1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Code for tracing calls in Linux kernel.
4 * Copyright (C) 2009-2016 Helge Deller <deller@gmx.de>
5 *
6 * based on code for x86 which is:
7 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
8 *
9 * future possible enhancements:
10 * - add CONFIG_STACK_TRACER
11 */
12
13 #include <linux/init.h>
14 #include <linux/ftrace.h>
15 #include <linux/uaccess.h>
16 #include <linux/kprobes.h>
17 #include <linux/ptrace.h>
18 #include <linux/jump_label.h>
19
20 #include <asm/assembly.h>
21 #include <asm/sections.h>
22 #include <asm/ftrace.h>
23 #include <asm/patch.h>
24
25 #define __hot __section(".text.hot")
26
27 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
28 static DEFINE_STATIC_KEY_FALSE(ftrace_graph_enable);
29
30 /*
31 * Hook the return address and push it in the stack of return addrs
32 * in current thread info.
33 */
34 static void __hot prepare_ftrace_return(unsigned long *parent,
35 unsigned long self_addr)
36 {
37 unsigned long old;
38 extern int parisc_return_to_handler;
39
40 if (unlikely(ftrace_graph_is_dead()))
41 return;
42
43 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
44 return;
45
46 old = *parent;
47
48 if (!function_graph_enter(old, self_addr, 0, NULL))
49 /* activate parisc_return_to_handler() as return point */
50 *parent = (unsigned long) &parisc_return_to_handler;
51 }
52 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
53
54 static ftrace_func_t ftrace_func;
55
56 asmlinkage void notrace __hot ftrace_function_trampoline(unsigned long parent,
57 unsigned long self_addr,
58 unsigned long org_sp_gr3,
59 struct ftrace_regs *fregs)
60 {
61 extern struct ftrace_ops *function_trace_op;
62
63 ftrace_func(self_addr, parent, function_trace_op, fregs);
64
65 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
66 if (static_branch_unlikely(&ftrace_graph_enable)) {
67 unsigned long *parent_rp;
68
69 /* calculate pointer to %rp in stack */
70 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET);
71 /* sanity check: parent_rp should hold parent */
72 if (*parent_rp != parent)
73 return;
74
75 prepare_ftrace_return(parent_rp, self_addr);
76 return;
77 }
78 #endif
79 }
80
81 #if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_FUNCTION_GRAPH_TRACER)
82 int ftrace_enable_ftrace_graph_caller(void)
83 {
84 static_key_enable(&ftrace_graph_enable.key);
85 return 0;
86 }
87
88 int ftrace_disable_ftrace_graph_caller(void)
89 {
90 static_key_enable(&ftrace_graph_enable.key);
91 return 0;
92 }
93 #endif
94
95 #ifdef CONFIG_DYNAMIC_FTRACE
96 int ftrace_update_ftrace_func(ftrace_func_t func)
97 {
98 ftrace_func = func;
99 return 0;
100 }
101
102 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
103 unsigned long addr)
104 {
105 return 0;
106 }
107
108 unsigned long ftrace_call_adjust(unsigned long addr)
109 {
110 return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4;
111 }
112
113 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
114 {
115 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
116 u32 *tramp;
117 int size, ret, i;
118 void *ip;
119
120 #ifdef CONFIG_64BIT
121 unsigned long addr2 =
122 (unsigned long)dereference_function_descriptor((void *)addr);
123
124 u32 ftrace_trampoline[] = {
125 0x73c10208, /* std,ma r1,100(sp) */
126 0x0c2110c1, /* ldd -10(r1),r1 */
127 0xe820d002, /* bve,n (r1) */
128 addr2 >> 32,
129 addr2 & 0xffffffff,
130 0xe83f1fd7, /* b,l,n .-14,r1 */
131 };
132
133 u32 ftrace_trampoline_unaligned[] = {
134 addr2 >> 32,
135 addr2 & 0xffffffff,
136 0x37de0200, /* ldo 100(sp),sp */
137 0x73c13e01, /* std r1,-100(sp) */
138 0x34213ff9, /* ldo -4(r1),r1 */
139 0x50213fc1, /* ldd -20(r1),r1 */
140 0xe820d002, /* bve,n (r1) */
141 0xe83f1fcf, /* b,l,n .-20,r1 */
142 };
143
144 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) >
145 FTRACE_PATCHABLE_FUNCTION_SIZE);
146 #else
147 u32 ftrace_trampoline[] = {
148 (u32)addr,
149 0x6fc10080, /* stw,ma r1,40(sp) */
150 0x48213fd1, /* ldw -18(r1),r1 */
151 0xe820c002, /* bv,n r0(r1) */
152 0xe83f1fdf, /* b,l,n .-c,r1 */
153 };
154 #endif
155
156 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) >
157 FTRACE_PATCHABLE_FUNCTION_SIZE);
158
159 size = sizeof(ftrace_trampoline);
160 tramp = ftrace_trampoline;
161
162 #ifdef CONFIG_64BIT
163 if (rec->ip & 0x4) {
164 size = sizeof(ftrace_trampoline_unaligned);
165 tramp = ftrace_trampoline_unaligned;
166 }
167 #endif
168
169 ip = (void *)(rec->ip + 4 - size);
170
171 ret = copy_from_kernel_nofault(insn, ip, size);
172 if (ret)
173 return ret;
174
175 for (i = 0; i < size / 4; i++) {
176 if (insn[i] != INSN_NOP)
177 return -EINVAL;
178 }
179
180 __patch_text_multiple(ip, tramp, size);
181 return 0;
182 }
183
184 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
185 unsigned long addr)
186 {
187 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
188 int i;
189
190 for (i = 0; i < ARRAY_SIZE(insn); i++)
191 insn[i] = INSN_NOP;
192
193 __patch_text((void *)rec->ip, INSN_NOP);
194 __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn),
195 insn, sizeof(insn)-4);
196 return 0;
197 }
198 #endif
199
200 #ifdef CONFIG_KPROBES_ON_FTRACE
201 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
202 struct ftrace_ops *ops, struct ftrace_regs *fregs)
203 {
204 struct kprobe_ctlblk *kcb;
205 struct pt_regs *regs;
206 struct kprobe *p;
207 int bit;
208
209 if (unlikely(kprobe_ftrace_disabled))
210 return;
211
212 bit = ftrace_test_recursion_trylock(ip, parent_ip);
213 if (bit < 0)
214 return;
215
216 regs = ftrace_get_regs(fregs);
217 p = get_kprobe((kprobe_opcode_t *)ip);
218 if (unlikely(!p) || kprobe_disabled(p))
219 goto out;
220
221 if (kprobe_running()) {
222 kprobes_inc_nmissed_count(p);
223 goto out;
224 }
225
226 __this_cpu_write(current_kprobe, p);
227
228 kcb = get_kprobe_ctlblk();
229 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
230
231 regs->iaoq[0] = ip;
232 regs->iaoq[1] = ip + 4;
233
234 if (!p->pre_handler || !p->pre_handler(p, regs)) {
235 regs->iaoq[0] = ip + 4;
236 regs->iaoq[1] = ip + 8;
237
238 if (unlikely(p->post_handler)) {
239 kcb->kprobe_status = KPROBE_HIT_SSDONE;
240 p->post_handler(p, regs, 0);
241 }
242 }
243 __this_cpu_write(current_kprobe, NULL);
244 out:
245 ftrace_test_recursion_unlock(bit);
246 }
247 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
248
249 int arch_prepare_kprobe_ftrace(struct kprobe *p)
250 {
251 p->ainsn.insn = NULL;
252 return 0;
253 }
254 #endif
255
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