From 25078dc1f74be16b858e914f52cc8f4d03c2271a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 16 Dec 2018 17:53:49 +0100 Subject: powerpc: use mm zones more sensibly Powerpc has somewhat odd usage where ZONE_DMA is used for all memory on common 64-bit configfs, and ZONE_DMA32 is used for 31-bit schemes. Move to a scheme closer to what other architectures use (and I dare to say the intent of the system): - ZONE_DMA: optionally for memory < 31-bit (64-bit embedded only) - ZONE_NORMAL: everything addressable by the kernel - ZONE_HIGHMEM: memory > 32-bit for 32-bit kernels Also provide information on how ZONE_DMA is used by defining ARCH_ZONE_DMA_BITS. Contains various fixes from Benjamin Herrenschmidt. Signed-off-by: Christoph Hellwig Signed-off-by: Michael Ellerman --- arch/powerpc/mm/mem.c | 47 +++++++++++++++++------------------------------ 1 file changed, 17 insertions(+), 30 deletions(-) (limited to 'arch/powerpc/mm') diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 065c37d54b49..20394e52fe27 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -246,35 +246,19 @@ static int __init mark_nonram_nosave(void) } #endif -static bool zone_limits_final; - /* - * The memory zones past TOP_ZONE are managed by generic mm code. - * These should be set to zero since that's what every other - * architecture does. + * Zones usage: + * + * We setup ZONE_DMA to be 31-bits on all platforms and ZONE_NORMAL to be + * everything else. GFP_DMA32 page allocations automatically fall back to + * ZONE_DMA. + * + * By using 31-bit unconditionally, we can exploit ARCH_ZONE_DMA_BITS to + * inform the generic DMA mapping code. 32-bit only devices (if not handled + * by an IOMMU anyway) will take a first dip into ZONE_NORMAL and get + * otherwise served by ZONE_DMA. */ -static unsigned long max_zone_pfns[MAX_NR_ZONES] = { - [0 ... TOP_ZONE ] = ~0UL, - [TOP_ZONE + 1 ... MAX_NR_ZONES - 1] = 0 -}; - -/* - * Restrict the specified zone and all more restrictive zones - * to be below the specified pfn. May not be called after - * paging_init(). - */ -void __init limit_zone_pfn(enum zone_type zone, unsigned long pfn_limit) -{ - int i; - - if (WARN_ON(zone_limits_final)) - return; - - for (i = zone; i >= 0; i--) { - if (max_zone_pfns[i] > pfn_limit) - max_zone_pfns[i] = pfn_limit; - } -} +static unsigned long max_zone_pfns[MAX_NR_ZONES]; /* * Find the least restrictive zone that is entirely below the @@ -324,11 +308,14 @@ void __init paging_init(void) printk(KERN_DEBUG "Memory hole size: %ldMB\n", (long int)((top_of_ram - total_ram) >> 20)); +#ifdef CONFIG_ZONE_DMA + max_zone_pfns[ZONE_DMA] = min(max_low_pfn, 0x7fffffffUL >> PAGE_SHIFT); +#endif + max_zone_pfns[ZONE_NORMAL] = max_low_pfn; #ifdef CONFIG_HIGHMEM - limit_zone_pfn(ZONE_NORMAL, lowmem_end_addr >> PAGE_SHIFT); + max_zone_pfns[ZONE_HIGHMEM] = max_pfn; #endif - limit_zone_pfn(TOP_ZONE, top_of_ram >> PAGE_SHIFT); - zone_limits_final = true; + free_area_init_nodes(max_zone_pfns); mark_nonram_nosave(); -- cgit v1.2.3