On Sun, May 20, 2012 at 2:46 PM, John David Anglin <dave.anglin@xxxxxxxx> wrote: > On 20-May-12, at 5:04 AM, Al Viro wrote: > >> Actually, looks like I am missing something, but it's not particulary >> subtle. >> SYSCALL_TRACE is needed for do_syscall_trace_enter() to do anything; >> any of SYSCALL_TRACE/SINGLESTEP/BLOCKSTEP is makes >> do_syscall_trace_leave() >> do things. So checking one bit in flags is not enough - any of those 3 is >> a reason for taking the slow path. The point still stands, though - >> mfctl %cr30, %r1 >> LDREG TI_FLAGS(%r1),%r1 >> ldi (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | _TIF_BLOCKSTEP), >> %r19 >> and,COND(=) %r19, %r1, %r0 >> b,n .Ltracesys >> would still be no worse on the fast path and would not hit the slow path >> in >> a lot of cases when the current code does it for no apparent reason. >> >> Comments? > > > This looks good to me. There is similar code in entry.S. > > I added the above change to my patch set for stable 3.3.6. System still > boots. I singled stepped /bin/ls through a directory listing and it seemed > to work. I'm running this through the ringer on my local system. I'll send out an update when I'm done testing. Cheers, Carlos. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
