kernel: arch: move arch_swap() declaration

Moves the arch_swap() declaration out of kernel_arch_interface.h and into the various architectures' kernel_arch_func.h. This permits the arch_swap() to be inlined on ARM, but extern'd on the other architectures that still implement arch_swap(). Inlining this function on ARM has shown at least a +5% performance boost according to the thread_metric benchmark on the disco_l475_iot1 board. Signed-off-by: Peter Mitsis <[email protected]>
zephyrproject-rtos · Dec 3, 2024 · dcaad72 · dcaad72
1 parent c896dd3
commit dcaad72
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Showing 11 changed files with 46 additions and 82 deletions.
diff --git a/arch/arm/core/cortex_a_r/CMakeLists.txt b/arch/arm/core/cortex_a_r/CMakeLists.txt
@@ -24,4 +24,4 @@ zephyr_library_sources_ifdef(CONFIG_SEMIHOST semihost.c)
 zephyr_library_sources_ifdef(CONFIG_THREAD_LOCAL_STORAGE __aeabi_read_tp.S)
 zephyr_library_sources_ifdef(CONFIG_ARCH_CACHE cache.c)
 zephyr_library_sources_ifdef(CONFIG_USE_SWITCH switch.S)
-zephyr_library_sources_ifndef(CONFIG_USE_SWITCH swap.c swap_helper.S exc_exit.S)
+zephyr_library_sources_ifndef(CONFIG_USE_SWITCH swap_helper.S exc_exit.S)
diff --git a/arch/arm/core/cortex_a_r/swap.c b/arch/arm/core/cortex_a_r/swap.c
diff --git a/arch/arm/core/cortex_m/CMakeLists.txt b/arch/arm/core/cortex_m/CMakeLists.txt
@@ -11,7 +11,6 @@ zephyr_library_sources(
   scb.c
   thread_abort.c
   vector_table.S
-  swap.c
   swap_helper.S
   irq_manage.c
   prep_c.c

diff --git a/arch/arm/core/cortex_m/swap.c b/arch/arm/core/cortex_m/swap.c
diff --git a/arch/arm/include/cortex_a_r/kernel_arch_func.h b/arch/arm/include/cortex_a_r/kernel_arch_func.h
@@ -37,6 +37,21 @@ static ALWAYS_INLINE void arch_kernel_init(void)
 
 #ifndef CONFIG_USE_SWITCH
 
+static ALWAYS_INLINE int arch_swap(unsigned int key)
+{
+	/* store off key and return value */
+	arch_current_thread()->arch.basepri = key;
+	arch_current_thread()->arch.swap_return_value = -EAGAIN;
+
+	z_arm_cortex_r_svc();
+	irq_unlock(key);
+
+	/* Context switch is performed here. Returning implies the
+	 * thread has been context-switched-in again.
+	 */
+	return arch_current_thread()->arch.swap_return_value;
+}
+
 static ALWAYS_INLINE void
 arch_thread_return_value_set(struct k_thread *thread, unsigned int value)
 {

diff --git a/arch/arm/include/cortex_m/kernel_arch_func.h b/arch/arm/include/cortex_m/kernel_arch_func.h
@@ -84,6 +84,25 @@ extern FUNC_NORETURN void z_arm_userspace_enter(k_thread_entry_t user_entry,
 
 extern void z_arm_fatal_error(unsigned int reason, const struct arch_esf *esf);
 
+static ALWAYS_INLINE int arch_swap(unsigned int key)
+{
+	/* store off key and return value */
+	arch_current_thread()->arch.basepri = key;
+	arch_current_thread()->arch.swap_return_value = -EAGAIN;
+
+	/* set pending bit to make sure we will take a PendSV exception */
+	SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
+
+	/* clear mask or enable all irqs to take a pendsv */
+	irq_unlock(0);
+
+	/* Context switch is performed here. Returning implies the
+	 * thread has been context-switched-in again.
+	 */
+	return arch_current_thread()->arch.swap_return_value;
+}
+
+
 #endif /* _ASMLANGUAGE */
 
 #ifdef __cplusplus

diff --git a/arch/mips/include/kernel_arch_func.h b/arch/mips/include/kernel_arch_func.h
@@ -47,6 +47,8 @@ static inline bool arch_is_in_isr(void)
 	return _current_cpu->nested != 0U;
 }
 
+int arch_swap(unsigned int key);
+
 #ifdef CONFIG_IRQ_OFFLOAD
 void z_irq_do_offload(void);
 #endif

diff --git a/arch/nios2/include/kernel_arch_func.h b/arch/nios2/include/kernel_arch_func.h
@@ -51,6 +51,8 @@ static inline bool arch_is_in_isr(void)
 	return _kernel.cpus[0].nested != 0U;
 }
 
+int arch_swap(unsigned int key);
+
 #ifdef CONFIG_IRQ_OFFLOAD
 void z_irq_do_offload(void);
 #endif

diff --git a/arch/posix/include/kernel_arch_func.h b/arch/posix/include/kernel_arch_func.h
@@ -42,6 +42,8 @@ static inline bool arch_is_in_isr(void)
 	return _kernel.cpus[0].nested != 0U;
 }
 
+int arch_swap(unsigned int key);
+
 #endif /* _ASMLANGUAGE */
 
 #endif /* ZEPHYR_ARCH_POSIX_INCLUDE_KERNEL_ARCH_FUNC_H_ */
diff --git a/arch/x86/include/ia32/kernel_arch_func.h b/arch/x86/include/ia32/kernel_arch_func.h
@@ -37,6 +37,8 @@ arch_thread_return_value_set(struct k_thread *thread, unsigned int value)
 
 extern void arch_cpu_atomic_idle(unsigned int key);
 
+int arch_swap(unsigned int key);
+
 /* ASM code to fiddle with registers to enable the MMU with PAE paging */
 void z_x86_enable_paging(void);
 

diff --git a/kernel/include/kernel_arch_interface.h b/kernel/include/kernel_arch_interface.h
@@ -129,7 +129,9 @@ void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
  *        location, which must be updated.
  */
 static inline void arch_switch(void *switch_to, void **switched_from);
-#else
+#endif
+
+#if !defined(CONFIG_USE_SWITCH) || defined(__DOXYGEN__)
 /**
  * Cooperatively context switch
  *