diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-11-21 16:36:27 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-11-23 11:14:33 +0100 |
| commit | 39efd4ec9a2967e9720be7b66d9a4b31a58dbf61 (patch) | |
| tree | 084c2ba72e4ffaf2dcc3d3c89f7ce32ab93d9827 /arch/s390/kernel/signal.c | |
| parent | c68dba202f54a4c9c68a8bb83d426bf8a00c99f8 (diff) | |
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 <arnez@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/signal.c')
| -rw-r--r-- | arch/s390/kernel/signal.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c index d1259d875074..c3ff70a7b247 100644 --- a/arch/s390/kernel/signal.c +++ b/arch/s390/kernel/signal.c @@ -461,6 +461,8 @@ void do_signal(struct pt_regs *regs) /* Restart system call with magic TIF bit. */ regs->gprs[2] = regs->orig_gpr2; set_thread_flag(TIF_SYSCALL); + if (test_thread_flag(TIF_SINGLE_STEP)) + set_thread_flag(TIF_PER_TRAP); break; } } |