2017-03-02 23:07 GMT+01:00 Mike Lui <mike.d....@gmail.com>: > Hi Ivo, > > I didn't get a response, but I found a snippet in the original paper: > https://www.cs.columbia.edu/~junfeng/09fa-e6998/papers/valgrind.pdf > > Table 1 says these functions are only for syscalls and the valgrind core. Is > that still correct?
Hi Mike, As comment on line 517 in pub_tool_tooliface.h says, these are callback functions which the Valgrind core (framework) use to pass various events to the analysis tool. Tool can be one of memcheck, helgrind, drd, cachegrind, callgrind, massif, ... [1] Various tools are interested in slightly different events, so they do or don't register event callbacks. Syscall is just one type of such an event. > callbacks specifically refer to events within the core, right? >> > Does this mean that they bear no relevance to profiling the user >> > application? User application usually does not interact with these events. What are you trying to achieve? What is your goal? Asking too detailed question without knowing the context (what are you up to) does not usually lead to meaningful answers. >> > Am I correct that a "mem_write" callback only gets called for memory >> > write that happens during translation, internal signal handling, etc, along >> > with the "new_mmap" calls? Nope. pre_mem_write and post_mem_write are callbacks for events emited by Valgrind core (framework) when it intercepted a syscall on behalf of the application. Because Valgrind has no idea what is happening during a syscall inside kernel, this is described by so called "syscall wrappers". They tend to describe things such as "this particular piece of memory is going to be written to by kernel during syscall (pre_mem_write)" and "this particular piece of memory was written to by kernel during syscall (post_mem_write)". > If I were to instrument the application under test then I'd go through the > callback given in "basic_tool_funcs", correct? Instrumentation happens automatically, depending on the analysis tool selected at Valgrind startup. I recommend you to read Valgrind intro [1] and core [2], at least the initial part. I. [1] http://valgrind.org/docs/manual/manual-intro.html [2] http://valgrind.org/docs/manual/manual-core.html ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
