tests/kernel: Avoid C library calls from interrupt handlers

On arm64, GCC feels free to use floating point registers for essentially
anything unless we build with -mgeneral-regs-only. After the FPU gets used
in an interrupt handler, interrupts are disabled as there's no place to
save the registers during a nested exception. As the C library may be built
separately without this flag, we cannot use any of its functions or risk
having nested exceptions fail.

Switch printk usage to k_str_out and stick to (mostly) Zephyr internal
functions to ensure nested interrupts work correctly.

Signed-off-by: Keith Packard <keithp@keithp.com>

Author: keith-packard

subsys/testsuite/include/zephyr/interrupt_util.h

@@ -7,6 +7,8 @@
 #ifndef INTERRUPT_UTIL_H_
 #define INTERRUPT_UTIL_H_
 
+#define k_str_out_count(s) k_str_out(s, sizeof(s) - 1);
+
 #if defined(CONFIG_CPU_CORTEX_M)
 #include <cmsis_core.h>
 
@@ -57,7 +59,7 @@ static inline uint32_t get_available_nvic_line(uint32_t initial_offset)
 
 static inline void trigger_irq(int irq)
 {
-	printk("Triggering irq : %d\n", irq);
+	k_str_out_count("Triggering irq\n");
 #if defined(CONFIG_SOC_TI_LM3S6965_QEMU) || defined(CONFIG_CPU_CORTEX_M0) ||                       \
 	defined(CONFIG_CPU_CORTEX_M0PLUS) || defined(CONFIG_CPU_CORTEX_M1) ||                      \
 	defined(CONFIG_ARMV6_M_ARMV8_M_BASELINE)
@@ -74,7 +76,7 @@ static inline void trigger_irq(int irq)
 
 static inline void trigger_irq(int irq)
 {
-	printk("Triggering irq : %d\n", irq);
+	k_str_out_count("Triggering irq\n");
 
 	/* Ensure that the specified IRQ number is a valid SGI interrupt ID */
 	zassert_true(irq <= 15, "%u is not a valid SGI interrupt ID", irq);
@@ -96,7 +98,7 @@ static inline void trigger_irq(int irq)
 #elif defined(CONFIG_ARC)
 static inline void trigger_irq(int irq)
 {
-	printk("Triggering irq : %d\n", irq);
+	k_str_out_count("Triggering irq\n");
 	z_arc_v2_aux_reg_write(_ARC_V2_AUX_IRQ_HINT, irq);
 }
 

tests/kernel/interrupt/CMakeLists.txt

@@ -16,6 +16,10 @@ target_sources(app PRIVATE
     src/nested_irq.c
     )
 
+if(CONFIG_ARM64)
+  add_compile_options(-mgeneral-regs-only)
+endif()
+
 target_sources_ifdef(CONFIG_DYNAMIC_INTERRUPTS app PRIVATE src/dynamic_isr.c)
 target_sources_ifdef(CONFIG_X86 app PRIVATE src/regular_isr.c)
 target_sources_ifdef(CONFIG_SHARED_INTERRUPTS app PRIVATE src/static_shared_irq.c)

tests/kernel/interrupt/src/nested_irq.c

@@ -102,19 +102,19 @@ void isr1(const void *param)
 {
 	ARG_UNUSED(param);
 
-	printk("isr1: Enter\n");
+	k_str_out_count("isr1: Enter\n");
 
 	/* Set verification token */
 	isr1_result = ISR1_TOKEN;
 
-	printk("isr1: Leave\n");
+	k_str_out_count("isr1: Leave\n");
 }
 
 void isr0(const void *param)
 {
 	ARG_UNUSED(param);
 
-	printk("isr0: Enter\n");
+	k_str_out_count("isr0: Enter\n");
 
 	/* Set verification token */
 	isr0_result = ISR0_TOKEN;
@@ -128,7 +128,7 @@ void isr0(const void *param)
 	/* Validate nested ISR result token */
 	zassert_equal(isr1_result, ISR1_TOKEN, "isr1 did not execute");
 
-	printk("isr0: Leave\n");
+	k_str_out_count("isr0: Leave\n");
 }
 
 /**