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From: Jeremy F. <je...@go...> - 2005-02-15 02:51:36
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On Mon, 2005-02-14 at 21:07 -0500, Greg Parker wrote: > Jeremy Fitzhardinge writes: > > Come to think of it, if there are only a small number of superpages, > > then just mprotecting them on entry/exit to generated code would be > > pretty cheap (since you'd only have to do the Valgrind one(s), which is > > at most one mprotect per superblock, and fewer if they're contiguous). > > It might get expensive if there are lots of syscalls, but it would save > > on extra code per memory reference... > > You mean mprotect the superblock itself when moving in and out of > Valgrind? That won't work because part of the generated code needs > to read and write things like the shadow memory and the ThreadState. > The generated simulation can't touch them, but the generated > instrumentation and scaffolding must. Yep, you're right. Scratch that. J |