arch/nds32/kernel/ftrace.c

   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         struct ftrace_graph_ent trace;
 215         unsigned long old;
 216         int err;
 217
 218         if (unlikely(atomic_read(&current->tracing_graph_pause)))
 219                 return;
 220
 221         old = *parent;
 222
 223         trace.func = self_addr;
 224         trace.depth = current->curr_ret_stack + 1;
 225
 226         /* Only trace if the calling function expects to */
 227         if (!ftrace_graph_entry(&trace))
 228                 return;
 229
 230         err = ftrace_push_return_trace(old, self_addr, &trace.depth,
 231                                        frame_pointer, NULL);
 232
 233         if (err == -EBUSY)
 234                 return;
 235
 236         *parent = return_hooker;
 237 }
 238
 239 noinline void ftrace_graph_caller(void)
 240 {
 241         unsigned long *parent_ip =
 242                 (unsigned long *)(__builtin_frame_address(2) - 4);
 243
 244         unsigned long selfpc =
 245                 (unsigned long)(__builtin_return_address(1) - MCOUNT_INSN_SIZE);
 246
 247         unsigned long frame_pointer =
 248                 (unsigned long)__builtin_frame_address(3);
 249
 250         prepare_ftrace_return(parent_ip, selfpc, frame_pointer);
 251 }
 252
 253 extern unsigned long ftrace_return_to_handler(unsigned long frame_pointer);
 254 void __naked return_to_handler(void)
 255 {
 256         __asm__ __volatile__ (
 257                 /* save state needed by the ABI     */
 258                 "smw.adm $r0,[$sp],$r1,#0x0  \n\t"
 259
 260                 /* get original return address      */
 261                 "move $r0, $fp               \n\t"
 262                 "bal ftrace_return_to_handler\n\t"
 263                 "move $lp, $r0               \n\t"
 264
 265                 /* restore state nedded by the ABI  */
 266                 "lmw.bim $r0,[$sp],$r1,#0x0  \n\t");
 267 }
 268
 269 #ifdef CONFIG_DYNAMIC_FTRACE
 270 extern unsigned long ftrace_graph_call;
 271
 272 static int ftrace_modify_graph_caller(bool enable)
 273 {
 274         unsigned long pc = (unsigned long)&ftrace_graph_call;
 275         unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 276         unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
 277
 278         ftrace_gen_call_insn(call_insn, (unsigned long)ftrace_graph_caller);
 279
 280         if (enable)
 281                 return ftrace_modify_code(pc, nop_insn, call_insn, true);
 282         else
 283                 return ftrace_modify_code(pc, call_insn, nop_insn, true);
 284 }
 285
 286 int ftrace_enable_ftrace_graph_caller(void)
 287 {
 288         return ftrace_modify_graph_caller(true);
 289 }
 290
 291 int ftrace_disable_ftrace_graph_caller(void)
 292 {
 293         return ftrace_modify_graph_caller(false);
 294 }
 295 #endif /* CONFIG_DYNAMIC_FTRACE */
 296
 297 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 298
 299
 300 #ifdef CONFIG_TRACE_IRQFLAGS
 301 noinline void __trace_hardirqs_off(void)
 302 {
 303         trace_hardirqs_off();
 304 }
 305 noinline void __trace_hardirqs_on(void)
 306 {
 307         trace_hardirqs_on();
 308 }
 309 #endif /* CONFIG_TRACE_IRQFLAGS */