Re: [RFC PATCH v2 01/11] ptwrite uprobes: Add infrastructure for ptwrite uprobes
From: sashiko-bot@kernel.org
Date: 2026-09-17 23:19:47
Also in:
linux-perf-users
uprobes currently always require entering the kernel to log anything. While that works well, it is rather slow. Modern Intel CPUs have the ptwrite instruction, which can log data to the Processor Trace buffer. Add support in uprobes for patching PTWRITE instead of kernel entries. When a user collects Processor Trace with perf the logged data will appear in the PT log, otherwise the instructions will be nops. PTWRITE provides much faster logging, but it is missing various features that the full featured probes have. The instrumentation is similar to optimized uprobes. Add a trampoline page. Replace the original instruction (5 byte nop) with a jump to the trampoline. The nop restriction will be relaxed in a later patch. The trampoline does ptwrites and then jumps back. Build the high-level infrastructure without any x86-64-specific parts (except for one data structure). Add register/unregister, basic data structures and high level hooks. Add weak stubs to handle the no uprobes or different architectures case. Assisted-by: omp:gpt-5.6-luna Signed-off-by: Andi Kleen <ak@kernel.org>
Sashiko has reviewed this patch and found no issues. It looks great! -- Sashiko AI review · https://sashiko.dev/#/patchset/20260917230127.924985-2-ak@kernel.org?part=1