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Date: Thu, 26 Jan 2017 12:26:27 +0100
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Andy Lutomirski <luto@...capital.net>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Fenghua Yu <fenghua.yu@...el.com>,
"H . Peter Anvin" <hpa@...or.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Oleg Nesterov <oleg@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Rik van Riel <riel@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Yu-cheng Yu <yu-cheng.yu@...el.com>
Subject: [PATCH 5/7] 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: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@...el.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/include/asm/fpu/internal.h | 4 +++-
arch/x86/kernel/fpu/core.c | 16 ++++++++++------
arch/x86/kernel/fpu/signal.c | 4 +++-
arch/x86/mm/pkeys.c | 3 +--
4 files changed, 17 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index d6307e76837c..3a1cd8344a6b 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -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->fpregs_cached = 0;
else
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 2973afdb39f1..4fed80d08bd7 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -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 = ¤t->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 != ¤t->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 = ¤t->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 == ¤t->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"
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 684025654d0c..a88083ba7f8b 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -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;
diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
index e2c23472233e..4d24269c071f 100644
--- a/arch/x86/mm/pkeys.c
+++ b/arch/x86/mm/pkeys.c
@@ -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;
--
2.7.4
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