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kernel: userspace: reserve stack space to store local data

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This enables reserving little space on the top of stack to store
data local to thread when CONFIG_USERSPACE. The first customer
of this is errno.

Note that ARC, due to how it lays out the user stack and
privilege stack, sets the pointer itself rather than
relying on the common way.

Fixes: #9067

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2018-08-16 15:42:28 -07:00 • committed by Anas Nashif
commit fc182430c0
5 changed files with 54 additions and 10 deletions
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18
include/kernel.h
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@ -503,6 +503,12 @@ struct _mem_domain_info {
#endif /* CONFIG_USERSPACE */
#ifdef CONFIG_THREAD_USERSPACE_LOCAL_DATA
struct _thread_userspace_local_data {
int errno_var;
};
#endif
/**
* @ingroup thread_apis
* Thread Structure
@ -538,14 +544,12 @@ struct k_thread {
void *custom_data;
#endif
#ifdef CONFIG_THREAD_USERSPACE_LOCAL_DATA
struct _thread_userspace_local_data *userspace_local_data;
#endif
#ifdef CONFIG_ERRNO
#ifdef CONFIG_USERSPACE
/* Set to the lowest area in the thread stack since this needs to
* be directly read/writable by user mode. Not ideal, but best we
* can do until we have thread-local storage
*/
int *errno_location;
#else
#ifndef CONFIG_USERSPACE
/** per-thread errno variable */
int errno_var;
#endif