/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * arch/arm/lib/call_with_stack.S
 *
 * Copyright (C) 2011 ARM Ltd.
 * Written by Will Deacon <will.deacon@arm.com>
 */

#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/unwind.h>

/*
 * void call_with_stack(void (*fn)(void *), void *arg, void *sp)
 *
 * Change the stack to that pointed at by sp, then invoke fn(arg) with
 * the new stack.
 *
 * The sequence below follows the APCS frame convention for frame pointer
 * unwinding, and implements the unwinder annotations needed by the EABI
 * unwinder.
 */

ENTRY(call_with_stack)
#if defined(CONFIG_UNWINDER_FRAME_POINTER) && defined(CONFIG_CC_IS_GCC)
        mov     ip, sp
        push    {fp, ip, lr, pc}
        sub     fp, ip, #4
#else
UNWIND( .fnstart                )
UNWIND( .save   {fpreg, lr}     )
        push    {fpreg, lr}
UNWIND( .setfp  fpreg, sp       )
        mov     fpreg, sp
#endif
        mov     sp, r2
        mov     r2, r0
        mov     r0, r1

        bl_r    r2

#if defined(CONFIG_UNWINDER_FRAME_POINTER) && defined(CONFIG_CC_IS_GCC)
        ldmdb   fp, {fp, sp, pc}
#else
        mov     sp, fpreg
        pop     {fpreg, pc}
UNWIND( .fnend                  )
#endif
        .globl call_with_stack_end
call_with_stack_end:
ENDPROC(call_with_stack)