On Monday 12 March 2007 11:42, Bodo Stroesser wrote: > Blaisorblade wrote: > > On Tuesday 06 March 2007 00:26, Blaisorblade wrote: > > > On Tuesday 06 March 2007 00:10, Jeff Dike wrote: > > > > On Tue, Mar 06, 2007 at 12:03:26AM +0100, Blaisorblade wrote: > > > > > > No, RCX corruption is different - that happens when a sysexit > > > > is done > > > > > > > > from a system call where userspace wasn't prepared to save and > > > > > > restore RCX. sigreturn is the best example. > > > > > > > > > > Hmm... we should finally fix that, at some point. Or... now that > > > > > you explain it this way, it could even seem unfixable... is it? Or > > > > > maybe sysreturn should become a syscall where the return must > > > > > happen > > > > through > > > > > > > the slow return path (iret), if that exists for x86_64. > > > > > > > > This is fixed, and has been for a while. The fix was, as you > > > > suggest, return through iret in this case. > > > > Hmm, return through IRET is implemented for sys_rt_sigreturn since 2.6.0 > > (with > > a couple of changes, yeah, but...). > > > > Was the original Bodo's report bogus? No, he actually found a much harder > > issue. > > > > I've attached the log of that IRC here for reference. > > I took a quick look into 2.6.21-rc3, arch/x86_64/entry.S. AFAICS, the > problem I supposed in the IRC is fixed. Now a ptraced syscall always > returns through IRET. Thus, *all* registers in user space exactly will have > the contents, which the tracing process wrote at end of syscall.
About 32bit emulation (arch/x86_64/ia32/ia32entry.S), it too returns through IRET when ptrace is active. Ok. Now it would then be time to look again at SKAS support? Well, nothing easy it seems - I've done a quick test of 32bit UML over 64bit host again and had no luck. -- Inform me of my mistakes, so I can add them to my list! Paolo Giarrusso, aka Blaisorblade http://www.user-mode-linux.org/~blaisorblade Chiacchiera con i tuoi amici in tempo reale! http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
