// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2001-2008 Silicon Graphics, Inc. All rights reserved. * * 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/nmi.h> #include <linux/genalloc.h> #include <linux/gfp.h> #include <linux/pgtable.h> #include <asm/efi.h> #include <asm/page.h> #include <asm/pal.h> #include <linux/atomic.h> #include <asm/tlbflush.h> 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_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); smp_call_function(uncached_ipi_visibility, uc_pool, 1); if (atomic_read(&uc_pool->status)) goto failed; } else if (status != PAL_VISIBILITY_OK) goto failed; preempt_disable(); 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); smp_call_function(uncached_ipi_mc_drain, uc_pool, 1); if (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 * 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_online_node(nid) { 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);