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