zdtm: add rseq02 transition test with NO_RESTART CS flag

Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>

test/zdtm/transition/Makefile

@@ -24,6 +24,7 @@ TST_NOFILE	=	\
 		pid_reuse	\
 		pidfd_store_sk \
 		rseq01		\
+		rseq02		\
 
 
 TST_FILE	=	\
@@ -82,6 +83,7 @@ ptrace:		LDFLAGS += -pthread
 fork2:		CFLAGS += -D FORK2
 thread-bomb.o:	CFLAGS += -pthread
 thread-bomb:	LDFLAGS += -pthread
+rseq02:		CFLAGS += -D NORESTART
 
 %: %.sh
 	cp $< $@

test/zdtm/transition/rseq01.c

@@ -58,6 +58,18 @@ enum rseq_flags {
 	RSEQ_FLAG_UNREGISTER = (1 << 0),
 };
 
+enum rseq_cs_flags_bit {
+	RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,
+	RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,
+	RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,
+};
+
+enum rseq_cs_flags {
+	RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT = (1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
+	RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL = (1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
+	RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE = (1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
+};
+
 struct rseq {
 	uint32_t cpu_id_start;
 	uint32_t cpu_id;
@@ -111,6 +123,7 @@ static int rseq_addv(intptr_t *v, intptr_t count, int cpu)
 {
 	double a = 10000000000000000.0;
 	double b = -1;
+	uint64_t rseq_cs1 = 0, rseq_cs2 = 0;
 
 	/* clang-format off */
 	__asm__ __volatile__ goto(
@@ -134,6 +147,9 @@ static int rseq_addv(intptr_t *v, intptr_t count, int cpu)
 		"fsqrt\n\t" /* heavy instruction */
 		"dec %%rcx\n\t"
 		"jnz 5b\n\t"
+		"movq %%rax, %[rseq_cs_check2]\n\t"
+		"movq %[rseq_cs], %%rax\n\t"
+		"movq %%rax, %[rseq_cs_check1]\n\t"
 		"fstpl %[y]\n\t"
 		"2:\n\t"
 		".pushsection __rseq_failure, \"ax\"\n\t"
@@ -149,6 +165,8 @@ static int rseq_addv(intptr_t *v, intptr_t count, int cpu)
 		: [cpu_id]              "r" (cpu),
 		[current_cpu_id]      "m" (rseq_ptr->cpu_id),
 		[rseq_cs]             "m" (rseq_ptr->rseq_cs),
+		[rseq_cs_check1]       "m" (rseq_cs1),
+		[rseq_cs_check2]       "m" (rseq_cs2),
 		/* final store input */
 		[v]                   "m" (*v),
 		[count]               "er" (count),
@@ -159,9 +177,22 @@ static int rseq_addv(intptr_t *v, intptr_t count, int cpu)
 	);
 	/* clang-format on */
 	rseq_after_asm_goto();
+	test_msg("exit %lx %lx %f %f\n", rseq_cs1, rseq_cs2, a, b);
+	if (rseq_cs1 != rseq_cs2) {
+		/*
+		 * It means that we finished critical section
+		 * *normally* (haven't jumped to abort) but the kernel had cleaned up
+		 * rseq_ptr->rseq_cs before we left critical section
+		 * and CRIU didn't restore it correctly.
+		 * That's a bug picture.
+		 */
+		return -1;
+	}
+
 	return 0;
 abort:
 	rseq_after_asm_goto();
+	test_msg("abort %lx %lx %f %f\n", rseq_cs1, rseq_cs2, a, b);
 	return -1;
 }
 
@@ -183,16 +214,32 @@ int main(int argc, char *argv[])
 		fail("calloc");
 		exit(EXIT_FAILURE);
 	}
+
 	register_thread();
 
+	/*
+	 * We want to test that RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
+	 * is handled properly by CRIU, but that flag can be used
+	 * only with all another flags set.
+	 * Please, refer to
+	 * https://github.com/torvalds/linux/blob/ce522ba9/kernel/rseq.c#L192
+	 */
+#ifdef NORESTART
+	rseq_ptr->flags = RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT | RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL |
+			  RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE;
+#endif
+
 	test_daemon();
 
 	while (test_go()) {
 		cpu = RSEQ_ACCESS_ONCE(rseq_ptr->cpu_id_start);
 		ret = rseq_addv(&cpu_data[cpu], 2, cpu);
 
+/* NORESTART is NOT set */
+#ifndef NORESTART
 		/* just ignore abort */
 		ret = 0;
+#endif
 
 		if (ret)
 			break;

test/zdtm/transition/rseq02.c

@@ -0,0 +1 @@
+rseq01.c

test/zdtm/transition/rseq02.desc

@@ -0,0 +1 @@
+rseq01.desc