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powerpc: Save the TAR register earlier

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This moves us to save the Target Address Register (TAR) a earlier in
__switch_to.  It introduces a new function save_tar() to do this.

We need to save the TAR earlier as we will overwrite it in the transactional
memory reclaim/recheckpoint path.  We are going to do this in a subsequent
patch which will fix saving the TAR register when it's modified inside a
transaction.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> [v3.10]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Neuling
2013-08-09 17:29:30 +10:00
committed by Benjamin Herrenschmidt
parent 2517617e0d
commit c2d52644e2
3 changed files with 19 additions and 9 deletions
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9
arch/powerpc/include/asm/switch_to.h
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@@ -15,6 +15,15 @@ extern struct task_struct *__switch_to(struct task_struct *,
struct thread_struct;
extern struct task_struct *_switch(struct thread_struct *prev,
struct thread_struct *next);
#ifdef CONFIG_PPC_BOOK3S_64
static inline void save_tar(struct thread_struct *prev)
{
if (cpu_has_feature(CPU_FTR_ARCH_207S))
prev->tar = mfspr(SPRN_TAR);
}
#else
static inline void save_tar(struct thread_struct *prev) {}
#endif
extern void giveup_fpu(struct task_struct *);
extern void load_up_fpu(void);