insn_decode_from_regs(9)

📦 version 7.3.1, in nixpkgs unstable

💅 insn_decode_from_regs — like, the decode-ur-instruction era 💅

okay so bestie, welcome to the Kernel API Manual entry for insn_decode_from_regs(9) — yes it's a section 9 page, yes that means kernel internals, yes we're gonna get through it together 🫶 grab a snack, this one's actually not that long.

✨ NAME ✨

insn_decode_from_regs — decode an instruction 💫

🌸 SYNOPSIS 🌸

bool insn_decode_from_regs (struct insn *insn , struct pt_regs *regs , unsigned char buf[MAX_INSN_SIZE] , int buf_size );

look at her. returns a bool, takes four things, slays 💅

🎀 ARGUMENTS 🎀

  • insn — the structure where the decoded instruction gets stored, i.e. the lil home the results move into 🏠
  • regs — structure holding the register values exactly as they looked when you entered kernel mode, like a little snapshot of the moment 📸
  • buf — the buffer holding the instruction bytes themselves, the raw material fr
  • buf_size — how many instruction bytes are actually available in buf, because we do NOT read past the edge in this house 🙈

🦋 DESCRIPTION 🦋

So what she does: she decodes the instruction that's sitting there in buf, and she stores the decoding results in insn. That's the main character move ✨

She also determines the correct address and operand sizes — yes both, she's multi-talented, we stan 👑

And the return situation:

True if the instruction was decoded, False otherwise. it's giving binary, it's giving yes or no, periodt 💀

🌈 SEE ALSO 🌈

this is the group chat, and everyone's invited. all of these live in the kernel file ./arch/x86/lib/insn-eval.c:

twenty-seven besties. twenty-seven. i counted. go read them all iykyk 📚✨

lowkey a whole ecosystem in ./arch/x86/lib and she's just one icon in it 💜

okay that's the page!! mwah 💋 and for the credits portion of the program: this little masterpiece lives under ./arch/x86/lib, dated October 2026 — that's the source and version, bestie, we do NOT skip the footer 🍓💖 bye!! 🧚‍♀️

📦 where this page comes from