modify_ftrace_direct(9)

💖 modify_ftrace_direct(9) 💖

okay so bestie, this is the Kernel API Manual page for modify_ftrace_direct(9) — the function that’s literally here to modify an existing direct 'multi' call to call something else. it’s giving kernel-level main character energy, and we’re gonna read it together, fr fr. 💅

✨ NAME ✨

modify_ftrace_direct — modify an existing direct 'multi' call to call something else. periodt.

🌸 SYNOPSIS 🌸

int modify_ftrace_direct (struct ftrace_ops *ops , unsigned long addr );

🎀 ARGUMENTS 🎀

• ops — the address of the struct ftrace_ops object. yeah, that one 🫶
• addr — the address of the new trampoline to call at ops functions.

🦋 DESCRIPTION 🦋

So what’s the vibe? This is used to unregister the direct caller that’s currently registered, and then register a new one — addr — on the functions registered in the ops object. basically a switcheroo, but for callbacks. iconic behavior, honestly. ✨

⚠️ important little caveat, bestie: the way that there’s a window between ftrace_shutdown and ftrace_startup calls where there will be no callbacks called is lowkey ominous, ngl. not me stressing about the gap 😭

🔥 RETURN 🔥

• zero on success. slay. 💖
• Non zero on error, which includes -EINVAL — the ops object was not properly registered.

🌈 SEE ALSO 🌈

Kernel file: ./kernel/trace/ftrace.c

• ftrace_lookup_ip(9)
• ftrace_free_filter(9)
• ftrace_hash_move(9)
• ftrace_location_range(9)
• ftrace_location(9)
• ftrace_text_reserved(9)
• ftrace_bug(9)
• ftrace_update_record(9)
• ftrace_test_record(9)
• ftrace_get_addr_new(9)
• ftrace_get_addr_curr(9)
• ftrace_rec_iter_start(9)
• ftrace_rec_iter_next(9)
• ftrace_rec_iter_record(9)
• ftrace_run_stop_machine(9)
• arch_ftrace_update_code(9)
• ftrace_startup_subops(9)
• ftrace_shutdown_subops(9)
• ftrace_regex_open(9)
• allocate_ftrace_func_mapper(9)
• ftrace_func_mapper_find_ip(9)
• ftrace_func_mapper_add_ip(9)
• ftrace_func_mapper_remove_ip(9)
• free_ftrace_func_mapper(9)
• register_ftrace_direct(9)
• unregister_ftrace_direct(9)
• modify_ftrace_direct_nolock(9)
• hash_add(9)
• update_ftrace_direct_add(9)
• hash_sub(9)
• update_ftrace_direct_del(9)
• update_ftrace_direct_mod(9)
• ftrace_set_filter_ip(9)
• ftrace_set_filter_ips(9)
• ftrace_ops_set_global_filter(9)
• ftrace_set_filter(9)
• ftrace_set_notrace(9)
• ftrace_set_global_filter(9)
• ftrace_set_global_notrace(9)
• ftrace_ops_get_func(9)
• ftrace_kill(9)
• ftrace_is_dead(9)
• register_ftrace_function(9)
• unregister_ftrace_function(9)
• ftrace_lookup_symbols(9)

xoxo, bestie — this page is sourced from ./kernel/trace, dated October 2026. stay iconic, and maybe go touch some kernel code 💖✨