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2020-12-29 Thread Shawn Landden 



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Shawn Landden

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2020-12-20 Thread Shawn Landden 



-- 
Shawn Landden

[RESEND v4 PATCH 2/2] [PowerPC] Allow use of SIMD in interrupts from kernel code

2019-05-18 Thread Shawn Landden 
This even allows simd in preemptible kernel code,
as does x86, although this is rarely safe (could be used with
kthread_create_on_cpu). All callers are disabling preemption.

v4: fix build without CONFIG_AVX
change commit message
Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/switch_to.h |  15 +---
 arch/powerpc/kernel/process.c| 117 +++
 2 files changed, 88 insertions(+), 44 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h 
b/arch/powerpc/include/asm/switch_to.h
index 5b03d8a82..c79f7d24a 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -30,10 +30,7 @@ extern void enable_kernel_fp(void);
 extern void flush_fp_to_thread(struct task_struct *);
 extern void giveup_fpu(struct task_struct *);
 extern void save_fpu(struct task_struct *);
-static inline void disable_kernel_fp(void)
-{
-   msr_check_and_clear(MSR_FP);
-}
+extern void disable_kernel_fp(void);
 #else
 static inline void save_fpu(struct task_struct *t) { }
 static inline void flush_fp_to_thread(struct task_struct *t) { }
@@ -44,10 +41,7 @@ extern void enable_kernel_altivec(void);
 extern void flush_altivec_to_thread(struct task_struct *);
 extern void giveup_altivec(struct task_struct *);
 extern void save_altivec(struct task_struct *);
-static inline void disable_kernel_altivec(void)
-{
-   msr_check_and_clear(MSR_VEC);
-}
+extern void disable_kernel_altivec(void);
 #else
 static inline void save_altivec(struct task_struct *t) { }
 static inline void __giveup_altivec(struct task_struct *t) { }
@@ -56,10 +50,7 @@ static inline void __giveup_altivec(struct task_struct *t) { 
}
 #ifdef CONFIG_VSX
 extern void enable_kernel_vsx(void);
 extern void flush_vsx_to_thread(struct task_struct *);
-static inline void disable_kernel_vsx(void)
-{
-   msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
-}
+extern void disable_kernel_vsx(void);
 #endif
 
 #ifdef CONFIG_SPE
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index ef534831f..0136fd132 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -170,6 +170,29 @@ void __msr_check_and_clear(unsigned long bits)
 EXPORT_SYMBOL(__msr_check_and_clear);
 
 #ifdef CONFIG_PPC_FPU
+/*
+ * Track whether the kernel is using the FPU state
+ * currently.
+ *
+ * This flag is used:
+ *
+ *   - by IRQ context code to potentially use the FPU
+ * if it's unused.
+ *
+ *   - to debug kernel_fpu/altivec/vsx_begin()/end() correctness
+ */
+static DEFINE_PER_CPU(bool, in_kernel_fpu);
+
+static bool kernel_fpu_disabled(void)
+{
+   return this_cpu_read(in_kernel_fpu);
+}
+
+static bool interrupted_kernel_fpu_idle(void)
+{
+   return !kernel_fpu_disabled();
+}
+
 static void __giveup_fpu(struct task_struct *tsk)
 {
unsigned long msr;
@@ -230,7 +253,8 @@ void enable_kernel_fp(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_FP);
 
@@ -251,6 +275,15 @@ void enable_kernel_fp(void)
 }
 EXPORT_SYMBOL(enable_kernel_fp);
 
+void disable_kernel_fp(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, false);
+
+   msr_check_and_clear(MSR_FP);
+}
+EXPORT_SYMBOL(disable_kernel_fp);
+
 static int restore_fp(struct task_struct *tsk)
 {
if (tsk->thread.load_fp || tm_active_with_fp(tsk)) {
@@ -260,6 +293,37 @@ static int restore_fp(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+struct pt_regs *regs = get_irq_regs();
+
+return regs && user_mode(regs);
+}
+
+/*
+ * Can we use FPU in kernel mode with the
+ * whole "kernel_fpu/altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool may_use_simd(void)
+{
+return !in_interrupt() ||
+interrupted_user_mode() ||
+interrupted_kernel_fpu_idle();
+}
+EXPORT_SYMBOL(may_use_simd);
+
 #else
 static int restore_fp(struct task_struct *tsk) { return 0; }
 #endif /* CONFIG_PPC_FPU */
@@ -295,7 +359,8 @@ void enable_kernel_altivec(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_VEC);
 
@@ -316,6 +381,14 @@ void enable_kernel_altivec(void)
 }
 EXPORT_SYMBOL(enable_kernel_altivec);
 
+extern void disable_kernel_altivec(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu)

[RESEND v4 PATCH 1/2] [PowerPC] Add simd.h implementation

2019-05-18 Thread Shawn Landden 
Based off the x86 one.

WireGuard really wants to be able to do SIMD in interrupts,
so it can accelerate its in-bound path.

v4: allow using the may_use_simd symbol even when it always
returns false (via include guards)
Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 17 +
 arch/powerpc/kernel/process.c   | 30 ++
 2 files changed, 47 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..2fe26f258
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+#ifdef CONFIG_PPC_FPU
+extern bool may_use_simd(void);
+#else
+static inline bool may_use_simd(void)
+{
+   return false;
+}
+#endif
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index dd9e0d538..ef534831f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -345,6 +345,36 @@ static int restore_altivec(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+   struct pt_regs *regs = get_irq_regs();
+
+   return regs && user_mode(regs);
+}
+
+/*
+ * Can we use FPU in kernel mode with the
+ * whole "kernel_fpu/altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool may_use_simd(void)
+{
+   return !in_interrupt() ||
+   interrupted_user_mode();
+}
+EXPORT_SYMBOL(may_use_simd);
+
 #else
 #define loadvec(thr) 0
 static inline int restore_altivec(struct task_struct *tsk) { return 0; }
-- 
2.21.0.1020.gf2820cf01a

Re: Latest Git kernel: Section mismatch in reference from the variable start_here_multiplatform to the function .init.text:.early_setup()

2019-05-16 Thread Shawn Landden 
Hi

El mié., 15 may. 2019 5:17, Christophe Leroy 
escribió:

> Hi,
>
> Le 15/05/2019 à 12:09, Christian Zigotzky a écrit :
> > Hi All,
> >
> > I got the following error messages with the latest Git kernel today:
> >
> > GEN .version
> >CHK include/generated/compile.h
> >LD  vmlinux.o
> >MODPOST vmlinux.o
> > WARNING: vmlinux.o(.text+0x302a): Section mismatch in reference from the
> > variable start_here_multiplatform to the function
> .init.text:.early_setup()
> > The function start_here_multiplatform() references
> > the function __init .early_setup().
> > This is often because start_here_multiplatform lacks a __init
> > annotation or the annotation of .early_setup is wrong.
> >
> >MODINFO modules.builtin.modinfo
> >KSYM.tmp_kallsyms1.o
> >KSYM.tmp_kallsyms2.o
> >LD  vmlinux
> >SORTEX  vmlinux
> >SYSMAP  System.map
> >CHKHEAD vmlinux
> >
> > What does it mean?
>
The best first thing to do with these type of errors is to Google them. If
you see there are patches just assume somebody else is working on it. That
saves everybody time, because these things tend to get duplicate reports.

>
> I proposed a patch for it at https://patchwork.ozlabs.org/patch/1097845/
>
> Christophe
>
> >
> > Please find attached the kernel config.
> >
> > Thanks,
> > Christian
> >
>

Re: [v4 PATCH 1/2] [PowerPC] Add simd.h implementation

2019-05-15 Thread Shawn Landden 
On Wed, May 15, 2019 at 1:27 AM Christophe Leroy
 wrote:
> Could you please as usual list here the changes provided by each version
> to ease the review ?
A bunch of embarrassing stuff that caused it not to build on some
set-ups (the functions were under the wrong include guards), and I
added include guards on simd.h so that you can use may_use_simd() even
if you don't have the FPU enabled (ARM's simd.h does this).

[v4 PATCH 2/2] [PowerPC] Allow use of SIMD in interrupts from kernel code

2019-05-14 Thread Shawn Landden 
This second patch is separate because it could be wrong,
like I am not sure about how kernel thread migration works,
and it is even allowing simd in preemptible kernel code.

v4: fix build without CONFIG_AVX

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/switch_to.h |  15 +---
 arch/powerpc/kernel/process.c| 117 +++
 2 files changed, 88 insertions(+), 44 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h 
b/arch/powerpc/include/asm/switch_to.h
index 5b03d8a82..c79f7d24a 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -30,10 +30,7 @@ extern void enable_kernel_fp(void);
 extern void flush_fp_to_thread(struct task_struct *);
 extern void giveup_fpu(struct task_struct *);
 extern void save_fpu(struct task_struct *);
-static inline void disable_kernel_fp(void)
-{
-   msr_check_and_clear(MSR_FP);
-}
+extern void disable_kernel_fp(void);
 #else
 static inline void save_fpu(struct task_struct *t) { }
 static inline void flush_fp_to_thread(struct task_struct *t) { }
@@ -44,10 +41,7 @@ extern void enable_kernel_altivec(void);
 extern void flush_altivec_to_thread(struct task_struct *);
 extern void giveup_altivec(struct task_struct *);
 extern void save_altivec(struct task_struct *);
-static inline void disable_kernel_altivec(void)
-{
-   msr_check_and_clear(MSR_VEC);
-}
+extern void disable_kernel_altivec(void);
 #else
 static inline void save_altivec(struct task_struct *t) { }
 static inline void __giveup_altivec(struct task_struct *t) { }
@@ -56,10 +50,7 @@ static inline void __giveup_altivec(struct task_struct *t) { 
}
 #ifdef CONFIG_VSX
 extern void enable_kernel_vsx(void);
 extern void flush_vsx_to_thread(struct task_struct *);
-static inline void disable_kernel_vsx(void)
-{
-   msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
-}
+extern void disable_kernel_vsx(void);
 #endif
 
 #ifdef CONFIG_SPE
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index ef534831f..0136fd132 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -170,6 +170,29 @@ void __msr_check_and_clear(unsigned long bits)
 EXPORT_SYMBOL(__msr_check_and_clear);
 
 #ifdef CONFIG_PPC_FPU
+/*
+ * Track whether the kernel is using the FPU state
+ * currently.
+ *
+ * This flag is used:
+ *
+ *   - by IRQ context code to potentially use the FPU
+ * if it's unused.
+ *
+ *   - to debug kernel_fpu/altivec/vsx_begin()/end() correctness
+ */
+static DEFINE_PER_CPU(bool, in_kernel_fpu);
+
+static bool kernel_fpu_disabled(void)
+{
+   return this_cpu_read(in_kernel_fpu);
+}
+
+static bool interrupted_kernel_fpu_idle(void)
+{
+   return !kernel_fpu_disabled();
+}
+
 static void __giveup_fpu(struct task_struct *tsk)
 {
unsigned long msr;
@@ -230,7 +253,8 @@ void enable_kernel_fp(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_FP);
 
@@ -251,6 +275,15 @@ void enable_kernel_fp(void)
 }
 EXPORT_SYMBOL(enable_kernel_fp);
 
+void disable_kernel_fp(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, false);
+
+   msr_check_and_clear(MSR_FP);
+}
+EXPORT_SYMBOL(disable_kernel_fp);
+
 static int restore_fp(struct task_struct *tsk)
 {
if (tsk->thread.load_fp || tm_active_with_fp(tsk)) {
@@ -260,6 +293,37 @@ static int restore_fp(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+struct pt_regs *regs = get_irq_regs();
+
+return regs && user_mode(regs);
+}
+
+/*
+ * Can we use FPU in kernel mode with the
+ * whole "kernel_fpu/altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool may_use_simd(void)
+{
+return !in_interrupt() ||
+interrupted_user_mode() ||
+interrupted_kernel_fpu_idle();
+}
+EXPORT_SYMBOL(may_use_simd);
+
 #else
 static int restore_fp(struct task_struct *tsk) { return 0; }
 #endif /* CONFIG_PPC_FPU */
@@ -295,7 +359,8 @@ void enable_kernel_altivec(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_VEC);
 
@@ -316,6 +381,14 @@ void enable_kernel_altivec(void)
 }
 EXPORT_SYMBOL(enable_kernel_altivec);
 
+extern void disable_kernel_altivec(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_k

[v4 PATCH 1/2] [PowerPC] Add simd.h implementation

2019-05-14 Thread Shawn Landden 
Based off the x86 one.

WireGuard really wants to be able to do SIMD in interrupts,
so it can accelerate its in-bound path.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 17 +
 arch/powerpc/kernel/process.c   | 30 ++
 2 files changed, 47 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..2fe26f258
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+#ifdef CONFIG_PPC_FPU
+extern bool may_use_simd(void);
+#else
+static inline bool may_use_simd(void)
+{
+   return false;
+}
+#endif
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index dd9e0d538..ef534831f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -345,6 +345,36 @@ static int restore_altivec(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+   struct pt_regs *regs = get_irq_regs();
+
+   return regs && user_mode(regs);
+}
+
+/*
+ * Can we use FPU in kernel mode with the
+ * whole "kernel_fpu/altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool may_use_simd(void)
+{
+   return !in_interrupt() ||
+   interrupted_user_mode();
+}
+EXPORT_SYMBOL(may_use_simd);
+
 #else
 #define loadvec(thr) 0
 static inline int restore_altivec(struct task_struct *tsk) { return 0; }
-- 
2.21.0.1020.gf2820cf01a

[PATCH 1/2] [PowerPC] Add simd.h implementation

2019-05-14 Thread Shawn Landden 
Based off the x86 one.

WireGuard really wants to be able to do SIMD in interrupts,
so it can accelerate its in-bound path.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 17 +
 arch/powerpc/kernel/process.c   | 30 ++
 2 files changed, 47 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..2fe26f258
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+#ifdef CONFIG_PPC_FPU
+extern bool may_use_simd(void);
+#else
+static inline bool may_use_simd(void)
+{
+   return false;
+}
+#endif
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index dd9e0d538..ef534831f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -345,6 +345,36 @@ static int restore_altivec(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+   struct pt_regs *regs = get_irq_regs();
+
+   return regs && user_mode(regs);
+}
+
+/*
+ * Can we use FPU in kernel mode with the
+ * whole "kernel_fpu/altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool may_use_simd(void)
+{
+   return !in_interrupt() ||
+   interrupted_user_mode();
+}
+EXPORT_SYMBOL(may_use_simd);
+
 #else
 #define loadvec(thr) 0
 static inline int restore_altivec(struct task_struct *tsk) { return 0; }
-- 
2.21.0.1020.gf2820cf01a

Re: [PATCH] powerpc: Allow may_use_simd() to function as feature detection

2019-05-14 Thread Shawn Landden 
Wireguard is not in the kernel (yet) and uses these symbols. (It is
IS_ENABLED so doesn't need it, but I think it is reasonable) I think these
enable/disable symbols should not be marked GPL-only.

El mar., 14 may. 2019 13:06, Segher Boessenkool 
escribió:

> On Tue, May 14, 2019 at 09:49:18AM -0300, Shawn Landden wrote:
> > ARM does this, so we might as well too.
> > I am a bit confused however as CONFIG_ALTIVEC does not select
> > CONFIG_PPC_FPU. Would you ever have altivec without a fpu?
>
> There is no hardware like that, none supported anyway.  It does not make
> very much sense, and it cannot happen with VSX, so no hardware like it
> will ever show up most likely.
>
> It is much simpler to just make a Kconfig dependency (or a select) between
> the symbols than to have to add code like this patch.
>


>
> Segher
>

Re: [PATCH 1/2] [PowerPC] Add simd.h implementation

2019-05-14 Thread Shawn Landden 
On Tue, May 14, 2019 at 12:43 AM Benjamin Herrenschmidt
 wrote:
>
> On Mon, 2019-05-13 at 22:44 -0300, Shawn Landden wrote:
> > +
> > +/*
> > + * Were we in user mode when we were
> > + * interrupted?
> > + *
> > + * Doing kernel_altivec/vsx_begin/end() is ok if we are running
> > + * in an interrupt context from user mode - we'll just
> > + * save the FPU state as required.
> > + */
> > +static bool interrupted_user_mode(void)
> > +{
> > +   struct pt_regs *regs = get_irq_regs();
> > +
> > +   return regs && user_mode(regs);
> > +}
> > +
>
> That's interesting  it *could* work but we'll have to careful audit
> the code to make sure thats ok.
>
> We probably also want to handle the case where the CPU is in the idle
> loop.
That is the next patch. It is best to split these up because then git
bisect works better, and these are higher-risk changes.
>
> Do we always save the user state when switching out these days ? If
> yes, then there's no "live" state to worry about...
>
> Cheers,
> Ben.
>
>

Re: [v2 2/2] [PowerPC] Allow use of SIMD in interrupts from kernel code

2019-05-14 Thread Shawn Landden 
On Tue, May 14, 2019 at 2:22 AM Russell Currey  wrote:
>
> On Mon, 2019-05-13 at 23:23 -0300, Shawn Landden wrote:
> > This second patch is separate because it could be wrong,
> > like I am not sure about how kernel thread migration works,
> > and it is even allowing simd in preemptible kernel code.
> >
> > Signed-off-by: Shawn Landden 
> > ---
>
> Hi Shawn,
>
> This patch doesn't build on 64-bit embedded (ppc64e_defconfig):
>
> arch/powerpc/kernel/process.c:194:13: error: 'interrupted_kernel_fpu_idle' 
> defined but not used [-Werror=unused-function]
>  static bool interrupted_kernel_fpu_idle(void)
>  ^~~
Thanks for noticing this. I knew what I needed to do, and this was
just sloppiness on my end.
>
> and otherwise adds two sparse warnings:
>
> +arch/powerpc/kernel/process.c:356:13: warning: function 
> 'disable_kernel_altivec' with external linkage has definition
> +arch/powerpc/kernel/process.c:416:6: warning: symbol 'may_use_simd' was not 
> declared. Should it be static?
This is the same problem as above.
>
> There's also some style issues (spaces instead of tabs).
Yes, I have to be careful using nano on a VPS.

New patch coming in 1 sec.
>
> Reported by snowpatch (see https://patchwork.ozlabs.org/patch/1099181/)
>
> - Russell
>

[v3 2/2] [PowerPC] Allow use of SIMD in interrupts from kernel code

2019-05-14 Thread Shawn Landden 
This second patch is separate because it could be wrong,
like I am not sure about how kernel thread migration works,
and it is even allowing simd in preemptible kernel code.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/switch_to.h | 15 ++-
 arch/powerpc/kernel/process.c| 60 ++--
 2 files changed, 59 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h 
b/arch/powerpc/include/asm/switch_to.h
index 5b03d8a82..c79f7d24a 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -30,10 +30,7 @@ extern void enable_kernel_fp(void);
 extern void flush_fp_to_thread(struct task_struct *);
 extern void giveup_fpu(struct task_struct *);
 extern void save_fpu(struct task_struct *);
-static inline void disable_kernel_fp(void)
-{
-   msr_check_and_clear(MSR_FP);
-}
+extern void disable_kernel_fp(void);
 #else
 static inline void save_fpu(struct task_struct *t) { }
 static inline void flush_fp_to_thread(struct task_struct *t) { }
@@ -44,10 +41,7 @@ extern void enable_kernel_altivec(void);
 extern void flush_altivec_to_thread(struct task_struct *);
 extern void giveup_altivec(struct task_struct *);
 extern void save_altivec(struct task_struct *);
-static inline void disable_kernel_altivec(void)
-{
-   msr_check_and_clear(MSR_VEC);
-}
+extern void disable_kernel_altivec(void);
 #else
 static inline void save_altivec(struct task_struct *t) { }
 static inline void __giveup_altivec(struct task_struct *t) { }
@@ -56,10 +50,7 @@ static inline void __giveup_altivec(struct task_struct *t) { 
}
 #ifdef CONFIG_VSX
 extern void enable_kernel_vsx(void);
 extern void flush_vsx_to_thread(struct task_struct *);
-static inline void disable_kernel_vsx(void)
-{
-   msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
-}
+extern void disable_kernel_vsx(void);
 #endif
 
 #ifdef CONFIG_SPE
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index ef534831f..4ffc9c664 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -170,6 +170,29 @@ void __msr_check_and_clear(unsigned long bits)
 EXPORT_SYMBOL(__msr_check_and_clear);
 
 #ifdef CONFIG_PPC_FPU
+/*
+ * Track whether the kernel is using the FPU state
+ * currently.
+ *
+ * This flag is used:
+ *
+ *   - by IRQ context code to potentially use the FPU
+ * if it's unused.
+ *
+ *   - to debug kernel_fpu/altivec/vsx_begin()/end() correctness
+ */
+static DEFINE_PER_CPU(bool, in_kernel_fpu);
+
+static bool kernel_fpu_disabled(void)
+{
+   return this_cpu_read(in_kernel_fpu);
+}
+
+static bool interrupted_kernel_fpu_idle(void)
+{
+   return !kernel_fpu_disabled();
+}
+
 static void __giveup_fpu(struct task_struct *tsk)
 {
unsigned long msr;
@@ -230,7 +253,8 @@ void enable_kernel_fp(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_FP);
 
@@ -251,6 +275,15 @@ void enable_kernel_fp(void)
 }
 EXPORT_SYMBOL(enable_kernel_fp);
 
+void disable_kernel_fp(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, false);
+
+   msr_check_and_clear(MSR_FP);
+}
+EXPORT_SYMBOL(disable_kernel_fp);
+
 static int restore_fp(struct task_struct *tsk)
 {
if (tsk->thread.load_fp || tm_active_with_fp(tsk)) {
@@ -295,7 +328,8 @@ void enable_kernel_altivec(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_VEC);
 
@@ -316,6 +350,14 @@ void enable_kernel_altivec(void)
 }
 EXPORT_SYMBOL(enable_kernel_altivec);
 
+extern void disable_kernel_altivec(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, false);
+   msr_check_and_clear(MSR_VEC);
+}
+EXPORT_SYMBOL(disable_kernel_altivec);
+
 /*
  * Make sure the VMX/Altivec register state in the
  * the thread_struct is up to date for task tsk.
@@ -371,7 +413,8 @@ static bool interrupted_user_mode(void)
 bool may_use_simd(void)
 {
return !in_interrupt() ||
-   interrupted_user_mode();
+   interrupted_user_mode() ||
+   interrupted_kernel_fpu_idle();
 }
 EXPORT_SYMBOL(may_use_simd);
 
@@ -411,7 +454,8 @@ void enable_kernel_vsx(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
 
@@ -433,6 +477,14 @@ void enable_kernel_vsx(void)
 }
 EXPORT_SYMBOL(enable_kernel_vsx);
 
+void disable_kernel_vsx(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, false);
+   msr_check_and_clear(MSR_FP|MSR_VEC

[v3 1/2] [PowerPC] Add simd.h implementation

2019-05-14 Thread Shawn Landden 
Based off the x86 one.

WireGuard really wants to be able to do SIMD in interrupts,
so it can accelerate its in-bound path.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 17 +
 arch/powerpc/kernel/process.c   | 30 ++
 2 files changed, 47 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..2fe26f258
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+#ifdef CONFIG_PPC_FPU
+extern bool may_use_simd(void);
+#else
+static inline bool may_use_simd(void)
+{
+   return false;
+}
+#endif
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index dd9e0d538..ef534831f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -345,6 +345,36 @@ static int restore_altivec(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+   struct pt_regs *regs = get_irq_regs();
+
+   return regs && user_mode(regs);
+}
+
+/*
+ * Can we use FPU in kernel mode with the
+ * whole "kernel_fpu/altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool may_use_simd(void)
+{
+   return !in_interrupt() ||
+   interrupted_user_mode();
+}
+EXPORT_SYMBOL(may_use_simd);
+
 #else
 #define loadvec(thr) 0
 static inline int restore_altivec(struct task_struct *tsk) { return 0; }
-- 
2.21.0.1020.gf2820cf01a

[PATCH] powerpc: Allow may_use_simd() to function as feature detection

2019-05-14 Thread Shawn Landden 
ARM does this, so we might as well too.
I am a bit confused however as CONFIG_ALTIVEC does not select
CONFIG_PPC_FPU. Would you ever have altivec without a fpu?

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 7 +++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
index 9b066d633..2fe26f258 100644
--- a/arch/powerpc/include/asm/simd.h
+++ b/arch/powerpc/include/asm/simd.h
@@ -7,4 +7,11 @@
  * It's always ok in process context (ie "not interrupt")
  * but it is sometimes ok even from an irq.
  */
+#ifdef CONFIG_PPC_FPU
 extern bool may_use_simd(void);
+#else
+static inline bool may_use_simd(void)
+{
+   return false;
+}
+#endif
-- 
2.21.0.1020.gf2820cf01a

[v2 2/2] [PowerPC] Allow use of SIMD in interrupts from kernel code

2019-05-13 Thread Shawn Landden 
This second patch is separate because it could be wrong,
like I am not sure about how kernel thread migration works,
and it is even allowing simd in preemptible kernel code.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/switch_to.h | 15 ++-
 arch/powerpc/kernel/process.c| 60 ++--
 2 files changed, 59 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h 
b/arch/powerpc/include/asm/switch_to.h
index 5b03d8a82..c79f7d24a 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -30,10 +30,7 @@ extern void enable_kernel_fp(void);
 extern void flush_fp_to_thread(struct task_struct *);
 extern void giveup_fpu(struct task_struct *);
 extern void save_fpu(struct task_struct *);
-static inline void disable_kernel_fp(void)
-{
-   msr_check_and_clear(MSR_FP);
-}
+extern void disable_kernel_fp(void);
 #else
 static inline void save_fpu(struct task_struct *t) { }
 static inline void flush_fp_to_thread(struct task_struct *t) { }
@@ -44,10 +41,7 @@ extern void enable_kernel_altivec(void);
 extern void flush_altivec_to_thread(struct task_struct *);
 extern void giveup_altivec(struct task_struct *);
 extern void save_altivec(struct task_struct *);
-static inline void disable_kernel_altivec(void)
-{
-   msr_check_and_clear(MSR_VEC);
-}
+extern void disable_kernel_altivec(void);
 #else
 static inline void save_altivec(struct task_struct *t) { }
 static inline void __giveup_altivec(struct task_struct *t) { }
@@ -56,10 +50,7 @@ static inline void __giveup_altivec(struct task_struct *t) { 
}
 #ifdef CONFIG_VSX
 extern void enable_kernel_vsx(void);
 extern void flush_vsx_to_thread(struct task_struct *);
-static inline void disable_kernel_vsx(void)
-{
-   msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
-}
+extern void disable_kernel_vsx(void);
 #endif
 
 #ifdef CONFIG_SPE
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index ef534831f..d15f2cb51 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -170,6 +170,29 @@ void __msr_check_and_clear(unsigned long bits)
 EXPORT_SYMBOL(__msr_check_and_clear);
 
 #ifdef CONFIG_PPC_FPU
+/*
+ * Track whether the kernel is using the FPU state
+ * currently.
+ *
+ * This flag is used:
+ *
+ *   - by IRQ context code to potentially use the FPU
+ * if it's unused.
+ *
+ *   - to debug kernel_fpu/altivec/vsx_begin()/end() correctness
+ */
+static DEFINE_PER_CPU(bool, in_kernel_fpu);
+
+static bool kernel_fpu_disabled(void)
+{
+return this_cpu_read(in_kernel_fpu);
+}
+
+static bool interrupted_kernel_fpu_idle(void)
+{
+return !kernel_fpu_disabled();
+}
+
 static void __giveup_fpu(struct task_struct *tsk)
 {
unsigned long msr;
@@ -230,7 +253,8 @@ void enable_kernel_fp(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_FP);
 
@@ -251,6 +275,15 @@ void enable_kernel_fp(void)
 }
 EXPORT_SYMBOL(enable_kernel_fp);
 
+void disable_kernel_fp(void)
+{
+WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+this_cpu_write(in_kernel_fpu, false);
+
+msr_check_and_clear(MSR_FP);
+}
+EXPORT_SYMBOL(disable_kernel_fp);
+
 static int restore_fp(struct task_struct *tsk)
 {
if (tsk->thread.load_fp || tm_active_with_fp(tsk)) {
@@ -295,7 +328,8 @@ void enable_kernel_altivec(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_VEC);
 
@@ -316,6 +350,14 @@ void enable_kernel_altivec(void)
 }
 EXPORT_SYMBOL(enable_kernel_altivec);
 
+extern void disable_kernel_altivec(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, false);
+   msr_check_and_clear(MSR_VEC);
+}
+EXPORT_SYMBOL(disable_kernel_altivec);
+
 /*
  * Make sure the VMX/Altivec register state in the
  * the thread_struct is up to date for task tsk.
@@ -371,7 +413,8 @@ static bool interrupted_user_mode(void)
 bool may_use_simd(void)
 {
return !in_interrupt() ||
-   interrupted_user_mode();
+   interrupted_user_mode() ||
+   interrupted_kernel_fpu_idle();
 }
 EXPORT_SYMBOL(may_use_simd);
 
@@ -411,7 +454,8 @@ void enable_kernel_vsx(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, true);
 
cpumsr = msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
 
@@ -433,6 +477,14 @@ void enable_kernel_vsx(void)
 }
 EXPORT_SYMBOL(enable_kernel_vsx);
 
+void disable_kernel_vsx(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_fpu));
+   this_cpu_write(in_kernel_fpu, false);
+   msr_check_and_clear(MSR_FP

[v2 1/2] [PowerPC] Add simd.h implementation

2019-05-13 Thread Shawn Landden 
Based off the x86 one.

WireGuard really wants to be able to do SIMD in interrupts,
so it can accelerate its in-bound path.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 10 ++
 arch/powerpc/kernel/process.c   | 30 ++
 2 files changed, 40 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..9b066d633
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+extern bool may_use_simd(void);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index dd9e0d538..ef534831f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -345,6 +345,36 @@ static int restore_altivec(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+   struct pt_regs *regs = get_irq_regs();
+
+   return regs && user_mode(regs);
+}
+
+/*
+ * Can we use FPU in kernel mode with the
+ * whole "kernel_fpu/altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool may_use_simd(void)
+{
+   return !in_interrupt() ||
+   interrupted_user_mode();
+}
+EXPORT_SYMBOL(may_use_simd);
+
 #else
 #define loadvec(thr) 0
 static inline int restore_altivec(struct task_struct *tsk) { return 0; }
-- 
2.21.0.1020.gf2820cf01a

[PATCH 2/2] [PowerPC] Allow use of SIMD in interrupts from kernel code

2019-05-13 Thread Shawn Landden 
This second patch is separate because it could be wrong,
like I am not sure about how kernel thread migration works,
and it is even allowing simd in preemptible kernel code.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h  |  8 +
 arch/powerpc/include/asm/switch_to.h | 10 ++
 arch/powerpc/kernel/process.c| 50 ++--
 3 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
index 2c02ad531..7b582b07e 100644
--- a/arch/powerpc/include/asm/simd.h
+++ b/arch/powerpc/include/asm/simd.h
@@ -7,7 +7,15 @@
  * It's always ok in process context (ie "not interrupt")
  * but it is sometimes ok even from an irq.
  */
+#ifdef CONFIG_ALTIVEC
+extern bool irq_simd_usable(void);
 static __must_check inline bool may_use_simd(void)
 {
return irq_simd_usable();
 }
+#else
+static inline bool may_use_simd(void)
+{
+   return false;
+}
+#endif
diff --git a/arch/powerpc/include/asm/switch_to.h 
b/arch/powerpc/include/asm/switch_to.h
index 5b03d8a82..537998997 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -44,10 +44,7 @@ extern void enable_kernel_altivec(void);
 extern void flush_altivec_to_thread(struct task_struct *);
 extern void giveup_altivec(struct task_struct *);
 extern void save_altivec(struct task_struct *);
-static inline void disable_kernel_altivec(void)
-{
-   msr_check_and_clear(MSR_VEC);
-}
+extern void disable_kernel_altivec(void);
 #else
 static inline void save_altivec(struct task_struct *t) { }
 static inline void __giveup_altivec(struct task_struct *t) { }
@@ -56,10 +53,7 @@ static inline void __giveup_altivec(struct task_struct *t) { 
}
 #ifdef CONFIG_VSX
 extern void enable_kernel_vsx(void);
 extern void flush_vsx_to_thread(struct task_struct *);
-static inline void disable_kernel_vsx(void)
-{
-   msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
-}
+extern void disable_kernel_vsx(void);
 #endif
 
 #ifdef CONFIG_SPE
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index e436d708a..41a0ab500 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -267,6 +267,29 @@ static int restore_fp(struct task_struct *tsk) { return 0; 
}
 #ifdef CONFIG_ALTIVEC
 #define loadvec(thr) ((thr).load_vec)
 
+/*
+ * Track whether the kernel is using the SIMD state
+ * currently.
+ *
+ * This flag is used:
+ *
+ *   - by IRQ context code to potentially use the FPU
+ * if it's unused.
+ *
+ *   - to debug kernel_altivec/vsx_begin()/end() correctness
+ */
+static DEFINE_PER_CPU(bool, in_kernel_simd);
+
+static bool kernel_simd_disabled(void)
+{
+   return this_cpu_read(in_kernel_simd);
+}
+
+static bool interrupted_kernel_simd_idle(void)
+{
+   return !kernel_simd_disabled();
+}
+
 static void __giveup_altivec(struct task_struct *tsk)
 {
unsigned long msr;
@@ -295,7 +318,9 @@ void enable_kernel_altivec(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_simd));
+   this_cpu_write(in_kernel_simd, true);
 
cpumsr = msr_check_and_set(MSR_VEC);
 
@@ -316,6 +341,14 @@ void enable_kernel_altivec(void)
 }
 EXPORT_SYMBOL(enable_kernel_altivec);
 
+extern void disable_kernel_altivec(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_simd));
+   this_cpu_write(in_kernel_simd, false);
+   msr_check_and_clear(MSR_VEC);
+}
+EXPORT_SYMBOL(disable_kernel_altivec);
+
 /*
  * Make sure the VMX/Altivec register state in the
  * the thread_struct is up to date for task tsk.
@@ -371,7 +404,8 @@ static bool interrupted_user_mode(void)
 bool irq_simd_usable(void)
 {
return !in_interrupt() ||
-   interrupted_user_mode();
+   interrupted_user_mode() ||
+   interrupted_kernel_simd_idle();
 }
 EXPORT_SYMBOL(irq_simd_usable);
 
@@ -411,7 +445,9 @@ void enable_kernel_vsx(void)
 {
unsigned long cpumsr;
 
-   WARN_ON(preemptible());
+   WARN_ON_ONCE(preemptible());
+   WARN_ON_ONCE(this_cpu_read(in_kernel_simd));
+   this_cpu_write(in_kernel_simd, true);
 
cpumsr = msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
 
@@ -433,6 +469,14 @@ void enable_kernel_vsx(void)
 }
 EXPORT_SYMBOL(enable_kernel_vsx);
 
+void disable_kernel_vsx(void)
+{
+   WARN_ON_ONCE(!this_cpu_read(in_kernel_simd));
+   this_cpu_write(in_kernel_simd, false);
+   msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
+}
+EXPORT_SYMBOL(disable_kernel_vsx);
+
 void flush_vsx_to_thread(struct task_struct *tsk)
 {
if (tsk->thread.regs) {
-- 
2.21.0.1020.gf2820cf01a

[PATCH 1/2] [PowerPC] Add simd.h implementation

2019-05-13 Thread Shawn Landden 
Based off the x86 one.

WireGuard really wants to be able to do SIMD in interrupts,
so it can accelerate its in-bound path.

Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 13 +
 arch/powerpc/kernel/process.c   | 30 ++
 2 files changed, 43 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..2c02ad531
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+static __must_check inline bool may_use_simd(void)
+{
+   return irq_simd_usable();
+}
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index dd9e0d538..e436d708a 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -345,6 +345,36 @@ static int restore_altivec(struct task_struct *tsk)
}
return 0;
 }
+
+/*
+ * Were we in user mode when we were
+ * interrupted?
+ *
+ * Doing kernel_altivec/vsx_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static bool interrupted_user_mode(void)
+{
+   struct pt_regs *regs = get_irq_regs();
+
+   return regs && user_mode(regs);
+}
+
+/*
+ * Can we use SIMD in kernel mode with the
+ * whole "kernel_altivec/vsx_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+bool irq_simd_usable(void)
+{
+   return !in_interrupt() ||
+   interrupted_user_mode();
+}
+EXPORT_SYMBOL(irq_simd_usable);
+
 #else
 #define loadvec(thr) 0
 static inline int restore_altivec(struct task_struct *tsk) { return 0; }
-- 
2.21.0.1020.gf2820cf01a

[PATCH] powerpc: add simd.h implementation specific to PowerPC

2019-05-12 Thread Shawn Landden 
It is safe to do SIMD in an interrupt on PowerPC.
Only disable when there is no SIMD available
(and this is a static branch).

Tested and works with the WireGuard (Zinc) patch I wrote that needs this.
Also improves performance of the crypto subsystem that checks this.

Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=203571
Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 15 +++
 1 file changed, 15 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..b3fecb95a
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#include 
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * As documented in Chapter 6.2.1 Machine Status Save/Restore Registers
+ * of Power ISA (2.07 and 3.0), all registers are saved/restored in an 
interrupt.
+ */
+static inline bool may_use_simd(void)
+{
+   return !cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE);
+}
-- 
2.21.0.1020.gf2820cf01a

[PATCH RESEND] powerpc: add simd.h implementation specific to PowerPC

2019-05-12 Thread Shawn Landden 
It is safe to do SIMD in an interrupt on PowerPC.
Only disable when there is no SIMD available
(and this is a static branch).

Tested and works with the WireGuard (Zinc) patch I wrote that needs this.
Also improves performance of the crypto subsystem that checks this.

Re-sending because this linuxppc-dev didn't seem to accept it.

Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=203571
Signed-off-by: Shawn Landden 
---
 arch/powerpc/include/asm/simd.h | 15 +++
 1 file changed, 15 insertions(+)
 create mode 100644 arch/powerpc/include/asm/simd.h

diff --git a/arch/powerpc/include/asm/simd.h b/arch/powerpc/include/asm/simd.h
new file mode 100644
index 0..b3fecb95a
--- /dev/null
+++ b/arch/powerpc/include/asm/simd.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#include 
+
+/*
+ * may_use_simd - whether it is allowable at this time to issue SIMD
+ *instructions or access the SIMD register file
+ *
+ * As documented in Chapter 6.2.1 Machine Status Save/Restore Registers
+ * of Power ISA (2.07 and 3.0), all registers are saved/restored in an 
interrupt.
+ */
+static inline bool may_use_simd(void)
+{
+   return !cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE);
+}
-- 
2.21.0.1020.gf2820cf01a