From: Martin Schwidefsky Date: Wed, 21 Nov 2012 15:36:27 +0000 (+0100) Subject: s390/ptrace: race of single stepping vs signal delivery X-Git-Tag: omap-for-v3.8/fixes-for-merge-window-v4-signed~29^2~25 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=39efd4ec9a2967e9720be7b66d9a4b31a58dbf61;p=pandora-kernel.git s390/ptrace: race of single stepping vs signal delivery The current single step code is racy in regard to concurrent delivery of signals. If a signal is delivered after a PER program check occurred but before the TIF_PER_TRAP bit has been checked in entry[64].S the code clears TIF_PER_TRAP and then calls do_signal. This is wrong, if the instruction completed (or has been suppressed) a SIGTRAP should be delivered to the debugger in any case. Only if the instruction has been nullified the SIGTRAP may not be send. The new logic always sets TIF_PER_TRAP if the program check indicates PER tracing but removes it again for all program checks that are nullifying. The effect is that for each change in the PSW address we now get a single SIGTRAP. Reported-by: Andreas Arnez Signed-off-by: Martin Schwidefsky --- Reading git-diff-tree failed