kernel: support using thread local storage for errno
This enables storing errno in the thread local storage area. With this enabled, a syscall to access errno can be avoided when userspace is also enabled. Signed-off-by: Daniel Leung <daniel.leung@intel.com>
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parent
2c8625ea7e
commit
62cf1960ad
5 changed files with 35 additions and 3 deletions
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@ -266,7 +266,9 @@ struct _mem_domain_info {
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#ifdef CONFIG_THREAD_USERSPACE_LOCAL_DATA
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struct _thread_userspace_local_data {
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#if defined(CONFIG_ERRNO) && !defined(CONFIG_ERRNO_IN_TLS)
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int errno_var;
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#endif
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};
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#endif
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@ -329,7 +331,7 @@ struct k_thread {
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struct _thread_userspace_local_data *userspace_local_data;
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#endif
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#ifdef CONFIG_ERRNO
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#if defined(CONFIG_ERRNO) && !defined(CONFIG_ERRNO_IN_TLS)
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#ifndef CONFIG_USERSPACE
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/** per-thread errno variable */
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int errno_var;
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@ -17,6 +17,14 @@ extern "C" {
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* and kernel.h
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*/
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#ifdef CONFIG_ERRNO_IN_TLS
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extern __thread int z_errno_var;
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static inline int *z_errno(void)
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{
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return &z_errno_var;
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}
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#else
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/**
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* return a pointer to a memory location containing errno
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*
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@ -27,10 +35,14 @@ extern "C" {
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*/
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__syscall int *z_errno(void);
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#endif /* CONFIG_ERRNO_IN_TLS */
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#ifdef __cplusplus
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}
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#endif
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#ifndef CONFIG_ERRNO_IN_TLS
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#include <syscalls/errno_private.h>
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#endif /* CONFIG_ERRNO_IN_TLS */
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#endif /* ZEPHYR_INCLUDE_SYS_ERRNO_PRIVATE_H_ */
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@ -195,16 +195,24 @@ config THREAD_CUSTOM_DATA
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config THREAD_USERSPACE_LOCAL_DATA
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bool
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depends on USERSPACE
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default y if ERRNO && !ERRNO_IN_TLS
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config ERRNO
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bool "Enable errno support"
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default y
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select THREAD_USERSPACE_LOCAL_DATA if USERSPACE
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help
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Enable per-thread errno in the kernel. Application and library code must
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include errno.h provided by the C library (libc) to use the errno
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symbol. The C library must access the per-thread errno via the
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_get_errno() symbol.
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z_errno() symbol.
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config ERRNO_IN_TLS
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bool "Store errno in thread local storage (TLS)"
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depends on ERRNO && THREAD_LOCAL_STORAGE
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default y
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help
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Use thread local storage to store errno instead of storing it in
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the kernel thread struct. This avoids a syscall if userspace is enabled.
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choice SCHED_ALGORITHM
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prompt "Scheduler priority queue algorithm"
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@ -23,6 +23,11 @@
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const int _k_neg_eagain = -EAGAIN;
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#ifdef CONFIG_ERRNO
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#ifdef CONFIG_ERRNO_IN_TLS
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__thread int z_errno_var;
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#else
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#ifdef CONFIG_USERSPACE
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int *z_impl_z_errno(void)
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{
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@ -44,4 +49,7 @@ int *z_impl_z_errno(void)
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return &_current->errno_var;
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}
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#endif /* CONFIG_USERSPACE */
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#endif /* CONFIG_ERRNO_IN_TLS */
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#endif /* CONFIG_ERRNO */
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@ -835,8 +835,10 @@ FUNC_NORETURN void k_thread_user_mode_enter(k_thread_entry_t entry,
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#ifdef CONFIG_USERSPACE
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__ASSERT(z_stack_is_user_capable(_current->stack_obj),
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"dropping to user mode with kernel-only stack object");
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#ifdef CONFIG_THREAD_USERSPACE_LOCAL_DATA
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memset(_current->userspace_local_data, 0,
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sizeof(struct _thread_userspace_local_data));
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#endif
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arch_user_mode_enter(entry, p1, p2, p3);
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#else
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/* XXX In this case we do not reset the stack */
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