From 1753dd1830367709144f68f539554dadd7a7ccba Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 7 Mar 2018 11:37:09 +1000 Subject: [PATCH] powerpc/mm/slice: Simplify and optimise slice context initialisation The slice state of an mm gets zeroed then initialised upon exec. This is the only caller of slice_set_user_psize now, so that can be removed and instead implement a faster and simplified approach that requires no locking or checking existing state. This speeds up vfork+exec+exit performance on POWER8 by 3%. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/slice.h | 8 ++- arch/powerpc/mm/mmu_context_book3s64.c | 9 +--- arch/powerpc/mm/mmu_context_nohash.c | 5 +- arch/powerpc/mm/slice.c | 72 +++++++------------------- 4 files changed, 23 insertions(+), 71 deletions(-) diff --git a/arch/powerpc/include/asm/slice.h b/arch/powerpc/include/asm/slice.h index 172711fadb1c..e40406cf5628 100644 --- a/arch/powerpc/include/asm/slice.h +++ b/arch/powerpc/include/asm/slice.h @@ -28,15 +28,13 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len, unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr); -void slice_set_user_psize(struct mm_struct *mm, unsigned int psize); void slice_set_range_psize(struct mm_struct *mm, unsigned long start, unsigned long len, unsigned int psize); -#endif /* __ASSEMBLY__ */ -#else /* CONFIG_PPC_MM_SLICES */ +void slice_init_new_context_exec(struct mm_struct *mm); + +#endif /* __ASSEMBLY__ */ -#define slice_set_range_psize(mm, start, len, psize) \ - slice_set_user_psize((mm), (psize)) #endif /* CONFIG_PPC_MM_SLICES */ #endif /* _ASM_POWERPC_SLICE_H */ diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c index 929d9ef7083f..80acad52b006 100644 --- a/arch/powerpc/mm/mmu_context_book3s64.c +++ b/arch/powerpc/mm/mmu_context_book3s64.c @@ -93,13 +93,6 @@ static int hash__init_new_context(struct mm_struct *mm) if (index < 0) return index; - /* - * In the case of exec, use the default limit, - * otherwise inherit it from the mm we are duplicating. - */ - if (!mm->context.slb_addr_limit) - mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW_USER64; - /* * The old code would re-promote on fork, we don't do that when using * slices as it could cause problem promoting slices that have been @@ -115,7 +108,7 @@ static int hash__init_new_context(struct mm_struct *mm) * check against 0 is OK. */ if (mm->context.id == 0) - slice_set_user_psize(mm, mmu_virtual_psize); + slice_init_new_context_exec(mm); subpage_prot_init_new_context(mm); diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c index d98f7e5c141b..be8f5c9d4d08 100644 --- a/arch/powerpc/mm/mmu_context_nohash.c +++ b/arch/powerpc/mm/mmu_context_nohash.c @@ -332,9 +332,6 @@ int init_new_context(struct task_struct *t, struct mm_struct *mm) pr_hard("initing context for mm @%p\n", mm); #ifdef CONFIG_PPC_MM_SLICES - if (!mm->context.slb_addr_limit) - mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW; - /* * We have MMU_NO_CONTEXT set to be ~0. Hence check * explicitly against context.id == 0. This ensures that we properly @@ -343,7 +340,7 @@ int init_new_context(struct task_struct *t, struct mm_struct *mm) * will have id != 0). */ if (mm->context.id == 0) - slice_set_user_psize(mm, mmu_virtual_psize); + slice_init_new_context_exec(mm); #endif mm->context.id = MMU_NO_CONTEXT; mm->context.active = 0; diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c index 5e9e1e57d580..7b51f962ce0c 100644 --- a/arch/powerpc/mm/slice.c +++ b/arch/powerpc/mm/slice.c @@ -671,70 +671,34 @@ unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr) } EXPORT_SYMBOL_GPL(get_slice_psize); -/* - * This is called by hash_page when it needs to do a lazy conversion of - * an address space from real 64K pages to combo 4K pages (typically - * when hitting a non cacheable mapping on a processor or hypervisor - * that won't allow them for 64K pages). - * - * This is also called in init_new_context() to change back the user - * psize from whatever the parent context had it set to - * N.B. This may be called before mm->context.id has been set. - * - * This function will only change the content of the {low,high)_slice_psize - * masks, it will not flush SLBs as this shall be handled lazily by the - * caller. - */ -void slice_set_user_psize(struct mm_struct *mm, unsigned int psize) +void slice_init_new_context_exec(struct mm_struct *mm) { - int index, mask_index; unsigned char *hpsizes, *lpsizes; - unsigned long flags; - unsigned int old_psize; - int i; + unsigned int psize = mmu_virtual_psize; - slice_dbg("slice_set_user_psize(mm=%p, psize=%d)\n", mm, psize); + slice_dbg("slice_init_new_context_exec(mm=%p)\n", mm); - VM_BUG_ON(radix_enabled()); - spin_lock_irqsave(&slice_convert_lock, flags); - - old_psize = mm->context.user_psize; - slice_dbg(" old_psize=%d\n", old_psize); - if (old_psize == psize) - goto bail; + /* + * In the case of exec, use the default limit. In the + * case of fork it is just inherited from the mm being + * duplicated. + */ +#ifdef CONFIG_PPC64 + mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW_USER64; +#else + mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW; +#endif mm->context.user_psize = psize; - wmb(); + /* + * Set all slice psizes to the default. + */ lpsizes = mm->context.low_slices_psize; - for (i = 0; i < SLICE_NUM_LOW; i++) { - mask_index = i & 0x1; - index = i >> 1; - if (((lpsizes[index] >> (mask_index * 4)) & 0xf) == old_psize) - lpsizes[index] = (lpsizes[index] & - ~(0xf << (mask_index * 4))) | - (((unsigned long)psize) << (mask_index * 4)); - } + memset(lpsizes, (psize << 4) | psize, SLICE_NUM_LOW >> 1); hpsizes = mm->context.high_slices_psize; - for (i = 0; i < SLICE_NUM_HIGH; i++) { - mask_index = i & 0x1; - index = i >> 1; - if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == old_psize) - hpsizes[index] = (hpsizes[index] & - ~(0xf << (mask_index * 4))) | - (((unsigned long)psize) << (mask_index * 4)); - } - - - - - slice_dbg(" lsps=%lx, hsps=%lx\n", - (unsigned long)mm->context.low_slices_psize, - (unsigned long)mm->context.high_slices_psize); - - bail: - spin_unlock_irqrestore(&slice_convert_lock, flags); + memset(hpsizes, (psize << 4) | psize, SLICE_NUM_HIGH >> 1); } void slice_set_range_psize(struct mm_struct *mm, unsigned long start, -- 2.30.2