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Subject[PATCH 4.9 33/35] x86/fpu: Remove struct fpu::counter
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rik van Riel <riel@redhat.com>

commit 3913cc3507575273beb165a5e027a081913ed507 upstream.

With the lazy FPU code gone, we no longer use the counter field
in struct fpu for anything. Get rid it.

Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-6-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Daniel Sangorrin <daniel.sangorrin@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/fpu/internal.h | 3 ---
arch/x86/include/asm/fpu/types.h | 11 -----------
arch/x86/include/asm/trace/fpu.h | 5 +----
arch/x86/kernel/fpu/core.c | 3 ---
4 files changed, 1 insertion(+), 21 deletions(-)

--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -581,16 +581,13 @@ switch_fpu_prepare(struct fpu *old_fpu,

/* Don't change CR0.TS if we just switch! */
if (fpu.preload) {
- new_fpu->counter++;
__fpregs_activate(new_fpu);
trace_x86_fpu_regs_activated(new_fpu);
prefetch(&new_fpu->state);
}
} else {
- old_fpu->counter = 0;
old_fpu->last_cpu = -1;
if (fpu.preload) {
- new_fpu->counter++;
if (fpu_want_lazy_restore(new_fpu, cpu))
fpu.preload = 0;
else
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -322,17 +322,6 @@ struct fpu {
unsigned char fpregs_active;

/*
- * @counter:
- *
- * This counter contains the number of consecutive context switches
- * during which the FPU stays used. If this is over a threshold, the
- * lazy FPU restore logic becomes eager, to save the trap overhead.
- * This is an unsigned char so that after 256 iterations the counter
- * wraps and the context switch behavior turns lazy again; this is to
- * deal with bursty apps that only use the FPU for a short time:
- */
- unsigned char counter;
- /*
* @state:
*
* In-memory copy of all FPU registers that we save/restore
--- a/arch/x86/include/asm/trace/fpu.h
+++ b/arch/x86/include/asm/trace/fpu.h
@@ -14,7 +14,6 @@ DECLARE_EVENT_CLASS(x86_fpu,
__field(struct fpu *, fpu)
__field(bool, fpregs_active)
__field(bool, fpstate_active)
- __field(int, counter)
__field(u64, xfeatures)
__field(u64, xcomp_bv)
),
@@ -23,17 +22,15 @@ DECLARE_EVENT_CLASS(x86_fpu,
__entry->fpu = fpu;
__entry->fpregs_active = fpu->fpregs_active;
__entry->fpstate_active = fpu->fpstate_active;
- __entry->counter = fpu->counter;
if (boot_cpu_has(X86_FEATURE_OSXSAVE)) {
__entry->xfeatures = fpu->state.xsave.header.xfeatures;
__entry->xcomp_bv = fpu->state.xsave.header.xcomp_bv;
}
),
- TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d counter: %d xfeatures: %llx xcomp_bv: %llx",
+ TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d xfeatures: %llx xcomp_bv: %llx",
__entry->fpu,
__entry->fpregs_active,
__entry->fpstate_active,
- __entry->counter,
__entry->xfeatures,
__entry->xcomp_bv
)
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -225,7 +225,6 @@ EXPORT_SYMBOL_GPL(fpstate_init);

int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
{
- dst_fpu->counter = 0;
dst_fpu->fpregs_active = 0;
dst_fpu->last_cpu = -1;

@@ -433,7 +432,6 @@ void fpu__restore(struct fpu *fpu)
trace_x86_fpu_before_restore(fpu);
fpregs_activate(fpu);
copy_kernel_to_fpregs(&fpu->state);
- fpu->counter++;
trace_x86_fpu_after_restore(fpu);
kernel_fpu_enable();
}
@@ -451,7 +449,6 @@ EXPORT_SYMBOL_GPL(fpu__restore);
void fpu__drop(struct fpu *fpu)
{
preempt_disable();
- fpu->counter = 0;

if (fpu->fpregs_active) {
/* Ignore delayed exceptions from user space */

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