[PATCH 1/3] powerpc: Complete FSCR context switch

[Jack Miller]

Previously we just saved the FSCR, but only restored it in some
settings, and never copied it thread to thread. This patch always
restores the FSCR and formalizes new threads inheriting its setting so
that later we can manipulate FSCR bits in start_thread.

Signed-off-by: Jack Miller <jack at codezen.org>
---
 arch/powerpc/kernel/process.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index b8500b4..00bf6f5 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1019,18 +1019,12 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 #ifdef CONFIG_PPC_BOOK3S_64
 	if (cpu_has_feature(CPU_FTR_DSCR)) {
 		u64 dscr = get_paca()->dscr_default;
-		u64 fscr = old_thread->fscr & ~FSCR_DSCR;
 
-		if (new_thread->dscr_inherit) {
+		if (new_thread->dscr_inherit)
 			dscr = new_thread->dscr;
-			fscr |= FSCR_DSCR;
-		}
 
 		if (old_thread->dscr != dscr)
 			mtspr(SPRN_DSCR, dscr);
-
-		if (old_thread->fscr != fscr)
-			mtspr(SPRN_FSCR, fscr);
 	}
 
 	if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
@@ -1041,6 +1035,9 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 		if (old_thread->ebbrr != new_thread->ebbrr)
 			mtspr(SPRN_EBBRR, new_thread->ebbrr);
 
+		if (old_thread->fscr != new_thread->fscr)
+			mtspr(SPRN_FSCR, new_thread->fscr);
+
 		if (old_thread->tar != new_thread->tar)
 			mtspr(SPRN_TAR, new_thread->tar);
 	}
@@ -1478,6 +1475,9 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 	}
 	if (cpu_has_feature(CPU_FTR_HAS_PPR))
 		p->thread.ppr = INIT_PPR;
+
+	if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		p->thread.fscr = mfspr(SPRN_FSCR);
 #endif
 	kregs->nip = ppc_function_entry(f);
 	return 0;
-- 
2.8.0