions, can be plausibly run even on hardware lacking the above
> + * optional ARM features. (SSBS bit preservation is an example: Kernel handles
> + * it transparently not caring at all about the effective set of supported
> + * features).
> + * On the other side we will expect to observe different behaviours if the
> + * feature is supported or not: usually getting a SIGILL when trying to use
> + * unsupported features. For this reason we have anyway in place some
> + * preliminary run-time checks about the cpu effectively supported features.
> + *
> + * This helper macro is meant to be used for regs readable at EL0, BUT some
> + * EL1 sysregs are indeed readable too through MRS emulation Kernel-mechanism
> + * if the required reg is included in the supported encoding space:
> + *
> + *  Documentation/arm64/cpu-feature-regsiters.txt
> + *
> + *  "The infrastructure emulates only the following system register space:
> + *   	Op0=3, Op1=0, CRn=0, CRm=0,4,5,6,7
> + */
> +#define get_regval(regname, out) \
> +	asm volatile("mrs %0, " __stringify(regname) : "=r" (out) :: "memory")
> +
> +/* Regs encoding and masks naming copied in from sysreg.h */
> +#define SYS_ID_AA64MMFR1_EL1	S3_0_C0_C7_1	/* MRS Emulated */
> +#define SYS_ID_AA64MMFR2_EL1	S3_0_C0_C7_2	/* MRS Emulated */
> +#define ID_AA64MMFR1_PAN_SHIFT	20
> +#define ID_AA64MMFR2_UAO_SHIFT	4
> +
> +/* Local Helpers */
> +#define IS_PAN_SUPPORTED(val) \
> +	(!!((val) & (0xfUL << ID_AA64MMFR1_PAN_SHIFT)))
> +#define IS_UAO_SUPPORTED(val) \
> +	(!!((val) & (0xfUL << ID_AA64MMFR2_UAO_SHIFT)))
> +
> +#define S3_MRS_SSBS_SYSREG		S3_3_C4_C2_6	/* EL0 supported */
> +
> +/*
> + * Feature flags used in tdescr.feats_required to specify
> + * any feature by the test
> + */
> +enum {
> +	FSSBS_BIT,
> +	FPAN_BIT,
> +	FUAO_BIT,
> +	FMAX_END
> +};
> +
> +#define FEAT_SSBS		(1UL << FSSBS_BIT)
> +#define FEAT_PAN		(1UL << FPAN_BIT)
> +#define FEAT_UAO		(1UL << FUAO_BIT)
> +
> +/*
> + * A descriptor used to describe and configure a test case.
> + * Fields with a non-trivial meaning are described inline in the following.
> + */
> +struct tdescr {
> +	/* KEEP THIS FIELD FIRST for easier lookup from assembly */
> +	void		*token;
> +	/* when disabled token based sanity checking is skipped in handler */
> +	bool		sanity_disabled;
> +	/* just a name for the test-case; manadatory field */
> +	char		*name;
> +	char		*descr;
> +	unsigned long	feats_required;
> +	/* bitmask of effectively supported feats: populated at run-time */
> +	unsigned long	feats_supported;
> +	bool		feats_ok;
> +	bool		initialized;
> +	unsigned int	minsigstksz;
> +	/* signum used as a test trigger. Zero if no trigger-signal is used */
> +	int		sig_trig;
> +	/*
> +	 * signum considered as a successful test completion.
> +	 * Zero when no signal is expected on success
> +	 */
> +	int		sig_ok;
> +	/* signum expected on unsupported CPU features. */
> +	int		sig_unsupp;
> +	/* a timeout in second for test completion */
> +	unsigned int	timeout;
> +	bool		triggered;
> +	bool		pass;
> +	/* optional sa_flags for the installed handler */
> +	int		sa_flags;
> +	ucontext_t	saved_uc;
> +
> +	/* a setup function to be called before test starts */
> +	int (*setup)(struct tdescr *td);
> +	void (*cleanup)(struct tdescr *td);
> +
> +	/* an optional function to be used as a trigger for test starting */
> +	int (*trigger)(struct tdescr *td);
> +	/*
> +	 * the actual test-core: invoked differently depending on the
> +	 * presence of the trigger function above; this is mandatory
> +	 */
> +	int (*run)(struct tdescr *td, siginfo_t *si, ucontext_t *uc);
> +
> +	/* an optional function for custom results' processing */
> +	void (*check_result)(struct tdescr *td);
> +
> +	void *priv;
> +};
> +#endif
> diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c
> new file mode 100644
> index 000000000000..ac0055f6340b
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c
> @@ -0,0 +1,261 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2019 ARM Limited */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <signal.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <assert.h>
> +#include <sys/auxv.h>
> +#include <linux/auxvec.h>
> +#include <ucontext.h>
> +
> +#include "test_signals.h"
> +#include "test_signals_utils.h"
> +#include "testcases/testcases.h"
> +
> +extern struct tdescr *current;
> +
> +static char *feats_store[FMAX_END] = {
> +	"SSBS",
> +	"PAN",
> +	"UAO"
> +};
> +
> +#define MAX_FEATS_SZ	128
> +static inline char *feats_to_string(unsigned long feats)
> +{
> +	static char feats_string[MAX_FEATS_SZ];
> +
> +	for (int i = 0; i < FMAX_END && feats_store[i][0]; i++) {
> +		if (feats & 1UL << i)
> +			snprintf(feats_string, MAX_FEATS_SZ - 1, "%s %s ",
> +				 feats_string, feats_store[i]);
> +	}
> +
> +	return feats_string;
> +}
> +
> +static void unblock_signal(int signum)
> +{
> +	sigset_t sset;
> +
> +	sigemptyset(&sset);
> +	sigaddset(&sset, signum);
> +	sigprocmask(SIG_UNBLOCK, &sset, NULL);
> +}
> +
> +static void default_result(struct tdescr *td, bool force_exit)
> +{
> +	if (td->pass)
> +		fprintf(stderr, "==>> completed. PASS(1)\n");
> +	else
> +		fprintf(stdout, "==>> completed. FAIL(0)\n");
> +	if (force_exit)
> +		exit(td->pass ? EXIT_SUCCESS : EXIT_FAILURE);
> +}
> +
> +static inline bool are_feats_ok(struct tdescr *td)
> +{
> +	return td ? td->feats_required == td->feats_supported : 0;
> +}
> +
> +static void default_handler(int signum, siginfo_t *si, void *uc)
> +{
> +	if (current->sig_trig && signum == current->sig_trig) {
> +		fprintf(stderr, "Handling SIG_TRIG\n");
> +		current->triggered = 1;
> +		/* ->run was asserted NON-NULL in test_setup() already */
> +		current->run(current, si, uc);
> +	} else if (signum == SIGILL && !current->initialized) {
> +		/*
> +		 * A SIGILL here while still not initialized means we failed
> +		 * even to asses the existence of features during init
> +		 */
> +		fprintf(stdout,
> +			"Got SIGILL test_init. Marking ALL features UNSUPPORTED.\n");
> +		current->feats_supported = 0;
> +	} else if (current->sig_ok && signum == current->sig_ok) {
> +		/* it's a bug in the test code when this assert fail */
> +		assert(!current->sig_trig || current->triggered);
> +		fprintf(stderr,
> +			"SIG_OK -- SP:%p  si_addr@:0x%p  si_code:%d  token@:0x%p  offset:%ld\n",
> +			((ucontext_t *)uc)->uc_mcontext.sp,
> +			si->si_addr, si->si_code, current->token,
> +			current->token - si->si_addr);
> +		/*
> +		 * fake_sigreturn tests, which have sanity_enabled=1, set, at
> +		 * the very last time, the token field to the SP address used
> +		 * to place the fake sigframe: so token==0 means we never made
> +		 * it to the end, segfaulting well-before, and the test is
> +		 * possibly broken.
> +		 */
> +		if (!current->sanity_disabled && !current->token) {
> +			fprintf(stdout,
> +				"current->token ZEROED...test is probably broken!\n");
> +			assert(0);
> +		}
> +		/*
> +		 * Trying to narrow down the SEGV to the ones generated by
> +		 * Kernel itself via arm64_notify_segfault()
> +		 */
> +		if (current->sig_ok == SIGSEGV && si->si_code != SEGV_ACCERR) {
> +			fprintf(stdout,
> +				"si_code != SEGV_ACCERR...test is probably broken!\n");
> +			assert(0);
> +		}
> +		fprintf(stderr, "Handling SIG_OK\n");
> +		current->pass = 1;
> +		/*
> +		 * Some tests can lead to SEGV loops: in such a case we want
> +		 * to terminate immediately exiting straight away
> +		 */
> +		default_result(current, 1);
> +	} else {
> +		if (signum == current->sig_unsupp && !are_feats_ok(current)) {
> +			fprintf(stderr, "-- RX SIG_UNSUPP on unsupported feature...OK\n");
> +			current->pass = 1;
> +		} else if (signum == SIGALRM && current->timeout) {
> +			fprintf(stderr, "-- Timeout !\n");
> +		} else {
> +			fprintf(stderr,
> +				"-- RX UNEXPECTED SIGNAL: %d\n", signum);
> +		}
> +		default_result(current, 1);
> +	}
> +}
> +
> +static int default_setup(struct tdescr *td)
> +{
> +	struct sigaction sa;
> +
> +	sa.sa_sigaction = default_handler;
> +	sa.sa_flags = SA_SIGINFO;
> +	if (td->sa_flags)
> +		sa.sa_flags |= td->sa_flags;
> +	sigemptyset(&sa.sa_mask);
> +	/* uncatchable signals naturally skipped ... */
> +	for (int sig = 1; sig < 32; sig++)
> +		sigaction(sig, &sa, NULL);
> +	/*
> +	 * RT Signals default disposition is Term but they cannot be
> +	 * generated by the Kernel in response to our tests; so just catch
> +	 * them all and report them as UNEXPECTED signals.
> +	 */
> +	for (int sig = SIGRTMIN; sig <= SIGRTMAX; sig++)
> +		sigaction(sig, &sa, NULL);
> +
> +	/* just in case...unblock explicitly all we need */
> +	if (td->sig_trig)
> +		unblock_signal(td->sig_trig);
> +	if (td->sig_ok)
> +		unblock_signal(td->sig_ok);
> +	if (td->sig_unsupp)
> +		unblock_signal(td->sig_unsupp);
> +
> +	if (td->timeout) {
> +		unblock_signal(SIGALRM);
> +		alarm(td->timeout);
> +	}
> +	fprintf(stderr, "Registered handlers for all signals.\n");
> +
> +	return 1;
> +}
> +
> +static inline int default_trigger(struct tdescr *td)
> +{
> +	return !raise(td->sig_trig);
> +}
> +
> +static int test_init(struct tdescr *td)
> +{
> +	td->minsigstksz = getauxval(AT_MINSIGSTKSZ);
> +	if (!td->minsigstksz)
> +		td->minsigstksz = MINSIGSTKSZ;
> +	fprintf(stderr, "Detected MINSTKSIGSZ:%d\n", td->minsigstksz);
> +
> +	if (td->feats_required) {
> +		bool feats_ok = false;
> +		td->feats_supported = 0;
> +		/*
> +		 * Checking for CPU required features using both the
> +		 * auxval and the arm64 MRS Emulation to read sysregs.
> +		 */
> +		if (getauxval(AT_HWCAP) & HWCAP_CPUID) {
> +			uint64_t val = 0;
> +
> +			if (td->feats_required & FEAT_SSBS) {
> +				/* Uses HWCAP to check capability */
> +				if (getauxval(AT_HWCAP) & HWCAP_SSBS)
> +					td->feats_supported |= FEAT_SSBS;
> +			}
> +			if (td->feats_required & FEAT_PAN) {
> +				/* Uses MRS emulation to check capability */
> +				get_regval(SYS_ID_AA64MMFR1_EL1, val);
> +				if (IS_PAN_SUPPORTED(val))
> +					td->feats_supported |= FEAT_PAN;
> +			}
> +			if (td->feats_required & FEAT_UAO) {
> +				/* Uses MRS emulation to check capability */
> +				get_regval(SYS_ID_AA64MMFR2_EL1 , val);
> +				if (IS_UAO_SUPPORTED(val))
> +					td->feats_supported |= FEAT_UAO;
> +			}
> +		} else {
> +			fprintf(stderr,
> +				"HWCAP_CPUID NOT available. Mark ALL feats UNSUPPORTED.\n");
> +		}
> +		feats_ok = are_feats_ok(td);
> +		fprintf(stderr,
> +			"Required Features: [%s] %ssupported\n",
> +			feats_ok ? feats_to_string(td->feats_supported) :
> +		        feats_to_string(td->feats_required ^ td->feats_supported),
> +			!feats_ok ? "NOT " : "");
> +	}
> +
> +	td->initialized = 1;
> +	return 1;
> +}
> +
> +int test_setup(struct tdescr *td)
> +{
> +	/* assert core invariants symptom of a rotten testcase */
> +	assert(current);
> +	assert(td);
> +	assert(td->name);
> +	assert(td->run);
> +
> +	if (!test_init(td))
> +		return 0;
> +
> +	if (td->setup)
> +		return td->setup(td);
> +	else
> +		return default_setup(td);
> +}
> +
> +int test_run(struct tdescr *td)
> +{
> +	if (td->sig_trig) {
> +		if (td->trigger)
> +			return td->trigger(td);
> +		else
> +			return default_trigger(td);
> +	} else {
> +		return td->run(td, NULL, NULL);
> +	}
> +}
> +
> +void test_result(struct tdescr *td)
> +{
> +	if (td->check_result)
> +		td->check_result(td);
> +	default_result(td, 0);
> +}
> +
> +void test_cleanup(struct tdescr *td)
> +{
> +	if (td->cleanup)
> +		td->cleanup(td);
> +}
> diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h
> new file mode 100644
> index 000000000000..8658d1a7d4b9
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2019 ARM Limited */
> +
> +#ifndef __TEST_SIGNALS_UTILS_H__
> +#define __TEST_SIGNALS_UTILS_H__
> +
> +#include "test_signals.h"
> +
> +int test_setup(struct tdescr *td);
> +void test_cleanup(struct tdescr *td);
> +int test_run(struct tdescr *td);
> +void test_result(struct tdescr *td);
> +#endif
> diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore
> new file mode 100644
> index 000000000000..8651272e3cfc
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore
> @@ -0,0 +1 @@
> +mangle_pstate_invalid_compat_toggle
> diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c
> new file mode 100644
> index 000000000000..971193e7501b
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2019 ARM Limited */
> +
> +#include "test_signals_utils.h"
> +#include "testcases.h"
> +
> +static int mangle_invalid_pstate_run(struct tdescr *td, siginfo_t *si,
> +				     ucontext_t *uc)
> +{
> +	ASSERT_GOOD_CONTEXT(uc);
> +
> +	/* This config should trigger a SIGSEGV by Kernel */
> +	uc->uc_mcontext.pstate ^= PSR_MODE32_BIT;
> +
> +	return 1;
> +}
> +
> +struct tdescr tde = {
> +		.sanity_disabled = true,
> +		.name = "MANGLE_PSTATE_INVALID_STATE_TOGGLE",
> +		.descr = "Mangling uc_mcontext with INVALID STATE_TOGGLE",
> +		.sig_trig = SIGUSR1,
> +		.sig_ok = SIGSEGV,
> +		.run = mangle_invalid_pstate_run,
> +};
> diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.c b/tools/testing/selftests/arm64/signal/testcases/testcases.c
> new file mode 100644
> index 000000000000..a59785092e1f
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.c
> @@ -0,0 +1,150 @@
> +#include "testcases.h"
> +
> +struct _aarch64_ctx *get_header(struct _aarch64_ctx *head, uint32_t magic,
> +				size_t resv_sz, size_t *offset)
> +{
> +	size_t offs = 0;
> +	struct _aarch64_ctx *found = NULL;
> +
> +	if (!head || resv_sz < HDR_SZ)
> +		return found;
> +
> +	do {
> +		if (head->magic == magic) {
> +			found = head;
> +			break;
> +		}
> +		offs += head->size;
> +		head = GET_RESV_NEXT_HEAD(head);
> +	} while (offs < resv_sz - HDR_SZ);
> +
> +	if (offset)
> +		*offset = offs;
> +
> +	return found;
> +}
> +
> +bool validate_extra_context(struct extra_context *extra, char **err)
> +{
> +	struct _aarch64_ctx *term;
> +
> +	if (!extra || !err)
> +		return false;
> +
> +	fprintf(stderr, "Validating EXTRA...\n");
> +	term = GET_RESV_NEXT_HEAD(extra);
> +	if (!term || term->magic || term->size) {
> +		*err = "UN-Terminated EXTRA context";
> +		return false;
> +	}
> +	if (extra->datap & 0x0fUL)
> +		*err = "Extra DATAP misaligned";
> +	else if (extra->size & 0x0fUL)
> +		*err = "Extra SIZE misaligned";
> +	else if (extra->datap != (uint64_t)term + sizeof(*term))
> +		*err = "Extra DATAP misplaced (not contiguos)";
> +	if (*err)
> +		return false;
> +
> +	return true;
> +}
> +
> +bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err)
> +{
> +	bool terminated = false;
> +	size_t offs = 0;
> +	int flags = 0;
> +	struct extra_context *extra = NULL;
> +	struct _aarch64_ctx *head =
> +		(struct _aarch64_ctx *)uc->uc_mcontext.__reserved;
> +
> +	if (!err)
> +		return false;
> +	/* Walk till the end terminator verifying __reserved contents */
> +	while (head && !terminated && offs < resv_sz) {
> +		if ((uint64_t)head & 0x0fUL) {
> +			*err = "Misaligned HEAD";
> +			return false;
> +		}
> +
> +		switch (head->magic) {
> +			case 0:
> +				if (head->size)
> +					*err = "Bad size for MAGIC0";
> +				else
> +					terminated = true;
> +				break;
> +			case FPSIMD_MAGIC:
> +				if (flags & FPSIMD_CTX)
> +					*err = "Multiple FPSIMD_MAGIC";
> +				else if (head->size !=
> +					 sizeof(struct fpsimd_context))
> +					*err = "Bad size for fpsimd_context";
> +				flags |= FPSIMD_CTX;
> +				break;
> +			case ESR_MAGIC:
> +				if (head->size != sizeof(struct esr_context))
> +					fprintf(stderr,
> +						"Bad size for esr_context is not an error...just ignore.\n");
> +				break;
> +			case SVE_MAGIC:
> +				if (flags & SVE_CTX)
> +					*err = "Multiple SVE_MAGIC";
> +				else if (head->size !=
> +					 sizeof(struct sve_context))
> +					*err = "Bad size for sve_context";
> +				flags |= SVE_CTX;
> +				break;
> +			case EXTRA_MAGIC:
> +				if (flags & EXTRA_CTX)
> +					*err = "Multiple EXTRA_MAGIC";
> +				else if (head->size !=
> +					 sizeof(struct extra_context))
> +					*err = "Bad size for extra_context";
> +				flags |= EXTRA_CTX;
> +				extra = (struct extra_context *)head;
> +				break;
> +			case KSFT_BAD_MAGIC:
> +				/*
> +				 * This is a BAD magic header defined
> +				 * artificially by a testcase and surely
> +				 * unknown to the Kernel parse_user_sigframe().
> +				 * It MUST cause a Kernel induced SEGV
> +				 */
> +				*err = "BAD MAGIC !";
> +				break;
> +			default:
> +				/*
> +				 * A still unknown Magic: potentially freshly added
> +				 * to the Kernel code and still unknown to the
> +				 * tests.
> +				 */
> +				fprintf(stdout,
> +					"SKIP Unknown MAGIC: 0x%X - Is KSFT arm64/signal up to date ?\n",
> +					head->magic);
> +				break;
> +		}
> +
> +		if (*err)
> +			return false;
> +
> +		offs += head->size;
> +		if (resv_sz - offs < sizeof(*head)) {
> +			*err = "HEAD Overrun";
> +			return false;
> +		}
> +
> +		if (flags & EXTRA_CTX)
> +			if (!validate_extra_context(extra, err))
> +				return false;
> +
> +		head = GET_RESV_NEXT_HEAD(head);
> +	}
> +
> +	if (terminated && !(flags & FPSIMD_CTX)) {
> +		*err = "Missing FPSIMD";
> +		return false;
> +	}
> +
> +	return true;
> +}
> diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.h b/tools/testing/selftests/arm64/signal/testcases/testcases.h
> new file mode 100644
> index 000000000000..624717c71b1d
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.h
> @@ -0,0 +1,83 @@
> +#ifndef __TESTCASES_H__
> +#define __TESTCASES_H__
> +
> +#include <stdio.h>
> +#include <stdbool.h>
> +#include <stdint.h>
> +#include <unistd.h>
> +#include <ucontext.h>
> +#include <assert.h>
> +
> +/* Architecture specific sigframe definitions */
> +#include <asm/sigcontext.h>
> +
> +#define FPSIMD_CTX	(1 << 0)
> +#define SVE_CTX		(1 << 1)
> +#define EXTRA_CTX	(1 << 2)
> +
> +#define KSFT_BAD_MAGIC	0xdeadbeef
> +
> +#define HDR_SZ \
> +	sizeof(struct _aarch64_ctx)
> +
> +#define GET_SF_RESV_HEAD(sf) \
> +	(struct _aarch64_ctx *)(&(sf).uc.uc_mcontext.__reserved)
> +
> +#define GET_SF_RESV_SIZE(sf) \
> +	sizeof((sf).uc.uc_mcontext.__reserved)
> +
> +#define GET_UCP_RESV_SIZE(ucp) \
> +	sizeof((ucp)->uc_mcontext.__reserved)
> +
> +#define ASSERT_BAD_CONTEXT(uc) do {					\
> +	char *err = NULL;						\
> +	assert(!validate_reserved((uc), GET_UCP_RESV_SIZE((uc)), &err));\
> +	if (err)							\
> +		fprintf(stderr,						\
> +			"Using badly built context - ERR: %s\n", err);	\
> +} while(0)
> +
> +#define ASSERT_GOOD_CONTEXT(uc) do {					 \
> +	char *err = NULL;						 \
> +	if (!validate_reserved((uc), GET_UCP_RESV_SIZE((uc)), &err)) {	 \
> +		if (err)						 \
> +			fprintf(stderr,					 \
> +				"Detected BAD context - ERR: %s\n", err);\
> +		assert(0);						 \
> +	} else {							 \
> +		fprintf(stderr, "uc context validated.\n");		 \
> +	}								 \
> +} while(0)
> +
> +/* head->size accounts both for payload and header _aarch64_ctx size ! */
> +#define GET_RESV_NEXT_HEAD(h) \
> +	(struct _aarch64_ctx *)((char *)(h) + (h)->size)
> +
> +struct fake_sigframe {
> +	siginfo_t	info;
> +	ucontext_t	uc;
> +};
> +
> +
> +bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err);
> +
> +bool validate_extra_context(struct extra_context *extra, char **err);
> +
> +struct _aarch64_ctx *get_header(struct _aarch64_ctx *head, uint32_t magic,
> +				size_t resv_sz, size_t *offset);
> +
> +static inline struct _aarch64_ctx *get_terminator(struct _aarch64_ctx *head,
> +						  size_t resv_sz,
> +						  size_t *offset)
> +{
> +	return get_header(head, 0, resv_sz, offset);
> +}
> +
> +static inline void write_terminator_record(struct _aarch64_ctx *tail)
> +{
> +	if (tail) {
> +		tail->magic = 0;
> +		tail->size = 0;
> +	}
> +}
> +#endif
> 

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