Commit 82975bc6 authored Nov 21, 2014 by Andy Lutomirski Committed by Linus Torvalds Nov 23, 2014

uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME



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.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 90e362f4

arch/x86/include/asm/thread_info.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)

		/* flags to check in __switch_to() */
		#define _TIF_WORK_CTXSW \

kernel/events/uprobes.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}
		}

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