/*
* Save the userland FPSIMD state of 'current' to memory, but only if the state
* currently held in the registers does in fact belong to 'current'
*/
void fpsimd_preserve_current_state(void)
{
preempt_disable();
if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
fpsimd_save_state(¤t->thread.fpsimd_state);
preempt_enable();
}
void fpsimd_thread_switch(struct task_struct *next)
{
/*
* Save the current FPSIMD state to memory, but only if whatever is in
* the registers is in fact the most recent userland FPSIMD state of
* 'current'.
*/
if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
fpsimd_save_state(¤t->thread.fpsimd_state);
if (next->mm) {
/*
* If we are switching to a task whose most recent userland
* FPSIMD state is already in the registers of *this* cpu,
* we can skip loading the state from memory. Otherwise, set
* the TIF_FOREIGN_FPSTATE flag so the state will be loaded
* upon the next return to userland.
*/
struct fpsimd_state *st = &next->thread.fpsimd_state;
if (__this_cpu_read(fpsimd_last_state) == st
&& st->cpu == smp_processor_id())
clear_ti_thread_flag(task_thread_info(next),
TIF_FOREIGN_FPSTATE);
else
set_ti_thread_flag(task_thread_info(next),
TIF_FOREIGN_FPSTATE);
}
}
void fpsimd_thread_switch(struct task_struct *next)
{
/* check if not kernel threads */
if (current->mm)
fpsimd_save_state(¤t->thread.fpsimd_state);
if (next->mm)
fpsimd_load_state(&next->thread.fpsimd_state);
}
/*
* Kernel-side NEON support functions
*/
void kernel_neon_begin(void)
{
/* Avoid using the NEON in interrupt context */
BUG_ON(in_interrupt());
preempt_disable();
if (current->mm)
fpsimd_save_state(¤t->thread.fpsimd_state);
}
/*
* Save the userland FPSIMD state of 'current' to memory, but only if the state
* currently held in the registers does in fact belong to 'current'
*/
void fpsimd_preserve_current_state(void)
{
if (!system_supports_fpsimd())
return;
preempt_disable();
if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
fpsimd_save_state(¤t->thread.fpsimd_state);
preempt_enable();
}
static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
unsigned long cmd, void *v)
{
switch (cmd) {
case CPU_PM_ENTER:
if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
fpsimd_save_state(¤t->thread.fpsimd_state);
break;
case CPU_PM_EXIT:
if (current->mm)
set_thread_flag(TIF_FOREIGN_FPSTATE);
break;
case CPU_PM_ENTER_FAILED:
default:
return NOTIFY_DONE;
}
return NOTIFY_OK;
}
static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
{
struct fpsimd_state *fpsimd = ¤t->thread.fpsimd_state;
int err;
/* dump the hardware registers to the fpsimd_state structure */
fpsimd_save_state(fpsimd);
/* copy the FP and status/control registers */
err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
__put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
__put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
/* copy the magic/size information */
__put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
__put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
return err ? -EFAULT : 0;
}
/*
* Kernel-side NEON support functions
*/
void kernel_neon_begin_partial(u32 num_regs)
{
if (in_interrupt()) {
struct fpsimd_partial_state *s = this_cpu_ptr(
in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
BUG_ON(num_regs > 32);
fpsimd_save_partial_state(s, roundup(num_regs, 2));
} else {
/*
* Save the userland FPSIMD state if we have one and if we
* haven't done so already. Clear fpsimd_last_state to indicate
* that there is no longer userland FPSIMD state in the
* registers.
*/
preempt_disable();
if (current->mm)
fpsimd_save_state(¤t->thread.fpsimd_state);
}
}
/*
* Ensure FPSIMD/SVE storage in memory for the loaded context is up to
* date with respect to the CPU registers.
*
* Softirqs (and preemption) must be disabled.
*/
void fpsimd_save(void)
{
struct user_fpsimd_state *st = __this_cpu_read(fpsimd_last_state.st);
/* set by fpsimd_bind_task_to_cpu() or fpsimd_bind_state_to_cpu() */
WARN_ON(!in_softirq() && !irqs_disabled());
if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
if (system_supports_sve() && test_thread_flag(TIF_SVE)) {
if (WARN_ON(sve_get_vl() != current->thread.sve_vl)) {
/*
* Can't save the user regs, so current would
* re-enter user with corrupt state.
* There's no way to recover, so kill it:
*/
force_signal_inject(SIGKILL, SI_KERNEL, 0);
return;
}
sve_save_state(sve_pffr(¤t->thread), &st->fpsr);
} else
fpsimd_save_state(st);
}
}
/*
* Kernel-side NEON support functions
*/
void kernel_neon_begin_partial(u32 num_regs)
{
if (WARN_ON(!system_supports_fpsimd()))
return;
if (in_interrupt()) {
struct fpsimd_partial_state *s = this_cpu_ptr(
in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
BUG_ON(num_regs > 32);
fpsimd_save_partial_state(s, roundup(num_regs, 2));
} else {
/*
* Save the userland FPSIMD state if we have one and if we
* haven't done so already. Clear fpsimd_last_state to indicate
* that there is no longer userland FPSIMD state in the
* registers.
*/
preempt_disable();
if (current->mm &&
!test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
fpsimd_save_state(¤t->thread.fpsimd_state);
this_cpu_write(fpsimd_last_state, NULL);
}
}
