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arch: arm: thread built-in stack guard implementation

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This commit activates the built-in stack guard on the main_thread
before jumping to it upon system initialization. Stack guard is
activated if BUILTIN_STACK_GUARD is enabled by the user. The
commit also activates built-in thread stack guards at every
context switch, if BUILTIN_STACK_GUARD enabled by the user.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
This commit is contained in:
Ioannis Glaropoulos 2018-03-11 22:29:25 +01:00 • committed by Anas Nashif
commit 8d1b013f3c
4 changed files with 44 additions and 0 deletions
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1
arch/arm/core/Kconfig
View file

@ -37,6 +37,7 @@ config CPU_HAS_SYSTICK
config BUILTIN_STACK_GUARD
bool "Thread Stack Guards based on built-in ARM stack limit checking"
depends on CPU_CORTEX_M_HAS_SPLIM
select THREAD_STACK_INFO
default n
help
Enable Thread/Interrupt Stack Guards via built-in Stack Pointer

8
arch/arm/core/swap_helper.S
View file

@ -175,6 +175,14 @@ _thread_irq_disabled:
pop {r2, lr}
#endif /* CONFIG_MPU_STACK_GUARD */
#ifdef CONFIG_BUILTIN_STACK_GUARD
/* r2 contains k_thread */
add r0, r2, #0
push {r2, lr}
blx configure_builtin_stack_guard
pop {r2, lr}
#endif /* CONFIG_BUILTIN_STACK_GUARD */
#ifdef CONFIG_USERSPACE
/* restore mode */
ldr r0, [r2, #_thread_offset_to_mode]

26
arch/arm/core/thread.c
View file

@ -141,3 +141,29 @@ FUNC_NORETURN void _arch_user_mode_enter(k_thread_entry_t user_entry,
}
#endif
#if defined(CONFIG_BUILTIN_STACK_GUARD)
/*
* @brief Configure ARM built-in stack guard
*
* This function configures per thread stack guards by reprogramming
* the built-in Process Stack Pointer Limit Register (PSPLIM).
*
* @param thread thread info data structure.
*/
void configure_builtin_stack_guard(struct k_thread *thread)
{
#if defined(CONFIG_USERSPACE)
u32_t guard_start = thread->arch.priv_stack_start ?
(u32_t)thread->arch.priv_stack_start :
(u32_t)thread->stack_obj;
#else
u32_t guard_start = thread->stack_info.start;
#endif
#if defined(CONFIG_CPU_CORTEX_M_HAS_SPLIM)
__set_PSPLIM(guard_start);
#else
#error "Built-in PSP limit checks not supported by HW"
#endif
}
#endif /* CONFIG_BUIILTIN_STACK_GUARD */

9
arch/arm/include/kernel_arch_func.h
View file

@ -59,6 +59,15 @@ _arch_switch_to_main_thread(struct k_thread *main_thread,
/* the ready queue cache already contains the main thread */
#if defined(CONFIG_BUILTIN_STACK_GUARD)
/* Set PSPLIM register for built-in stack guarding of main thread. */
#if defined(CONFIG_CPU_CORTEX_M_HAS_SPLIM)
__set_PSPLIM((u32_t)main_stack);
#else
#error "Built-in PSP limit checks not supported by HW"
#endif
#endif /* CONFIG_BUILTIN_STACK_GUARD */
__asm__ __volatile__(
/* move to main() thread stack */