instrument_memcpy_before(9)

💖 NAME 💖

okay so welcome to the instrument_memcpy_before(9) page, bestie — it's from the Kernel API Manual, and the whole vibe is: add instrumentation before a non-instrumented memcpy. slay. That's literally the name and the mission, no cap.

✨ SYNOPSIS ✨

the signature is giving "tiny but important":

void instrument_memcpy_before (void *to , const void *from , unsigned long n );

🎀 ARGUMENTS 🎀

• to — destination address 💅
• from — source address 🫶
• n — number of bytes to copy ✨

💅 DESCRIPTION 💅

okay so the actual job: instrument memory accesses that happen in custom memcpy implementations. lowkey crucial.

the instrumentation should be inserted before the memcpy call. periodt. that's the whole instruction, bestie — before, not after, not "somewhere in the vicinity". 🙈

🦋 SEE ALSO 🦋

Kernel file: ./include/linux/instrumented.h is the home base, and here's the whole squad:

• instrument_read(9)
• instrument_write(9)
• instrument_read_write(9)
• instrument_atomic_read(9)
• instrument_atomic_write(9)
• instrument_atomic_read_write(9)
• instrument_copy_to_user(9)
• instrument_copy_from_user_before(9)
• instrument_copy_from_user_after(9)
• instrument_memcpy_after(9)
• instrument_get_user(9)
• instrument_put_user(9)

mwah 💋 this page is from ./include/linux, dated October 2026, and it's the instrument_memcpy_before(9) manual page. bye bestie, go instrument that memcpy before the call 🧚💜