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 #ifndef CONFIG_ARM64
   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 static unsigned long my_tramp = (unsigned long)my_tramp1;
 229 static unsigned long tramps[2] = {
 230         (unsigned long)my_tramp1,
 231         (unsigned long)my_tramp2,
 232 };
 233
 234 static struct ftrace_ops direct;
 235
 236 static int simple_thread(void *arg)
 237 {
 238         static int t;
 239         int ret = 0;
 240
 241         while (!kthread_should_stop()) {
 242                 set_current_state(TASK_INTERRUPTIBLE);
 243                 schedule_timeout(2 * HZ);
 244
 245                 if (ret)
 246                         continue;
 247                 t ^= 1;
 248                 ret = modify_ftrace_direct(&direct, tramps[t]);
 249                 if (!ret)
 250                         my_tramp = tramps[t];
 251                 WARN_ON_ONCE(ret);
 252         }
 253
 254         return 0;
 255 }
 256
 257 static struct task_struct *simple_tsk;
 258
 259 static int __init ftrace_direct_multi_init(void)
 260 {
 261         int ret;
 262
 263         ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
 264         ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
 265
 266         ret = register_ftrace_direct(&direct, my_tramp);
 267
 268         if (!ret)
 269                 simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
 270         return ret;
 271 }
 272
 273 static void __exit ftrace_direct_multi_exit(void)
 274 {
 275         kthread_stop(simple_tsk);
 276         unregister_ftrace_direct(&direct, my_tramp, true);
 277 }
 278
 279 module_init(ftrace_direct_multi_init);
 280 module_exit(ftrace_direct_multi_exit);
 281
 282 MODULE_AUTHOR("Jiri Olsa");
 283 MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()");
 284 MODULE_LICENSE("GPL");