summaryrefslogtreecommitdiffstats
path: root/arch/arm64/kernel/probes/uprobes.c
blob: a412d8edbcd24428150a16e93ae059d45817b355 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2014-2016 Pratyush Anand <panand@redhat.com>
 */
#include <linux/highmem.h>
#include <linux/ptrace.h>
#include <linux/uprobes.h>
#include <asm/cacheflush.h>

#include "decode-insn.h"

#define UPROBE_INV_FAULT_CODE	UINT_MAX

void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
		void *src, unsigned long len)
{
	void *xol_page_kaddr = kmap_atomic(page);
	void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK);

	/* Initialize the slot */
	memcpy(dst, src, len);

	/* flush caches (dcache/icache) */
	sync_icache_aliases(dst, len);

	kunmap_atomic(xol_page_kaddr);
}

unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
{
	return instruction_pointer(regs);
}

int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
		unsigned long addr)
{
	probe_opcode_t insn;

	/* TODO: Currently we do not support AARCH32 instruction probing */
	if (mm->context.flags & MMCF_AARCH32)
		return -ENOTSUPP;
	else if (!IS_ALIGNED(addr, AARCH64_INSN_SIZE))
		return -EINVAL;

	insn = *(probe_opcode_t *)(&auprobe->insn[0]);

	switch (arm_probe_decode_insn(insn, &auprobe->api)) {
	case INSN_REJECTED:
		return -EINVAL;

	case INSN_GOOD_NO_SLOT:
		auprobe->simulate = true;
		break;

	default:
		break;
	}

	return 0;
}

int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
	struct uprobe_task *utask = current->utask;

	/* Initialize with an invalid fault code to detect if ol insn trapped */
	current->thread.fault_code = UPROBE_INV_FAULT_CODE;

	/* Instruction points to execute ol */
	instruction_pointer_set(regs, utask->xol_vaddr);

	user_enable_single_step(current);

	return 0;
}

int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
	struct uprobe_task *utask = current->utask;

	WARN_ON_ONCE(current->thread.fault_code != UPROBE_INV_FAULT_CODE);

	/* Instruction points to execute next to breakpoint address */
	instruction_pointer_set(regs, utask->vaddr + 4);

	user_disable_single_step(current);

	return 0;
}
bool arch_uprobe_xol_was_trapped(struct task_struct *t)
{
	/*
	 * Between arch_uprobe_pre_xol and arch_uprobe_post_xol, if an xol
	 * insn itself is trapped, then detect the case with the help of
	 * invalid fault code which is being set in arch_uprobe_pre_xol
	 */
	if (t->thread.fault_code != UPROBE_INV_FAULT_CODE)
		return true;

	return false;
}

bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
	probe_opcode_t insn;
	unsigned long addr;

	if (!auprobe->simulate)
		return false;

	insn = *(probe_opcode_t *)(&auprobe->insn[0]);
	addr = instruction_pointer(regs);

	if (auprobe->api.handler)
		auprobe->api.handler(insn, addr, regs);

	return true;
}

void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
	struct uprobe_task *utask = current->utask;

	/*
	 * Task has received a fatal signal, so reset back to probbed
	 * address.
	 */
	instruction_pointer_set(regs, utask->vaddr);

	user_disable_single_step(current);
}

bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
		struct pt_regs *regs)
{
	/*
	 * If a simple branch instruction (B) was called for retprobed
	 * assembly label then return true even when regs->sp and ret->stack
	 * are same. It will ensure that cleanup and reporting of return
	 * instances corresponding to callee label is done when
	 * handle_trampoline for called function is executed.
	 */
	if (ctx == RP_CHECK_CHAIN_CALL)
		return regs->sp <= ret->stack;
	else
		return regs->sp < ret->stack;
}

unsigned long
arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
				  struct pt_regs *regs)
{
	unsigned long orig_ret_vaddr;

	orig_ret_vaddr = procedure_link_pointer(regs);
	/* Replace the return addr with trampoline addr */
	procedure_link_pointer_set(regs, trampoline_vaddr);

	return orig_ret_vaddr;
}

int arch_uprobe_exception_notify(struct notifier_block *self,
				 unsigned long val, void *data)
{
	return NOTIFY_DONE;
}

static int uprobe_breakpoint_handler(struct pt_regs *regs,
		unsigned int esr)
{
	if (uprobe_pre_sstep_notifier(regs))
		return DBG_HOOK_HANDLED;

	return DBG_HOOK_ERROR;
}

static int uprobe_single_step_handler(struct pt_regs *regs,
		unsigned int esr)
{
	struct uprobe_task *utask = current->utask;

	WARN_ON(utask && (instruction_pointer(regs) != utask->xol_vaddr + 4));
	if (uprobe_post_sstep_notifier(regs))
		return DBG_HOOK_HANDLED;

	return DBG_HOOK_ERROR;
}

/* uprobe breakpoint handler hook */
static struct break_hook uprobes_break_hook = {
	.imm = UPROBES_BRK_IMM,
	.fn = uprobe_breakpoint_handler,
};

/* uprobe single step handler hook */
static struct step_hook uprobes_step_hook = {
	.fn = uprobe_single_step_handler,
};

static int __init arch_init_uprobes(void)
{
	register_user_break_hook(&uprobes_break_hook);
	register_user_step_hook(&uprobes_step_hook);

	return 0;
}

device_initcall(arch_init_uprobes);