[PATCH 0/4] powerpc: several cleanup patches for the FPU

[PATCH 0/4] powerpc: several cleanup patches for the FPU

[Kevin Hao]

All these patches passed the build test for the following configurations:
	ppc40x_defconfig
        ppc64e_defconfig
        ppc64_defconfig
	mpc85xx_defconfig
	mpc85xx_smp_defconfig
        corenet32_smp_defconfig
        corenet64_smp_defconfig
        ppc44x_defconfig
	mpc885_ads_defconfig
        pseries_defconfig

Also passed the boot test on a t4240qds board.

Kevin Hao (4):
  powerpc: remove the unused function disable_kernel_fp()
  powerpc: remove the redundant flush_fp_to_thread() in
    setup_sigcontext()
  powerpc: make flush_fp_to_thread() nop when CONFIG_PPC_FPU is disabled
  powerpc: remove the empty giveup_fpu() function on 32bit kernel

 arch/powerpc/include/asm/switch_to.h | 11 ++++++++---
 arch/powerpc/kernel/head_40x.S       |  8 --------
 arch/powerpc/kernel/head_44x.S       | 10 ----------
 arch/powerpc/kernel/head_8xx.S       |  4 ----
 arch/powerpc/kernel/head_fsl_booke.S | 10 ----------
 arch/powerpc/kernel/misc_64.S        | 13 -------------
 arch/powerpc/kernel/ppc_ksyms.c      |  2 ++
 arch/powerpc/kernel/process.c        |  2 ++
 arch/powerpc/kernel/signal_64.c      |  2 --
 arch/powerpc/math-emu/math.c         |  3 +--
 10 files changed, 13 insertions(+), 52 deletions(-)

-- 
1.8.1.4

[PATCH 1/4] powerpc: remove the unused function disable_kernel_fp()

[Kevin Hao]

The only using of function disable_kernel_fp() was already dropped
in the commit 5daf9071 (powerpc: merge align.c).

Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
 arch/powerpc/include/asm/switch_to.h |  1 -
 arch/powerpc/kernel/misc_64.S        | 13 -------------
 2 files changed, 14 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 49a13e0..33e1cd8 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -18,7 +18,6 @@ extern struct task_struct *_switch(struct thread_struct *prev,
 
 extern void giveup_fpu(struct task_struct *);
 extern void load_up_fpu(void);
-extern void disable_kernel_fp(void);
 extern void enable_kernel_fp(void);
 extern void flush_fp_to_thread(struct task_struct *);
 extern void enable_kernel_altivec(void);
diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 6820e45..8110abe 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -416,19 +416,6 @@ _GLOBAL(scom970_write)
 	blr
 #endif /* CONFIG_CPU_FREQ_PMAC64 || CONFIG_CPU_FREQ_MAPLE */
 
-
-/*
- * disable_kernel_fp()
- * Disable the FPU.
- */
-_GLOBAL(disable_kernel_fp)
-	mfmsr	r3
-	rldicl	r0,r3,(63-MSR_FP_LG),1
-	rldicl	r3,r0,(MSR_FP_LG+1),0
-	mtmsrd	r3			/* disable use of fpu now */
-	isync
-	blr
-
 /* kexec_wait(phys_cpu)
  *
  * wait for the flag to change, indicating this kernel is going away but
-- 
1.8.1.4

[PATCH 2/4] powerpc: remove the redundant flush_fp_to_thread() in setup_sigcontext()

[Kevin Hao]

In commit c6e6771b(powerpc: Introduce VSX thread_struct and CONFIG_VSX)
we add a invocation of flush_fp_to_thread() before copying the FPR or
VSR to users. But we already invoke the flush_fp_to_thread() in this
function. So remove one of them.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
 arch/powerpc/kernel/signal_64.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 887e99d..cb833bf 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -96,8 +96,6 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 	unsigned long msr = regs->msr;
 	long err = 0;
 
-	flush_fp_to_thread(current);
-
 #ifdef CONFIG_ALTIVEC
 	err |= __put_user(v_regs, &sc->v_regs);
 
-- 
1.8.1.4

[PATCH 3/4] powerpc: make flush_fp_to_thread() nop when CONFIG_PPC_FPU is disabled

[Kevin Hao]

In the current kernel, the function flush_fp_to_thread() is not
dependent on CONFIG_PPC_FPU. So most invocations of this function
is not wrapped by CONFIG_PPC_FPU. Even through we don't really
save the FPRs to the thread struct if CONFIG_PPC_FPU is not enabled,
but there does have some runtime overhead such as the check for
tsk->thread.regs and preempt disable and enable. It really make
no sense to do that. So make it a nop when CONFIG_PPC_FPU is
disabled. Also remove the wrapped #ifdef CONFIG_PPC_FPU
when invoking this function.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
 arch/powerpc/include/asm/switch_to.h | 7 ++++++-
 arch/powerpc/kernel/process.c        | 2 ++
 arch/powerpc/math-emu/math.c         | 3 +--
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 33e1cd8..39cf0f6 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -19,7 +19,6 @@ extern struct task_struct *_switch(struct thread_struct *prev,
 extern void giveup_fpu(struct task_struct *);
 extern void load_up_fpu(void);
 extern void enable_kernel_fp(void);
-extern void flush_fp_to_thread(struct task_struct *);
 extern void enable_kernel_altivec(void);
 extern void load_up_altivec(struct task_struct *);
 extern int emulate_altivec(struct pt_regs *);
@@ -37,6 +36,12 @@ static inline void discard_lazy_cpu_state(void)
 }
 #endif
 
+#ifdef CONFIG_PPC_FPU
+extern void flush_fp_to_thread(struct task_struct *);
+#else
+static inline void flush_fp_to_thread(struct task_struct *t) { }
+#endif
+
 #ifdef CONFIG_ALTIVEC
 extern void flush_altivec_to_thread(struct task_struct *);
 extern void giveup_altivec(struct task_struct *);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index c517dbe..0ec255a 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -74,6 +74,7 @@ struct task_struct *last_task_used_vsx = NULL;
 struct task_struct *last_task_used_spe = NULL;
 #endif
 
+#ifdef CONFIG_PPC_FPU
 /*
  * Make sure the floating-point register state in the
  * the thread_struct is up to date for task tsk.
@@ -107,6 +108,7 @@ void flush_fp_to_thread(struct task_struct *tsk)
 	}
 }
 EXPORT_SYMBOL_GPL(flush_fp_to_thread);
+#endif
 
 void enable_kernel_fp(void)
 {
diff --git a/arch/powerpc/math-emu/math.c b/arch/powerpc/math-emu/math.c
index f9ef347..d1ebac7 100644
--- a/arch/powerpc/math-emu/math.c
+++ b/arch/powerpc/math-emu/math.c
@@ -7,6 +7,7 @@
 
 #include <asm/uaccess.h>
 #include <asm/reg.h>
+#include <asm/switch_to.h>
 
 #include <asm/sfp-machine.h>
 #include <math-emu/double.h>
@@ -425,9 +426,7 @@ do_mathemu(struct pt_regs *regs)
 	 * is flushed into the thread_struct before attempting
 	 * emulation
 	 */
-#ifdef CONFIG_PPC_FPU
 	flush_fp_to_thread(current);
-#endif
 
 	eflag = func(op0, op1, op2, op3);
 
-- 
1.8.1.4

[PATCH 4/4] powerpc: remove the empty giveup_fpu() function on 32bit kernel

[Kevin Hao]

Instead of implementing an empty giveup_fpu() function for each
32bit processor type, replace them with an unique empty inline
function.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
 arch/powerpc/include/asm/switch_to.h |  3 ++-
 arch/powerpc/kernel/head_40x.S       |  8 --------
 arch/powerpc/kernel/head_44x.S       | 10 ----------
 arch/powerpc/kernel/head_8xx.S       |  4 ----
 arch/powerpc/kernel/head_fsl_booke.S | 10 ----------
 arch/powerpc/kernel/ppc_ksyms.c      |  2 ++
 6 files changed, 4 insertions(+), 33 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 39cf0f6..2c7edde 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -16,7 +16,6 @@ struct thread_struct;
 extern struct task_struct *_switch(struct thread_struct *prev,
 				   struct thread_struct *next);
 
-extern void giveup_fpu(struct task_struct *);
 extern void load_up_fpu(void);
 extern void enable_kernel_fp(void);
 extern void enable_kernel_altivec(void);
@@ -38,8 +37,10 @@ static inline void discard_lazy_cpu_state(void)
 
 #ifdef CONFIG_PPC_FPU
 extern void flush_fp_to_thread(struct task_struct *);
+extern void giveup_fpu(struct task_struct *);
 #else
 static inline void flush_fp_to_thread(struct task_struct *t) { }
+static inline void giveup_fpu(struct task_struct *t) { }
 #endif
 
 #ifdef CONFIG_ALTIVEC
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 8a9b6f5..67ee0d6 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -822,14 +822,6 @@ finish_tlb_load:
 	rfi			/* Should sync shadow TLBs */
 	b	.		/* prevent prefetch past rfi */
 
-/* extern void giveup_fpu(struct task_struct *prev)
- *
- * The PowerPC 4xx family of processors do not have an FPU, so this just
- * returns.
- */
-_ENTRY(giveup_fpu)
-	blr
-
 /* This is where the main kernel code starts.
  */
 start_here:
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 97e2671..c334f53 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -784,16 +784,6 @@ _GLOBAL(__fixup_440A_mcheck)
 	sync
 	blr
 
-/*
- * extern void giveup_fpu(struct task_struct *prev)
- *
- * The 44x core does not have an FPU.
- */
-#ifndef CONFIG_PPC_FPU
-_GLOBAL(giveup_fpu)
-	blr
-#endif
-
 _GLOBAL(set_context)
 
 #ifdef CONFIG_BDI_SWITCH
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index b2a5860..1b92a97 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -691,10 +691,6 @@ modified_instr:
 	b	151b
 #endif
 
-	.globl	giveup_fpu
-giveup_fpu:
-	blr
-
 /*
  * This is where the main kernel code starts.
  */
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index d10a7ca..289afaf 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -948,16 +948,6 @@ _GLOBAL(giveup_spe)
 #endif /* CONFIG_SPE */
 
 /*
- * extern void giveup_fpu(struct task_struct *prev)
- *
- * Not all FSL Book-E cores have an FPU
- */
-#ifndef CONFIG_PPC_FPU
-_GLOBAL(giveup_fpu)
-	blr
-#endif
-
-/*
  * extern void abort(void)
  *
  * At present, this routine just applies a system reset.
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index c296665..689ef81 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -96,7 +96,9 @@ EXPORT_SYMBOL(pci_dram_offset);
 
 EXPORT_SYMBOL(start_thread);
 
+#ifdef CONFIG_PPC_FPU
 EXPORT_SYMBOL(giveup_fpu);
+#endif
 #ifdef CONFIG_ALTIVEC
 EXPORT_SYMBOL(giveup_altivec);
 #endif /* CONFIG_ALTIVEC */
-- 
1.8.1.4