Messages in this thread | | | Date | Tue, 28 Jan 2014 01:18:41 +0000 | From | Al Viro <> | Subject | Re: [RFC] de-asmify the x86-64 system call slowpath |
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On Mon, Jan 27, 2014 at 06:39:31PM +0100, Oleg Nesterov wrote: > On 01/27, Al Viro wrote: > > > > BTW, there's an additional pile of obfuscation: > > /* work to do on interrupt/exception return */ > > #define _TIF_WORK_MASK \ > > (0x0000FFFF & \ > > ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \ > > _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU)) > > > > /* work to do on any return to user space */ > > #define _TIF_ALLWORK_MASK \ > > ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ > > _TIF_NOHZ) > > Heh, yes ;) > > > Why is _TIF_UPROBE *not* a part > > of _TIF_DO_NOTIFY_MASK, for example? > > Yes, please see another email. That is why uprobe_deny_signal() > sets TIF_NOTIFY_RESUME along with TIF_UPROBE.
*grumble* Can it end up modifying *regs? From very cursory reading of kernel/events/uprobe.c it seems to do so, so we probably want to leave via iretq if that has hit, right?
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