From 1753dd1830367709144f68f539554dadd7a7ccba Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 7 Mar 2018 11:37:09 +1000 Subject: 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/mm/slice.c | 72 +++++++++++++------------------------------------ 1 file changed, 18 insertions(+), 54 deletions(-) (limited to 'arch/powerpc/mm/slice.c') 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, -- cgit