prober_user(9)

💅 prober_user(9) — the kernel API page, but make it make sense

okay so bestie, welcome to prober_user, a little function from the prober_user(9) corner of the Kernel API Manual. it's short, it's iconic, and it does exactly one job: probe user read access. let's get into it 🫶

---

✨ NAME ✨

prober_user — Probe user read access 🌸

---

✨ SYNOPSIS ✨

prober_user (sr , va );

that's the whole vibe. two args, no drama 💅

---

✨ ARGUMENTS ✨

• sr — Space regster. (yes, the page literally says "regster" — the typo is part of the lore now, we stan anyway 🎀 it means space register.)
• va — Virtual address. the address we're checking, bestie 📍

---

✨ RETURN ✨

Non-zero if address is accessible. ⭐

so like… non-zero = yes you can read it, zero = nope, don't touch. that's the entire return contract, no cap 🙈

---

✨ DESCRIPTION ✨

okay so here's the situation, and it's giving very specific-low-level-lore 🦋

Due to the way _PAGE_READ is handled in TLB entries, we need a special check to determine whether a user address is accessible.

so it's not just a vibes-based check, it's a whole two-step thing:

1. The ldb instruction does the initial access check. 👑
2. If it is successful, the probe instruction checks user access rights. 🔥

literally a main-character duo. ldb goes first, and then probe finishes the job if step one slayed. if ldb doesn't succeed, we don't even get to the probe part. periodt. 💀

---

✨ SEE ALSO ✨

• Kernel file ./arch/parisc/include/asm/special_insns.h 📂 — go read it, iykyk 💜

---

💖 friendly reminder that this is kernel-level address checking, so don't just guess at what "accessible" means — the page says the check is special because of how _PAGE_READ lives in TLB entries. that's the whole reason this function exists, bestie. no invented extra tips here, just the facts, and the facts ate. ✨

---

and that's the page!! 🌈 source/version is ./arch/parisc/include/asm and the date on this beauty is October 2026 — signed, sealed, delivered, and stamped with a 🎀 from your favorite Unix bestie. bye bestie, go probe responsibly 💅💖