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A common pattern when using the ftrace_direct_multi API is to unregister the ops and also immediately free its filter. We've noticed it's very easy for users to miss calling ftrace_free_filter(). This adds a "free_filters" argument to unregister_ftrace_direct_multi() to both remind the user they should free filters and also to make their life easier. Link: https://lkml.kernel.org/r/20230321140424.345218-2-revest@chromium.org Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Florent Revest <revest@chromium.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
// 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 <linux/sched/stat.h>
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#include <asm/asm-offsets.h>
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extern void my_direct_func(unsigned long ip);
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void my_direct_func(unsigned long ip)
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{
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trace_printk("ip %lx\n", ip);
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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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" movq 8(%rbp), %rdi\n"
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" call my_direct_func\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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" lgr %r2,%r0\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 struct ftrace_ops direct;
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static int __init ftrace_direct_multi_init(void)
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{
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ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
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ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
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return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
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}
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static void __exit ftrace_direct_multi_exit(void)
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{
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unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp, true);
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}
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module_init(ftrace_direct_multi_init);
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module_exit(ftrace_direct_multi_exit);
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MODULE_AUTHOR("Jiri Olsa");
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MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
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MODULE_LICENSE("GPL");
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