Hi, Here is the v3 series of probe-event to support user-space access. In this version I removed unneeded kernel_uaccess_faults_ok patch, included PeterZ's user_access_ok(), and simplifies non-pagefault user-space read functions according to the discussion on the previous sereis.
https://lkml.kernel.org/r/155110348217.21156.3874419272673328527.stgit@devbox - [1/5]: New: introduce user_access_ok - [2/5]: New: user user_access_ok() in user_access_begin() - [3/5]: Simplify implementation using strncpy_from_user - [4/5]: Simplify implementation using strnlen_user - [5/5]: Update documentation PeterZ, I imported your patch in this series, and add a short description. If there is any misundrestanding, please tell me. ==== Kprobe event user-space memory access features: For user-space access extension, this series adds 2 features, "ustring" type and user-space dereference syntax. "ustring" is used for recording a null-terminated string in user-space from kprobe events. "ustring" type is easy, it is able to use instead of "string" type, so if you want to record a user-space string via "__user char *", you can use ustring type instead of string. For example, echo 'p do_sys_open path=+0($arg2):ustring' >> kprobe_events will record the path string from user-space. The user-space dereference syntax is also simple. Thi just adds 'u' prefix before an offset value. +|-u<OFFSET>(<FETCHARG>) e.g. +u8(%ax), +u0(+0(%si)) This is more generic. If you want to refer the variable in user- space from its address or access a field in data structure in user-space, you need to use this. For example, if you probe do_sched_setscheduler(pid, policy, param) and record param->sched_priority, you can add new probe as below; p do_sched_setscheduler priority=+u0($arg3) Actually, with this feature, "ustring" type is not absolutely necessary, because these are same meanings. +0($arg2):ustring == +u0($arg2):string Note that kprobe event provides these methods, but it doesn't change it from kernel to user automatically because we do not know whether the given address is in userspace or kernel on some arch. For perf-probe, we can add some attribute for each argument which indicate that the variable in user space. But still we can not decide it automatically by DWARF since __user attribute is not transrated to DWARF attribute. Thank you, --- Masami Hiramatsu (4): uaccess: Use user_access_ok() in user_access_begin() uaccess: Add non-pagefault user-space read functions tracing/probe: Add ustring type for user-space string tracing/probe: Support user-space dereference Peter Zijlstra (1): uaccess: Add user_access_ok() Documentation/trace/kprobetrace.rst | 26 ++++++++- Documentation/trace/uprobetracer.rst | 9 ++- arch/x86/include/asm/uaccess.h | 10 +++- include/linux/uaccess.h | 33 ++++++++++++ kernel/trace/trace.c | 7 +-- kernel/trace/trace_kprobe.c | 43 ++++++++++++++++ kernel/trace/trace_probe.c | 39 +++++++++++--- kernel/trace/trace_probe.h | 3 + kernel/trace/trace_probe_tmpl.h | 37 +++++++++++-- kernel/trace/trace_uprobe.c | 19 +++++++ mm/maccess.c | 94 ++++++++++++++++++++++++++++++++-- 11 files changed, 287 insertions(+), 33 deletions(-) -- Masami Hiramatsu (Linaro) <[email protected]>
