xtensa: initialize privileged stack during thread init (1dc02fcb) · Commits · Wenxi XU / zephyr

This adds the bits to initialize the privileged stack for each thread during thread initialization. This prevents information leaking if the thread stack is reused, and also aids in calculating stack space usage during system calls. Signed-off-by:

Daniel Leung <daniel.leung@intel.com>

arch/xtensa/core/thread.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -72,6 +72,18 @@ static void init_stack(struct k_thread thread, int *stack_top,
		frame->bsa.ps = PS_WOE \| PS_UM \| PS_CALLINC(1);
		#ifdef CONFIG_USERSPACE
		if ((thread->base.user_options & K_USER) == K_USER) {
		#ifdef CONFIG_INIT_STACKS
		/* setup_thread_stack() does not initialize the architecture specific
		* privileged stack. So we need to do it manually here as this function
		* is called by arch_new_thread() via z_setup_new_thread() after
		* setup_thread_stack() but before thread starts running.
		*
		* Note that only user threads have privileged stacks and kernel
		* only threads do not.
		*/
		(void)memset(&header->privilege_stack[0], 0xaa, sizeof(header->privilege_stack));
		#endif

		frame->bsa.pc = (uintptr_t)arch_user_mode_enter;
		} else {
		frame->bsa.pc = (uintptr_t)z_thread_entry;

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