tests: arm: cortex_m: test dynamic lazy stacking on Cortex-m

Test the dynamic lazy stacking activation on Cortex-M.

Signed-off-by: Ioannis Glaropoulos <[email protected]>

Author: ioannisg

tests/arch/arm/arm_thread_swap/src/arm_thread_arch.c

@@ -111,6 +111,10 @@ static void verify_callee_saved(const _callee_saved_t *src,
 }
 
 #if defined(CONFIG_FPU) && defined(CONFIG_FPU_SHARING)
+
+/* Create the alternative thread with K_FP_REGS options */
+#define ALT_THREAD_OPTIONS K_FP_REGS
+
 /* Arbitrary values for the floating-point callee-saved registers */
 struct _preempt_float ztest_thread_fp_callee_saved_regs = {
 	.s16 = 0x11111111, .s17 = 0x22222222,
@@ -194,6 +198,9 @@ static void verify_fp_callee_saved(const struct _preempt_float *src,
 	);
 }
 
+#else
+/* No options passed */
+#define ALT_THREAD_OPTIONS 0
 #endif /* CONFIG_FPU && CONFIG_FPU_SHARING */
 
 static void alt_thread_entry(void)
@@ -246,6 +253,25 @@ static void alt_thread_entry(void)
 		"CONTROL.FPCA is not cleared at initialization: 0x%x\n",
 		__get_CONTROL());
 
+	/* Verify that the _current_ (alt) thread is
+	 * initialized with mode.FPCA cleared
+	 */
+	zassert_true((_current->arch.mode & CONTROL_FPCA_Msk) == 0,
+		"Alt thread FPCA flag not clear at initialization\n");
+#if defined(CONFIG_MPU_STACK_GUARD)
+	/* Alt thread is created with K_FP_REGS set, so we
+	 * expect lazy stacking and long guard to be enabled.
+	 */
+	zassert_true((_current->arch.mode &
+		Z_ARM_MODE_MPU_GUARD_FLOAT_Msk) != 0,
+		"Alt thread MPU GUAR DFLOAT flag not set at initialization\n");
+	zassert_true((_current->base.user_options & K_FP_REGS) != 0,
+		"Alt thread K_FP_REGS not set at initialization\n");
+	zassert_true((FPU->FPCCR & FPU_FPCCR_LSPEN_Msk) != 0,
+		"Lazy FP Stacking not set at initialization\n");
+#endif
+
+
 	/* Verify that the _current_ (alt) thread is initialized with FPSCR cleared. */
 	zassert_true(__get_FPSCR() == 0,
 		"(Alt thread) FPSCR is not cleared at initialization: 0x%x\n", __get_FPSCR());
@@ -422,6 +448,15 @@ void test_arm_thread_swap(void)
 	 */
 	zassert_true((_current->arch.mode & CONTROL_FPCA_Msk) == 0,
 		"Thread FPCA flag not clear at initialization\n");
+#if defined(CONFIG_MPU_STACK_GUARD)
+	zassert_true((_current->arch.mode &
+		Z_ARM_MODE_MPU_GUARD_FLOAT_Msk) == 0,
+		"Thread MPU GUAR DFLOAT flag not clear at initialization\n");
+	zassert_true((_current->base.user_options & K_FP_REGS) == 0,
+		"Thread K_FP_REGS not clear at initialization\n");
+	zassert_true((FPU->FPCCR & FPU_FPCCR_LSPEN_Msk) == 0,
+		"Lazy FP Stacking not clear at initialization\n");
+#endif
 #endif /* CONFIG_FPU && CONFIG_FPU_SHARING */
 
 	/* Create an alternative (supervisor) testing thread */
@@ -430,7 +465,7 @@ void test_arm_thread_swap(void)
 		K_THREAD_STACK_SIZEOF(alt_thread_stack),
 		(k_thread_entry_t)alt_thread_entry,
 		NULL, NULL, NULL,
-		K_PRIO_COOP(PRIORITY), 0,
+		K_PRIO_COOP(PRIORITY), ALT_THREAD_OPTIONS,
 		K_NO_WAIT);
 
 	/* Verify context-switch has not occurred. */
@@ -632,6 +667,20 @@ void test_arm_thread_swap(void)
 	zassert_true((__get_FPSCR() & 0x1) == 0x1,
 		"FPSCR bit-0 not restored at swap: 0x%x\n", __get_FPSCR());
 
+	/* The main test thread is using the FP registers, and the .mode
+	 * flag and MPU GUARD flag are now updated.
+	 */
+	zassert_true((_current->arch.mode & CONTROL_FPCA_Msk) != 0,
+		"Thread FPCA flag not set after main returned back\n");
+#if defined(CONFIG_MPU_STACK_GUARD)
+	zassert_true((_current->arch.mode &
+		Z_ARM_MODE_MPU_GUARD_FLOAT_Msk) != 0,
+		"Thread MPU GUARD FLOAT flag not set\n");
+	zassert_true((_current->base.user_options & K_FP_REGS) != 0,
+		"Thread K_FPREGS not set after main returned back\n");
+	zassert_true((FPU->FPCCR & FPU_FPCCR_LSPEN_Msk) != 0,
+		"Lazy FP Stacking not set after main returned back\n");
+#endif
 #endif /* CONFIG_FPU && CONFIG_FPU_SHARING */
 
 }