kselftest: arm64: mangle_pstate_invalid_compat_toggle and common utils

Add some arm64/signal specific boilerplate and utility code to help
further testcases' development.

Introduce also one simple testcase mangle_pstate_invalid_compat_toggle
and some related helpers: it is a simple mangle testcase which messes
with the ucontext_t from within the signal handler, trying to toggle
PSTATE state bits to switch the system between 32bit/64bit execution
state. Expects SIGSEGV on test PASS.

Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 283 insertions, 0 deletions

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..fbce41750590
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c
@@ -0,0 +1,283 @@
+// 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 const *const feats_names[FMAX_END] = {
+	" SSBS ",
+};
+
+#define MAX_FEATS_SZ	128
+static char feats_string[MAX_FEATS_SZ];
+
+static inline char *feats_to_string(unsigned long feats)
+{
+	size_t flen = MAX_FEATS_SZ - 1;
+
+	for (int i = 0; i < FMAX_END; i++) {
+		if (feats & (1UL << i)) {
+			size_t tlen = strlen(feats_names[i]);
+
+			assert(flen > tlen);
+			flen -= tlen;
+			strncat(feats_string, feats_names[i], flen);
+		}
+	}
+
+	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);
+}
+
+/*
+ * The following handle_signal_* helpers are used by main default_handler
+ * and are meant to return true when signal is handled successfully:
+ * when false is returned instead, it means that the signal was somehow
+ * unexpected in that context and it was NOT handled; default_handler will
+ * take care of such unexpected situations.
+ */
+
+static bool handle_signal_unsupported(struct tdescr *td,
+				      siginfo_t *si, void *uc)
+{
+	if (feats_ok(td))
+		return false;
+
+	/* Mangling PC to avoid loops on original SIGILL */
+	((ucontext_t *)uc)->uc_mcontext.pc += 4;
+
+	if (!td->initialized) {
+		fprintf(stderr,
+			"Got SIG_UNSUPP @test_init. Ignore.\n");
+	} else {
+		fprintf(stderr,
+			"-- RX SIG_UNSUPP on unsupported feat...OK\n");
+		td->pass = 1;
+		default_result(current, 1);
+	}
+
+	return true;
+}
+
+static bool handle_signal_trigger(struct tdescr *td,
+				  siginfo_t *si, void *uc)
+{
+	td->triggered = 1;
+	/* ->run was asserted NON-NULL in test_setup() already */
+	td->run(td, si, uc);
+
+	return true;
+}
+
+static bool handle_signal_ok(struct tdescr *td,
+			     siginfo_t *si, void *uc)
+{
+	/*
+	 * it's a bug in the test code when this assert fail:
+	 * if sig_trig was defined, it must have been used before getting here.
+	 */
+	assert(!td->sig_trig || td->triggered);
+	fprintf(stderr,
+		"SIG_OK -- SP:0x%llX  si_addr@:%p  si_code:%d  token@:%p  offset:%ld\n",
+		((ucontext_t *)uc)->uc_mcontext.sp,
+		si->si_addr, si->si_code, td->token, td->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 (!td->sanity_disabled && !td->token) {
+		fprintf(stdout,
+			"current->token ZEROED...test is probably broken!\n");
+		abort();
+	}
+	/*
+	 * Trying to narrow down the SEGV to the ones generated by Kernel itself
+	 * via arm64_notify_segfault(). This is a best-effort check anyway, and
+	 * the si_code check may need to change if this aspect of the kernel
+	 * ABI changes.
+	 */
+	if (td->sig_ok == SIGSEGV && si->si_code != SEGV_ACCERR) {
+		fprintf(stdout,
+			"si_code != SEGV_ACCERR...test is probably broken!\n");
+		abort();
+	}
+	td->pass = 1;
+	/*
+	 * Some tests can lead to SEGV loops: in such a case we want to
+	 * terminate immediately exiting straight away; some others are not
+	 * supposed to outlive the signal handler code, due to the content of
+	 * the fake sigframe which caused the signal itself.
+	 */
+	default_result(current, 1);
+
+	return true;
+}
+
+static void default_handler(int signum, siginfo_t *si, void *uc)
+{
+	if (current->sig_unsupp && signum == current->sig_unsupp &&
+	    handle_signal_unsupported(current, si, uc)) {
+		fprintf(stderr, "Handled SIG_UNSUPP\n");
+	} else if (current->sig_trig && signum == current->sig_trig &&
+		   handle_signal_trigger(current, si, uc)) {
+		fprintf(stderr, "Handled SIG_TRIG\n");
+	} else if (current->sig_ok && signum == current->sig_ok &&
+		   handle_signal_ok(current, si, uc)) {
+		fprintf(stderr, "Handled SIG_OK\n");
+	} 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 | SA_RESTART;
+	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) {
+		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_SSBS)
+			td->feats_supported |= FEAT_SSBS;
+		if (feats_ok(td))
+			fprintf(stderr,
+				"Required Features: [%s] supported\n",
+				feats_to_string(td->feats_required &
+						td->feats_supported));
+		else
+			fprintf(stderr,
+				"Required Features: [%s] NOT supported\n",
+				feats_to_string(td->feats_required &
+						~td->feats_supported));
+	}
+
+	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);
+}