16.04.2012 16:31, Bart Oldeman wrote: > For x86-64 dosemu jumps to DPMI code using the "iretl" instruction > that is valid in userland and pops all of eip, cs, eflags, esp, and ss > (that's its behaviour in long mode). However, if the popped cs is a > selector to a 16-bit PM segment, the high 16 bits of esp don't change > (the famous CPU issue). So we want them to be zero. Any 47-bit value > of rsp=xxxx0000xxxx is fine. Oh my, thats a real shit. :(( Then maybe you should at least check whether the saved value was actually zero, and print an error if not. There is a more reliable workaround that I implemented in the kernel. You can use stack at any address, but with a special LDT-entry, which base is adjusted every time according to the value of the saved ESP, so that the needed bits in the RSP to match them. I'd say its a shit too, but at least it will allow to restore the precise value, and will avoid the need for searching of the right page...
> The loop tries to mmap 0x100000000 which > usually works but if this address was already mapped before it tries > higher addresses. (an alternative method is to parse /proc/self/maps). :( I agree that parsing /proc/self/maps just for that, was of a questionable benefit. But: this all is very questionable. I mean, there is a kernel, which will trash ESP asynchronously anyway. So was there any use to do all that recovery to just have the ESP screwed up by the kernel a microsecond later? Of course if there is a hope to have an in-kernel workaround too, then yes. Hmm... how was this not a problem before? I think, before it was done with LSS. Is it possible to just do it again, with good old LSS? ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Dosemu-devel mailing list Dosemu-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dosemu-devel
