text: On Tue, 2018-02-20 at 13:50 +1100, Michael Neuling wrote: > On Tue, 2018-02-20 at 11:22 +1100, Cyril Bur wrote: > > > The comment from the cover sheet should be here > > > --- > > arch/powerpc/include/asm/exception-64s.h | 25 +++++++++++++++++++++ > > arch/powerpc/kernel/entry_64.S | 5 +++++ > > arch/powerpc/kernel/process.c | 37 > > ++++++++++++++++++++++++++++---- > > 3 files changed, 63 insertions(+), 4 deletions(-) > > > > diff --git a/arch/powerpc/include/asm/exception-64s.h > > b/arch/powerpc/include/asm/exception-64s.h > > index 471b2274fbeb..f904f19a9ec2 100644 > > --- a/arch/powerpc/include/asm/exception-64s.h > > +++ b/arch/powerpc/include/asm/exception-64s.h > > @@ -35,6 +35,7 @@ > > * implementations as possible. > > */ > > #include <asm/head-64.h> > > +#include <asm/tm.h> > > > > /* PACA save area offsets (exgen, exmc, etc) */ > > #define EX_R9 0 > > @@ -127,6 +128,26 @@ > > hrfid; \ > > b hrfi_flush_fallback > > > > +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM > > +#define TM_KERNEL_ENTRY > > \ > > + ld r3,_MSR(r1); \ > > + /* Probably don't need to check if coming from user/kernel */ \ > > + /* If TM is suspended or active then we must have come from*/ \ > > + /* userspace */ \ > > + andi. r0,r3,MSR_PR; \ > > + beq 1f; \ > > + rldicl. r3,r3,(64-MSR_TS_LG),(64-2); /* SUSPENDED or ACTIVE*/ \ > > + beql+ 1f; /* Not SUSPENDED or ACTIVE */ \ > > + bl save_nvgprs; \ > > + RECONCILE_IRQ_STATE(r10,r11); \ > > + li r3,TM_CAUSE_MISC; \ > > + bl tm_reclaim_current; /* uint8 cause */ \ > > +1: > > + > > +#else /* CONFIG_PPC_TRANSACTIONAL_MEM */ > > +#define TM_KERNEL_ENTRY > > +#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */ > > + > > #ifdef CONFIG_RELOCATABLE > > #define __EXCEPTION_RELON_PROLOG_PSERIES_1(label, h) > > \ > > mfspr r11,SPRN_##h##SRR0; /* save SRR0 */ \ > > @@ -675,6 +696,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL) > > EXCEPTION_PROLOG_COMMON(trap, area); \ > > /* Volatile regs are potentially clobbered here */ \ > > additions; \ > > + /* This is going to need to go somewhere else as well */\ > > + /* See comment in tm_recheckpoint() */\ > > + TM_KERNEL_ENTRY; \ > > addi r3,r1,STACK_FRAME_OVERHEAD; \ > > bl hdlr; \ > > b ret > > @@ -689,6 +713,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL) > > EXCEPTION_PROLOG_COMMON_3(trap); \ > > /* Volatile regs are potentially clobbered here */ \ > > additions; \ > > + TM_KERNEL_ENTRY; \ > > addi r3,r1,STACK_FRAME_OVERHEAD; \ > > bl hdlr > > > > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > > index 2cb5109a7ea3..107c15c6f48b 100644 > > --- a/arch/powerpc/kernel/entry_64.S > > +++ b/arch/powerpc/kernel/entry_64.S > > @@ -126,6 +126,11 @@ BEGIN_FW_FTR_SECTION > > 33: > > END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR) > > #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE && CONFIG_PPC_SPLPAR */ > > + TM_KERNEL_ENTRY > > + REST_GPR(0,r1) > > + REST_4GPRS(3,r1) > > + REST_2GPRS(7,r1) > > + addi r9,r1,STACK_FRAME_OVERHEAD > > Why are we doing these restores here now?
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  The syscall handler expects the syscall params to still be in their respective regs. > > > > > /* > > * A syscall should always be called with interrupts enabled > > diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c > > index 77dc6d8288eb..ea75da0fd506 100644 > > --- a/arch/powerpc/kernel/process.c > > +++ b/arch/powerpc/kernel/process.c > > @@ -951,6 +951,23 @@ void tm_recheckpoint(struct thread_struct *thread) > > if (!(thread->regs->msr & MSR_TM)) > > return; > > > > + /* > > + * This is 'that' comment. > > I think I'm in the loop here but I don't actually know what this means. > > Senior Mikey moment or Crazy Cyril comments? I'll let the peanut gallery > decide. > Oh quite possibly crazy Cyril comment that will have to be... normalised. I should actually delete this and see if that's still the case. > > + * > > + * If we get where with tm suspended or active then something > > s/where/here/ > > > + * has gone wrong. I've added this now as a proof of concept. > > + * > > + * The problem I'm seeing without it is an attempt to > > + * recheckpoint a CPU without a previous reclaim. > > + * > > + * I'm probably missed an exception entry with the > > + * TM_KERNEL_ENTRY macro. Should be easy enough to find. > > + */ > > + if (MSR_TM_ACTIVE(mfmsr())) > > + return; > > I don't really get this. Wouldn't this test apply now? > > > + > > + tm_enable(); > > Why did we add this? > Ah yes that was a cleanup I noticed along the way and clearly forgot to finish. At the moment there's a bunch of tm_enable()s either before calling functions like tm_recheckpoint() or tm_reclaim_current() or inside helpers (tm_reclaim_current() for example again). I feel like callers shouldn't have to worry, it should be up to the function actually doing the TM work to enable it. > > + > > /* We really can't be interrupted here as the TEXASR registers can't > > * change and later in the trecheckpoint code, we have a userspace R1. > > * So let's hard disable over this region. > > @@ -1009,6 +1026,13 @@ static inline void tm_recheckpoint_new_task(struct > > task_struct *new) > > static inline void __switch_to_tm(struct task_struct *prev, > > struct task_struct *new) > > { > > + /* > > + * So, with the rework none of this code should not be needed. > > + * I've left in the reclaim for now. This *should* save us > > + * from any mistake in the new code. Also the > > + * enabling/disabling logic of MSR_TM really should be > > + * refactored into a common way with MSR_{FP,VEC,VSX} > > + */ > > if (cpu_has_feature(CPU_FTR_TM)) { > > if (tm_enabled(prev) || tm_enabled(new)) > > tm_enable(); > > @@ -1016,11 +1040,14 @@ static inline void __switch_to_tm(struct > > task_struct *prev, > > if (tm_enabled(prev)) { > > prev->thread.load_tm++; > > tm_reclaim_task(prev); > > - if (!MSR_TM_ACTIVE(prev->thread.regs->msr) && > > prev->thread.load_tm == 0) > > - prev->thread.regs->msr &= ~MSR_TM; > > + /* > > + * The disabling logic may be confused don't > > + * disable for now > > + * > > + * if (!MSR_TM_ACTIVE(prev->thread.regs->msr) && > > prev->thread.load_tm == 0) > > + * prev->thread.regs->msr &= ~MSR_TM; > > + */ > > Why are you doing this when you just remove all this code in the next patch? The next 3 or so patches will need squashing into this one before merging. > > } > > - > > - tm_recheckpoint_new_task(new); > > } > > } > > > > @@ -1055,6 +1082,8 @@ void restore_tm_state(struct pt_regs *regs) > > msr_diff = current->thread.ckpt_regs.msr & ~regs->msr; > > msr_diff &= MSR_FP | MSR_VEC | MSR_VSX; > > > > + tm_recheckpoint(¤t->thread); > > + > > So why do we do tm_recheckpoint at all? Shouldn't most of the tm_blah code go > away in process.c after all this? > I'm not sure I follow, we need to recheckpoint because we're going back to userspace? Or would you rather calling the tm.S code directly from the exception return path? Yes, I hope we'll be able to have a fairly big cleanup commit of tm_ code in process.c at the end of this series. > > /* Ensure that restore_math() will restore */ > > if (msr_diff & MSR_FP) > > current->thread.load_fp = 1;