1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2012 Rabin Vincent <rabin at rab.in>
4 */
5
6 #include <linux/kernel.h>
7 #include <linux/stddef.h>
8 #include <linux/errno.h>
9 #include <linux/highmem.h>
10 #include <linux/sched.h>
11 #include <linux/uprobes.h>
12 #include <linux/notifier.h>
13
14 #include <asm/opcodes.h>
15 #include <asm/traps.h>
16
17 #include "../decode.h"
18 #include "../decode-arm.h"
19 #include "core.h"
20
21 #define UPROBE_TRAP_NR UINT_MAX
22
23 bool is_swbp_insn(uprobe_opcode_t *insn)
24 {
25 return (__mem_to_opcode_arm(*insn) & 0x0fffffff) ==
26 (UPROBE_SWBP_ARM_INSN & 0x0fffffff);
27 }
28
29 int set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm,
30 unsigned long vaddr)
31 {
32 return uprobe_write_opcode(auprobe, mm, vaddr,
33 __opcode_to_mem_arm(auprobe->bpinsn));
34 }
35
36 bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs)
37 {
38 if (!auprobe->asi.insn_check_cc(regs->ARM_cpsr)) {
39 regs->ARM_pc += 4;
40 return true;
41 }
42
43 return false;
44 }
45
46 bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
47 {
48 probes_opcode_t opcode;
49
50 if (!auprobe->simulate)
51 return false;
52
53 opcode = __mem_to_opcode_arm(*(unsigned int *) auprobe->insn);
54
55 auprobe->asi.insn_singlestep(opcode, &auprobe->asi, regs);
56
57 return true;
58 }
59
60 unsigned long
61 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
62 struct pt_regs *regs)
63 {
64 unsigned long orig_ret_vaddr;
65
66 orig_ret_vaddr = regs->ARM_lr;
67 /* Replace the return addr with trampoline addr */
68 regs->ARM_lr = trampoline_vaddr;
69 return orig_ret_vaddr;
70 }
71
72 int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
73 unsigned long addr)
74 {
75 unsigned int insn;
76 unsigned int bpinsn;
77 enum probes_insn ret;
78
79 /* Thumb not yet support */
80 if (addr & 0x3)
81 return -EINVAL;
82
83 insn = __mem_to_opcode_arm(*(unsigned int *)auprobe->insn);
84 auprobe->ixol[0] = __opcode_to_mem_arm(insn);
85 auprobe->ixol[1] = __opcode_to_mem_arm(UPROBE_SS_ARM_INSN);
86
87 ret = arm_probes_decode_insn(insn, &auprobe->asi, false,
88 uprobes_probes_actions, NULL);
89 switch (ret) {
90 case INSN_REJECTED:
91 return -EINVAL;
92
93 case INSN_GOOD_NO_SLOT:
94 auprobe->simulate = true;
95 break;
96
97 case INSN_GOOD:
98 default:
99 break;
100 }
101
102 bpinsn = UPROBE_SWBP_ARM_INSN & 0x0fffffff;
103 if (insn >= 0xe0000000)
104 bpinsn |= 0xe0000000; /* Unconditional instruction */
105 else
106 bpinsn |= insn & 0xf0000000; /* Copy condition from insn */
107
108 auprobe->bpinsn = bpinsn;
109
110 return 0;
111 }
112
113 void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
114 void *src, unsigned long len)
115 {
116 void *xol_page_kaddr = kmap_atomic(page);
117 void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK);
118
119 preempt_disable();
120
121 /* Initialize the slot */
122 memcpy(dst, src, len);
123
124 /* flush caches (dcache/icache) */
125 flush_uprobe_xol_access(page, vaddr, dst, len);
126
127 preempt_enable();
128
129 kunmap_atomic(xol_page_kaddr);
130 }
131
132
133 int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
134 {
135 struct uprobe_task *utask = current->utask;
136
137 if (auprobe->prehandler)
138 auprobe->prehandler(auprobe, &utask->autask, regs);
139
140 utask->autask.saved_trap_no = current->thread.trap_no;
141 current->thread.trap_no = UPROBE_TRAP_NR;
142 regs->ARM_pc = utask->xol_vaddr;
143
144 return 0;
145 }
146
147 int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
148 {
149 struct uprobe_task *utask = current->utask;
150
151 WARN_ON_ONCE(current->thread.trap_no != UPROBE_TRAP_NR);
152
153 current->thread.trap_no = utask->autask.saved_trap_no;
154 regs->ARM_pc = utask->vaddr + 4;
155
156 if (auprobe->posthandler)
157 auprobe->posthandler(auprobe, &utask->autask, regs);
158
159 return 0;
160 }
161
162 bool arch_uprobe_xol_was_trapped(struct task_struct *t)
163 {
164 if (t->thread.trap_no != UPROBE_TRAP_NR)
165 return true;
166
167 return false;
168 }
169
170 void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
171 {
172 struct uprobe_task *utask = current->utask;
173
174 current->thread.trap_no = utask->autask.saved_trap_no;
175 instruction_pointer_set(regs, utask->vaddr);
176 }
177
178 int arch_uprobe_exception_notify(struct notifier_block *self,
179 unsigned long val, void *data)
180 {
181 return NOTIFY_DONE;
182 }
183
184 static int uprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
185 {
186 unsigned long flags;
187
188 local_irq_save(flags);
189 instr &= 0x0fffffff;
190 if (instr == (UPROBE_SWBP_ARM_INSN & 0x0fffffff))
191 uprobe_pre_sstep_notifier(regs);
192 else if (instr == (UPROBE_SS_ARM_INSN & 0x0fffffff))
193 uprobe_post_sstep_notifier(regs);
194 local_irq_restore(flags);
195
196 return 0;
197 }
198
199 unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
200 {
201 return instruction_pointer(regs);
202 }
203
204 static struct undef_hook uprobes_arm_break_hook = {
205 .instr_mask = 0x0fffffff,
206 .instr_val = (UPROBE_SWBP_ARM_INSN & 0x0fffffff),
207 .cpsr_mask = (PSR_T_BIT | MODE_MASK),
208 .cpsr_val = USR_MODE,
209 .fn = uprobe_trap_handler,
210 };
211
212 static struct undef_hook uprobes_arm_ss_hook = {
213 .instr_mask = 0x0fffffff,
214 .instr_val = (UPROBE_SS_ARM_INSN & 0x0fffffff),
215 .cpsr_mask = (PSR_T_BIT | MODE_MASK),
216 .cpsr_val = USR_MODE,
217 .fn = uprobe_trap_handler,
218 };
219
220 static int arch_uprobes_init(void)
221 {
222 register_undef_hook(&uprobes_arm_break_hook);
223 register_undef_hook(&uprobes_arm_ss_hook);
224
225 return 0;
226 }
227 device_initcall(arch_uprobes_init);
228
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