__get_user(9)

💖 __get_user (9) — from the Kernel API Manual, bestie 💖

okay so. picture this: you're in the kernel, you've got a pointer that points into user space, and you need exactly one lil variable out of it. that's this macro. it's get_user's chill-but-reckless cousin — same job, less checking. iykyk. 🦋

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✨ NAME ✨

__get_user — get a simple variable from user space, but with less checking. (yes, "less checking" is the whole personality. not me trusting you to do the checking yourself 😭)

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🎀 SYNOPSIS 🎀

__get_user (x , ptr );

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💅 ARGUMENTS 💅

• x — the variable where the result goes. this is your little receiving basket 🧺
• ptr — the source address, and it lives in user space. (say it with me: user space) 🌈

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🌸 CONTEXT 🌸

User context only. and heads up — this function may sleep if pagefaults are enabled. so like, don't go calling it from somewhere that can't handle a nap 💀

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🔥 DESCRIPTION 🔥

this macro copies a single simple variable from user space into kernel space. one. single. variable. it's giving minimalism ✨

it supports simple types like char and int, but not larger data types like structures or arrays. no bundles, no vibes-collections, just one cute lil scalar 🍓

ptr must have pointer-to-simple-variable type, and the result of dereferencing ptr must be assignable to x without a cast. like, it has to just fit. no forcing it. if you need a cast, the vibes are off and so is your code 🙈

⚠️ okay this part is serious, bestie: the caller must check the pointer with access_ok before calling this function. that's the "less checking" tax. this macro is not gonna do it for you. you check it. periodt. 👑

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⭐ RETURN ⭐

• 0 on success 🎉
• -EFAULT on error 💀

and on error, x is set to 0 — so it's never left all undefined and mysterious, which honestly? thoughtful. iconic behavior 👑

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🫶 SEE ALSO 🫶

• Kernel file ./arch/x86/include/asm/uaccess.h
• get_user(9)
• put_user(9)
• __put_user(9)

like, go read the whole uaccess.h family, they're all main characters in this saga 💜

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and that's the page!! brought to you by ./arch/x86/include/asm, dated October 2026 — mwah, go check your pointers, love u, bye!! 💖✨🎀🦋🌸💅