91 lines
2.1 KiB
C
91 lines
2.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/module.h>
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#include <linux/mm.h> /* for handle_mm_fault() */
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#include <linux/ftrace.h>
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#include <asm/asm-offsets.h>
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extern void my_direct_func(struct vm_area_struct *vma,
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unsigned long address, unsigned int flags);
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void my_direct_func(struct vm_area_struct *vma,
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unsigned long address, unsigned int flags)
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{
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trace_printk("handle mm fault vma=%p address=%lx flags=%x\n",
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vma, address, flags);
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}
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extern void my_tramp(void *);
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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_tramp, @function\n"
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" .globl my_tramp\n"
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" my_tramp:"
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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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" pushq %rdi\n"
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" pushq %rsi\n"
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" pushq %rdx\n"
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" call my_direct_func\n"
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" popq %rdx\n"
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" popq %rsi\n"
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" popq %rdi\n"
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" leave\n"
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ASM_RET
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" .size my_tramp, .-my_tramp\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_tramp, @function\n"
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" .globl my_tramp\n"
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" my_tramp:"
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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_func\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_tramp, .-my_tramp\n"
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" .popsection\n"
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);
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#endif /* CONFIG_S390 */
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static int __init ftrace_direct_init(void)
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{
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return register_ftrace_direct((unsigned long)handle_mm_fault,
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(unsigned long)my_tramp);
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}
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static void __exit ftrace_direct_exit(void)
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{
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unregister_ftrace_direct((unsigned long)handle_mm_fault,
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(unsigned long)my_tramp);
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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("Another example use case of using register_ftrace_direct()");
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MODULE_LICENSE("GPL");
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