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userspace: treat thread stacks as kernel objects

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We need to track permission on stack memory regions like we do
with other kernel objects. We want stacks to live in a memory
area that is outside the scope of memory domain permission
management. We need to be able track what stacks are in use,
and what stacks may be used by user threads trying to call
k_thread_create().

Some special handling is needed because thread stacks appear as
variously-sized arrays of struct _k_thread_stack_element which is
just a char. We need the entire array to be considered an object,
but also properly handle arrays of stacks.

Validation of stacks also requires that the bounds of the stack
are not exceeded. Various approaches were considered. Storing
the size in some header region of the stack itself would not allow
the stack to live in 'noinit'. Having a stack object be a data
structure that points to the stack buffer would confound our
current APIs for declaring stacks as arrays or struct members.
In the end, the struct _k_object was extended to store this size.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2017-10-15 14:17:48 -07:00 • committed by Andrew Boie
commit bca15da650
7 changed files with 105 additions and 59 deletions
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4
include/arch/arm/arch.h
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@ -135,7 +135,7 @@ extern "C" {
* @param size Size of the stack memory region
*/
#define _ARCH_THREAD_STACK_DEFINE(sym, size) \
struct _k_thread_stack_element __noinit __aligned(STACK_ALIGN) \
struct _k_thread_stack_element __kernel_noinit __aligned(STACK_ALIGN) \
sym[size+MPU_GUARD_ALIGN_AND_SIZE]
/**
@ -152,7 +152,7 @@ extern "C" {
* @param size Size of the stack memory region
*/
#define _ARCH_THREAD_STACK_ARRAY_DEFINE(sym, nmemb, size) \
struct _k_thread_stack_element __noinit __aligned(STACK_ALIGN) \
struct _k_thread_stack_element __kernel_noinit __aligned(STACK_ALIGN) \
sym[nmemb][size+MPU_GUARD_ALIGN_AND_SIZE]
/**