1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Traceprobe fetch helper inlines
4  */
5 
6 static nokprobe_inline void
fetch_store_raw(unsigned long val,struct fetch_insn * code,void * buf)7 fetch_store_raw(unsigned long val, struct fetch_insn *code, void *buf)
8 {
9 	switch (code->size) {
10 	case 1:
11 		*(u8 *)buf = (u8)val;
12 		break;
13 	case 2:
14 		*(u16 *)buf = (u16)val;
15 		break;
16 	case 4:
17 		*(u32 *)buf = (u32)val;
18 		break;
19 	case 8:
20 		//TBD: 32bit signed
21 		*(u64 *)buf = (u64)val;
22 		break;
23 	default:
24 		*(unsigned long *)buf = val;
25 	}
26 }
27 
28 static nokprobe_inline void
fetch_apply_bitfield(struct fetch_insn * code,void * buf)29 fetch_apply_bitfield(struct fetch_insn *code, void *buf)
30 {
31 	switch (code->basesize) {
32 	case 1:
33 		*(u8 *)buf <<= code->lshift;
34 		*(u8 *)buf >>= code->rshift;
35 		break;
36 	case 2:
37 		*(u16 *)buf <<= code->lshift;
38 		*(u16 *)buf >>= code->rshift;
39 		break;
40 	case 4:
41 		*(u32 *)buf <<= code->lshift;
42 		*(u32 *)buf >>= code->rshift;
43 		break;
44 	case 8:
45 		*(u64 *)buf <<= code->lshift;
46 		*(u64 *)buf >>= code->rshift;
47 		break;
48 	}
49 }
50 
51 /*
52  * These functions must be defined for each callsite.
53  * Return consumed dynamic data size (>= 0), or error (< 0).
54  * If dest is NULL, don't store result and return required dynamic data size.
55  */
56 static int
57 process_fetch_insn(struct fetch_insn *code, void *rec,
58 		   void *dest, void *base);
59 static nokprobe_inline int fetch_store_strlen(unsigned long addr);
60 static nokprobe_inline int
61 fetch_store_string(unsigned long addr, void *dest, void *base);
62 static nokprobe_inline int fetch_store_strlen_user(unsigned long addr);
63 static nokprobe_inline int
64 fetch_store_string_user(unsigned long addr, void *dest, void *base);
65 static nokprobe_inline int
66 probe_mem_read(void *dest, void *src, size_t size);
67 static nokprobe_inline int
68 probe_mem_read_user(void *dest, void *src, size_t size);
69 
70 static nokprobe_inline int
fetch_store_symstrlen(unsigned long addr)71 fetch_store_symstrlen(unsigned long addr)
72 {
73 	char namebuf[KSYM_SYMBOL_LEN];
74 	int ret;
75 
76 	ret = sprint_symbol(namebuf, addr);
77 	if (ret < 0)
78 		return 0;
79 
80 	return ret + 1;
81 }
82 
83 /*
84  * Fetch a null-terminated symbol string + offset. Caller MUST set *(u32 *)buf
85  * with max length and relative data location.
86  */
87 static nokprobe_inline int
fetch_store_symstring(unsigned long addr,void * dest,void * base)88 fetch_store_symstring(unsigned long addr, void *dest, void *base)
89 {
90 	int maxlen = get_loc_len(*(u32 *)dest);
91 	void *__dest;
92 
93 	if (unlikely(!maxlen))
94 		return -ENOMEM;
95 
96 	__dest = get_loc_data(dest, base);
97 
98 	return sprint_symbol(__dest, addr);
99 }
100 
101 /* common part of process_fetch_insn*/
102 static nokprobe_inline int
process_common_fetch_insn(struct fetch_insn * code,unsigned long * val)103 process_common_fetch_insn(struct fetch_insn *code, unsigned long *val)
104 {
105 	switch (code->op) {
106 	case FETCH_OP_IMM:
107 		*val = code->immediate;
108 		break;
109 	case FETCH_OP_COMM:
110 		*val = (unsigned long)current->comm;
111 		break;
112 	case FETCH_OP_DATA:
113 		*val = (unsigned long)code->data;
114 		break;
115 	default:
116 		return -EILSEQ;
117 	}
118 	return 0;
119 }
120 
121 /* From the 2nd stage, routine is same */
122 static nokprobe_inline int
process_fetch_insn_bottom(struct fetch_insn * code,unsigned long val,void * dest,void * base)123 process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
124 			   void *dest, void *base)
125 {
126 	struct fetch_insn *s3 = NULL;
127 	int total = 0, ret = 0, i = 0;
128 	u32 loc = 0;
129 	unsigned long lval = val;
130 
131 stage2:
132 	/* 2nd stage: dereference memory if needed */
133 	do {
134 		if (code->op == FETCH_OP_DEREF) {
135 			lval = val;
136 			ret = probe_mem_read(&val, (void *)val + code->offset,
137 					     sizeof(val));
138 		} else if (code->op == FETCH_OP_UDEREF) {
139 			lval = val;
140 			ret = probe_mem_read_user(&val,
141 				 (void *)val + code->offset, sizeof(val));
142 		} else
143 			break;
144 		if (ret)
145 			return ret;
146 		code++;
147 	} while (1);
148 
149 	s3 = code;
150 stage3:
151 	/* 3rd stage: store value to buffer */
152 	if (unlikely(!dest)) {
153 		switch (code->op) {
154 		case FETCH_OP_ST_STRING:
155 			ret = fetch_store_strlen(val + code->offset);
156 			code++;
157 			goto array;
158 		case FETCH_OP_ST_USTRING:
159 			ret = fetch_store_strlen_user(val + code->offset);
160 			code++;
161 			goto array;
162 		case FETCH_OP_ST_SYMSTR:
163 			ret = fetch_store_symstrlen(val + code->offset);
164 			code++;
165 			goto array;
166 		default:
167 			return -EILSEQ;
168 		}
169 	}
170 
171 	switch (code->op) {
172 	case FETCH_OP_ST_RAW:
173 		fetch_store_raw(val, code, dest);
174 		break;
175 	case FETCH_OP_ST_MEM:
176 		probe_mem_read(dest, (void *)val + code->offset, code->size);
177 		break;
178 	case FETCH_OP_ST_UMEM:
179 		probe_mem_read_user(dest, (void *)val + code->offset, code->size);
180 		break;
181 	case FETCH_OP_ST_STRING:
182 		loc = *(u32 *)dest;
183 		ret = fetch_store_string(val + code->offset, dest, base);
184 		break;
185 	case FETCH_OP_ST_USTRING:
186 		loc = *(u32 *)dest;
187 		ret = fetch_store_string_user(val + code->offset, dest, base);
188 		break;
189 	case FETCH_OP_ST_SYMSTR:
190 		loc = *(u32 *)dest;
191 		ret = fetch_store_symstring(val + code->offset, dest, base);
192 		break;
193 	default:
194 		return -EILSEQ;
195 	}
196 	code++;
197 
198 	/* 4th stage: modify stored value if needed */
199 	if (code->op == FETCH_OP_MOD_BF) {
200 		fetch_apply_bitfield(code, dest);
201 		code++;
202 	}
203 
204 array:
205 	/* the last stage: Loop on array */
206 	if (code->op == FETCH_OP_LP_ARRAY) {
207 		if (ret < 0)
208 			ret = 0;
209 		total += ret;
210 		if (++i < code->param) {
211 			code = s3;
212 			if (s3->op != FETCH_OP_ST_STRING &&
213 			    s3->op != FETCH_OP_ST_USTRING) {
214 				dest += s3->size;
215 				val += s3->size;
216 				goto stage3;
217 			}
218 			code--;
219 			val = lval + sizeof(char *);
220 			if (dest) {
221 				dest += sizeof(u32);
222 				*(u32 *)dest = update_data_loc(loc, ret);
223 			}
224 			goto stage2;
225 		}
226 		code++;
227 		ret = total;
228 	}
229 
230 	return code->op == FETCH_OP_END ? ret : -EILSEQ;
231 }
232 
233 /* Sum up total data length for dynamic arrays (strings) */
234 static nokprobe_inline int
__get_data_size(struct trace_probe * tp,struct pt_regs * regs)235 __get_data_size(struct trace_probe *tp, struct pt_regs *regs)
236 {
237 	struct probe_arg *arg;
238 	int i, len, ret = 0;
239 
240 	for (i = 0; i < tp->nr_args; i++) {
241 		arg = tp->args + i;
242 		if (unlikely(arg->dynamic)) {
243 			len = process_fetch_insn(arg->code, regs, NULL, NULL);
244 			if (len > 0)
245 				ret += len;
246 		}
247 	}
248 
249 	return ret;
250 }
251 
252 /* Store the value of each argument */
253 static nokprobe_inline void
store_trace_args(void * data,struct trace_probe * tp,void * rec,int header_size,int maxlen)254 store_trace_args(void *data, struct trace_probe *tp, void *rec,
255 		 int header_size, int maxlen)
256 {
257 	struct probe_arg *arg;
258 	void *base = data - header_size;
259 	void *dyndata = data + tp->size;
260 	u32 *dl;	/* Data location */
261 	int ret, i;
262 
263 	for (i = 0; i < tp->nr_args; i++) {
264 		arg = tp->args + i;
265 		dl = data + arg->offset;
266 		/* Point the dynamic data area if needed */
267 		if (unlikely(arg->dynamic))
268 			*dl = make_data_loc(maxlen, dyndata - base);
269 		ret = process_fetch_insn(arg->code, rec, dl, base);
270 		if (arg->dynamic && likely(ret > 0)) {
271 			dyndata += ret;
272 			maxlen -= ret;
273 		}
274 	}
275 }
276