| 1 | // SPDX-License-Identifier: GPL-2.0+ |
|---|---|
| 2 | /* |
| 3 | * Copyright (C) 2019 Helge Deller <deller@gmx.de> |
| 4 | * |
| 5 | * Based on arch/arm64/kernel/jump_label.c |
| 6 | */ |
| 7 | #include <linux/kernel.h> |
| 8 | #include <linux/jump_label.h> |
| 9 | #include <linux/bug.h> |
| 10 | #include <asm/alternative.h> |
| 11 | #include <asm/patch.h> |
| 12 | |
| 13 | static inline int reassemble_17(int as17) |
| 14 | { |
| 15 | return (((as17 & 0x10000) >> 16) | |
| 16 | ((as17 & 0x0f800) << 5) | |
| 17 | ((as17 & 0x00400) >> 8) | |
| 18 | ((as17 & 0x003ff) << 3)); |
| 19 | } |
| 20 | |
| 21 | void arch_jump_label_transform(struct jump_entry *entry, |
| 22 | enum jump_label_type type) |
| 23 | { |
| 24 | void *addr = (void *)jump_entry_code(entry); |
| 25 | u32 insn; |
| 26 | |
| 27 | if (type == JUMP_LABEL_JMP) { |
| 28 | void *target = (void *)jump_entry_target(entry); |
| 29 | int distance = target - addr; |
| 30 | /* |
| 31 | * Encode the PA1.1 "b,n" instruction with a 17-bit |
| 32 | * displacement. In case we hit the BUG(), we could use |
| 33 | * another branch instruction with a 22-bit displacement on |
| 34 | * 64-bit CPUs instead. But this seems sufficient for now. |
| 35 | */ |
| 36 | distance -= 8; |
| 37 | BUG_ON(distance > 262143 || distance < -262144); |
| 38 | insn = 0xe8000002 | reassemble_17(as17: distance >> 2); |
| 39 | } else { |
| 40 | insn = INSN_NOP; |
| 41 | } |
| 42 | |
| 43 | patch_text(addr, insn); |
| 44 | } |
| 45 |