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