On Fri, 2007-08-03 at 11:55 +1000, Michael Neuling wrote:
> We sometimes change the vmalloc segment in slb_flush_and_rebolt but we
> never updated with slb shadow buffer. This fixes it. Thanks to paulus
> for finding this.
>
> Also added some write barriers to ensure the shadow buffer is always
> valid.
>
> Signed-off-by: Michael Neuling <[EMAIL PROTECTED]>
Acked-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
> ---
> Integrated more comments from people.
>
> arch/powerpc/kernel/entry_64.S | 3 +++
> arch/powerpc/mm/hash_utils_64.c | 2 +-
> arch/powerpc/mm/slb.c | 28 ++++++++++++++++++----------
> include/asm-powerpc/mmu-hash64.h | 1 +
> 4 files changed, 23 insertions(+), 11 deletions(-)
>
> Index: linux-2.6-ozlabs/arch/powerpc/kernel/entry_64.S
> ===================================================================
> --- linux-2.6-ozlabs.orig/arch/powerpc/kernel/entry_64.S
> +++ linux-2.6-ozlabs/arch/powerpc/kernel/entry_64.S
> @@ -389,8 +389,11 @@ BEGIN_FTR_SECTION
> ld r9,PACA_SLBSHADOWPTR(r13)
> li r12,0
> std r12,SLBSHADOW_STACKESID(r9) /* Clear ESID */
> + eieio
> std r7,SLBSHADOW_STACKVSID(r9) /* Save VSID */
> + eieio
> std r0,SLBSHADOW_STACKESID(r9) /* Save ESID */
> + eieio
>
> slbie r6
> slbie r6 /* Workaround POWER5 < DD2.1 issue */
> Index: linux-2.6-ozlabs/arch/powerpc/mm/hash_utils_64.c
> ===================================================================
> --- linux-2.6-ozlabs.orig/arch/powerpc/mm/hash_utils_64.c
> +++ linux-2.6-ozlabs/arch/powerpc/mm/hash_utils_64.c
> @@ -759,7 +759,7 @@ int hash_page(unsigned long ea, unsigned
> mmu_psize_defs[mmu_vmalloc_psize].sllp) {
> get_paca()->vmalloc_sllp =
> mmu_psize_defs[mmu_vmalloc_psize].sllp;
> - slb_flush_and_rebolt();
> + slb_vmalloc_update();
> }
> #endif /* CONFIG_PPC_64K_PAGES */
>
> Index: linux-2.6-ozlabs/arch/powerpc/mm/slb.c
> ===================================================================
> --- linux-2.6-ozlabs.orig/arch/powerpc/mm/slb.c
> +++ linux-2.6-ozlabs/arch/powerpc/mm/slb.c
> @@ -53,7 +53,8 @@ static inline unsigned long mk_vsid_data
> return (get_kernel_vsid(ea) << SLB_VSID_SHIFT) | flags;
> }
>
> -static inline void slb_shadow_update(unsigned long esid, unsigned long vsid,
> +static inline void slb_shadow_update(unsigned long ea,
> + unsigned long flags,
> unsigned long entry)
> {
> /*
> @@ -61,11 +62,11 @@ static inline void slb_shadow_update(uns
> * updating it.
> */
> get_slb_shadow()->save_area[entry].esid = 0;
> - barrier();
> - get_slb_shadow()->save_area[entry].vsid = vsid;
> - barrier();
> - get_slb_shadow()->save_area[entry].esid = esid;
> -
> + smp_wmb();
> + get_slb_shadow()->save_area[entry].vsid = mk_vsid_data(ea, flags);
> + smp_wmb();
> + get_slb_shadow()->save_area[entry].esid = mk_esid_data(ea, entry);
> + smp_wmb();
> }
>
> static inline void create_shadowed_slbe(unsigned long ea, unsigned long
> flags,
> @@ -76,8 +77,7 @@ static inline void create_shadowed_slbe(
> * we don't get a stale entry here if we get preempted by PHYP
> * between these two statements.
> */
> - slb_shadow_update(mk_esid_data(ea, entry), mk_vsid_data(ea, flags),
> - entry);
> + slb_shadow_update(ea, flags, entry);
>
> asm volatile("slbmte %0,%1" :
> : "r" (mk_vsid_data(ea, flags)),
> @@ -104,8 +104,7 @@ void slb_flush_and_rebolt(void)
> ksp_esid_data &= ~SLB_ESID_V;
>
> /* Only third entry (stack) may change here so only resave that */
> - slb_shadow_update(ksp_esid_data,
> - mk_vsid_data(ksp_esid_data, lflags), 2);
> + slb_shadow_update(get_paca()->kstack, lflags, 2);
>
> /* We need to do this all in asm, so we're sure we don't touch
> * the stack between the slbia and rebolting it. */
> @@ -123,6 +122,15 @@ void slb_flush_and_rebolt(void)
> : "memory");
> }
>
> +void slb_vmalloc_update(void)
> +{
> + unsigned long vflags;
> +
> + vflags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_vmalloc_psize].sllp;
> + slb_shadow_update(VMALLOC_START, vflags, 1);
> + slb_flush_and_rebolt();
> +}
> +
> /* Flush all user entries from the segment table of the current processor. */
> void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
> {
> Index: linux-2.6-ozlabs/include/asm-powerpc/mmu-hash64.h
> ===================================================================
> --- linux-2.6-ozlabs.orig/include/asm-powerpc/mmu-hash64.h
> +++ linux-2.6-ozlabs/include/asm-powerpc/mmu-hash64.h
> @@ -262,6 +262,7 @@ extern void slb_initialize(void);
> extern void slb_flush_and_rebolt(void);
> extern void stab_initialize(unsigned long stab);
>
> +extern void slb_vmalloc_update(void);
> #endif /* __ASSEMBLY__ */
>
> /*
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