kprobe_on_func_entry(9)

💅 kprobe_on_func_entry(9) — a Kernel API Manual moment

ok so bestie, welcome to the Kernel API Manual entry for kprobe_on_func_entry(9). this one's a little vibe-checker function, she just looks at an address and tells you if it's the actual entry of a function or not. no cap, that's the whole gig. ✨

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🌸 NAME 🌸

kprobe_on_func_entry — check whether given address is function entry

like literally. that's her job. she checks. she reports. she leaves. 👑

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🎀 SYNOPSIS 🎀

int kprobe_on_func_entry (kprobe_opcode_t *addr , const char *sym ,
       unsigned long offset );

yes the spacing in the signature is giving "written by a kernel dev at 3am" and we respect it 💀 keep it exactly like that, bestie, it's canon.

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🦋 ARGUMENTS 🦋

• addr — Target address. the actual memory address you're curious about 🫶
• sym — Target symbol name. the name-brand version of the same question ✨
• offset — The offset from the symbol or the address. so like, your little scoot away from wherever you started 🌈

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🔥 DESCRIPTION 🔥

okay so here's the tea ☕: this function checks whether the given addr+offset or sym+offset lands exactly on the function entry address. that's it. that's the whole plot.

the receipts come back like this:

• returns 0 if it is the function entry — she ate, she's iconic, green light 💚
• returns -EINVAL if it is not the function entry 😭
• also returns -ENOENT if it fails the symbol or address lookup — like the lookup just ghosted her 👻

⚠️ real talk though, bestie: the caller must pass addr or sym (either one must be NULL — yep, exactly one of them, that's the rule), or this returns -EINVAL. so don't be out here passing both and then acting surprised. 🙈

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💜 SEE ALSO 💜

• Kernel file ./kernel/kprobes.c __get_insn_slot(9)
• kretprobe_find_ret_addr(9)

go read those too, they're lowkey part of the same friend group 🧚

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and that's the whole page, bestie, no notes 💅 this masterpiece came from ./kernel, dated October 2026, and she's officially catalogued as kprobe_on_func_entry(9). periodt. 🎀⭐