samples/ftrace/ftrace-direct-multi-modify.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/module.h>
   3 #include <linux/kthread.h>
   4 #include <linux/ftrace.h>
   5 #if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32)
   6 #include <asm/asm-offsets.h>
   7 #endif
   8
   9 extern void my_direct_func1(unsigned long ip);
  10 extern void my_direct_func2(unsigned long ip);
  11
  12 void my_direct_func1(unsigned long ip)
  13 {
  14         trace_printk("my direct func1 ip %lx\n", ip);
  15 }
  16
  17 void my_direct_func2(unsigned long ip)
  18 {
  19         trace_printk("my direct func2 ip %lx\n", ip);
  20 }
  21
  22 extern void my_tramp1(void *);
  23 extern void my_tramp2(void *);
  24
  25 #ifdef CONFIG_RISCV
  26 #include <asm/asm.h>
  27
  28 asm (
  29 "       .pushsection    .text, \"ax\", @progbits\n"
  30 "       .type           my_tramp1, @function\n"
  31 "       .globl          my_tramp1\n"
  32 "   my_tramp1:\n"
  33 "       addi    sp,sp,-3*"SZREG"\n"
  34 "       "REG_S" a0,0*"SZREG"(sp)\n"
  35 "       "REG_S" t0,1*"SZREG"(sp)\n"
  36 "       "REG_S" ra,2*"SZREG"(sp)\n"
  37 "       mv      a0,t0\n"
  38 "       call    my_direct_func1\n"
  39 "       "REG_L" a0,0*"SZREG"(sp)\n"
  40 "       "REG_L" t0,1*"SZREG"(sp)\n"
  41 "       "REG_L" ra,2*"SZREG"(sp)\n"
  42 "       addi    sp,sp,3*"SZREG"\n"
  43 "       jr      t0\n"
  44 "       .size           my_tramp1, .-my_tramp1\n"
  45
  46 "       .type           my_tramp2, @function\n"
  47 "       .globl          my_tramp2\n"
  48 "   my_tramp2:\n"
  49 "       addi    sp,sp,-3*"SZREG"\n"
  50 "       "REG_S" a0,0*"SZREG"(sp)\n"
  51 "       "REG_S" t0,1*"SZREG"(sp)\n"
  52 "       "REG_S" ra,2*"SZREG"(sp)\n"
  53 "       mv      a0,t0\n"
  54 "       call    my_direct_func2\n"
  55 "       "REG_L" a0,0*"SZREG"(sp)\n"
  56 "       "REG_L" t0,1*"SZREG"(sp)\n"
  57 "       "REG_L" ra,2*"SZREG"(sp)\n"
  58 "       addi    sp,sp,3*"SZREG"\n"
  59 "       jr      t0\n"
  60 "       .size           my_tramp2, .-my_tramp2\n"
  61 "       .popsection\n"
  62 );
  63
  64 #endif /* CONFIG_RISCV */
  65
  66 #ifdef CONFIG_X86_64
  67
  68 #include <asm/ibt.h>
  69 #include <asm/nospec-branch.h>
  70
  71 asm (
  72 "       .pushsection    .text, \"ax\", @progbits\n"
  73 "       .type           my_tramp1, @function\n"
  74 "       .globl          my_tramp1\n"
  75 "   my_tramp1:"
  76         ASM_ENDBR
  77 "       pushq %rbp\n"
  78 "       movq %rsp, %rbp\n"
  79         CALL_DEPTH_ACCOUNT
  80 "       pushq %rdi\n"
  81 "       movq 8(%rbp), %rdi\n"
  82 "       call my_direct_func1\n"
  83 "       popq %rdi\n"
  84 "       leave\n"
  85         ASM_RET
  86 "       .size           my_tramp1, .-my_tramp1\n"
  87
  88 "       .type           my_tramp2, @function\n"
  89 "       .globl          my_tramp2\n"
  90 "   my_tramp2:"
  91         ASM_ENDBR
  92 "       pushq %rbp\n"
  93 "       movq %rsp, %rbp\n"
  94         CALL_DEPTH_ACCOUNT
  95 "       pushq %rdi\n"
  96 "       movq 8(%rbp), %rdi\n"
  97 "       call my_direct_func2\n"
  98 "       popq %rdi\n"
  99 "       leave\n"
 100         ASM_RET
 101 "       .size           my_tramp2, .-my_tramp2\n"
 102 "       .popsection\n"
 103 );
 104
 105 #endif /* CONFIG_X86_64 */
 106
 107 #ifdef CONFIG_S390
 108
 109 asm (
 110 "       .pushsection    .text, \"ax\", @progbits\n"
 111 "       .type           my_tramp1, @function\n"
 112 "       .globl          my_tramp1\n"
 113 "   my_tramp1:"
 114 "       lgr             %r1,%r15\n"
 115 "       stmg            %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 116 "       stg             %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 117 "       aghi            %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
 118 "       stg             %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
 119 "       lgr             %r2,%r0\n"
 120 "       brasl           %r14,my_direct_func1\n"
 121 "       aghi            %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
 122 "       lmg             %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 123 "       lg              %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 124 "       lgr             %r1,%r0\n"
 125 "       br              %r1\n"
 126 "       .size           my_tramp1, .-my_tramp1\n"
 127 "\n"
 128 "       .type           my_tramp2, @function\n"
 129 "       .globl          my_tramp2\n"
 130 "   my_tramp2:"
 131 "       lgr             %r1,%r15\n"
 132 "       stmg            %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 133 "       stg             %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 134 "       aghi            %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
 135 "       stg             %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
 136 "       lgr             %r2,%r0\n"
 137 "       brasl           %r14,my_direct_func2\n"
 138 "       aghi            %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
 139 "       lmg             %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 140 "       lg              %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 141 "       lgr             %r1,%r0\n"
 142 "       br              %r1\n"
 143 "       .size           my_tramp2, .-my_tramp2\n"
 144 "       .popsection\n"
 145 );
 146
 147 #endif /* CONFIG_S390 */
 148
 149 #ifdef CONFIG_ARM64
 150
 151 asm (
 152 "       .pushsection    .text, \"ax\", @progbits\n"
 153 "       .type           my_tramp1, @function\n"
 154 "       .globl          my_tramp1\n"
 155 "   my_tramp1:"
 156 "       hint    34\n" // bti    c
 157 "       sub     sp, sp, #32\n"
 158 "       stp     x9, x30, [sp]\n"
 159 "       str     x0, [sp, #16]\n"
 160 "       mov     x0, x30\n"
 161 "       bl      my_direct_func1\n"
 162 "       ldp     x30, x9, [sp]\n"
 163 "       ldr     x0, [sp, #16]\n"
 164 "       add     sp, sp, #32\n"
 165 "       ret     x9\n"
 166 "       .size           my_tramp1, .-my_tramp1\n"
 167
 168 "       .type           my_tramp2, @function\n"
 169 "       .globl          my_tramp2\n"
 170 "   my_tramp2:"
 171 "       hint    34\n" // bti    c
 172 "       sub     sp, sp, #32\n"
 173 "       stp     x9, x30, [sp]\n"
 174 "       str     x0, [sp, #16]\n"
 175 "       mov     x0, x30\n"
 176 "       bl      my_direct_func2\n"
 177 "       ldp     x30, x9, [sp]\n"
 178 "       ldr     x0, [sp, #16]\n"
 179 "       add     sp, sp, #32\n"
 180 "       ret     x9\n"
 181 "       .size           my_tramp2, .-my_tramp2\n"
 182 "       .popsection\n"
 183 );
 184
 185 #endif /* CONFIG_ARM64 */
 186
 187 #ifdef CONFIG_LOONGARCH
 188 #include <asm/asm.h>
 189
 190 asm (
 191 "       .pushsection    .text, \"ax\", @progbits\n"
 192 "       .type           my_tramp1, @function\n"
 193 "       .globl          my_tramp1\n"
 194 "   my_tramp1:\n"
 195 "       addi.d  $sp, $sp, -32\n"
 196 "       st.d    $a0, $sp, 0\n"
 197 "       st.d    $t0, $sp, 8\n"
 198 "       st.d    $ra, $sp, 16\n"
 199 "       move    $a0, $t0\n"
 200 "       bl      my_direct_func1\n"
 201 "       ld.d    $a0, $sp, 0\n"
 202 "       ld.d    $t0, $sp, 8\n"
 203 "       ld.d    $ra, $sp, 16\n"
 204 "       addi.d  $sp, $sp, 32\n"
 205 "       jr      $t0\n"
 206 "       .size           my_tramp1, .-my_tramp1\n"
 207
 208 "       .type           my_tramp2, @function\n"
 209 "       .globl          my_tramp2\n"
 210 "   my_tramp2:\n"
 211 "       addi.d  $sp, $sp, -32\n"
 212 "       st.d    $a0, $sp, 0\n"
 213 "       st.d    $t0, $sp, 8\n"
 214 "       st.d    $ra, $sp, 16\n"
 215 "       move    $a0, $t0\n"
 216 "       bl      my_direct_func2\n"
 217 "       ld.d    $a0, $sp, 0\n"
 218 "       ld.d    $t0, $sp, 8\n"
 219 "       ld.d    $ra, $sp, 16\n"
 220 "       addi.d  $sp, $sp, 32\n"
 221 "       jr      $t0\n"
 222 "       .size           my_tramp2, .-my_tramp2\n"
 223 "       .popsection\n"
 224 );
 225
 226 #endif /* CONFIG_LOONGARCH */
 227
 228 #ifdef CONFIG_PPC
 229 #include <asm/ppc_asm.h>
 230
 231 #ifdef CONFIG_PPC64
 232 #define STACK_FRAME_SIZE 48
 233 #else
 234 #define STACK_FRAME_SIZE 24
 235 #endif
 236
 237 #if defined(CONFIG_PPC64_ELF_ABI_V2) && !defined(CONFIG_PPC_KERNEL_PCREL)
 238 #define PPC64_TOC_SAVE_AND_UPDATE                       \
 239 "       std             2, 24(1)\n"                     \
 240 "       bcl             20, 31, 1f\n"                   \
 241 "   1:  mflr            12\n"                           \
 242 "       ld              2, (99f - 1b)(12)\n"
 243 #define PPC64_TOC_RESTORE                               \
 244 "       ld              2, 24(1)\n"
 245 #define PPC64_TOC                                       \
 246 "   99: .quad           .TOC.@tocbase\n"
 247 #else
 248 #define PPC64_TOC_SAVE_AND_UPDATE ""
 249 #define PPC64_TOC_RESTORE ""
 250 #define PPC64_TOC ""
 251 #endif
 252
 253 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
 254 #define PPC_FTRACE_RESTORE_LR                           \
 255         PPC_LL"         0, "__stringify(PPC_LR_STKOFF)"(1)\n"   \
 256 "       mtlr            0\n"
 257 #define PPC_FTRACE_RET                                  \
 258 "       blr\n"
 259 #define PPC_FTRACE_RECOVER_IP                           \
 260 "       lwz             8, 4(3)\n"                      \
 261 "       li              9, 6\n"                         \
 262 "       slw             8, 8, 9\n"                      \
 263 "       sraw            8, 8, 9\n"                      \
 264 "       add             3, 3, 8\n"                      \
 265 "       addi            3, 3, 4\n"
 266 #else
 267 #define PPC_FTRACE_RESTORE_LR                           \
 268         PPC_LL"         0, "__stringify(PPC_LR_STKOFF)"(1)\n"   \
 269 "       mtctr           0\n"
 270 #define PPC_FTRACE_RET                                  \
 271 "       mtlr            0\n"                            \
 272 "       bctr\n"
 273 #define PPC_FTRACE_RECOVER_IP ""
 274 #endif
 275
 276 asm (
 277 "       .pushsection    .text, \"ax\", @progbits\n"
 278 "       .type           my_tramp1, @function\n"
 279 "       .globl          my_tramp1\n"
 280 "   my_tramp1:\n"
 281         PPC_STL"        0, "__stringify(PPC_LR_STKOFF)"(1)\n"
 282         PPC_STLU"       1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
 283 "       mflr            0\n"
 284         PPC_STL"        0, "__stringify(PPC_LR_STKOFF)"(1)\n"
 285         PPC_STLU"       1, -"__stringify(STACK_FRAME_SIZE)"(1)\n"
 286         PPC64_TOC_SAVE_AND_UPDATE
 287         PPC_STL"        3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
 288 "       mr              3, 0\n"
 289         PPC_FTRACE_RECOVER_IP
 290 "       bl              my_direct_func1\n"
 291         PPC_LL"         3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
 292         PPC64_TOC_RESTORE
 293 "       addi            1, 1, "__stringify(STACK_FRAME_SIZE)"\n"
 294         PPC_FTRACE_RESTORE_LR
 295 "       addi            1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n"
 296         PPC_LL"         0, "__stringify(PPC_LR_STKOFF)"(1)\n"
 297         PPC_FTRACE_RET
 298 "       .size           my_tramp1, .-my_tramp1\n"
 299
 300 "       .type           my_tramp2, @function\n"
 301 "       .globl          my_tramp2\n"
 302 "   my_tramp2:\n"
 303         PPC_STL"        0, "__stringify(PPC_LR_STKOFF)"(1)\n"
 304         PPC_STLU"       1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
 305 "       mflr            0\n"
 306         PPC_STL"        0, "__stringify(PPC_LR_STKOFF)"(1)\n"
 307         PPC_STLU"       1, -"__stringify(STACK_FRAME_SIZE)"(1)\n"
 308         PPC64_TOC_SAVE_AND_UPDATE
 309         PPC_STL"        3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
 310 "       mr              3, 0\n"
 311         PPC_FTRACE_RECOVER_IP
 312 "       bl              my_direct_func2\n"
 313         PPC_LL"         3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
 314         PPC64_TOC_RESTORE
 315 "       addi            1, 1, "__stringify(STACK_FRAME_SIZE)"\n"
 316         PPC_FTRACE_RESTORE_LR
 317 "       addi            1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n"
 318         PPC_LL"         0, "__stringify(PPC_LR_STKOFF)"(1)\n"
 319         PPC_FTRACE_RET
 320         PPC64_TOC
 321         "       .size           my_tramp2, .-my_tramp2\n"
 322 "       .popsection\n"
 323 );
 324
 325 #endif /* CONFIG_PPC */
 326
 327 static unsigned long my_tramp = (unsigned long)my_tramp1;
 328 static unsigned long tramps[2] = {
 329         (unsigned long)my_tramp1,
 330         (unsigned long)my_tramp2,
 331 };
 332
 333 static struct ftrace_ops direct;
 334
 335 static int simple_thread(void *arg)
 336 {
 337         static int t;
 338         int ret = 0;
 339
 340         while (!kthread_should_stop()) {
 341                 set_current_state(TASK_INTERRUPTIBLE);
 342                 schedule_timeout(2 * HZ);
 343
 344                 if (ret)
 345                         continue;
 346                 t ^= 1;
 347                 ret = modify_ftrace_direct(&direct, tramps[t]);
 348                 if (!ret)
 349                         my_tramp = tramps[t];
 350                 WARN_ON_ONCE(ret);
 351         }
 352
 353         return 0;
 354 }
 355
 356 static struct task_struct *simple_tsk;
 357
 358 static int __init ftrace_direct_multi_init(void)
 359 {
 360         int ret;
 361
 362         ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
 363         ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
 364
 365         ret = register_ftrace_direct(&direct, my_tramp);
 366
 367         if (!ret)
 368                 simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
 369         return ret;
 370 }
 371
 372 static void __exit ftrace_direct_multi_exit(void)
 373 {
 374         kthread_stop(simple_tsk);
 375         unregister_ftrace_direct(&direct, my_tramp, true);
 376 }
 377
 378 module_init(ftrace_direct_multi_init);
 379 module_exit(ftrace_direct_multi_exit);
 380
 381 MODULE_AUTHOR("Jiri Olsa");
 382 MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()");
 383 MODULE_LICENSE("GPL");