void set_task_blockstep(struct task_struct *task, bool on)
{
unsigned long debugctl;
/*
* Ensure irq/preemption can't change debugctl in between.
* Note also that both TIF_BLOCKSTEP and debugctl should
* be changed atomically wrt preemption.
*
* NOTE: this means that set/clear TIF_BLOCKSTEP is only safe if
* task is current or it can't be running, otherwise we can race
* with __switch_to_xtra(). We rely on ptrace_freeze_traced() but
* PTRACE_KILL is not safe.
*/
local_irq_disable();
debugctl = get_debugctlmsr();
if (on) {
debugctl |= DEBUGCTLMSR_BTF;
set_tsk_thread_flag(task, TIF_BLOCKSTEP);
} else {
debugctl &= ~DEBUGCTLMSR_BTF;
clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
}
if (task == current)
update_debugctlmsr(debugctl);
local_irq_enable();
}
static void set_task_blockstep(struct task_struct *task, bool on)
{
unsigned long debugctl;
/*
* Ensure irq/preemption can't change debugctl in between.
* Note also that both TIF_BLOCKSTEP and debugctl should
* be changed atomically wrt preemption.
* FIXME: this means that set/clear TIF_BLOCKSTEP is simply
* wrong if task != current, SIGKILL can wakeup the stopped
* tracee and set/clear can play with the running task, this
* can confuse the next __switch_to_xtra().
*/
local_irq_disable();
debugctl = get_debugctlmsr();
if (on) {
debugctl |= DEBUGCTLMSR_BTF;
set_tsk_thread_flag(task, TIF_BLOCKSTEP);
} else {
debugctl &= ~DEBUGCTLMSR_BTF;
clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
}
if (task == current)
update_debugctlmsr(debugctl);
local_irq_enable();
}
void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
struct tss_struct *tss)
{
struct thread_struct *prev, *next;
prev = &prev_p->thread;
next = &next_p->thread;
if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
unsigned long debugctl = get_debugctlmsr();
debugctl &= ~DEBUGCTLMSR_BTF;
if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
debugctl |= DEBUGCTLMSR_BTF;
update_debugctlmsr(debugctl);
}
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();
}
if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
/*
* Copy the relevant range of the IO bitmap.
* Normally this is 128 bytes or less:
*/
memcpy(tss->io_bitmap, next->io_bitmap_ptr,
max(prev->io_bitmap_max, next->io_bitmap_max));
/*
* Make sure that the TSS limit is correct for the CPU
* to notice the IO bitmap.
*/
refresh_TR();
} else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
/*
* Clear any possible leftover bits:
*/
memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
}
propagate_user_return_notify(prev_p, next_p);
}