x86: page-aligned stacks with guard page

Subsequent patches will set this guard page as unmapped,
triggering a page fault on access. If this is due to
stack overflow, a double fault will be triggered,
which we are now capable of handling with a switch to
a know good stack.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

arch/x86/core/thread.c

@@ -204,6 +204,9 @@ void _new_thread(struct k_thread *thread, char *pStackMem, size_t stackSize,
 
 	unsigned long *pInitialThread;
 
+#if _STACK_GUARD_SIZE
+	pStackMem += _STACK_GUARD_SIZE;
+#endif
 	_new_thread_init(thread, pStackMem, stackSize, priority, options);
 
 	/* carve the thread entry struct from the "base" of the stack */

arch/x86/include/kernel_arch_func.h

@@ -20,6 +20,8 @@ extern "C" {
 #define STACK_ROUND_UP(x) ROUND_UP(x, STACK_ALIGN_SIZE)
 #define STACK_ROUND_DOWN(x) ROUND_DOWN(x, STACK_ALIGN_SIZE)
 
+extern K_THREAD_STACK_DEFINE(_interrupt_stack, CONFIG_ISR_STACK_SIZE);
+
 /**
  *
  * @brief Performs architecture-specific initialization
@@ -32,10 +34,9 @@ extern "C" {
  */
 static inline void kernel_arch_init(void)
 {
-	extern char _interrupt_stack[CONFIG_ISR_STACK_SIZE];
-
 	_kernel.nested = 0;
-	_kernel.irq_stack = _interrupt_stack + CONFIG_ISR_STACK_SIZE;
+	_kernel.irq_stack = K_THREAD_STACK_BUFFER(_interrupt_stack) +
+				CONFIG_ISR_STACK_SIZE;
 }
 
 /**

include/arch/x86/arch.h

@@ -18,6 +18,7 @@
 #include <arch/x86/irq_controller.h>
 #include <kernel_arch_thread.h>
 #include <generated_dts_board.h>
+#include <mmustructs.h>
 
 #ifndef _ASMLANGUAGE
 #include <arch/x86/asm_inline.h>
@@ -530,25 +531,38 @@ extern FUNC_NORETURN void _SysFatalErrorHandler(unsigned int reason,
 						const NANO_ESF * pEsf);
 
 
+#ifdef CONFIG_X86_STACK_PROTECTION
+#define _STACK_GUARD_SIZE	MMU_PAGE_SIZE
+#define _STACK_BASE_ALIGN	MMU_PAGE_SIZE
+#else
+#define _STACK_GUARD_SIZE	0
+#define _STACK_BASE_ALIGN	STACK_ALIGN
+#endif
+
+
+
 /* All thread stacks, regardless of whether owned by application or kernel,
  * go in the .stacks input section, which will end up in the kernel's
  * noinit.
  */
 
 #define _ARCH_THREAD_STACK_DEFINE(sym, size) \
-	char _GENERIC_SECTION(.stacks) __aligned(STACK_ALIGN) sym[size]
+	char _GENERIC_SECTION(.stacks) __aligned(_STACK_BASE_ALIGN) \
+		sym[size + _STACK_GUARD_SIZE]
 
 #define _ARCH_THREAD_STACK_ARRAY_DEFINE(sym, nmemb, size) \
-	char _GENERIC_SECTION(.stacks) __aligned(STACK_ALIGN) sym[nmemb][size]
+	char _GENERIC_SECTION(.stacks) __aligned(_STACK_BASE_ALIGN) \
+		sym[nmemb][ROUND_UP(size, _STACK_BASE_ALIGN) + \
+			   _STACK_GUARD_SIZE]
 
 #define _ARCH_THREAD_STACK_MEMBER(sym, size) \
-	char __aligned(STACK_ALIGN) sym[size]
+	char __aligned(_STACK_BASE_ALIGN) sym[size + _STACK_GUARD_SIZE]
 
 #define _ARCH_THREAD_STACK_SIZEOF(sym) \
-	sizeof(sym)
+	(sizeof(sym) - _STACK_GUARD_SIZE)
 
 #define _ARCH_THREAD_STACK_BUFFER(sym) \
-	sym
+	(sym + _STACK_GUARD_SIZE)
 
 #if CONFIG_X86_KERNEL_OOPS
 #define _ARCH_EXCEPT(reason_p) do { \

kernel/init.c

@@ -121,14 +121,16 @@ K_THREAD_STACK_DEFINE(_interrupt_stack, CONFIG_ISR_STACK_SIZE);
 
 extern void idle(void *unused1, void *unused2, void *unused3);
 
-void k_call_stacks_analyze(void)
-{
 #if defined(CONFIG_INIT_STACKS) && defined(CONFIG_PRINTK)
-	extern char sys_work_q_stack[CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE];
+extern K_THREAD_STACK_DEFINE(sys_work_q_stack,
+			     CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE);
 #if defined(CONFIG_ARC) && CONFIG_RGF_NUM_BANKS != 1
-	extern char _firq_stack[CONFIG_FIRQ_STACK_SIZE];
+extern K_THREAD_STACK_DEFINE(_firq_stack, CONFIG_FIRQ_STACK_SIZE);
 #endif /* CONFIG_ARC */
 
+
+void k_call_stacks_analyze(void)
+{
 	printk("Kernel stacks:\n");
 	STACK_ANALYZE("main     ", _main_stack);
 	STACK_ANALYZE("idle     ", _idle_stack);
@@ -137,9 +139,10 @@ void k_call_stacks_analyze(void)
 #endif /* CONFIG_ARC */
 	STACK_ANALYZE("interrupt", _interrupt_stack);
 	STACK_ANALYZE("workqueue", sys_work_q_stack);
-
-#endif /* CONFIG_INIT_STACKS && CONFIG_PRINTK */
 }
+#else
+void k_call_stacks_analyze(void) { }
+#endif
 
 /**
  *