Em Fri, May 10, 2019 at 12:12:49AM +0900, Masami Hiramatsu escreveu: > Hi, > > Here is the v8 series of probe-event to support user-space access. > Previous version is here. > > https://lkml.kernel.org/r/155732230159.12756.15040196512285621636.stgit@devnote2 > > In this version, I fixed some typos/style issues and renamed fields > according to Ingo's comment, and added Ack from Steve. > > Also this version is rebased on the latest -tip/master tree.
Ingo, since this touches 'perf probe' and Steven already provided an Acked-by, if you're ok with it I can process these, testing the 'perf probe' changes and then ship it to you in my next pull req, ok? - Arnaldo > Changes in v8: > [2/6] Fix style issues and typos according to Ingo's comment. > [3/6] Fix style issues according to Ingo's comment. > [6/6] Fix a typo and rename user field to user_access field. > > > In summary, strncpy_from_user() should work as below > > - strncpy_from_user() can access user memory with set_fs(USER_DS) > in task context > > - strncpy_from_user() can access kernel memory with set_fs(KERNEL_DS) > in task context (e.g. devtmpfsd and init) > > - strncpy_from_user() can access user/kernel memory (depends on DS) > in IRQ context if pagefault is disabled. (both verified) > > Note that this changes the warning behavior when > CONFIG_DEBUG_ATOMIC_SLEEP=y, it still warns when > __copy_from_user_inatomic() is called in IRQ context, but don't > warn if pagefault is disabled because it will not sleep in > atomic. > > ==== > 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. > > > Thank you, > > --- > > Masami Hiramatsu (6): > x86/uaccess: Allow access_ok() in irq context if pagefault_disabled > uaccess: Add non-pagefault user-space read functions > tracing/probe: Add ustring type for user-space string > tracing/probe: Support user-space dereference > selftests/ftrace: Add user-memory access syntax testcase > perf-probe: Add user memory access attribute support > > > Documentation/trace/kprobetrace.rst | 28 ++++- > Documentation/trace/uprobetracer.rst | 10 +- > arch/x86/include/asm/uaccess.h | 4 - > include/linux/uaccess.h | 19 +++ > kernel/trace/trace.c | 7 + > kernel/trace/trace_kprobe.c | 37 ++++++ > kernel/trace/trace_probe.c | 37 +++++- > kernel/trace/trace_probe.h | 3 > kernel/trace/trace_probe_tmpl.h | 37 +++++- > kernel/trace/trace_uprobe.c | 19 +++ > mm/maccess.c | 122 > +++++++++++++++++++- > tools/perf/Documentation/perf-probe.txt | 3 > tools/perf/util/probe-event.c | 11 ++ > tools/perf/util/probe-event.h | 2 > tools/perf/util/probe-file.c | 7 + > tools/perf/util/probe-file.h | 1 > tools/perf/util/probe-finder.c | 19 ++- > .../ftrace/test.d/kprobe/kprobe_args_user.tc | 32 +++++ > 18 files changed, 357 insertions(+), 41 deletions(-) > create mode 100644 > tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_user.tc > > -- > Masami Hiramatsu (Linaro) <mhira...@kernel.org> -- - Arnaldo
