insn_get_modrm(9)

📦 version 7.3.1, in nixpkgs unstable

💅 insn_get_modrm — collect ModRM byte, if any

okay so real talk, this is a page from the Kernel API Manual (section 9, the kernel-functions girlies), and it's about grabbing that one little ModRM byte. let's get into it bestie 🫶

✨ SYNOPSIS ✨

int insn_get_modrm (struct insn *insn );

🎀 ARGUMENTS 🎀

  • insn — a struct insn that's holding your instruction. that's it, that's the whole arg 💖

🌸 DESCRIPTION 🌸

okay so what this does: it populates insn->modrm and then updates insn->next_byte so it points past the ModRM byte — if there is one, that is. no ModRM byte? nothing to point past. simple as that ✨

and if it needs to, it'll first go collect the bytes that come before it (the prefixes and the opcode(s)) — like, it's not gonna just vibe in there without the context, it does the homework first 📚

but here's the thing — no effect if insn->modrm.got is already 1. if you already got it, you already got it. it's giving "we been knew" 💅 no double-dipping.

⭐ RETURN ⭐

  • 0 — on success 🎉
  • < 0 — on error 😭

(yes that's the whole list. two outcomes. iconic minimalism.)

🦋 SEE ALSO 🦋

so the kernel file this lives in is ./tools/arch/x86/lib/insn.c, and honestly you should go meet the whole friend group:

like, this function is one member of a whole squad fr fr 🌈

and that's the page!! mwah 💋 this one's shipped out of ./tools/arch/x86/lib, dated October 2026, and it's insn_get_modrm(9) — go forth and decode, bestie, you're gonna slay 👑✨

📦 where this page comes from