Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 13 Nov 2014 23:01:12 -0800 | Subject | Re: [PATCH v2 2/2] uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME |
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On Thu, Nov 13, 2014 at 10:08 PM, Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote: > * Andy Lutomirski <luto@amacapital.net> [2014-11-13 14:31:21]: > >> x86 call do_notify_resume on paranoid returns if TIF_UPROBE is set >> but not on non-paranoid returns. I suspect that this is a mistake >> and that the code only works because int3 is paranoid. >> >> Setting _TIF_NOTIFY_RESUME in the uprobe code was probably a >> workaround for the x86 bug. With that bug fixed, we can remove > >> _TIF_NOTIFY_RESUME from the uprobes code. >> >> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> >> Reported-by: Oleg Nesterov <oleg@redhat.com> >> Signed-off-by: Andy Lutomirski <luto@amacapital.net> >> --- >> arch/x86/include/asm/thread_info.h | 2 +- >> kernel/events/uprobes.c | 1 - >> 2 files changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h >> index 854053889d4d..547e344a6dc6 100644 >> --- a/arch/x86/include/asm/thread_info.h >> +++ b/arch/x86/include/asm/thread_info.h >> @@ -141,7 +141,7 @@ struct thread_info { >> /* Only used for 64 bit */ >> #define _TIF_DO_NOTIFY_MASK \ >> (_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME | \ >> - _TIF_USER_RETURN_NOTIFY) >> + _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE) > > > The comment above says only for 64 bit. So would this still work for > i386? >
i386 seems to look at _TIF_WORK_MASK (which includes _TIF_UPROBE) for everything except syscalls and at _TIF_WORK_SYSCALL_EXIT for syscall return (which does not include _TIF_UPROBE). Is that okay?
--Andy
>> >> /* flags to check in __switch_to() */ >> #define _TIF_WORK_CTXSW \ >> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c >> index 1d0af8a2c646..ed8f2cde34c5 100644 >> --- a/kernel/events/uprobes.c >> +++ b/kernel/events/uprobes.c >> @@ -1640,7 +1640,6 @@ bool uprobe_deny_signal(void) >> if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { >> utask->state = UTASK_SSTEP_TRAPPED; >> set_tsk_thread_flag(t, TIF_UPROBE); >> - set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); >> } >> } >> >> -- >> 1.9.3 >> > > -- > Thanks and Regards > Srikar Dronamraju >
-- Andy Lutomirski AMA Capital Management, LLC
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