diff options
Diffstat (limited to 'kernel/arch/ia64/kernel/uncached.c')
-rw-r--r-- | kernel/arch/ia64/kernel/uncached.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/kernel/arch/ia64/kernel/uncached.c b/kernel/arch/ia64/kernel/uncached.c new file mode 100644 index 000000000..20e8a9b21 --- /dev/null +++ b/kernel/arch/ia64/kernel/uncached.c @@ -0,0 +1,281 @@ +/* + * Copyright (C) 2001-2008 Silicon Graphics, Inc. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of version 2 of the GNU General Public License + * as published by the Free Software Foundation. + * + * A simple uncached page allocator using the generic allocator. This + * allocator first utilizes the spare (spill) pages found in the EFI + * memmap and will then start converting cached pages to uncached ones + * at a granule at a time. Node awareness is implemented by having a + * pool of pages per node. + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/efi.h> +#include <linux/genalloc.h> +#include <linux/gfp.h> +#include <asm/page.h> +#include <asm/pal.h> +#include <asm/pgtable.h> +#include <linux/atomic.h> +#include <asm/tlbflush.h> +#include <asm/sn/arch.h> + + +extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *); + +struct uncached_pool { + struct gen_pool *pool; + struct mutex add_chunk_mutex; /* serialize adding a converted chunk */ + int nchunks_added; /* #of converted chunks added to pool */ + atomic_t status; /* smp called function's return status*/ +}; + +#define MAX_CONVERTED_CHUNKS_PER_NODE 2 + +struct uncached_pool uncached_pools[MAX_NUMNODES]; + + +static void uncached_ipi_visibility(void *data) +{ + int status; + struct uncached_pool *uc_pool = (struct uncached_pool *)data; + + status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL); + if ((status != PAL_VISIBILITY_OK) && + (status != PAL_VISIBILITY_OK_REMOTE_NEEDED)) + atomic_inc(&uc_pool->status); +} + + +static void uncached_ipi_mc_drain(void *data) +{ + int status; + struct uncached_pool *uc_pool = (struct uncached_pool *)data; + + status = ia64_pal_mc_drain(); + if (status != PAL_STATUS_SUCCESS) + atomic_inc(&uc_pool->status); +} + + +/* + * Add a new chunk of uncached memory pages to the specified pool. + * + * @pool: pool to add new chunk of uncached memory to + * @nid: node id of node to allocate memory from, or -1 + * + * This is accomplished by first allocating a granule of cached memory pages + * and then converting them to uncached memory pages. + */ +static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid) +{ + struct page *page; + int status, i, nchunks_added = uc_pool->nchunks_added; + unsigned long c_addr, uc_addr; + + if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0) + return -1; /* interrupted by a signal */ + + if (uc_pool->nchunks_added > nchunks_added) { + /* someone added a new chunk while we were waiting */ + mutex_unlock(&uc_pool->add_chunk_mutex); + return 0; + } + + if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) { + mutex_unlock(&uc_pool->add_chunk_mutex); + return -1; + } + + /* attempt to allocate a granule's worth of cached memory pages */ + + page = alloc_pages_exact_node(nid, + GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE, + IA64_GRANULE_SHIFT-PAGE_SHIFT); + if (!page) { + mutex_unlock(&uc_pool->add_chunk_mutex); + return -1; + } + + /* convert the memory pages from cached to uncached */ + + c_addr = (unsigned long)page_address(page); + uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET; + + /* + * There's a small race here where it's possible for someone to + * access the page through /dev/mem halfway through the conversion + * to uncached - not sure it's really worth bothering about + */ + for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++) + SetPageUncached(&page[i]); + + flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE); + + status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL); + if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) { + atomic_set(&uc_pool->status, 0); + status = smp_call_function(uncached_ipi_visibility, uc_pool, 1); + if (status || atomic_read(&uc_pool->status)) + goto failed; + } else if (status != PAL_VISIBILITY_OK) + goto failed; + + preempt_disable(); + + if (ia64_platform_is("sn2")) + sn_flush_all_caches(uc_addr, IA64_GRANULE_SIZE); + else + flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE); + + /* flush the just introduced uncached translation from the TLB */ + local_flush_tlb_all(); + + preempt_enable(); + + status = ia64_pal_mc_drain(); + if (status != PAL_STATUS_SUCCESS) + goto failed; + atomic_set(&uc_pool->status, 0); + status = smp_call_function(uncached_ipi_mc_drain, uc_pool, 1); + if (status || atomic_read(&uc_pool->status)) + goto failed; + + /* + * The chunk of memory pages has been converted to uncached so now we + * can add it to the pool. + */ + status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid); + if (status) + goto failed; + + uc_pool->nchunks_added++; + mutex_unlock(&uc_pool->add_chunk_mutex); + return 0; + + /* failed to convert or add the chunk so give it back to the kernel */ +failed: + for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++) + ClearPageUncached(&page[i]); + + free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT); + mutex_unlock(&uc_pool->add_chunk_mutex); + return -1; +} + + +/* + * uncached_alloc_page + * + * @starting_nid: node id of node to start with, or -1 + * @n_pages: number of contiguous pages to allocate + * + * Allocate the specified number of contiguous uncached pages on the + * the requested node. If not enough contiguous uncached pages are available + * on the requested node, roundrobin starting with the next higher node. + */ +unsigned long uncached_alloc_page(int starting_nid, int n_pages) +{ + unsigned long uc_addr; + struct uncached_pool *uc_pool; + int nid; + + if (unlikely(starting_nid >= MAX_NUMNODES)) + return 0; + + if (starting_nid < 0) + starting_nid = numa_node_id(); + nid = starting_nid; + + do { + if (!node_state(nid, N_HIGH_MEMORY)) + continue; + uc_pool = &uncached_pools[nid]; + if (uc_pool->pool == NULL) + continue; + do { + uc_addr = gen_pool_alloc(uc_pool->pool, + n_pages * PAGE_SIZE); + if (uc_addr != 0) + return uc_addr; + } while (uncached_add_chunk(uc_pool, nid) == 0); + + } while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid); + + return 0; +} +EXPORT_SYMBOL(uncached_alloc_page); + + +/* + * uncached_free_page + * + * @uc_addr: uncached address of first page to free + * @n_pages: number of contiguous pages to free + * + * Free the specified number of uncached pages. + */ +void uncached_free_page(unsigned long uc_addr, int n_pages) +{ + int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET); + struct gen_pool *pool = uncached_pools[nid].pool; + + if (unlikely(pool == NULL)) + return; + + if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET) + panic("uncached_free_page invalid address %lx\n", uc_addr); + + gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE); +} +EXPORT_SYMBOL(uncached_free_page); + + +/* + * uncached_build_memmap, + * + * @uc_start: uncached starting address of a chunk of uncached memory + * @uc_end: uncached ending address of a chunk of uncached memory + * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc()) + * + * Called at boot time to build a map of pages that can be used for + * memory special operations. + */ +static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg) +{ + int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET); + struct gen_pool *pool = uncached_pools[nid].pool; + size_t size = uc_end - uc_start; + + touch_softlockup_watchdog(); + + if (pool != NULL) { + memset((char *)uc_start, 0, size); + (void) gen_pool_add(pool, uc_start, size, nid); + } + return 0; +} + + +static int __init uncached_init(void) +{ + int nid; + + for_each_node_state(nid, N_ONLINE) { + uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid); + mutex_init(&uncached_pools[nid].add_chunk_mutex); + } + + efi_memmap_walk_uc(uncached_build_memmap, NULL); + return 0; +} + +__initcall(uncached_init); |