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
209
210
211
212
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* User-space Probes (UProbes) for powerpc
*
* Copyright IBM Corporation, 2007-2012
*
* Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@in.ibm.com>
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/uprobes.h>
#include <linux/uaccess.h>
#include <linux/kdebug.h>
#include <asm/sstep.h>
#include <asm/inst.h>
#define UPROBE_TRAP_NR UINT_MAX
/**
* is_trap_insn - check if the instruction is a trap variant
* @insn: instruction to be checked.
* Returns true if @insn is a trap variant.
*/
bool is_trap_insn(uprobe_opcode_t *insn)
{
return (is_trap(*insn));
}
/**
* arch_uprobe_analyze_insn
* @mm: the probed address space.
* @arch_uprobe: the probepoint information.
* @addr: vaddr to probe.
* Return 0 on success or a -ve number on error.
*/
int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
struct mm_struct *mm, unsigned long addr)
{
if (addr & 0x03)
return -EINVAL;
if (cpu_has_feature(CPU_FTR_ARCH_31) &&
ppc_inst_prefixed(ppc_inst_read(auprobe->insn)) &&
(addr & 0x3f) == 60) {
pr_info_ratelimited("Cannot register a uprobe on 64 byte unaligned prefixed instruction\n");
return -EINVAL;
}
return 0;
}
/*
* arch_uprobe_pre_xol - prepare to execute out of line.
* @auprobe: the probepoint information.
* @regs: reflects the saved user state of current task.
*/
int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct arch_uprobe_task *autask = ¤t->utask->autask;
autask->saved_trap_nr = current->thread.trap_nr;
current->thread.trap_nr = UPROBE_TRAP_NR;
regs_set_return_ip(regs, current->utask->xol_vaddr);
user_enable_single_step(current);
return 0;
}
/**
* uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
* @regs: Reflects the saved state of the task after it has hit a breakpoint
* instruction.
* Return the address of the breakpoint instruction.
*/
unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
{
return instruction_pointer(regs);
}
/*
* If xol insn itself traps and generates a signal (SIGILL/SIGSEGV/etc),
* then detect the case where a singlestepped instruction jumps back to its
* own address. It is assumed that anything like do_page_fault/do_trap/etc
* sets thread.trap_nr != UINT_MAX.
*
* arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr,
* arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to
* UPROBE_TRAP_NR == UINT_MAX set by arch_uprobe_pre_xol().
*/
bool arch_uprobe_xol_was_trapped(struct task_struct *t)
{
if (t->thread.trap_nr != UPROBE_TRAP_NR)
return true;
return false;
}
/*
* Called after single-stepping. To avoid the SMP problems that can
* occur when we temporarily put back the original opcode to
* single-step, we single-stepped a copy of the instruction.
*
* This function prepares to resume execution after the single-step.
*/
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
current->thread.trap_nr = utask->autask.saved_trap_nr;
/*
* On powerpc, except for loads and stores, most instructions
* including ones that alter code flow (branches, calls, returns)
* are emulated in the kernel. We get here only if the emulation
* support doesn't exist and have to fix-up the next instruction
* to be executed.
*/
regs_set_return_ip(regs, (unsigned long)ppc_inst_next((void *)utask->vaddr, auprobe->insn));
user_disable_single_step(current);
return 0;
}
/* callback routine for handling exceptions. */
int arch_uprobe_exception_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct die_args *args = data;
struct pt_regs *regs = args->regs;
/* regs == NULL is a kernel bug */
if (WARN_ON(!regs))
return NOTIFY_DONE;
/* We are only interested in userspace traps */
if (!user_mode(regs))
return NOTIFY_DONE;
switch (val) {
case DIE_BPT:
if (uprobe_pre_sstep_notifier(regs))
return NOTIFY_STOP;
break;
case DIE_SSTEP:
if (uprobe_post_sstep_notifier(regs))
return NOTIFY_STOP;
break;
default:
break;
}
return NOTIFY_DONE;
}
/*
* This function gets called when XOL instruction either gets trapped or
* the thread has a fatal signal, so reset the instruction pointer to its
* probed address.
*/
void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
struct uprobe_task *utask = current->utask;
current->thread.trap_nr = utask->autask.saved_trap_nr;
instruction_pointer_set(regs, utask->vaddr);
user_disable_single_step(current);
}
/*
* See if the instruction can be emulated.
* Returns true if instruction was emulated, false otherwise.
*/
bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
int ret;
/*
* emulate_step() returns 1 if the insn was successfully emulated.
* For all other cases, we need to single-step in hardware.
*/
ret = emulate_step(regs, ppc_inst_read(auprobe->insn));
if (ret > 0)
return true;
return false;
}
unsigned long
arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs)
{
unsigned long orig_ret_vaddr;
orig_ret_vaddr = regs->link;
/* Replace the return addr with trampoline addr */
regs->link = trampoline_vaddr;
return orig_ret_vaddr;
}
bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
struct pt_regs *regs)
{
if (ctx == RP_CHECK_CHAIN_CALL)
return regs->gpr[1] <= ret->stack;
else
return regs->gpr[1] < ret->stack;
}
|
