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kernel: introduce k_float_disable system call

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We introduce k_float_disable() system call, to allow threads to
disable floating point context preservation. The system call is
to be used in FP Sharing Registers mode (CONFIG_FP_SHARING=y).

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
This commit is contained in:
Ioannis Glaropoulos 2019-05-09 21:55:10 +02:00 • committed by Andrew Boie
commit a6cb8b06db
3 changed files with 61 additions and 0 deletions
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23
include/kernel.h
View file

@ -4906,6 +4906,29 @@ __syscall void k_str_out(char *c, size_t n);
extern void z_arch_start_cpu(int cpu_num, k_thread_stack_t *stack, int sz,
void (*fn)(int key, void *data), void *arg);
/**
* @brief Disable preservation of floating point context information.
*
* This routine informs the kernel that the specified thread
* will no longer be using the floating point registers.
*
* @warning
* Some architectures apply restrictions on how the disabling of floating
* point preservation may be requested, see z_arch_float_disable.
*
* @warning
* This routine should only be used to disable floating point support for
* a thread that currently has such support enabled.
*
* @param thread ID of thread.
*
* @retval 0 On success.
* @retval -ENOSYS If the floating point disabling is not implemented.
* -EINVAL If the floating point disabling could not be performed.
*/
__syscall int k_float_disable(struct k_thread *thread);
#ifdef __cplusplus
}
#endif

18
kernel/include/kernel_internal.h
View file

@ -51,6 +51,24 @@ extern void z_setup_new_thread(struct k_thread *new_thread,
void *p1, void *p2, void *p3,
int prio, u32_t options, const char *name);
#if defined(CONFIG_FLOAT) && defined(CONFIG_FP_SHARING)
/**
* @brief Disable floating point context preservation
*
* The function is used to disable the preservation of floating
* point context information for a particular thread.
*
* @note
* For ARM architecture, disabling floating point preservation
* - may only be requested for the current thread
* - cannot be requested in ISRs.
*
* @retval 0 On success.
* @retval -EINVAL If the floating point disabling could not be performed.
*/
extern int z_arch_float_disable(struct k_thread *thread);
#endif /* CONFIG_FLOAT && CONFIG_FP_SHARING */
#ifdef CONFIG_USERSPACE
/**
* @brief Get the maximum number of partitions for a memory domain

20
kernel/thread.c
View file

@ -727,4 +727,24 @@ void z_spin_lock_set_owner(struct k_spinlock *l)
l->thread_cpu = _current_cpu->id | (uintptr_t)_current;
}
int z_impl_k_float_disable(struct k_thread *thread)
{
#if defined(CONFIG_FLOAT) && defined(CONFIG_FP_SHARING)
return z_arch_float_disable(thread);
#else
return -ENOSYS;
#endif /* CONFIG_FLOAT && CONFIG_FP_SHARING */
}
#ifdef CONFIG_USERSPACE
Z_SYSCALL_HANDLER(k_float_disable, thread_p)
{
struct k_thread *thread = (struct k_thread *)thread_p;
Z_OOPS(Z_SYSCALL_OBJ(thread, K_OBJ_THREAD));
return z_impl_k_float_disable((struct k_thread *)thread_p);
}
#endif /* CONFIG_USERSPACE */
#endif