ftrace_init_nop(9)

✨ ftrace_init_nop(9) ✨

okay so bestie, welcome to page ftrace_init_nop(9) from the Kernel API Manual 💅 this one's a kernel-arch-flavored baddie and she is very particular about how you treat her 🫶

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🌸 NAME 🌸

ftrace_init_nop — initialize a nop call site ✨

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🎀 SYNOPSIS 🎀

int ftrace_init_nop (struct module *mod , struct dyn_ftrace *rec );

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💖 ARGUMENTS 💖

• mod — the module structure, but only if you're being called by module load initialization 👀
• rec — the call site record (think mcount/fentry), the actual spot we're poking at 🎯

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🔥 DESCRIPTION 🔥

okay so this is a very sensitive operation and the arch needs to take great care with it, no cap. like, this is not the moment to freestyle 😭

The operation should carefully read the location, then check to see if what is read is indeed what we expect it to be, and then — only on success of that compare — it should write to the location. read → verify → write, in that order, periodt 💅

The code segment at rec->ip should contain the contents created by the compiler 🧚

The return must be:

• 0 — on success 🎉
• -EFAULT — on error reading the location 😭
• -EINVAL — on a failed compare of the contents 💀
• -EPERM — on error writing to the location 🙈

any other value will be considered a failure, so don't be out here inventing your own return codes bestie, that's not the vibe ⭐

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🦋 SEE ALSO 🦋

Kernel file ./include/linux/ftrace.h, plus these iconic little references:

• stack_tracer_disable(9)
• stack_tracer_enable(9)
• ftrace_get_symaddr(9)
• ftrace_make_nop(9)
• ftrace_need_init_nop(9)
• ftrace_make_call(9)
• ftrace_modify_call(9)

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and that's the whole page, main character energy complete 👑 this lil gem lives in ./include/linux and it's dated October 2026 — signature ftrace_init_nop(9), mwah 💋🌸