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[PATCH 0/6] x86: Misc cleanups

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  [PATCH 0/6] x86: Misc cleanups Borislav Petkov <bp@alien8.de> - 2016-04-05 08:40 +0200
    [PATCH 4/6] x86/tsc: Save an indentation level in recalibrate_cpu_khz() Borislav Petkov <bp@alien8.de> - 2016-04-05 08:40 +0200
      Re: [PATCH 4/6] x86/tsc: Save an indentation level in  recalibrate_cpu_khz() Peter Zijlstra <peterz@infradead.org> - 2016-04-05 10:10 +0200
      [tip:x86/asm] x86/tsc: Save an indentation level in  recalibrate_cpu_khz() tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-04-13 13:50 +0200
    [PATCH 3/6] x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in notifier call Borislav Petkov <bp@alien8.de> - 2016-04-05 08:40 +0200
      Re: [PATCH 3/6] x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in  notifier call Peter Zijlstra <peterz@infradead.org> - 2016-04-05 10:10 +0200
      [tip:x86/asm] x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in  notifier call tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-04-13 13:50 +0200
    [PATCH 1/6] x86/fpu/regset: Use boot_cpu_has() Borislav Petkov <bp@alien8.de> - 2016-04-05 08:40 +0200
      Re: [PATCH 1/6] x86/fpu/regset: Use boot_cpu_has() Brian Gerst <brgerst@gmail.com> - 2016-04-05 16:00 +0200
        Re: [PATCH 1/6] x86/fpu/regset: Use boot_cpu_has() Borislav Petkov <bp@alien8.de> - 2016-04-05 17:20 +0200
      [tip:x86/asm] x86/fpu/regset: Replace static_cpu_has() usage with  boot_cpu_has() tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-04-13 13:50 +0200
    [PATCH 5/6] x86/fpu: Remove check_fpu() indirection Borislav Petkov <bp@alien8.de> - 2016-04-05 08:40 +0200
      [tip:x86/asm] x86/fpu: Remove check_fpu() indirection tip-bot for Borislav Petkov <tipbot@zytor.com> - 2016-04-13 13:50 +0200

#1371265 — [PATCH 0/6] x86: Misc cleanups

From: Borislav Petkov <bp@suse.de>

Hi,

here a bunch of minor cleanups ontop of the cpu_has_YYY removal pile.

Borislav Petkov (6):
  x86/fpu/regset: Use boot_cpu_has()
  x86/cpu: Simplify extended APIC ID detection on AMD
  x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in notifier call
  x86/tsc: Save an indentation level in recalibrate_cpu_khz()
  x86/fpu: Remove check_fpu() indirection
  x86/fpu: Get rid of x87 math exception helpers

 arch/x86/kernel/cpu/amd.c    | 17 ++++++++++-------
 arch/x86/kernel/fpu/bugs.c   | 16 +++++-----------
 arch/x86/kernel/fpu/core.c   | 44 +++++++++++++-------------------------------
 arch/x86/kernel/fpu/regset.c |  4 ++--
 arch/x86/kernel/tsc.c        | 23 ++++++++++-------------
 5 files changed, 40 insertions(+), 64 deletions(-)

-- 
2.7.3

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#1371267 — [PATCH 4/6] x86/tsc: Save an indentation level in recalibrate_cpu_khz()

From: Borislav Petkov <bp@suse.de>

... by flipping the check.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 arch/x86/kernel/tsc.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 5bb702c77e8f..38ba6de56ede 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -834,15 +834,15 @@ int recalibrate_cpu_khz(void)
 #ifndef CONFIG_SMP
 	unsigned long cpu_khz_old = cpu_khz;
 
-	if (boot_cpu_has(X86_FEATURE_TSC)) {
-		tsc_khz = x86_platform.calibrate_tsc();
-		cpu_khz = tsc_khz;
-		cpu_data(0).loops_per_jiffy =
-			cpufreq_scale(cpu_data(0).loops_per_jiffy,
-					cpu_khz_old, cpu_khz);
-		return 0;
-	} else
+	if (!boot_cpu_has(X86_FEATURE_TSC))
 		return -ENODEV;
+
+	tsc_khz = x86_platform.calibrate_tsc();
+	cpu_khz = tsc_khz;
+	cpu_data(0).loops_per_jiffy = cpufreq_scale(cpu_data(0).loops_per_jiffy,
+						    cpu_khz_old, cpu_khz);
+
+	return 0;
 #else
 	return -ENODEV;
 #endif
-- 
2.7.3

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#1371304 — Re: [PATCH 4/6] x86/tsc: Save an indentation level in recalibrate_cpu_khz()

On Tue, Apr 05, 2016 at 08:29:53AM +0200, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
> 
> ... by flipping the check.
> 
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Cc: Thomas Gleixner <tglx@linutronix.de>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

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#1377818 — [tip:x86/asm] x86/tsc: Save an indentation level in recalibrate_cpu_khz()

Commit-ID:  eff4677e9fb9b680d1d5f6ba079116548d072b7e
Gitweb:     http://git.kernel.org/tip/eff4677e9fb9b680d1d5f6ba079116548d072b7e
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 5 Apr 2016 08:29:53 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 13 Apr 2016 11:37:43 +0200

x86/tsc: Save an indentation level in recalibrate_cpu_khz()

... by flipping the check.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1459837795-2588-5-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/tsc.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 5bb702c..38ba6de 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -834,15 +834,15 @@ int recalibrate_cpu_khz(void)
 #ifndef CONFIG_SMP
 	unsigned long cpu_khz_old = cpu_khz;
 
-	if (boot_cpu_has(X86_FEATURE_TSC)) {
-		tsc_khz = x86_platform.calibrate_tsc();
-		cpu_khz = tsc_khz;
-		cpu_data(0).loops_per_jiffy =
-			cpufreq_scale(cpu_data(0).loops_per_jiffy,
-					cpu_khz_old, cpu_khz);
-		return 0;
-	} else
+	if (!boot_cpu_has(X86_FEATURE_TSC))
 		return -ENODEV;
+
+	tsc_khz = x86_platform.calibrate_tsc();
+	cpu_khz = tsc_khz;
+	cpu_data(0).loops_per_jiffy = cpufreq_scale(cpu_data(0).loops_per_jiffy,
+						    cpu_khz_old, cpu_khz);
+
+	return 0;
 #else
 	return -ENODEV;
 #endif

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#1371268 — [PATCH 3/6] x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in notifier call

From: Borislav Petkov <bp@suse.de>

... because the notifier-registering routine already does that. Also,
rename cpufreq_tsc() init call to something more telling.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 arch/x86/kernel/tsc.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index a0346bc51833..5bb702c77e8f 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -922,9 +922,6 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 	struct cpufreq_freqs *freq = data;
 	unsigned long *lpj;
 
-	if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
-		return 0;
-
 	lpj = &boot_cpu_data.loops_per_jiffy;
 #ifdef CONFIG_SMP
 	if (!(freq->flags & CPUFREQ_CONST_LOOPS))
@@ -954,7 +951,7 @@ static struct notifier_block time_cpufreq_notifier_block = {
 	.notifier_call  = time_cpufreq_notifier
 };
 
-static int __init cpufreq_tsc(void)
+static int __init cpufreq_register_tsc_scaling(void)
 {
 	if (!boot_cpu_has(X86_FEATURE_TSC))
 		return 0;
@@ -965,7 +962,7 @@ static int __init cpufreq_tsc(void)
 	return 0;
 }
 
-core_initcall(cpufreq_tsc);
+core_initcall(cpufreq_register_tsc_scaling);
 
 #endif /* CONFIG_CPU_FREQ */
 
-- 
2.7.3

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#1371305 — Re: [PATCH 3/6] x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in notifier call

On Tue, Apr 05, 2016 at 08:29:52AM +0200, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
> 
> ... because the notifier-registering routine already does that. Also,
> rename cpufreq_tsc() init call to something more telling.
> 
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Cc: Thomas Gleixner <tglx@linutronix.de>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

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#1377840 — [tip:x86/asm] x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in notifier call

Commit-ID:  a841cca74ea7612508aee161c89987b2646ed769
Gitweb:     http://git.kernel.org/tip/a841cca74ea7612508aee161c89987b2646ed769
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 5 Apr 2016 08:29:52 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 13 Apr 2016 11:37:43 +0200

x86/tsc: Do not check X86_FEATURE_CONSTANT_TSC in notifier call

... because the notifier-registering routine already does that. Also,
rename cpufreq_tsc() init call to something more telling.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1459837795-2588-4-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/tsc.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index a0346bc..5bb702c 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -922,9 +922,6 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 	struct cpufreq_freqs *freq = data;
 	unsigned long *lpj;
 
-	if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
-		return 0;
-
 	lpj = &boot_cpu_data.loops_per_jiffy;
 #ifdef CONFIG_SMP
 	if (!(freq->flags & CPUFREQ_CONST_LOOPS))
@@ -954,7 +951,7 @@ static struct notifier_block time_cpufreq_notifier_block = {
 	.notifier_call  = time_cpufreq_notifier
 };
 
-static int __init cpufreq_tsc(void)
+static int __init cpufreq_register_tsc_scaling(void)
 {
 	if (!boot_cpu_has(X86_FEATURE_TSC))
 		return 0;
@@ -965,7 +962,7 @@ static int __init cpufreq_tsc(void)
 	return 0;
 }
 
-core_initcall(cpufreq_tsc);
+core_initcall(cpufreq_register_tsc_scaling);
 
 #endif /* CONFIG_CPU_FREQ */
 

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#1371269 — [PATCH 1/6] x86/fpu/regset: Use boot_cpu_has()

From: Borislav Petkov <bp@suse.de>

fpregs_{g,s}et() are not sizzling-hot paths to justify the need for
static_cpu_has(). Use the normal boot_cpu_has() helper.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/fpu/regset.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index bc5e76c1d7c5..81422dfb152b 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -278,7 +278,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 
 	fpu__activate_fpstate_read(fpu);
 
-	if (!static_cpu_has(X86_FEATURE_FPU))
+	if (!boot_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
 
 	if (!boot_cpu_has(X86_FEATURE_FXSR))
@@ -309,7 +309,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 	fpu__activate_fpstate_write(fpu);
 	fpstate_sanitize_xstate(fpu);
 
-	if (!static_cpu_has(X86_FEATURE_FPU))
+	if (!boot_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
 
 	if (!boot_cpu_has(X86_FEATURE_FXSR))
-- 
2.7.3

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#1371614 — Re: [PATCH 1/6] x86/fpu/regset: Use boot_cpu_has()

On Tue, Apr 5, 2016 at 2:29 AM, Borislav Petkov <bp@alien8.de> wrote:
> From: Borislav Petkov <bp@suse.de>
>
> fpregs_{g,s}et() are not sizzling-hot paths to justify the need for
> static_cpu_has(). Use the normal boot_cpu_has() helper.
>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
>  arch/x86/kernel/fpu/regset.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
> index bc5e76c1d7c5..81422dfb152b 100644
> --- a/arch/x86/kernel/fpu/regset.c
> +++ b/arch/x86/kernel/fpu/regset.c
> @@ -278,7 +278,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
>
>         fpu__activate_fpstate_read(fpu);
>
> -       if (!static_cpu_has(X86_FEATURE_FPU))
> +       if (!boot_cpu_has(X86_FEATURE_FPU))
>                 return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
>
>         if (!boot_cpu_has(X86_FEATURE_FXSR))
> @@ -309,7 +309,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
>         fpu__activate_fpstate_write(fpu);
>         fpstate_sanitize_xstate(fpu);
>
> -       if (!static_cpu_has(X86_FEATURE_FPU))
> +       if (!boot_cpu_has(X86_FEATURE_FPU))
>                 return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
>
>         if (!boot_cpu_has(X86_FEATURE_FXSR))

I think the general rule should be always use static_cpu_has() for
runtime checks, since it reduces down to a single jmp/nop instruction
after alternatives run.  Even if it's not a hot path, it saves a bit
of runtime memory.  boot_cpu_has() is fine for run-once init code.

--
Brian Gerst

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#1371711 — Re: [PATCH 1/6] x86/fpu/regset: Use boot_cpu_has()

On Tue, Apr 05, 2016 at 09:51:55AM -0400, Brian Gerst wrote:
> I think the general rule should be always use static_cpu_has() for
> runtime checks, since it reduces down to a single jmp/nop instruction
> after alternatives run.  Even if it's not a hot path, it saves a bit
> of runtime memory.

So gcc generates a MOV and a TEST for boot_cpu_has(). Not exactly the
bloat or slowdown.

So I look at those differently: static_cpu_has()

a) should be used on hotpaths

b) is used as such to annotate those - i.e., "ah, there's a
static_cpu_has(), this is a hot path, I better be careful what I'm doing
here."

boot_cpu_has() in all the rest.

And saving a couple of bytes per call site but increasing alternatives
application time by milli- or microseconds... Meh. I don't see it being
really worth the trouble. But this is just me.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

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#1377815 — [tip:x86/asm] x86/fpu/regset: Replace static_cpu_has() usage with boot_cpu_has()

Commit-ID:  78df526c74a4db696e1e058b9869471937d0773b
Gitweb:     http://git.kernel.org/tip/78df526c74a4db696e1e058b9869471937d0773b
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 5 Apr 2016 08:29:50 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 13 Apr 2016 11:37:42 +0200

x86/fpu/regset: Replace static_cpu_has() usage with boot_cpu_has()

fpregs_{g,s}et() are not sizzling-hot paths to justify the need for
static_cpu_has(). Use the normal boot_cpu_has() helper.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1459837795-2588-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/fpu/regset.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index bc5e76c..81422df 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -278,7 +278,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 
 	fpu__activate_fpstate_read(fpu);
 
-	if (!static_cpu_has(X86_FEATURE_FPU))
+	if (!boot_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
 
 	if (!boot_cpu_has(X86_FEATURE_FXSR))
@@ -309,7 +309,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 	fpu__activate_fpstate_write(fpu);
 	fpstate_sanitize_xstate(fpu);
 
-	if (!static_cpu_has(X86_FEATURE_FPU))
+	if (!boot_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
 
 	if (!boot_cpu_has(X86_FEATURE_FXSR))

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#1371271 — [PATCH 5/6] x86/fpu: Remove check_fpu() indirection

From: Borislav Petkov <bp@suse.de>

Rename it to fpu__init_check_bugs() and do the CPU feature check at
entry, thus getting rid of the old fpu__init_check_bugs() wrapper.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/kernel/fpu/bugs.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/fpu/bugs.c b/arch/x86/kernel/fpu/bugs.c
index 224b5ec52195..aad34aafc0e0 100644
--- a/arch/x86/kernel/fpu/bugs.c
+++ b/arch/x86/kernel/fpu/bugs.c
@@ -21,11 +21,15 @@ static double __initdata y = 3145727.0;
  * We should really only care about bugs here
  * anyway. Not features.
  */
-static void __init check_fpu(void)
+void __init fpu__init_check_bugs(void)
 {
 	u32 cr0_saved;
 	s32 fdiv_bug;
 
+	/* kernel_fpu_begin/end() relies on patched alternative instructions. */
+	if (!boot_cpu_has(X86_FEATURE_FPU))
+		return;
+
 	/* We might have CR0::TS set already, clear it: */
 	cr0_saved = read_cr0();
 	write_cr0(cr0_saved & ~X86_CR0_TS);
@@ -59,13 +63,3 @@ static void __init check_fpu(void)
 		pr_warn("Hmm, FPU with FDIV bug\n");
 	}
 }
-
-void __init fpu__init_check_bugs(void)
-{
-	/*
-	 * kernel_fpu_begin/end() in check_fpu() relies on the patched
-	 * alternative instructions.
-	 */
-	if (boot_cpu_has(X86_FEATURE_FPU))
-		check_fpu();
-}
-- 
2.7.3

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#1377823 — [tip:x86/asm] x86/fpu: Remove check_fpu() indirection

Commit-ID:  de82fbc3823b7b15ee03466ebfb1c5ec7cc1a941
Gitweb:     http://git.kernel.org/tip/de82fbc3823b7b15ee03466ebfb1c5ec7cc1a941
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 5 Apr 2016 08:29:54 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 13 Apr 2016 11:37:43 +0200

x86/fpu: Remove check_fpu() indirection

Rename it to fpu__init_check_bugs() and do the CPU feature check at
entry, thus getting rid of the old fpu__init_check_bugs() wrapper.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1459837795-2588-6-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/fpu/bugs.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/fpu/bugs.c b/arch/x86/kernel/fpu/bugs.c
index 224b5ec..aad34aa 100644
--- a/arch/x86/kernel/fpu/bugs.c
+++ b/arch/x86/kernel/fpu/bugs.c
@@ -21,11 +21,15 @@ static double __initdata y = 3145727.0;
  * We should really only care about bugs here
  * anyway. Not features.
  */
-static void __init check_fpu(void)
+void __init fpu__init_check_bugs(void)
 {
 	u32 cr0_saved;
 	s32 fdiv_bug;
 
+	/* kernel_fpu_begin/end() relies on patched alternative instructions. */
+	if (!boot_cpu_has(X86_FEATURE_FPU))
+		return;
+
 	/* We might have CR0::TS set already, clear it: */
 	cr0_saved = read_cr0();
 	write_cr0(cr0_saved & ~X86_CR0_TS);
@@ -59,13 +63,3 @@ static void __init check_fpu(void)
 		pr_warn("Hmm, FPU with FDIV bug\n");
 	}
 }
-
-void __init fpu__init_check_bugs(void)
-{
-	/*
-	 * kernel_fpu_begin/end() in check_fpu() relies on the patched
-	 * alternative instructions.
-	 */
-	if (boot_cpu_has(X86_FEATURE_FPU))
-		check_fpu();
-}

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