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c7edc9e3 DL |
1 | /* |
2 | * Copyright (C) 2012 Rabin Vincent <rabin at rab.in> | |
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 | ||
9 | #include <linux/kernel.h> | |
10 | #include <linux/stddef.h> | |
11 | #include <linux/errno.h> | |
12 | #include <linux/highmem.h> | |
13 | #include <linux/sched.h> | |
14 | #include <linux/uprobes.h> | |
15 | #include <linux/notifier.h> | |
16 | ||
17 | #include <asm/opcodes.h> | |
18 | #include <asm/traps.h> | |
19 | ||
20 | #include "probes.h" | |
21 | #include "probes-arm.h" | |
22 | #include "uprobes.h" | |
23 | ||
24 | #define UPROBE_TRAP_NR UINT_MAX | |
25 | ||
26 | bool is_swbp_insn(uprobe_opcode_t *insn) | |
27 | { | |
28 | return (__mem_to_opcode_arm(*insn) & 0x0fffffff) == | |
29 | (UPROBE_SWBP_ARM_INSN & 0x0fffffff); | |
30 | } | |
31 | ||
32 | int set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, | |
33 | unsigned long vaddr) | |
34 | { | |
35 | return uprobe_write_opcode(mm, vaddr, | |
36 | __opcode_to_mem_arm(auprobe->bpinsn)); | |
37 | } | |
38 | ||
39 | bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
40 | { | |
41 | if (!auprobe->asi.insn_check_cc(regs->ARM_cpsr)) { | |
42 | regs->ARM_pc += 4; | |
43 | return true; | |
44 | } | |
45 | ||
46 | return false; | |
47 | } | |
48 | ||
49 | bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
50 | { | |
51 | probes_opcode_t opcode; | |
52 | ||
53 | if (!auprobe->simulate) | |
54 | return false; | |
55 | ||
56 | opcode = __mem_to_opcode_arm(*(unsigned int *) auprobe->insn); | |
57 | ||
58 | auprobe->asi.insn_singlestep(opcode, &auprobe->asi, regs); | |
59 | ||
60 | return true; | |
61 | } | |
62 | ||
63 | unsigned long | |
64 | arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, | |
65 | struct pt_regs *regs) | |
66 | { | |
67 | unsigned long orig_ret_vaddr; | |
68 | ||
69 | orig_ret_vaddr = regs->ARM_lr; | |
70 | /* Replace the return addr with trampoline addr */ | |
71 | regs->ARM_lr = trampoline_vaddr; | |
72 | return orig_ret_vaddr; | |
73 | } | |
74 | ||
75 | int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, | |
76 | unsigned long addr) | |
77 | { | |
78 | unsigned int insn; | |
79 | unsigned int bpinsn; | |
80 | enum probes_insn ret; | |
81 | ||
82 | /* Thumb not yet support */ | |
83 | if (addr & 0x3) | |
84 | return -EINVAL; | |
85 | ||
86 | insn = __mem_to_opcode_arm(*(unsigned int *)auprobe->insn); | |
87 | auprobe->ixol[0] = __opcode_to_mem_arm(insn); | |
88 | auprobe->ixol[1] = __opcode_to_mem_arm(UPROBE_SS_ARM_INSN); | |
89 | ||
90 | ret = arm_probes_decode_insn(insn, &auprobe->asi, false, | |
91 | uprobes_probes_actions); | |
92 | switch (ret) { | |
93 | case INSN_REJECTED: | |
94 | return -EINVAL; | |
95 | ||
96 | case INSN_GOOD_NO_SLOT: | |
97 | auprobe->simulate = true; | |
98 | break; | |
99 | ||
100 | case INSN_GOOD: | |
101 | default: | |
102 | break; | |
103 | } | |
104 | ||
105 | bpinsn = UPROBE_SWBP_ARM_INSN & 0x0fffffff; | |
106 | if (insn >= 0xe0000000) | |
107 | bpinsn |= 0xe0000000; /* Unconditional instruction */ | |
108 | else | |
109 | bpinsn |= insn & 0xf0000000; /* Copy condition from insn */ | |
110 | ||
111 | auprobe->bpinsn = bpinsn; | |
112 | ||
113 | return 0; | |
114 | } | |
115 | ||
72e6ae28 VK |
116 | void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, |
117 | void *src, unsigned long len) | |
118 | { | |
119 | void *xol_page_kaddr = kmap_atomic(page); | |
120 | void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK); | |
121 | ||
122 | preempt_disable(); | |
123 | ||
124 | /* Initialize the slot */ | |
125 | memcpy(dst, src, len); | |
126 | ||
127 | /* flush caches (dcache/icache) */ | |
128 | flush_uprobe_xol_access(page, vaddr, dst, len); | |
129 | ||
130 | preempt_enable(); | |
131 | ||
132 | kunmap_atomic(xol_page_kaddr); | |
133 | } | |
134 | ||
135 | ||
c7edc9e3 DL |
136 | int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) |
137 | { | |
138 | struct uprobe_task *utask = current->utask; | |
139 | ||
140 | if (auprobe->prehandler) | |
141 | auprobe->prehandler(auprobe, &utask->autask, regs); | |
142 | ||
143 | utask->autask.saved_trap_no = current->thread.trap_no; | |
144 | current->thread.trap_no = UPROBE_TRAP_NR; | |
145 | regs->ARM_pc = utask->xol_vaddr; | |
146 | ||
147 | return 0; | |
148 | } | |
149 | ||
150 | int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
151 | { | |
152 | struct uprobe_task *utask = current->utask; | |
153 | ||
154 | WARN_ON_ONCE(current->thread.trap_no != UPROBE_TRAP_NR); | |
155 | ||
156 | current->thread.trap_no = utask->autask.saved_trap_no; | |
157 | regs->ARM_pc = utask->vaddr + 4; | |
158 | ||
159 | if (auprobe->posthandler) | |
160 | auprobe->posthandler(auprobe, &utask->autask, regs); | |
161 | ||
162 | return 0; | |
163 | } | |
164 | ||
165 | bool arch_uprobe_xol_was_trapped(struct task_struct *t) | |
166 | { | |
167 | if (t->thread.trap_no != UPROBE_TRAP_NR) | |
168 | return true; | |
169 | ||
170 | return false; | |
171 | } | |
172 | ||
173 | void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
174 | { | |
175 | struct uprobe_task *utask = current->utask; | |
176 | ||
177 | current->thread.trap_no = utask->autask.saved_trap_no; | |
178 | instruction_pointer_set(regs, utask->vaddr); | |
179 | } | |
180 | ||
181 | int arch_uprobe_exception_notify(struct notifier_block *self, | |
182 | unsigned long val, void *data) | |
183 | { | |
184 | return NOTIFY_DONE; | |
185 | } | |
186 | ||
187 | static int uprobe_trap_handler(struct pt_regs *regs, unsigned int instr) | |
188 | { | |
189 | unsigned long flags; | |
190 | ||
191 | local_irq_save(flags); | |
192 | instr &= 0x0fffffff; | |
193 | if (instr == (UPROBE_SWBP_ARM_INSN & 0x0fffffff)) | |
194 | uprobe_pre_sstep_notifier(regs); | |
195 | else if (instr == (UPROBE_SS_ARM_INSN & 0x0fffffff)) | |
196 | uprobe_post_sstep_notifier(regs); | |
197 | local_irq_restore(flags); | |
198 | ||
199 | return 0; | |
200 | } | |
201 | ||
202 | unsigned long uprobe_get_swbp_addr(struct pt_regs *regs) | |
203 | { | |
204 | return instruction_pointer(regs); | |
205 | } | |
206 | ||
207 | static struct undef_hook uprobes_arm_break_hook = { | |
208 | .instr_mask = 0x0fffffff, | |
209 | .instr_val = (UPROBE_SWBP_ARM_INSN & 0x0fffffff), | |
210 | .cpsr_mask = MODE_MASK, | |
211 | .cpsr_val = USR_MODE, | |
212 | .fn = uprobe_trap_handler, | |
213 | }; | |
214 | ||
215 | static struct undef_hook uprobes_arm_ss_hook = { | |
216 | .instr_mask = 0x0fffffff, | |
217 | .instr_val = (UPROBE_SS_ARM_INSN & 0x0fffffff), | |
218 | .cpsr_mask = MODE_MASK, | |
219 | .cpsr_val = USR_MODE, | |
220 | .fn = uprobe_trap_handler, | |
221 | }; | |
222 | ||
223 | static int arch_uprobes_init(void) | |
224 | { | |
225 | register_undef_hook(&uprobes_arm_break_hook); | |
226 | register_undef_hook(&uprobes_arm_ss_hook); | |
227 | ||
228 | return 0; | |
229 | } | |
230 | device_initcall(arch_uprobes_init); |