ldr w\tmpnr, [\state, #16 * 2 + 4]
msr fpcr, x\tmpnr
.endm
-
-.altmacro
-.macro fpsimd_save_partial state, numnr, tmpnr1, tmpnr2
- mrs x\tmpnr1, fpsr
- str w\numnr, [\state, #8]
- mrs x\tmpnr2, fpcr
- stp w\tmpnr1, w\tmpnr2, [\state]
- adr x\tmpnr1, 0f
- add \state, \state, x\numnr, lsl #4
- sub x\tmpnr1, x\tmpnr1, x\numnr, lsl #1
- br x\tmpnr1
- .irp qa, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 0
- .irp qb, %(qa + 1)
- stp q\qa, q\qb, [\state, # -16 * \qa - 16]
- .endr
- .endr
-0:
-.endm
-
-.macro fpsimd_restore_partial state, tmpnr1, tmpnr2
- ldp w\tmpnr1, w\tmpnr2, [\state]
- msr fpsr, x\tmpnr1
- msr fpcr, x\tmpnr2
- adr x\tmpnr1, 0f
- ldr w\tmpnr2, [\state, #8]
- add \state, \state, x\tmpnr2, lsl #4
- sub x\tmpnr1, x\tmpnr1, x\tmpnr2, lsl #1
- br x\tmpnr1
- .irp qa, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 0
- .irp qb, %(qa + 1)
- ldp q\qa, q\qb, [\state, # -16 * \qa - 16]
- .endr
- .endr
-0:
-.endm
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/signal.h>
-#include <linux/hardirq.h>
#include <asm/fpsimd.h>
#include <asm/cputype.h>
#define FPEXC_IXF (1 << 4)
#define FPEXC_IDF (1 << 7)
-/*
- * In order to reduce the number of times the FPSIMD state is needlessly saved
- * and restored, we need to keep track of two things:
- * (a) for each task, we need to remember which CPU was the last one to have
- * the task's FPSIMD state loaded into its FPSIMD registers;
- * (b) for each CPU, we need to remember which task's userland FPSIMD state has
- * been loaded into its FPSIMD registers most recently, or whether it has
- * been used to perform kernel mode NEON in the meantime.
- *
- * For (a), we add a 'cpu' field to struct fpsimd_state, which gets updated to
- * the id of the current CPU everytime the state is loaded onto a CPU. For (b),
- * we add the per-cpu variable 'fpsimd_last_state' (below), which contains the
- * address of the userland FPSIMD state of the task that was loaded onto the CPU
- * the most recently, or NULL if kernel mode NEON has been performed after that.
- *
- * With this in place, we no longer have to restore the next FPSIMD state right
- * when switching between tasks. Instead, we can defer this check to userland
- * resume, at which time we verify whether the CPU's fpsimd_last_state and the
- * task's fpsimd_state.cpu are still mutually in sync. If this is the case, we
- * can omit the FPSIMD restore.
- *
- * As an optimization, we use the thread_info flag TIF_FOREIGN_FPSTATE to
- * indicate whether or not the userland FPSIMD state of the current task is
- * present in the registers. The flag is set unless the FPSIMD registers of this
- * CPU currently contain the most recent userland FPSIMD state of the current
- * task.
- *
- * For a certain task, the sequence may look something like this:
- * - the task gets scheduled in; if both the task's fpsimd_state.cpu field
- * contains the id of the current CPU, and the CPU's fpsimd_last_state per-cpu
- * variable points to the task's fpsimd_state, the TIF_FOREIGN_FPSTATE flag is
- * cleared, otherwise it is set;
- *
- * - the task returns to userland; if TIF_FOREIGN_FPSTATE is set, the task's
- * userland FPSIMD state is copied from memory to the registers, the task's
- * fpsimd_state.cpu field is set to the id of the current CPU, the current
- * CPU's fpsimd_last_state pointer is set to this task's fpsimd_state and the
- * TIF_FOREIGN_FPSTATE flag is cleared;
- *
- * - the task executes an ordinary syscall; upon return to userland, the
- * TIF_FOREIGN_FPSTATE flag will still be cleared, so no FPSIMD state is
- * restored;
- *
- * - the task executes a syscall which executes some NEON instructions; this is
- * preceded by a call to kernel_neon_begin(), which copies the task's FPSIMD
- * register contents to memory, clears the fpsimd_last_state per-cpu variable
- * and sets the TIF_FOREIGN_FPSTATE flag;
- *
- * - the task gets preempted after kernel_neon_end() is called; as we have not
- * returned from the 2nd syscall yet, TIF_FOREIGN_FPSTATE is still set so
- * whatever is in the FPSIMD registers is not saved to memory, but discarded.
- */
-static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state);
-
/*
* Trapped FP/ASIMD access.
*/
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))
+ /* check if not kernel threads */
+ if (current->mm)
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);
- }
+ if (next->mm)
+ fpsimd_load_state(&next->thread.fpsimd_state);
}
void fpsimd_flush_thread(void)
-{
- memset(¤t->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
- set_thread_flag(TIF_FOREIGN_FPSTATE);
-}
-
-/*
- * 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();
-}
-
-/*
- * Load the userland FPSIMD state of 'current' from memory, but only if the
- * FPSIMD state already held in the registers is /not/ the most recent FPSIMD
- * state of 'current'
- */
-void fpsimd_restore_current_state(void)
-{
- preempt_disable();
- if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
- struct fpsimd_state *st = ¤t->thread.fpsimd_state;
-
- fpsimd_load_state(st);
- this_cpu_write(fpsimd_last_state, st);
- st->cpu = smp_processor_id();
- }
- preempt_enable();
-}
-
-/*
- * Load an updated userland FPSIMD state for 'current' from memory and set the
- * flag that indicates that the FPSIMD register contents are the most recent
- * FPSIMD state of 'current'
- */
-void fpsimd_update_current_state(struct fpsimd_state *state)
{
preempt_disable();
- fpsimd_load_state(state);
- if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
- struct fpsimd_state *st = ¤t->thread.fpsimd_state;
-
- this_cpu_write(fpsimd_last_state, st);
- st->cpu = smp_processor_id();
- }
+ memset(¤t->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
+ fpsimd_load_state(¤t->thread.fpsimd_state);
preempt_enable();
}
-/*
- * Invalidate live CPU copies of task t's FPSIMD state
- */
-void fpsimd_flush_task_state(struct task_struct *t)
-{
- t->thread.fpsimd_state.cpu = NR_CPUS;
-}
-
#ifdef CONFIG_KERNEL_MODE_NEON
-static DEFINE_PER_CPU(struct fpsimd_partial_state, hardirq_fpsimdstate);
-static DEFINE_PER_CPU(struct fpsimd_partial_state, softirq_fpsimdstate);
-
/*
* Kernel-side NEON support functions
*/
-void kernel_neon_begin_partial(u32 num_regs)
+void kernel_neon_begin(void)
{
- if (in_interrupt()) {
- struct fpsimd_partial_state *s = this_cpu_ptr(
- in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
+ /* Avoid using the NEON in interrupt context */
+ BUG_ON(in_interrupt());
+ preempt_disable();
- 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);
- }
+ if (current->mm)
+ fpsimd_save_state(¤t->thread.fpsimd_state);
}
-EXPORT_SYMBOL(kernel_neon_begin_partial);
+EXPORT_SYMBOL(kernel_neon_begin);
void kernel_neon_end(void)
{
- if (in_interrupt()) {
- struct fpsimd_partial_state *s = this_cpu_ptr(
- in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
- fpsimd_load_partial_state(s);
- } else {
- preempt_enable();
- }
+ if (current->mm)
+ fpsimd_load_state(¤t->thread.fpsimd_state);
+
+ preempt_enable();
}
EXPORT_SYMBOL(kernel_neon_end);
{
switch (cmd) {
case CPU_PM_ENTER:
- if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
+ if (current->mm)
fpsimd_save_state(¤t->thread.fpsimd_state);
break;
case CPU_PM_EXIT:
if (current->mm)
- set_thread_flag(TIF_FOREIGN_FPSTATE);
+ fpsimd_load_state(¤t->thread.fpsimd_state);
break;
case CPU_PM_ENTER_FAILED:
default:
projects / firefly-linux-kernel-4.4.55.git / commitdiff