diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2015-07-14 15:26:34 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-03-04 16:58:54 +0300 |
| commit | bf9ad37dc8a30cce22ae95d6c2ca6abf8731d305 (patch) | |
| tree | edf1be3cce67320700c09e473e1f40ab93114c84 /include/linux/sched.h | |
| parent | 0ce055f85335e48bc571114d61a70ae217039362 (diff) | |
| download | linux-bf9ad37dc8a30cce22ae95d6c2ca6abf8731d305.tar.xz | |
signal, x86: Delay calling signals in atomic on RT enabled kernels
On x86_64 we must disable preemption before we enable interrupts
for stack faults, int3 and debugging, because the current task is using
a per CPU debug stack defined by the IST. If we schedule out, another task
can come in and use the same stack and cause the stack to be corrupted
and crash the kernel on return.
When CONFIG_PREEMPT_RT is enabled, spinlock_t locks become sleeping, and
one of these is the spin lock used in signal handling.
Some of the debug code (int3) causes do_trap() to send a signal.
This function calls a spinlock_t lock that has been converted to a
sleeping lock. If this happens, the above issues with the corrupted
stack is possible.
Instead of calling the signal right away, for PREEMPT_RT and x86,
the signal information is stored on the stacks task_struct and
TIF_NOTIFY_RESUME is set. Then on exit of the trap, the signal resume
code will send the signal when preemption is enabled.
[ rostedt: Switched from #ifdef CONFIG_PREEMPT_RT to
ARCH_RT_DELAYS_SIGNAL_SEND and added comments to the code. ]
[bigeasy: Add on 32bit as per Yang Shi, minor rewording. ]
[ tglx: Use a config option ]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/Ygq5aBB/qMQw6aP5@linutronix.de
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 75ba8aa60248..098e37fd770a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1087,6 +1087,9 @@ struct task_struct { /* Restored if set_restore_sigmask() was used: */ sigset_t saved_sigmask; struct sigpending pending; +#ifdef CONFIG_RT_DELAYED_SIGNALS + struct kernel_siginfo forced_info; +#endif unsigned long sas_ss_sp; size_t sas_ss_size; unsigned int sas_ss_flags; |