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Linux/arch/nds32/kernel/ftrace.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 
  3 #include <linux/ftrace.h>
  4 #include <linux/uaccess.h>
  5 #include <asm/cacheflush.h>
  6 
  7 #ifndef CONFIG_DYNAMIC_FTRACE
  8 extern void (*ftrace_trace_function)(unsigned long, unsigned long,
  9                                      struct ftrace_ops*, struct pt_regs*);
 10 extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
 11 extern void ftrace_graph_caller(void);
 12 
 13 noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
 14                                   struct ftrace_ops *op, struct pt_regs *regs)
 15 {
 16         __asm__ ("");  /* avoid to optimize as pure function */
 17 }
 18 
 19 noinline void _mcount(unsigned long parent_ip)
 20 {
 21         /* save all state by the compiler prologue */
 22 
 23         unsigned long ip = (unsigned long)__builtin_return_address(0);
 24 
 25         if (ftrace_trace_function != ftrace_stub)
 26                 ftrace_trace_function(ip - MCOUNT_INSN_SIZE, parent_ip,
 27                                       NULL, NULL);
 28 
 29 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 30         if (ftrace_graph_return != (trace_func_graph_ret_t)ftrace_stub
 31             || ftrace_graph_entry != ftrace_graph_entry_stub)
 32                 ftrace_graph_caller();
 33 #endif
 34 
 35         /* restore all state by the compiler epilogue */
 36 }
 37 EXPORT_SYMBOL(_mcount);
 38 
 39 #else /* CONFIG_DYNAMIC_FTRACE */
 40 
 41 noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
 42                                   struct ftrace_ops *op, struct pt_regs *regs)
 43 {
 44         __asm__ ("");  /* avoid to optimize as pure function */
 45 }
 46 
 47 noinline void __naked _mcount(unsigned long parent_ip)
 48 {
 49         __asm__ ("");  /* avoid to optimize as pure function */
 50 }
 51 EXPORT_SYMBOL(_mcount);
 52 
 53 #define XSTR(s) STR(s)
 54 #define STR(s) #s
 55 void _ftrace_caller(unsigned long parent_ip)
 56 {
 57         /* save all state needed by the compiler prologue */
 58 
 59         /*
 60          * prepare arguments for real tracing function
 61          * first  arg : __builtin_return_address(0) - MCOUNT_INSN_SIZE
 62          * second arg : parent_ip
 63          */
 64         __asm__ __volatile__ (
 65                 "move $r1, %0                              \n\t"
 66                 "addi $r0, %1, #-" XSTR(MCOUNT_INSN_SIZE) "\n\t"
 67                 :
 68                 : "r" (parent_ip), "r" (__builtin_return_address(0)));
 69 
 70         /* a placeholder for the call to a real tracing function */
 71         __asm__ __volatile__ (
 72                 "ftrace_call:           \n\t"
 73                 "nop                    \n\t"
 74                 "nop                    \n\t"
 75                 "nop                    \n\t");
 76 
 77 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 78         /* a placeholder for the call to ftrace_graph_caller */
 79         __asm__ __volatile__ (
 80                 "ftrace_graph_call:     \n\t"
 81                 "nop                    \n\t"
 82                 "nop                    \n\t"
 83                 "nop                    \n\t");
 84 #endif
 85         /* restore all state needed by the compiler epilogue */
 86 }
 87 
 88 int __init ftrace_dyn_arch_init(void)
 89 {
 90         return 0;
 91 }
 92 
 93 int ftrace_arch_code_modify_prepare(void)
 94 {
 95         set_all_modules_text_rw();
 96         return 0;
 97 }
 98 
 99 int ftrace_arch_code_modify_post_process(void)
100 {
101         set_all_modules_text_ro();
102         return 0;
103 }
104 
105 static unsigned long gen_sethi_insn(unsigned long addr)
106 {
107         unsigned long opcode = 0x46000000;
108         unsigned long imm = addr >> 12;
109         unsigned long rt_num = 0xf << 20;
110 
111         return ENDIAN_CONVERT(opcode | rt_num | imm);
112 }
113 
114 static unsigned long gen_ori_insn(unsigned long addr)
115 {
116         unsigned long opcode = 0x58000000;
117         unsigned long imm = addr & 0x0000fff;
118         unsigned long rt_num = 0xf << 20;
119         unsigned long ra_num = 0xf << 15;
120 
121         return ENDIAN_CONVERT(opcode | rt_num | ra_num | imm);
122 }
123 
124 static unsigned long gen_jral_insn(unsigned long addr)
125 {
126         unsigned long opcode = 0x4a000001;
127         unsigned long rt_num = 0x1e << 20;
128         unsigned long rb_num = 0xf << 10;
129 
130         return ENDIAN_CONVERT(opcode | rt_num | rb_num);
131 }
132 
133 static void ftrace_gen_call_insn(unsigned long *call_insns,
134                                  unsigned long addr)
135 {
136         call_insns[0] = gen_sethi_insn(addr); /* sethi $r15, imm20u       */
137         call_insns[1] = gen_ori_insn(addr);   /* ori   $r15, $r15, imm15u */
138         call_insns[2] = gen_jral_insn(addr);  /* jral  $lp,  $r15         */
139 }
140 
141 static int __ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
142                                 unsigned long *new_insn, bool validate)
143 {
144         unsigned long orig_insn[3];
145 
146         if (validate) {
147                 if (probe_kernel_read(orig_insn, (void *)pc, MCOUNT_INSN_SIZE))
148                         return -EFAULT;
149                 if (memcmp(orig_insn, old_insn, MCOUNT_INSN_SIZE))
150                         return -EINVAL;
151         }
152 
153         if (probe_kernel_write((void *)pc, new_insn, MCOUNT_INSN_SIZE))
154                 return -EPERM;
155 
156         return 0;
157 }
158 
159 static int ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
160                               unsigned long *new_insn, bool validate)
161 {
162         int ret;
163 
164         ret = __ftrace_modify_code(pc, old_insn, new_insn, validate);
165         if (ret)
166                 return ret;
167 
168         flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
169 
170         return ret;
171 }
172 
173 int ftrace_update_ftrace_func(ftrace_func_t func)
174 {
175         unsigned long pc = (unsigned long)&ftrace_call;
176         unsigned long old_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
177         unsigned long new_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
178 
179         if (func != ftrace_stub)
180                 ftrace_gen_call_insn(new_insn, (unsigned long)func);
181 
182         return ftrace_modify_code(pc, old_insn, new_insn, false);
183 }
184 
185 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
186 {
187         unsigned long pc = rec->ip;
188         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
189         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
190 
191         ftrace_gen_call_insn(call_insn, addr);
192 
193         return ftrace_modify_code(pc, nop_insn, call_insn, true);
194 }
195 
196 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
197                     unsigned long addr)
198 {
199         unsigned long pc = rec->ip;
200         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
201         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
202 
203         ftrace_gen_call_insn(call_insn, addr);
204 
205         return ftrace_modify_code(pc, call_insn, nop_insn, true);
206 }
207 #endif /* CONFIG_DYNAMIC_FTRACE */
208 
209 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
210 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
211                            unsigned long frame_pointer)
212 {
213         unsigned long return_hooker = (unsigned long)&return_to_handler;
214         unsigned long old;
215 
216         if (unlikely(atomic_read(&current->tracing_graph_pause)))
217                 return;
218 
219         old = *parent;
220 
221         if (!function_graph_enter(old, self_addr, frame_pointer, NULL))
222                 *parent = return_hooker;
223 }
224 
225 noinline void ftrace_graph_caller(void)
226 {
227         unsigned long *parent_ip =
228                 (unsigned long *)(__builtin_frame_address(2) - 4);
229 
230         unsigned long selfpc =
231                 (unsigned long)(__builtin_return_address(1) - MCOUNT_INSN_SIZE);
232 
233         unsigned long frame_pointer =
234                 (unsigned long)__builtin_frame_address(3);
235 
236         prepare_ftrace_return(parent_ip, selfpc, frame_pointer);
237 }
238 
239 extern unsigned long ftrace_return_to_handler(unsigned long frame_pointer);
240 void __naked return_to_handler(void)
241 {
242         __asm__ __volatile__ (
243                 /* save state needed by the ABI     */
244                 "smw.adm $r0,[$sp],$r1,#0x0  \n\t"
245 
246                 /* get original return address      */
247                 "move $r0, $fp               \n\t"
248                 "bal ftrace_return_to_handler\n\t"
249                 "move $lp, $r0               \n\t"
250 
251                 /* restore state nedded by the ABI  */
252                 "lmw.bim $r0,[$sp],$r1,#0x0  \n\t");
253 }
254 
255 #ifdef CONFIG_DYNAMIC_FTRACE
256 extern unsigned long ftrace_graph_call;
257 
258 static int ftrace_modify_graph_caller(bool enable)
259 {
260         unsigned long pc = (unsigned long)&ftrace_graph_call;
261         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
262         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
263 
264         ftrace_gen_call_insn(call_insn, (unsigned long)ftrace_graph_caller);
265 
266         if (enable)
267                 return ftrace_modify_code(pc, nop_insn, call_insn, true);
268         else
269                 return ftrace_modify_code(pc, call_insn, nop_insn, true);
270 }
271 
272 int ftrace_enable_ftrace_graph_caller(void)
273 {
274         return ftrace_modify_graph_caller(true);
275 }
276 
277 int ftrace_disable_ftrace_graph_caller(void)
278 {
279         return ftrace_modify_graph_caller(false);
280 }
281 #endif /* CONFIG_DYNAMIC_FTRACE */
282 
283 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
284 
285 
286 #ifdef CONFIG_TRACE_IRQFLAGS
287 noinline void __trace_hardirqs_off(void)
288 {
289         trace_hardirqs_off();
290 }
291 noinline void __trace_hardirqs_on(void)
292 {
293         trace_hardirqs_on();
294 }
295 #endif /* CONFIG_TRACE_IRQFLAGS */
296 

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