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Commit f1c8cd01 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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

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: default avatarIngo Molnar <mingo@kernel.org>
parent b6aa8555

arch/x86/include/asm/fpu/internal.h

+3 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/fpu/core.c

+10 −6
Original line number Diff line number Diff line
@@ -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"

arch/x86/kernel/fpu/signal.c

+3 −1
Original line number Diff line number Diff line
@@ -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;

arch/x86/mm/pkeys.c

+1 −2
Original line number Diff line number Diff line
@@ -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;