-static 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();
-}
-
-static void hard_enable_TSC(void)
-{
- write_cr4(read_cr4() & ~X86_CR4_TSD);
-}
-
-static void enable_TSC(void)
-{
- preempt_disable();
- if (test_and_clear_thread_flag(TIF_NOTSC))
- /*
- * Must flip the CPU state synchronously with
- * TIF_NOTSC in the current running context.
- */
- hard_enable_TSC();
- preempt_enable();
-}
-
-int get_tsc_mode(unsigned long adr)
-{
- unsigned int val;
-
- if (test_thread_flag(TIF_NOTSC))
- val = PR_TSC_SIGSEGV;
- else
- val = PR_TSC_ENABLE;
-
- return put_user(val, (unsigned int __user *)adr);
-}
-
-int set_tsc_mode(unsigned int val)
-{
- if (val == PR_TSC_SIGSEGV)
- disable_TSC();
- else if (val == PR_TSC_ENABLE)
- enable_TSC();
- else
- return -EINVAL;
-
- return 0;
-}
-
-#ifdef CONFIG_X86_DS
-static int update_debugctl(struct thread_struct *prev,
- struct thread_struct *next, unsigned long debugctl)
-{
- unsigned long ds_prev = 0;
- unsigned long ds_next = 0;
-
- if (prev->ds_ctx)
- ds_prev = (unsigned long)prev->ds_ctx->ds;
- if (next->ds_ctx)
- ds_next = (unsigned long)next->ds_ctx->ds;
-
- if (ds_next != ds_prev) {
- /* we clear debugctl to make sure DS
- * is not in use when we change it */
- debugctl = 0;
- update_debugctlmsr(0);
- wrmsr(MSR_IA32_DS_AREA, ds_next, 0);
- }
- return debugctl;
-}
-#else
-static int update_debugctl(struct thread_struct *prev,
- struct thread_struct *next, unsigned long debugctl)
-{
- return debugctl;
-}
-#endif /* CONFIG_X86_DS */
-
-static noinline void
-__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
- struct tss_struct *tss)
-{
- struct thread_struct *prev, *next;
- unsigned long debugctl;
-
- prev = &prev_p->thread;
- next = &next_p->thread;
-
- debugctl = update_debugctl(prev, next, prev->debugctlmsr);
-
- if (next->debugctlmsr != debugctl)
- update_debugctlmsr(next->debugctlmsr);
-
- if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
- set_debugreg(next->debugreg0, 0);
- set_debugreg(next->debugreg1, 1);
- set_debugreg(next->debugreg2, 2);
- set_debugreg(next->debugreg3, 3);
- /* no 4 and 5 */
- set_debugreg(next->debugreg6, 6);
- set_debugreg(next->debugreg7, 7);
- }
-
- 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();
- }
-
-#ifdef CONFIG_X86_PTRACE_BTS
- if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
- ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
-
- if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
- ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
-#endif /* CONFIG_X86_PTRACE_BTS */
-
-
- if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
- /*
- * Disable the bitmap via an invalid offset. We still cache
- * the previous bitmap owner and the IO bitmap contents:
- */
- tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
- return;
- }
-
- if (likely(next == tss->io_bitmap_owner)) {
- /*
- * Previous owner of the bitmap (hence the bitmap content)
- * matches the next task, we dont have to do anything but
- * to set a valid offset in the TSS:
- */
- tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
- return;
- }
- /*
- * Lazy TSS's I/O bitmap copy. We set an invalid offset here
- * and we let the task to get a GPF in case an I/O instruction
- * is performed. The handler of the GPF will verify that the
- * faulting task has a valid I/O bitmap and, it true, does the
- * real copy and restart the instruction. This will save us
- * redundant copies when the currently switched task does not
- * perform any I/O during its timeslice.
- */
- tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
-}