New kernel API proposal (NetBSD)

[krytarowski]

I'm researching an addition of a new kernel API in NetBSD. My motivation is to support the StopTheWorld() operation that is used in few types of G/C (including bdwgc) and in LLVM LSan.

pinspect(2) - process self-introspection

int
pinspect(int request, void *addr, int data);

Operations:

• PI_ENABLE - stop the world -- suspend execution of all the (native) threads besides the calling one; the change of state of threads is invisible to the processes unless executed under a debugger (no signals sent, etc)
• PI_DISABLE - resume the world
• PI_GETREGS - addr specifies destination buffer; data specifies (native) thread id; process must be stopped [or better PI_GETCONTEXT to get ucontext(2)]

This interface resembles a little bit stripped down ptrace(2) for self-debugging.

Does this make sense? The current implementation of StopTheWorld() in LSan for Linux is awful: vfork(2)/clone(2) + ptrace(2) + editing shared data.

I would like to reuse the same interface for bdwgc as well. I expect that the kernel API will be immune to threading issues (as long as we have a correct kernel), independent from pthread(3), invisible to the world (like ps(1), top(1)), not-conflicting with debuggers (ptrace(2)), simple to use.. and hopefully quick for multiple threads.

I intend to craft something that will be maximally useful and if possible open for other use-cases (suggestions?) of process self-introspecting.

https://github.com/llvm-mirror/compiler-rt/blob/8d93d94612443a03d2e211d944e3097f66ba75d5/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc

[ivmai]

+ @wangp @cpu82 @hboehm @magv @Constellation

[ivmai]

+ @wangp @cpu82 @hboehm @magv @Constellation

[krytarowski]

Ping? I think I will add a ptrace wrapper for C and C++ programs.

[krytarowski]

Ping? I think I will add a ptrace wrapper for C and C++ programs.