arm-trusted-firmware/lib/stack_protector/aarch32/asm_stack_protector.S

/*
 * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <arch.h>
#include <asm_macros.S>
#include <assert_macros.S>

	.globl	update_stack_protector_canary

/* -----------------------------------------------------------------------
 * void update_stack_protector_canary(void)
 *
 * Change the value of the canary used for stack smashing attacks protection.
 * Note: This must be called when it is safe to call C code, but this cannot be
 * called by C code. Doing this will make the check fail when the calling
 * function returns.
 * -----------------------------------------------------------------------
 */

func update_stack_protector_canary
	/* Use r4 as it is callee-saved */
	mov	r4, lr
	bl	plat_get_stack_protector_canary

	/* Update the canary with the returned value */
	ldr	r1,  =__stack_chk_guard
	str	r0, [r1]
	bx	r4
endfunc update_stack_protector_canary