* Tony Lindgren <tony@xxxxxxxxxxx> [100902 12:20]:
> * Tony Lindgren <tony@xxxxxxxxxxx> [100902 10:35]:
> > * Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> [100902 10:00]:
> > > On Thu, Sep 02, 2010 at 09:18:47AM -0700, Tony Lindgren wrote:
> > >
> > > > --- a/arch/arm/include/asm/smp_plat.h
> > > > +++ b/arch/arm/include/asm/smp_plat.h
> > > > @@ -39,4 +39,20 @@ static inline int cache_ops_need_broadcast(void)
> > > > #define UP(instr...) _str(instr)
> > > > #endif
> > > >
> > > > +static inline int smp_on_up(void)
> > > > +{
> > > > +#ifdef CONFIG_SMP_ON_UP
> > > > + int smp_on_up;
> > > > +
> > > > + asm( \
> > > > + SMP(mov %0, #0) \
> > > > + UP(mov %0, #1) \
> > > > + : "=r" (smp_on_up));
> > > > +
> > > > + return smp_on_up;
> > > > +#else
> > > > + return 0;
> > > > +#endif
> > >
> > > I think this is the wrong approach - rather than a function which tells us
> > > just if we are a SMP kernel running on UP, why not something which returns
> > > whether we're running on SMP and use that to eliminate some of these ifdefs?
> >
> > Sure. Will has something like this in his patches:
> >
> > static inline int cpu_is_part_of_mp_system(void)
> > {
> > u32 mpidr;
> > asm volatile("mrc p15, 0, %0, c0, c0, 5" : "=r" (mpidr));
> > return (mpidr >> 31) ? !(mpidr >> 30) : 0;
> > }
> >
> > BTW, so far looks like we should only need this during init to set up things.
>
> Here's this one updated to replace smp_cpu() instead of smp_on_up().
Heh, turns out there's a bit of a bug in the code snippet above :) It should
be !((mpidr >> 30) & 1) instead, otherwise it always returns 0.
Regards,
Tony
From: Tony Lindgren <tony@xxxxxxxxxxx>
Date: Mon, 30 Aug 2010 14:00:54 -0700
Subject: [PATCH] ARM: Add inline function smp_cpu() for early init testing
Add inline function smp_cpu() for early init checks, and
change build_mem_type_table to use it.
Inline function copied from cpu_is_part_of_mp_system() by
Will Deacon <will.deacon@xxxxxxx>.
Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h
index 8db3512..060213e 100644
--- a/arch/arm/include/asm/smp_plat.h
+++ b/arch/arm/include/asm/smp_plat.h
@@ -39,4 +39,11 @@ static inline int cache_ops_need_broadcast(void)
#define UP(instr...) _str(instr)
#endif
+static inline int smp_cpu(void)
+{
+ u32 mpidr;
+ asm volatile("mrc p15, 0, %0, c0, c0, 5" : "=r" (mpidr));
+ return (mpidr >> 31) ? !((mpidr >> 30) & 1) : 0;
+}
+
#endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 6e1c4f6..2bfaefd 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -430,15 +430,17 @@ static void __init build_mem_type_table(void)
/*
* Mark memory with the "shared" attribute for SMP systems
*/
- user_pgprot |= L_PTE_SHARED;
- kern_pgprot |= L_PTE_SHARED;
- vecs_pgprot |= L_PTE_SHARED;
- mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_S;
- mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_SHARED;
- mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_S;
- mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED;
- mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
- mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S;
+ if (smp_cpu()) {
+ user_pgprot |= L_PTE_SHARED;
+ kern_pgprot |= L_PTE_SHARED;
+ vecs_pgprot |= L_PTE_SHARED;
+ mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_S;
+ mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_SHARED;
+ mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_S;
+ mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED;
+ mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
+ mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S;
+ }
#endif
}
