arch/arm/lib/call_with_stack.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * arch/arm/lib/call_with_stack.S
   4  *
   5  * Copyright (C) 2011 ARM Ltd.
   6  * Written by Will Deacon <will.deacon@arm.com>
   7  */
   8
   9 #include <linux/linkage.h>
  10 #include <asm/assembler.h>
  11 #include <asm/unwind.h>
  12
  13 /*
  14  * void call_with_stack(void (*fn)(void *), void *arg, void *sp)
  15  *
  16  * Change the stack to that pointed at by sp, then invoke fn(arg) with
  17  * the new stack.
  18  *
  19  * The sequence below follows the APCS frame convention for frame pointer
  20  * unwinding, and implements the unwinder annotations needed by the EABI
  21  * unwinder.
  22  */
  23
  24 ENTRY(call_with_stack)
  25 #if defined(CONFIG_UNWINDER_FRAME_POINTER) && defined(CONFIG_CC_IS_GCC)
  26         mov     ip, sp
  27         push    {fp, ip, lr, pc}
  28         sub     fp, ip, #4
  29 #else
  30 UNWIND( .fnstart                )
  31 UNWIND( .save   {fpreg, lr}     )
  32         push    {fpreg, lr}
  33 UNWIND( .setfp  fpreg, sp       )
  34         mov     fpreg, sp
  35 #endif
  36         mov     sp, r2
  37         mov     r2, r0
  38         mov     r0, r1
  39
  40         bl_r    r2
  41
  42 #if defined(CONFIG_UNWINDER_FRAME_POINTER) && defined(CONFIG_CC_IS_GCC)
  43         ldmdb   fp, {fp, sp, pc}
  44 #else
  45         mov     sp, fpreg
  46         pop     {fpreg, pc}
  47 UNWIND( .fnend                  )
  48 #endif
  49         .globl call_with_stack_end
  50 call_with_stack_end:
  51 ENDPROC(call_with_stack)