On Thu, Aug 18, 2016 at 11:44:20AM +0200, Christophe Leroy wrote: > SPRN_ICR must be read for clearing the internal freeze signal which > is asserted by the single step exception, otherwise the timebase and > decrementer remain freezed
Minor nit: s/freezed/frozen/ If the timebase and decrementer are frozen even for a few cycles, this probably upsets timekeeping. I consider this a completely stupid design decision, and maybe I'm not alone. Gabriel > > Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr> > --- > arch/powerpc/include/asm/reg_8xx.h | 1 + > arch/powerpc/kernel/traps.c | 8 ++++++++ > 2 files changed, 9 insertions(+) > > diff --git a/arch/powerpc/include/asm/reg_8xx.h > b/arch/powerpc/include/asm/reg_8xx.h > index feaf641..6dae71f 100644 > --- a/arch/powerpc/include/asm/reg_8xx.h > +++ b/arch/powerpc/include/asm/reg_8xx.h > @@ -17,6 +17,7 @@ > #define SPRN_DC_DAT 570 /* Read-only data register */ > > /* Misc Debug */ > +#define SPRN_ICR 148 > #define SPRN_DPDR 630 > #define SPRN_MI_CAM 816 > #define SPRN_MI_RAM0 817 > diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c > index 2cb5892..0f1f0ce 100644 > --- a/arch/powerpc/kernel/traps.c > +++ b/arch/powerpc/kernel/traps.c > @@ -400,8 +400,16 @@ static inline int check_io_access(struct pt_regs *regs) > #define REASON_TRAP 0x20000 > > #define single_stepping(regs) ((regs)->msr & MSR_SE) > +#ifdef CONFIG_PPC_8xx > +static inline void clear_single_step(struct pt_regs *regs) > +{ > + regs->msr &= ~MSR_SE; > + mfspr(SPRN_ICR); > +} > +#else > #define clear_single_step(regs) ((regs)->msr &= ~MSR_SE) > #endif > +#endif > > #if defined(CONFIG_4xx) > int machine_check_4xx(struct pt_regs *regs) > -- > 2.1.0