On Mon, 8 Jan 2001, Kevin D. Kissell wrote: > > Obviously, you don't want to allow unprivileged users to flush caches as > > a whole as it could lead to a DoS. > > By that logic, we should not allow users to allocate more virtual > memory than there is physical memory in the system! A pathological > swap program is arguably far a far worse denial of service attack There are limits -- see `info setrlimit'. There is no way to prevent a program from executing: while (1) flush_cache_all(); though but the system's performance would suffer much. Remember there is real world out there... Which means sysmips(FLUSH_CACHE, ...) needs to be fixed or removed. > than flushing the caches - so long as by "flush" we mean invalidate > with writeback (on copyback caches), of course. What's wrong with cacheflush(addr, count, which) that actually checks if <addr; addr+count> lies within the caller's address space before performing the flush and returns -EPERM otherwise? It would make the caller crawl like a turtle if it wished to but it would leave other processes alone. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
