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