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.
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