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/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2025 IBM Corporation, Saket Kumar Bhaskar <skb99@linux.ibm.com> */
#include <linux/linkage.h>
#include <asm/ppc_asm.h>
/*
* arch_bpf_timed_may_goto() trampoline for powerpc64
*
* Custom BPF convention (verifier/JIT):
* - input: stack offset in BPF_REG_AX (r12)
* - output: updated count in BPF_REG_AX (r12)
*
* Call bpf_check_timed_may_goto(ptr) with normal powerpc64 ABI:
* - r3 = ptr, return in r3
*
* Preserve BPF regs R0-R5 (mapping: r8, r3-r7).
*/
SYM_FUNC_START(arch_bpf_timed_may_goto)
/* Prologue: save LR, allocate frame */
mflr r0
std r0, 16(r1)
stdu r1, -112(r1)
/* Save BPF registers R0 - R5 (r8, r3-r7) */
std r3, 32(r1)
std r4, 40(r1)
std r5, 48(r1)
std r6, 56(r1)
std r7, 64(r1)
std r8, 72(r1)
/*
* r3 = BPF_REG_FP + BPF_REG_AX
* BPF_REG_FP is r31; BPF_REG_AX is r12 (stack offset in bytes).
*/
add r3, r31, r12
bl bpf_check_timed_may_goto
/* Put return value back into AX */
mr r12, r3
/* Restore BPF registers R0 - R5 (r8, r3-r7) */
ld r3, 32(r1)
ld r4, 40(r1)
ld r5, 48(r1)
ld r6, 56(r1)
ld r7, 64(r1)
ld r8, 72(r1)
/* Epilogue: pop frame, restore LR, return */
addi r1, r1, 112
ld r0, 16(r1)
mtlr r0
blr
SYM_FUNC_END(arch_bpf_timed_may_goto)
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