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On Mon, 16 Dec 2002, Linus Torvalds wrote: > > Ok, I did the vsyscall page too, and tried to make it do the right thing > (but I didn't bother to test it on a non-SEP machine). > > I'm pushing the changes out right now, but basically it boils down to the > fact that with these changes, user space can instead of doing an > > int $0x80 > > instruction for a system call just do a > > call 0xfffff000 I thought that last page was intentionally left invalid? So that, for example, *(char *)MAP_FAILED will give SIGSEGV; whereas now I can read a 0 there (and perhaps you should be using get_zeroed_page rather than __get_free_page?). I cannot name anything which relies on that page being invalid, but think it would be safer to keep that it way; though I guess more compatibility pain to use the next page down (or could seg lim be used? I forget the granularity restrictions). Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | |||||||||
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