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| 2 | |
| 3 | * arch/arm64/kernel/return_address.c
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| 4 | *
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| 5 | * Copyright (C) 2013 Linaro Limited
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| 6 | * Author: AKASHI Takahiro <[email protected]>
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| 7 |
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| 8 |
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| 9 | #include <linux/export.h>
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| 10 | #include <linux/ftrace.h>
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| 11 | #include <linux/kprobes.h>
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| 12 | #include <linux/stacktrace.h>
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| 13 |
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| 14 | #include <asm/stack_pointer.h>
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| 15 |
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| 16 | struct return_address_data {
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| 17 | unsigned int level;
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| 18 | void *addr;
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| 19 | };
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| 20 |
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| 21 | static bool save_return_addr(void *d, unsigned long pc)
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| 22 | {
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| 23 | struct return_address_data *data = d;
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| 24 |
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| 25 | if (!data->level) {
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| 26 | data->addr = (void *)pc;
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| 27 | return false;
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| 28 | } else {
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| 29 | --data->level;
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| 30 | return true;
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| 31 | }
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| 32 | }
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| 33 | NOKPROBE_SYMBOL(save_return_addr);
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| 34 |
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| 35 | void *return_address(unsigned int level)
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| 36 | {
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| 37 | struct return_address_data data;
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| 38 |
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| 39 | data.level = level + 2;
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| 40 | data.addr = NULL;
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| 41 |
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| 42 | arch_stack_walk(save_return_addr, &data, current, NULL);
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| 43 |
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| 44 | if (!data.level)
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| 45 | return data.addr;
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| 46 | else
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| 47 | return NULL;
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| 48 | }
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| 49 | EXPORT_SYMBOL_GPL(return_address);
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| 50 | NOKPROBE_SYMBOL(return_address);
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