Hello, Kostik. You wrote 10 мая 2010 г., 18:58:17:
>> I'm proting some application from Linux, which discover its stack >> bounds by reading and pasing "/proc/self/maps". FreeBSD have >> "/prov/curproc/map", but I can not find how to determine which record >> is for stack (I've looked into implementation of proc_fs, but it >> doesn't contain any specail processing for process stack). >> >> How could I determine stack bounds of current process on FreeBSD >> 7/8/9? > I think the right question is why the program needs the information at all. > Really, the system has no data to answer your question. Which stack are > you asking for ? The stack of main thread, set up by kernel, is very > different from the stack established by the threading library for > newly created thread. What should happen for signal altstacks ? > Also, the threading library clips the main thread stack to match its > size with default stack size (I do think this is unsafe and wrong). It is port of new openjdk7 build. It adds function with this comment in Linux-specific code (BSD port is based on Linux one): // Linux uses a growable mapping for the stack, and if the mapping for // the stack guard pages is not removed when we detach a thread the // stack cannot grow beyond the pages where the stack guard was // mapped. If at some point later in the process the stack expands to // that point, the Bsd kernel cannot expand the stack any further // because the guard pages are in the way, and a segfault occurs. // // However, it's essential not to split the stack region by unmapping // a region (leaving a hole) that's already part of the stack mapping, // so if the stack mapping has already grown beyond the guard pages at // the time we create them, we have to truncate the stack mapping. // So, we need to know the extent of the stack mapping when // create_stack_guard_pages() is called. // Find the bounds of the stack mapping. Return true for success. // // We only need this for stacks that are growable: at the time of // writing thread stacks don't use growable mappings (i.e. those // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this // only applies to the main thread. // If the (growable) stack mapping already extends beyond the point // where we're going to put our guard pages, truncate the mapping at // that point by munmap()ping it. This ensures that when we later // munmap() the guard pages we don't leave a hole in the stack // mapping. Solaris code simple map/unmap needed pages, and Linux port checks stack region and applies special processing for growable stack area... I'm not sure, should BSD port behaves as Linux or as Solaris one. -- // Black Lion AKA Lev Serebryakov <l...@freebsd.org> _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"