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 |
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(addr: stack)) { |
99 | addr = *stack++; |
100 | if (__kernel_text_address(addr)) |
101 | trace(data, addr, 0); |
102 | } |
103 | } |
104 | #endif /* CONFIG_FRAME_POINTER */ |
105 | |
106 | |