diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index b3a9d24dba25..7176f84f95a4 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -141,6 +141,44 @@ void ist_exit(struct pt_regs *regs, enum ctx_state prev_state) rcu_nmi_exit(); } +/** + * ist_begin_non_atomic() - begin a non-atomic section in an IST exception + * @regs: regs passed to the IST exception handler + * + * IST exception handlers normally cannot schedule. As a special + * exception, if the exception interrupted userspace code (i.e. + * user_mode_vm(regs) would return true) and the exception was not + * a double fault, it can be safe to schedule. ist_begin_non_atomic() + * begins a non-atomic section within an ist_enter()/ist_exit() region. + * Callers are responsible for enabling interrupts themselves inside + * the non-atomic section, and callers must call is_end_non_atomic() + * before ist_exit(). + */ +void ist_begin_non_atomic(struct pt_regs *regs) +{ + BUG_ON(!user_mode_vm(regs)); + + /* + * Sanity check: we need to be on the normal thread stack. This + * will catch asm bugs and any attempt to use ist_preempt_enable + * from double_fault. + */ + BUG_ON(((current_stack_pointer() ^ this_cpu_read_stable(kernel_stack)) + & ~(THREAD_SIZE - 1)) != 0); + + preempt_count_sub(HARDIRQ_OFFSET); +} + +/** + * ist_end_non_atomic() - begin a non-atomic section in an IST exception + * + * Ends a non-atomic section started with ist_begin_non_atomic(). + */ +void ist_end_non_atomic(void) +{ + preempt_count_add(HARDIRQ_OFFSET); +} + static nokprobe_inline int do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str, struct pt_regs *regs, long error_code) |