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eecac38b SH |
1 | /* |
2 | * OpenRISC unwinder.c | |
3 | * | |
4 | * Reusable arch specific api for unwinding stacks. | |
5 | * | |
6 | * Copyright (C) 2017 Stafford Horne <shorne@gmail.com> | |
7 | * | |
8 | * This file is licensed under the terms of the GNU General Public License | |
9 | * version 2. This program is licensed "as is" without any warranty of any | |
10 | * kind, whether express or implied. | |
11 | */ | |
12 | ||
13 | #include <linux/sched/task_stack.h> | |
14 | #include <linux/kernel.h> | |
15 | ||
16 | #include <asm/unwinder.h> | |
17 | ||
18 | #ifdef CONFIG_FRAME_POINTER | |
19 | struct or1k_frameinfo { | |
20 | unsigned long *fp; | |
21 | unsigned long ra; | |
22 | unsigned long top; | |
23 | }; | |
24 | ||
25 | /* | |
26 | * Verify a frameinfo structure. The return address should be a valid text | |
27 | * address. The frame pointer may be null if its the last frame, otherwise | |
28 | * the frame pointer should point to a location in the stack after the the | |
29 | * top of the next frame up. | |
30 | */ | |
31 | static inline int or1k_frameinfo_valid(struct or1k_frameinfo *frameinfo) | |
32 | { | |
33 | return (frameinfo->fp == NULL || | |
34 | (!kstack_end(frameinfo->fp) && | |
35 | frameinfo->fp > &frameinfo->top)) && | |
36 | __kernel_text_address(frameinfo->ra); | |
37 | } | |
38 | ||
39 | /* | |
40 | * Create a stack trace doing scanning which is frame pointer aware. We can | |
41 | * get reliable stack traces by matching the previously found frame | |
42 | * pointer with the top of the stack address every time we find a valid | |
43 | * or1k_frameinfo. | |
44 | * | |
45 | * Ideally the stack parameter will be passed as FP, but it can not be | |
46 | * guaranteed. Therefore we scan each address looking for the first sign | |
47 | * of a return address. | |
48 | * | |
49 | * The OpenRISC stack frame looks something like the following. The | |
50 | * location SP is held in r1 and location FP is held in r2 when frame pointers | |
51 | * enabled. | |
52 | * | |
53 | * SP -> (top of stack) | |
54 | * - (callee saved registers) | |
55 | * - (local variables) | |
56 | * FP-8 -> previous FP \ | |
57 | * FP-4 -> return address |- or1k_frameinfo | |
58 | * FP -> (previous top of stack) / | |
59 | */ | |
60 | void unwind_stack(void *data, unsigned long *stack, | |
61 | void (*trace)(void *data, unsigned long addr, int reliable)) | |
62 | { | |
63 | unsigned long *next_fp = NULL; | |
64 | struct or1k_frameinfo *frameinfo = NULL; | |
65 | int reliable = 0; | |
66 | ||
67 | while (!kstack_end(stack)) { | |
68 | frameinfo = container_of(stack, | |
69 | struct or1k_frameinfo, | |
70 | top); | |
71 | ||
72 | if (__kernel_text_address(frameinfo->ra)) { | |
73 | if (or1k_frameinfo_valid(frameinfo) && | |
74 | (next_fp == NULL || | |
75 | next_fp == &frameinfo->top)) { | |
76 | reliable = 1; | |
77 | next_fp = frameinfo->fp; | |
78 | } else | |
79 | reliable = 0; | |
80 | ||
81 | trace(data, frameinfo->ra, reliable); | |
82 | } | |
83 | stack++; | |
84 | } | |
85 | } | |
86 | ||
87 | #else /* CONFIG_FRAME_POINTER */ | |
88 | ||
89 | /* | |
90 | * Create a stack trace by doing a simple scan treating all text addresses | |
91 | * as return addresses. | |
92 | */ | |
93 | void unwind_stack(void *data, unsigned long *stack, | |
94 | void (*trace)(void *data, unsigned long addr, int reliable)) | |
95 | { | |
96 | unsigned long addr; | |
97 | ||
98 | while (!kstack_end(stack)) { | |
99 | addr = *stack++; | |
100 | if (__kernel_text_address(addr)) | |
101 | trace(data, addr, 0); | |
102 | } | |
103 | } | |
104 | #endif /* CONFIG_FRAME_POINTER */ | |
105 |