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| 3 | * arch/arm/kernel/return_address.c
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| 4 | *
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| 5 | * Copyright (C) 2009 Uwe Kleine-Koenig <[email protected]>
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| 6 | * for Pengutronix
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| 7 |
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| 8 | #include <linux/export.h>
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| 9 | #include <linux/ftrace.h>
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| 10 | #include <linux/sched.h>
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| 11 |
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| 12 | #include <asm/stacktrace.h>
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| 13 |
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| 14 | struct return_address_data {
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| 15 | unsigned int level;
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| 16 | void *addr;
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| 17 | };
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| 18 |
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| 19 | static bool save_return_addr(void *d, unsigned long pc)
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| 20 | {
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| 21 | struct return_address_data *data = d;
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| 22 |
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| 23 | if (!data->level) {
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| 24 | data->addr = (void *)pc;
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| 25 |
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| 26 | return false;
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| 27 | } else {
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| 28 | --data->level;
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| 29 | return true;
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| 30 | }
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| 31 | }
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| 32 |
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| 33 | void *return_address(unsigned int level)
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| 34 | {
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| 35 | struct return_address_data data;
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| 36 | struct stackframe frame;
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| 37 |
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| 38 | data.level = level + 2;
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| 39 | data.addr = NULL;
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| 40 |
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| 41 | frame.fp = (unsigned long)__builtin_frame_address(0);
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| 42 | frame.sp = current_stack_pointer;
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| 43 | frame.lr = (unsigned long)__builtin_return_address(0);
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| 44 | here:
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| 45 | frame.pc = (unsigned long)&&here;
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| 46 | #ifdef CONFIG_KRETPROBES
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| 47 | frame.kr_cur = NULL;
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| 48 | frame.tsk = current;
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| 49 | #endif
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| 50 | frame.ex_frame = false;
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| 51 |
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| 52 | walk_stackframe(&frame, save_return_addr, &data);
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| 53 |
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| 54 | if (!data.level)
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| 55 | return data.addr;
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| 56 | else
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| 57 | return NULL;
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| 58 | }
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| 59 |
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| 60 | EXPORT_SYMBOL_GPL(return_address);
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