return 1;
}
-static noinline void __switch_to_xtra(struct task_struct *next_p,
- struct tss_struct *tss)
+#ifdef CONFIG_SECCOMP
+void hard_disable_TSC(void)
+{
+ write_cr4(read_cr4() | X86_CR4_TSD);
+}
+void disable_TSC(void)
+{
+ preempt_disable();
+ if (!test_and_set_thread_flag(TIF_NOTSC))
+ /*
+ * Must flip the CPU state synchronously with
+ * TIF_NOTSC in the current running context.
+ */
+ hard_disable_TSC();
+ preempt_enable();
+}
+void hard_enable_TSC(void)
+{
+ write_cr4(read_cr4() & ~X86_CR4_TSD);
+}
+#endif /* CONFIG_SECCOMP */
+
+static noinline void
+__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
+ struct tss_struct *tss)
{
struct thread_struct *next;
set_debugreg(next->debugreg[7], 7);
}
+#ifdef CONFIG_SECCOMP
+ if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
+ test_tsk_thread_flag(next_p, TIF_NOTSC)) {
+ /* prev and next are different */
+ if (test_tsk_thread_flag(next_p, TIF_NOTSC))
+ hard_disable_TSC();
+ else
+ hard_enable_TSC();
+ }
+#endif
+
if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
/*
* Disable the bitmap via an invalid offset. We still cache
tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
}
-/*
- * This function selects if the context switch from prev to next
- * has to tweak the TSC disable bit in the cr4.
- */
-static inline void disable_tsc(struct task_struct *prev_p,
- struct task_struct *next_p)
-{
- struct thread_info *prev, *next;
-
- /*
- * gcc should eliminate the ->thread_info dereference if
- * has_secure_computing returns 0 at compile time (SECCOMP=n).
- */
- prev = task_thread_info(prev_p);
- next = task_thread_info(next_p);
-
- if (has_secure_computing(prev) || has_secure_computing(next)) {
- /* slow path here */
- if (has_secure_computing(prev) &&
- !has_secure_computing(next)) {
- write_cr4(read_cr4() & ~X86_CR4_TSD);
- } else if (!has_secure_computing(prev) &&
- has_secure_computing(next))
- write_cr4(read_cr4() | X86_CR4_TSD);
- }
-}
-
/*
* switch_to(x,yn) should switch tasks from x to y.
*
/*
* Now maybe handle debug registers and/or IO bitmaps
*/
- if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW)
- || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)))
- __switch_to_xtra(next_p, tss);
-
- disable_tsc(prev_p, next_p);
+ if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
+ task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
+ __switch_to_xtra(prev_p, next_p, tss);
/*
* Leave lazy mode, flushing any hypercalls made here.