257 lines
5.4 KiB
C
257 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/ftrace.h>
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#ifndef CONFIG_ARM64
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#include <asm/asm-offsets.h>
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#endif
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extern void my_direct_func1(void);
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extern void my_direct_func2(void);
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void my_direct_func1(void)
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{
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trace_printk("my direct func1\n");
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}
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void my_direct_func2(void)
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{
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trace_printk("my direct func2\n");
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}
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extern void my_tramp1(void *);
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extern void my_tramp2(void *);
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static unsigned long my_ip = (unsigned long)schedule;
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#ifdef CONFIG_RISCV
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#include <asm/asm.h>
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp1, @function\n"
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" .globl my_tramp1\n"
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" my_tramp1:\n"
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" addi sp,sp,-2*"SZREG"\n"
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" "REG_S" t0,0*"SZREG"(sp)\n"
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" "REG_S" ra,1*"SZREG"(sp)\n"
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" call my_direct_func1\n"
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" "REG_L" t0,0*"SZREG"(sp)\n"
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" "REG_L" ra,1*"SZREG"(sp)\n"
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" addi sp,sp,2*"SZREG"\n"
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" jr t0\n"
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" .size my_tramp1, .-my_tramp1\n"
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" .type my_tramp2, @function\n"
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" .globl my_tramp2\n"
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" my_tramp2:\n"
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" addi sp,sp,-2*"SZREG"\n"
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" "REG_S" t0,0*"SZREG"(sp)\n"
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" "REG_S" ra,1*"SZREG"(sp)\n"
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" call my_direct_func2\n"
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" "REG_L" t0,0*"SZREG"(sp)\n"
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" "REG_L" ra,1*"SZREG"(sp)\n"
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" addi sp,sp,2*"SZREG"\n"
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" jr t0\n"
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" .size my_tramp2, .-my_tramp2\n"
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" .popsection\n"
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);
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#endif /* CONFIG_RISCV */
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#ifdef CONFIG_X86_64
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#include <asm/ibt.h>
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#include <asm/nospec-branch.h>
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp1, @function\n"
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" .globl my_tramp1\n"
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" my_tramp1:"
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ASM_ENDBR
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" pushq %rbp\n"
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" movq %rsp, %rbp\n"
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CALL_DEPTH_ACCOUNT
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" call my_direct_func1\n"
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" leave\n"
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" .size my_tramp1, .-my_tramp1\n"
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ASM_RET
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" .type my_tramp2, @function\n"
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" .globl my_tramp2\n"
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" my_tramp2:"
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ASM_ENDBR
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" pushq %rbp\n"
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" movq %rsp, %rbp\n"
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CALL_DEPTH_ACCOUNT
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" call my_direct_func2\n"
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" leave\n"
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ASM_RET
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" .size my_tramp2, .-my_tramp2\n"
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" .popsection\n"
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);
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#endif /* CONFIG_X86_64 */
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#ifdef CONFIG_S390
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp1, @function\n"
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" .globl my_tramp1\n"
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" my_tramp1:"
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" lgr %r1,%r15\n"
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" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
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" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
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" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
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" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
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" brasl %r14,my_direct_func1\n"
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" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
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" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
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" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
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" lgr %r1,%r0\n"
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" br %r1\n"
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" .size my_tramp1, .-my_tramp1\n"
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" .type my_tramp2, @function\n"
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" .globl my_tramp2\n"
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" my_tramp2:"
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" lgr %r1,%r15\n"
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" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
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" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
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" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
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" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
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" brasl %r14,my_direct_func2\n"
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" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
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" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
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" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
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" lgr %r1,%r0\n"
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" br %r1\n"
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" .size my_tramp2, .-my_tramp2\n"
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" .popsection\n"
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);
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#endif /* CONFIG_S390 */
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#ifdef CONFIG_ARM64
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp1, @function\n"
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" .globl my_tramp1\n"
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" my_tramp1:"
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" hint 34\n" // bti c
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" sub sp, sp, #16\n"
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" stp x9, x30, [sp]\n"
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" bl my_direct_func1\n"
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" ldp x30, x9, [sp]\n"
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" add sp, sp, #16\n"
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" ret x9\n"
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" .size my_tramp1, .-my_tramp1\n"
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" .type my_tramp2, @function\n"
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" .globl my_tramp2\n"
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" my_tramp2:"
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" hint 34\n" // bti c
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" sub sp, sp, #16\n"
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" stp x9, x30, [sp]\n"
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" bl my_direct_func2\n"
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" ldp x30, x9, [sp]\n"
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" add sp, sp, #16\n"
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" ret x9\n"
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" .size my_tramp2, .-my_tramp2\n"
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" .popsection\n"
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);
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#endif /* CONFIG_ARM64 */
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#ifdef CONFIG_LOONGARCH
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp1, @function\n"
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" .globl my_tramp1\n"
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" my_tramp1:\n"
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" addi.d $sp, $sp, -16\n"
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" st.d $t0, $sp, 0\n"
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" st.d $ra, $sp, 8\n"
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" bl my_direct_func1\n"
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" ld.d $t0, $sp, 0\n"
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" ld.d $ra, $sp, 8\n"
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" addi.d $sp, $sp, 16\n"
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" jr $t0\n"
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" .size my_tramp1, .-my_tramp1\n"
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" .type my_tramp2, @function\n"
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" .globl my_tramp2\n"
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" my_tramp2:\n"
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" addi.d $sp, $sp, -16\n"
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" st.d $t0, $sp, 0\n"
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" st.d $ra, $sp, 8\n"
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" bl my_direct_func2\n"
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" ld.d $t0, $sp, 0\n"
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" ld.d $ra, $sp, 8\n"
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" addi.d $sp, $sp, 16\n"
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" jr $t0\n"
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" .size my_tramp2, .-my_tramp2\n"
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" .popsection\n"
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);
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#endif /* CONFIG_LOONGARCH */
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static struct ftrace_ops direct;
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static unsigned long my_tramp = (unsigned long)my_tramp1;
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static unsigned long tramps[2] = {
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(unsigned long)my_tramp1,
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(unsigned long)my_tramp2,
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};
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static int simple_thread(void *arg)
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{
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static int t;
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int ret = 0;
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while (!kthread_should_stop()) {
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set_current_state(TASK_INTERRUPTIBLE);
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schedule_timeout(2 * HZ);
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if (ret)
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continue;
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t ^= 1;
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ret = modify_ftrace_direct(&direct, tramps[t]);
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if (!ret)
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my_tramp = tramps[t];
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WARN_ON_ONCE(ret);
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}
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return 0;
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}
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static struct task_struct *simple_tsk;
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static int __init ftrace_direct_init(void)
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{
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int ret;
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ftrace_set_filter_ip(&direct, (unsigned long) my_ip, 0, 0);
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ret = register_ftrace_direct(&direct, my_tramp);
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if (!ret)
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simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
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return ret;
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}
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static void __exit ftrace_direct_exit(void)
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{
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kthread_stop(simple_tsk);
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unregister_ftrace_direct(&direct, my_tramp, true);
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}
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module_init(ftrace_direct_init);
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module_exit(ftrace_direct_exit);
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MODULE_AUTHOR("Steven Rostedt");
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MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()");
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MODULE_LICENSE("GPL");
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