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From: Cyril Bur <cyrilbur@gmail.com>
To: linuxppc-dev@ozlabs.org
Cc: mikey@neuling.org, anton@samba.org
Subject: [PATCH v4 9/9] powerpc: Add the ability to save VSX without giving it up
Date: Mon, 15 Feb 2016 16:07:30 +1100	[thread overview]
Message-ID: <1455512850-2543-10-git-send-email-cyrilbur@gmail.com> (raw)
In-Reply-To: <1455512850-2543-1-git-send-email-cyrilbur@gmail.com>

This patch adds the ability to be able to save the VSX registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.

This patch builds on a previous optimisation for the FPU and VEC registers
in the thread copy path to avoid a possibly pointless reload of VSX state.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
---
 arch/powerpc/include/asm/switch_to.h |  4 ----
 arch/powerpc/kernel/ppc_ksyms.c      |  4 ----
 arch/powerpc/kernel/process.c        | 42 +++++++++++++++++++++++++-----------
 arch/powerpc/kernel/vector.S         | 17 ---------------
 4 files changed, 30 insertions(+), 37 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 9028822..17c8380 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -56,14 +56,10 @@ 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 *);
-extern void giveup_vsx(struct task_struct *);
-extern void __giveup_vsx(struct task_struct *);
 static inline void disable_kernel_vsx(void)
 {
 	msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
 }
-#else
-static inline void __giveup_vsx(struct task_struct *t) { }
 #endif
 
 #ifdef CONFIG_SPE
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index 41e1607..ef7024da 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -28,10 +28,6 @@ EXPORT_SYMBOL(load_vr_state);
 EXPORT_SYMBOL(store_vr_state);
 #endif
 
-#ifdef CONFIG_VSX
-EXPORT_SYMBOL_GPL(__giveup_vsx);
-#endif
-
 #ifdef CONFIG_EPAPR_PARAVIRT
 EXPORT_SYMBOL(epapr_hypercall_start);
 #endif
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 14c09d2..d7a9df5 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -280,19 +280,31 @@ static inline int restore_altivec(struct task_struct *tsk) { return 0; }
 #endif /* CONFIG_ALTIVEC */
 
 #ifdef CONFIG_VSX
-void giveup_vsx(struct task_struct *tsk)
+static void __giveup_vsx(struct task_struct *tsk)
 {
-	check_if_tm_restore_required(tsk);
-
-	msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
 	if (tsk->thread.regs->msr & MSR_FP)
 		__giveup_fpu(tsk);
 	if (tsk->thread.regs->msr & MSR_VEC)
 		__giveup_altivec(tsk);
+	tsk->thread.regs->msr &= ~MSR_VSX;
+}
+
+static void giveup_vsx(struct task_struct *tsk)
+{
+	check_if_tm_restore_required(tsk);
+
+	msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
 	__giveup_vsx(tsk);
 	msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
 }
-EXPORT_SYMBOL(giveup_vsx);
+
+static void save_vsx(struct task_struct *tsk)
+{
+	if (tsk->thread.regs->msr & MSR_FP)
+		save_fpu(tsk);
+	if (tsk->thread.regs->msr & MSR_VEC)
+		save_altivec(tsk);
+}
 
 void enable_kernel_vsx(void)
 {
@@ -335,6 +347,7 @@ static int restore_vsx(struct task_struct *tsk)
 }
 #else
 static inline int restore_vsx(struct task_struct *tsk) { return 0; }
+static inline void save_vsx(struct task_struct *tsk) { }
 #endif /* CONFIG_VSX */
 
 #ifdef CONFIG_SPE
@@ -478,14 +491,19 @@ void save_all(struct task_struct *tsk)
 
 	msr_check_and_set(msr_all_available);
 
-	if (usermsr & MSR_FP)
-		save_fpu(tsk);
-
-	if (usermsr & MSR_VEC)
-		save_altivec(tsk);
+	/*
+	 * Saving the way the register space is in hardware, save_vsx boils
+	 * down to a save_fpu() and save_altivec()
+	 */
+	if (usermsr & MSR_VSX) {
+		save_vsx(tsk);
+	} else {
+		if (usermsr & MSR_FP)
+			save_fpu(tsk);
 
-	if (usermsr & MSR_VSX)
-		__giveup_vsx(tsk);
+		if (usermsr & MSR_VEC)
+			save_altivec(tsk);
+	}
 
 	if (usermsr & MSR_SPE)
 		__giveup_spe(tsk);
diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index 51b0c17..1c2e7a3 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -151,23 +151,6 @@ _GLOBAL(load_up_vsx)
 	std	r12,_MSR(r1)
 	b	fast_exception_return
 
-/*
- * __giveup_vsx(tsk)
- * Disable VSX for the task given as the argument.
- * Does NOT save vsx registers.
- */
-_GLOBAL(__giveup_vsx)
-	addi	r3,r3,THREAD		/* want THREAD of task */
-	ld	r5,PT_REGS(r3)
-	cmpdi	0,r5,0
-	beq	1f
-	ld	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
-	lis	r3,MSR_VSX@h
-	andc	r4,r4,r3		/* disable VSX for previous task */
-	std	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
-1:
-	blr
-
 #endif /* CONFIG_VSX */
 
 
-- 
2.7.1

      parent reply	other threads:[~2016-02-15  5:09 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-15  5:07 [PATCH v4 0/9] FP/VEC/VSX switching optimisations Cyril Bur
2016-02-15  5:07 ` [PATCH v4 1/9] selftests/powerpc: Test the preservation of FPU and VMX regs across syscall Cyril Bur
2016-02-15 16:59   ` Naveen N. Rao
2016-02-16  0:06     ` Cyril Bur
2016-02-16  5:02       ` Naveen N. Rao
2016-02-16  5:32       ` Michael Ellerman
2016-02-15  5:07 ` [PATCH v4 2/9] selftests/powerpc: Test preservation of FPU and VMX regs across preemption Cyril Bur
2016-02-15  5:07 ` [PATCH v4 3/9] selftests/powerpc: Test FPU and VMX regs in signal ucontext Cyril Bur
2016-02-15  5:07 ` [PATCH v4 4/9] powerpc: Explicitly disable math features when copying thread Cyril Bur
2016-02-15  5:07 ` [PATCH v4 5/9] powerpc: Restore FPU/VEC/VSX if previously used Cyril Bur
2016-02-15  5:07 ` [PATCH v4 6/9] powerpc: Prepare for splitting giveup_{fpu, altivec, vsx} in two Cyril Bur
2016-02-15  5:07 ` [PATCH v4 7/9] powerpc: Add the ability to save FPU without giving it up Cyril Bur
2016-02-15  5:07 ` [PATCH v4 8/9] powerpc: Add the ability to save Altivec " Cyril Bur
2016-02-15  5:07 ` Cyril Bur [this message]

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