| Message ID | 1375855918-3625-2-git-send-email-mikey@neuling.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, Aug 07, 2013 at 04:11:56PM +1000, Michael Neuling wrote: > Add save_tar() function to save the Target Address Register (TAR). This will > be used in a future patch to save the TAR earlier than it currently is. > > Signed-off-by: Michael Neuling <mikey@neuling.org> > Cc: <stable@vger.kernel.org> > --- > arch/powerpc/include/asm/switch_to.h | 5 +++++ > arch/powerpc/kernel/entry_64.S | 12 ++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h > index 49a13e0..4531068 100644 > --- a/arch/powerpc/include/asm/switch_to.h > +++ b/arch/powerpc/include/asm/switch_to.h > @@ -15,6 +15,11 @@ 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 > +extern void _save_tar(struct thread_struct *prev); > +#else > +static inline void _save_tar(struct thread_struct *prev) {} > +#endif > > extern void giveup_fpu(struct task_struct *); > extern void load_up_fpu(void); > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > index 4674fe6..32e18f3 100644 > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S > @@ -389,6 +389,18 @@ DSCR_DEFAULT: > .tc dscr_default[TC],dscr_default > > .section ".text" > +#ifdef CONFIG_PPC_BOOK3S_64 > +_GLOBAL(_save_tar) > + /* > + * Back up the TAR across context switches. Note that the TAR is not > + * available for use in the kernel. (To provide this, the TAR should > + * be backed up/restored on exception entry/exit instead, and be in > + * pt_regs. FIXME, this should be in pt_regs anyway (for debug).) > + */ > + mfspr r0,SPRN_TAR > + std r0,THREAD_TAR(r3) > + blr > +#endif Why not do this in C, as in prev->tar = mfspr(SPRN_TAR); ? Paul.
> > +#ifdef CONFIG_PPC_BOOK3S_64 > > +_GLOBAL(_save_tar) > > + /* > > + * Back up the TAR across context switches. Note that the TAR is not > > + * available for use in the kernel. (To provide this, the TAR should > > + * be backed up/restored on exception entry/exit instead, and be in > > + * pt_regs. FIXME, this should be in pt_regs anyway (for debug).) > > + */ > > + mfspr r0,SPRN_TAR > > + std r0,THREAD_TAR(r3) > > + blr > > +#endif > > Why not do this in C, as in prev->tar = mfspr(SPRN_TAR); ? Good point! I'd just copied the original code which was inline asm in _switch(). Thanks, Mikey
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h index 49a13e0..4531068 100644 --- a/arch/powerpc/include/asm/switch_to.h +++ b/arch/powerpc/include/asm/switch_to.h @@ -15,6 +15,11 @@ 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 +extern void _save_tar(struct thread_struct *prev); +#else +static inline void _save_tar(struct thread_struct *prev) {} +#endif extern void giveup_fpu(struct task_struct *); extern void load_up_fpu(void); diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 4674fe6..32e18f3 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -389,6 +389,18 @@ DSCR_DEFAULT: .tc dscr_default[TC],dscr_default .section ".text" +#ifdef CONFIG_PPC_BOOK3S_64 +_GLOBAL(_save_tar) + /* + * Back up the TAR across context switches. Note that the TAR is not + * available for use in the kernel. (To provide this, the TAR should + * be backed up/restored on exception entry/exit instead, and be in + * pt_regs. FIXME, this should be in pt_regs anyway (for debug).) + */ + mfspr r0,SPRN_TAR + std r0,THREAD_TAR(r3) + blr +#endif /* * This routine switches between two different tasks. The process
Add save_tar() function to save the Target Address Register (TAR). This will be used in a future patch to save the TAR earlier than it currently is. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> --- arch/powerpc/include/asm/switch_to.h | 5 +++++ arch/powerpc/kernel/entry_64.S | 12 ++++++++++++ 2 files changed, 17 insertions(+)