arch_ptrace_stop_needed(9)

🦋 arch_ptrace_stop_needed(9) 🦋

okay so welcome to the Kernel API Manual, bestie — today’s main character is arch_ptrace_stop_needed(9), and it is lowkey giving “tiny decision hook with big responsibilities” energy. 💅

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💖 NAME 💖

• arch_ptrace_stop_needed — decide whether arch_ptrace_stop() should be called. periodt.

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✨ SYNOPSIS ✨

arch_ptrace_stop_needed

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🌸 DESCRIPTION 🌸

This one gets called with the siglock held, and its whole job is to decide whether it’s necessary to release the siglock and call arch_ptrace_stop. no cap, that’s the vibe. 🫶

It can literally be defined to a constant if arch_ptrace_stop is never required — or if it always is. On machines where this makes sense, it should be defined to a quick test to optimize out calling arch_ptrace_stop when it would be superfluous. iconic optimization behavior, honestly. ⭐

For example: if the thread has not been back to user mode since the last stop, the thread state might indicate that nothing needs to be done. yep, sometimes the answer is just “we’re good.” 💀

This is guaranteed to be invoked once before a task stops for ptrace and may include arch-specific operations necessary prior to a ptrace stop. so yeah, it’s not just a random drive-by function — it’s got a guaranteed little moment before the ptrace stop. 👑

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👀 SEE ALSO 👀

The kernel file ./include/linux/ptrace.h is right here, bestie:

• ptrace_may_access(9)
• ptrace_parent(9)
• ptrace_event_enabled(9)
• ptrace_event(9)
• ptrace_event_pid(9)
• ptrace_init_task(9)
• ptrace_release_task(9)
• arch_has_single_step(9)
• user_enable_single_step(9)
• user_disable_single_step(9)
• arch_has_block_step(9)
• user_enable_block_step(9)
• arch_ptrace_stop(9)
• ptrace_report_syscall_permit_entry(9)
• ptrace_report_syscall_exit(9)

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mwah 💋 this little manual moment came from ./include/linux, dated October 2026, and it’s officially arch_ptrace_stop_needed(9) — bye bestie, go be iconic with your ptrace stops 🎀🦋💜