On 02/14/2013 09:55 PM, Cyrill Gorcunov wrote: > On Thu, Feb 14, 2013 at 11:21:12AM -0800, H. Peter Anvin wrote: >> On 02/14/2013 11:18 AM, Oleg Nesterov wrote: >>> On 02/14, H. Peter Anvin wrote: >>>> >>>> On 02/14/2013 07:00 AM, Oleg Nesterov wrote: >>>>> On 02/14, Denys Vlasenko wrote: >>>>>> >>>>>> Determining personality of a ptraced process is a murky area. >>>>>> On x86, for years strace was looking at segment selectors, >>>>>> which is conceptually wrong: see, for example, >>>>>> https://lkml.org/lkml/2012/1/18/320 >>>>>> >>>> >>>> One proposal that keeps being on the table is to export a regset with >>>> metadatam, including process mode at launch (i386, x86-64, x32). >>> >>> Yes... but if this metadata includes TS_COMPAT-is-set, then strace should >>> do PTRACE_GETREGSET(REGSET_META) + PTRACE_GETREGSET(REGSET_GENERAL) every >>> time. Or REGSET_META should include META+GENERAL. >>> >>> IOW, it is not clear to me what this "meta" should actually report. >> >> That is one of the things that needs to be nailed down. In particular, >> what are the things people need. > > Indeed, having some "official" way for compat bit retrieval would be > a great thing for us (c/r camp) since we've just met the same problem. > And at moment I sticked for the same trick as gdb does (cs/ds test). > > But, guys, if only I'm not missing something completely obvious, > can't we simply provide task-compat bit to userspace in say /proc/pid/stat > or something? Then the strace/gdb would be able to always know if > the tracee is actually in compat mode. Or I miss something fundamental > here?
strace needs to get that data on every syscall entry in the traced process. Doing open/read/close on every syscall entry is going to slow it down a lot. -- vda -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
