1 // SPDX-License-Identifier: GPL-2.0-only
2
3 #include <linux/highmem.h>
4 #include <linux/ptrace.h>
5 #include <linux/uprobes.h>
6
7 #include "decode-insn.h"
8
9 #define UPROBE_TRAP_NR UINT_MAX
10
is_swbp_insn(uprobe_opcode_t * insn)11 bool is_swbp_insn(uprobe_opcode_t *insn)
12 {
13 #ifdef CONFIG_RISCV_ISA_C
14 return (*insn & 0xffff) == UPROBE_SWBP_INSN;
15 #else
16 return *insn == UPROBE_SWBP_INSN;
17 #endif
18 }
19
uprobe_get_swbp_addr(struct pt_regs * regs)20 unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
21 {
22 return instruction_pointer(regs);
23 }
24
arch_uprobe_analyze_insn(struct arch_uprobe * auprobe,struct mm_struct * mm,unsigned long addr)25 int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
26 unsigned long addr)
27 {
28 probe_opcode_t opcode;
29
30 opcode = *(probe_opcode_t *)(&auprobe->insn[0]);
31
32 auprobe->insn_size = GET_INSN_LENGTH(opcode);
33
34 switch (riscv_probe_decode_insn(&opcode, &auprobe->api)) {
35 case INSN_REJECTED:
36 return -EINVAL;
37
38 case INSN_GOOD_NO_SLOT:
39 auprobe->simulate = true;
40 break;
41
42 case INSN_GOOD:
43 auprobe->simulate = false;
44 break;
45
46 default:
47 return -EINVAL;
48 }
49
50 return 0;
51 }
52
arch_uprobe_pre_xol(struct arch_uprobe * auprobe,struct pt_regs * regs)53 int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
54 {
55 struct uprobe_task *utask = current->utask;
56
57 utask->autask.saved_cause = current->thread.bad_cause;
58 current->thread.bad_cause = UPROBE_TRAP_NR;
59
60 instruction_pointer_set(regs, utask->xol_vaddr);
61
62 regs->status &= ~SR_SPIE;
63
64 return 0;
65 }
66
arch_uprobe_post_xol(struct arch_uprobe * auprobe,struct pt_regs * regs)67 int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
68 {
69 struct uprobe_task *utask = current->utask;
70
71 WARN_ON_ONCE(current->thread.bad_cause != UPROBE_TRAP_NR);
72
73 instruction_pointer_set(regs, utask->vaddr + auprobe->insn_size);
74
75 regs->status |= SR_SPIE;
76
77 return 0;
78 }
79
arch_uprobe_xol_was_trapped(struct task_struct * t)80 bool arch_uprobe_xol_was_trapped(struct task_struct *t)
81 {
82 if (t->thread.bad_cause != UPROBE_TRAP_NR)
83 return true;
84
85 return false;
86 }
87
arch_uprobe_skip_sstep(struct arch_uprobe * auprobe,struct pt_regs * regs)88 bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
89 {
90 probe_opcode_t insn;
91 unsigned long addr;
92
93 if (!auprobe->simulate)
94 return false;
95
96 insn = *(probe_opcode_t *)(&auprobe->insn[0]);
97 addr = instruction_pointer(regs);
98
99 if (auprobe->api.handler)
100 auprobe->api.handler(insn, addr, regs);
101
102 return true;
103 }
104
arch_uprobe_abort_xol(struct arch_uprobe * auprobe,struct pt_regs * regs)105 void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
106 {
107 struct uprobe_task *utask = current->utask;
108
109 /*
110 * Task has received a fatal signal, so reset back to probbed
111 * address.
112 */
113 instruction_pointer_set(regs, utask->vaddr);
114
115 regs->status &= ~SR_SPIE;
116 }
117
arch_uretprobe_is_alive(struct return_instance * ret,enum rp_check ctx,struct pt_regs * regs)118 bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
119 struct pt_regs *regs)
120 {
121 if (ctx == RP_CHECK_CHAIN_CALL)
122 return regs->sp <= ret->stack;
123 else
124 return regs->sp < ret->stack;
125 }
126
127 unsigned long
arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,struct pt_regs * regs)128 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
129 struct pt_regs *regs)
130 {
131 unsigned long ra;
132
133 ra = regs->ra;
134
135 regs->ra = trampoline_vaddr;
136
137 return ra;
138 }
139
arch_uprobe_exception_notify(struct notifier_block * self,unsigned long val,void * data)140 int arch_uprobe_exception_notify(struct notifier_block *self,
141 unsigned long val, void *data)
142 {
143 return NOTIFY_DONE;
144 }
145
uprobe_breakpoint_handler(struct pt_regs * regs)146 bool uprobe_breakpoint_handler(struct pt_regs *regs)
147 {
148 if (uprobe_pre_sstep_notifier(regs))
149 return true;
150
151 return false;
152 }
153
uprobe_single_step_handler(struct pt_regs * regs)154 bool uprobe_single_step_handler(struct pt_regs *regs)
155 {
156 if (uprobe_post_sstep_notifier(regs))
157 return true;
158
159 return false;
160 }
161
arch_uprobe_copy_ixol(struct page * page,unsigned long vaddr,void * src,unsigned long len)162 void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
163 void *src, unsigned long len)
164 {
165 /* Initialize the slot */
166 void *kaddr = kmap_atomic(page);
167 void *dst = kaddr + (vaddr & ~PAGE_MASK);
168
169 memcpy(dst, src, len);
170
171 /* Add ebreak behind opcode to simulate singlestep */
172 if (vaddr) {
173 dst += GET_INSN_LENGTH(*(probe_opcode_t *)src);
174 *(uprobe_opcode_t *)dst = __BUG_INSN_32;
175 }
176
177 kunmap_atomic(kaddr);
178
179 /*
180 * We probably need flush_icache_user_page() but it needs vma.
181 * This should work on most of architectures by default. If
182 * architecture needs to do something different it can define
183 * its own version of the function.
184 */
185 flush_dcache_page(page);
186 }
187