1 /**
2 * Copyright (C) ARM Limited 2010-2013. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 */
10 /*
11 * EABI backtrace stores {fp,lr} on the stack.
12 */
13 struct stack_frame_eabi {
14 union {
15 struct {
16 unsigned long fp;
17 // May be the fp in the case of a leaf function or clang
18 unsigned long lr;
19 // If lr is really the fp, lr2 is the corresponding lr
20 unsigned long lr2;
21 };
22 // Used to read 32 bit fp/lr from a 64 bit kernel
23 struct {
24 u32 fp_32;
25 // same as lr above
26 u32 lr_32;
27 // same as lr2 above
28 u32 lr2_32;
29 };
30 };
31 };
33 static void arm_backtrace_eabi(int cpu, struct pt_regs *const regs, unsigned int depth)
34 {
35 #if defined(__arm__) || defined(__aarch64__)
36 struct stack_frame_eabi *curr;
37 struct stack_frame_eabi bufcurr;
38 #if defined(__arm__)
39 const bool is_compat = false;
40 unsigned long fp = regs->ARM_fp;
41 unsigned long sp = regs->ARM_sp;
42 unsigned long lr = regs->ARM_lr;
43 const int gcc_frame_offset = sizeof(unsigned long);
44 #else
45 // Is userspace aarch32 (32 bit)
46 const bool is_compat = compat_user_mode(regs);
47 unsigned long fp = (is_compat ? regs->regs[11] : regs->regs[29]);
48 unsigned long sp = (is_compat ? regs->compat_sp : regs->sp);
49 unsigned long lr = (is_compat ? regs->compat_lr : regs->regs[30]);
50 const int gcc_frame_offset = (is_compat ? sizeof(u32) : 0);
51 #endif
52 // clang frame offset is always zero
53 int is_user_mode = user_mode(regs);
55 // pc (current function) has already been added
57 if (!is_user_mode) {
58 return;
59 }
61 // Add the lr (parent function)
62 // entry preamble may not have executed
63 gator_add_trace(cpu, lr);
65 // check fp is valid
66 if (fp == 0 || fp < sp) {
67 return;
68 }
70 // Get the current stack frame
71 curr = (struct stack_frame_eabi *)(fp - gcc_frame_offset);
72 if ((unsigned long)curr & 3) {
73 return;
74 }
76 while (depth-- && curr) {
77 if (!access_ok(VERIFY_READ, curr, sizeof(struct stack_frame_eabi)) ||
78 __copy_from_user_inatomic(&bufcurr, curr, sizeof(struct stack_frame_eabi))) {
79 return;
80 }
82 fp = (is_compat ? bufcurr.fp_32 : bufcurr.fp);
83 lr = (is_compat ? bufcurr.lr_32 : bufcurr.lr);
85 #define calc_next(reg) ((reg) - gcc_frame_offset)
86 // Returns true if reg is a valid fp
87 #define validate_next(reg, curr) \
88 ((reg) != 0 && (calc_next(reg) & 3) == 0 && (unsigned long)(curr) < calc_next(reg))
90 // Try lr from the stack as the fp because gcc leaf functions do not push lr
91 // If gcc_frame_offset is non-zero, the lr will also be the clang fp
92 // This assumes code is at a lower address than the stack
93 if (validate_next(lr, curr)) {
94 fp = lr;
95 lr = (is_compat ? bufcurr.lr2_32 : bufcurr.lr2);
96 }
98 gator_add_trace(cpu, lr);
100 if (!validate_next(fp, curr)) {
101 return;
102 }
104 // Move to the next stack frame
105 curr = (struct stack_frame_eabi *)calc_next(fp);
106 }
107 #endif
108 }
110 #if defined(__arm__) || defined(__aarch64__)
111 static int report_trace(struct stackframe *frame, void *d)
112 {
113 unsigned int *depth = d, cookie = NO_COOKIE;
114 unsigned long addr = frame->pc;
116 if (*depth) {
117 #if defined(MODULE)
118 unsigned int cpu = get_physical_cpu();
119 struct module *mod = __module_address(addr);
120 if (mod) {
121 cookie = get_cookie(cpu, current, mod->name, false);
122 addr = addr - (unsigned long)mod->module_core;
123 }
124 #endif
125 marshal_backtrace(addr & ~1, cookie);
126 (*depth)--;
127 }
129 return *depth == 0;
130 }
131 #endif
133 // Uncomment the following line to enable kernel stack unwinding within gator, note it can also be defined from the Makefile
134 // #define GATOR_KERNEL_STACK_UNWINDING
135 static void kernel_backtrace(int cpu, struct pt_regs *const regs)
136 {
137 #if defined(__arm__) || defined(__aarch64__)
138 #ifdef GATOR_KERNEL_STACK_UNWINDING
139 int depth = gator_backtrace_depth;
140 #else
141 int depth = 1;
142 #endif
143 struct stackframe frame;
144 if (depth == 0)
145 depth = 1;
146 #if defined(__arm__)
147 frame.fp = regs->ARM_fp;
148 frame.sp = regs->ARM_sp;
149 frame.lr = regs->ARM_lr;
150 frame.pc = regs->ARM_pc;
151 #else
152 frame.fp = regs->regs[29];
153 frame.sp = regs->sp;
154 frame.pc = regs->pc;
155 #endif
156 walk_stackframe(&frame, report_trace, &depth);
157 #else
158 marshal_backtrace(PC_REG & ~1, NO_COOKIE);
159 #endif
160 }