Re: [PATCH V2 01/02] MIPS: Build uasm-generated code only once toavoid CPU Hotplug problem

[David Daney]

On 03/20/2013 04:14 PM, David Daney wrote:
> On 03/17/2013 05:49 AM, Huacai Chen wrote:
> > This and the next patch resolve memory corruption problems while CPU
> > hotplug. Without these patches, memory corruption can triggered easily
> > as below:
[...]
> We were seeing the same crashes, this patch set seems to fix the problem.
>
> Acked-by: David Daney <david.daney@xxxxxxxxxx>

On second thought...


> > ---
> >   arch/mips/include/asm/cpu-features.h               |    3 +++
> >   .../asm/mach-loongson/cpu-feature-overrides.h      |    1 +
> >   arch/mips/mm/page.c                                |   10 ++++++++++
> >   arch/mips/mm/tlbex.c                               |   10 ++++++++--
> >   4 files changed, 22 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/mips/include/asm/cpu-features.h
> > b/arch/mips/include/asm/cpu-features.h
> > index 1a57e8b..e5ec8fc 100644
> > --- a/arch/mips/include/asm/cpu-features.h
> > +++ b/arch/mips/include/asm/cpu-features.h
> > @@ -113,6 +113,9 @@
> >   #ifndef cpu_has_pindexed_dcache
> >   #define cpu_has_pindexed_dcache (cpu_data[0].dcache.flags &
> > MIPS_CACHE_PINDEX)
> >   #endif
> > +#ifndef cpu_has_local_ebase
> > +#define cpu_has_local_ebase    1


This really should default to 0 and only be set for (??who knows what??).

David Daney


> > +#endif
> >
> >   /*
> >    * I-Cache snoops remote store.     This only matters on SMP.  Some
> > multiprocessors
> > diff --git
> > a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
> > b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
> > index 75fd8c0..c0f3ef4 100644
> > --- a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
> > +++ b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
> > @@ -57,5 +57,6 @@
> >   #define cpu_has_vint        0
> >   #define cpu_has_vtag_icache    0
> >   #define cpu_has_watch        1
> > +#define cpu_has_local_ebase    0
> >
> >   #endif /* __ASM_MACH_LOONGSON_CPU_FEATURE_OVERRIDES_H */
> > diff --git a/arch/mips/mm/page.c b/arch/mips/mm/page.c
> > index a29fba5..4eb8dcf 100644
> > --- a/arch/mips/mm/page.c
> > +++ b/arch/mips/mm/page.c
> > @@ -247,6 +247,11 @@ void __cpuinit build_clear_page(void)
> >       struct uasm_label *l = labels;
> >       struct uasm_reloc *r = relocs;
> >       int i;
> > +    static atomic_t run_once = ATOMIC_INIT(0);
> > +
> > +    if (atomic_xchg(&run_once, 1)) {
> > +        return;
> > +    }
> >
> >       memset(labels, 0, sizeof(labels));
> >       memset(relocs, 0, sizeof(relocs));
> > @@ -389,6 +394,11 @@ void __cpuinit build_copy_page(void)
> >       struct uasm_label *l = labels;
> >       struct uasm_reloc *r = relocs;
> >       int i;
> > +    static atomic_t run_once = ATOMIC_INIT(0);
> > +
> > +    if (atomic_xchg(&run_once, 1)) {
> > +        return;
> > +    }
> >
> >       memset(labels, 0, sizeof(labels));
> >       memset(relocs, 0, sizeof(relocs));
> > diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
> > index 820e661..6bc28b4 100644
> > --- a/arch/mips/mm/tlbex.c
> > +++ b/arch/mips/mm/tlbex.c
> > @@ -2162,8 +2162,11 @@ void __cpuinit build_tlb_refill_handler(void)
> >       case CPU_TX3922:
> >       case CPU_TX3927:
> >   #ifndef CONFIG_MIPS_PGD_C0_CONTEXT
> > -        build_r3000_tlb_refill_handler();
> > +        if (cpu_has_local_ebase)
> > +            build_r3000_tlb_refill_handler();
> >           if (!run_once) {
> > +            if (!cpu_has_local_ebase)
> > +                build_r3000_tlb_refill_handler();
> >               build_r3000_tlb_load_handler();
> >               build_r3000_tlb_store_handler();
> >               build_r3000_tlb_modify_handler();
> > @@ -2192,9 +2195,12 @@ void __cpuinit build_tlb_refill_handler(void)
> >               build_r4000_tlb_load_handler();
> >               build_r4000_tlb_store_handler();
> >               build_r4000_tlb_modify_handler();
> > +            if (!cpu_has_local_ebase)
> > +                build_r4000_tlb_refill_handler();
> >               run_once++;
> >           }
> > -        build_r4000_tlb_refill_handler();
> > +        if (cpu_has_local_ebase)
> > +            build_r4000_tlb_refill_handler();
> >       }
> >   }

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