insn_get_modrm_reg_ptr(9)

📦 version 7.3.1, in nixpkgs unstable

💅 insn_get_modrm_reg_ptr(9) — Kernel API Manual 🎀

okay so bestie, this is a page from the Kernel API Manual, and it's genuinely one of the shorter ones — a little baby function that nonetheless does something very specific and slays at it. Let's get into it ✨

🌸 NAME 🌸

insn_get_modrm_reg_ptr — obtain a register pointer based on the ModRM byte. that's it, that's the whole vibe 🫶

💖 SYNOPSIS 💖

unsigned long * insn_get_modrm_reg_ptr (struct insn *insn , struct pt_regs *regs );

like, look at that signature. beautiful. no notes. 😌

🦋 ARGUMENTS 🦋

  • insn — the instruction that's carrying the ModRM byte. it's literally the whole reason we're here 💫
  • regs — the register values, exactly as they looked when you entered kernel mode. think of it as a little snapshot of the moment you walked in the door 📸

⭐ DESCRIPTION ⭐

so here's the tea ☕ — this function hands you back the register indicated by the reg part of the ModRM byte. and it gives it to you as a pointer within pt_regs, which is lowkey the whole point. no copy, no drama, just a pointer straight into your saved register state. iconic behavior, honestly 👑

🔥 SEE ALSO 🔥

bestie there are SO many siblings. this function does not exist in a vacuum, bestie, it's part of a whole friend group over in the kernel file ./arch/x86/lib/insn-eval.c — and here's the entire group chat, everybody's invited 🎉:

no cap, that's the whole list. go read them all, i'll wait 🧚💜

💀 reminder: this page comes from ./arch/x86/lib, dated October 2026. so if you're quoting it in the group chat, cite your source, bestie 🎀✨
📦 where this page comes from