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x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active

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We want to simplify the FPU state machine by eliminating fpu->fpregs_active,
and we can do that because the two state flags (::fpregs_active and
::fpstate_active) are set essentially together.

The old lazy FPU switching code used to make a distinction - but there's
no lazy switching code anymore, we always switch in an 'eager' fashion.

Do this by first changing all substantial uses of fpu->fpregs_active
to fpu->fpstate_active and adding a few debug checks to double check
our assumption is correct.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170923130016.21448-19-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2017-09-23 15:00:01 +02:00
parent b6aa85558d
commit f1c8cd0176
4 changed files with 17 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/include/asm/fpu/internal.h
View File

@ -556,7 +556,9 @@ static inline void fpregs_activate(struct fpu *fpu)
static inline void
switch_fpu_prepare(struct fpu *old_fpu, int cpu)
{
if (old_fpu->fpregs_active) {
WARN_ON_FPU(old_fpu->fpregs_active != old_fpu->fpstate_active);
if (old_fpu->fpstate_active) {
if (!copy_fpregs_to_fpstate(old_fpu))
old_fpu->last_cpu = -1;
else

16
arch/x86/kernel/fpu/core.c
View File

@ -100,7 +100,7 @@ void __kernel_fpu_begin(void)
kernel_fpu_disable();
if (fpu->fpregs_active) {
if (fpu->fpstate_active) {
/*
* Ignore return value -- we don't care if reg state
* is clobbered.
@ -116,7 +116,7 @@ void __kernel_fpu_end(void)
{
struct fpu *fpu = &current->thread.fpu;
if (fpu->fpregs_active)
if (fpu->fpstate_active)
copy_kernel_to_fpregs(&fpu->state);
kernel_fpu_enable();
@ -147,8 +147,10 @@ void fpu__save(struct fpu *fpu)
WARN_ON_FPU(fpu != &current->thread.fpu);
preempt_disable();
WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active);
trace_x86_fpu_before_save(fpu);
if (fpu->fpregs_active) {
if (fpu->fpstate_active) {
if (!copy_fpregs_to_fpstate(fpu)) {
copy_kernel_to_fpregs(&fpu->state);
}
@ -262,11 +264,12 @@ EXPORT_SYMBOL_GPL(fpu__activate_curr);
*/
void fpu__activate_fpstate_read(struct fpu *fpu)
{
WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active);
/*
* If fpregs are active (in the current CPU), then
* copy them to the fpstate:
*/
if (fpu->fpregs_active) {
if (fpu->fpstate_active) {
fpu__save(fpu);
} else {
if (!fpu->fpstate_active) {
@ -362,12 +365,13 @@ void fpu__current_fpstate_write_end(void)
{
struct fpu *fpu = &current->thread.fpu;
WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active);
/*
* 'fpu' now has an updated copy of the state, but the
* registers may still be out of date. Update them with
* an XRSTOR if they are active.
*/
if (fpu->fpregs_active)
if (fpu->fpstate_active)
copy_kernel_to_fpregs(&fpu->state);
/*
@ -417,7 +421,7 @@ void fpu__drop(struct fpu *fpu)
if (fpu == &current->thread.fpu) {
WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active);
if (fpu->fpregs_active) {
if (fpu->fpstate_active) {
/* Ignore delayed exceptions from user space */
asm volatile("1: fwait\n"
"2:\n"

4
arch/x86/kernel/fpu/signal.c
View File

@ -171,7 +171,9 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
sizeof(struct user_i387_ia32_struct), NULL,
(struct _fpstate_32 __user *) buf) ? -1 : 1;
if (fpu->fpregs_active || using_compacted_format()) {
WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active);
if (fpu->fpstate_active || using_compacted_format()) {
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;

3
arch/x86/mm/pkeys.c
View File

@ -18,7 +18,6 @@
#include <asm/cpufeature.h> /* boot_cpu_has, ... */
#include <asm/mmu_context.h> /* vma_pkey() */
#include <asm/fpu/internal.h> /* fpregs_active() */
int __execute_only_pkey(struct mm_struct *mm)
{
@ -45,7 +44,7 @@ int __execute_only_pkey(struct mm_struct *mm)
*/
preempt_disable();
if (!need_to_set_mm_pkey &&
current->thread.fpu.fpregs_active &&
current->thread.fpu.fpstate_active &&
!__pkru_allows_read(read_pkru(), execute_only_pkey)) {
preempt_enable();
return execute_only_pkey;