cregit-Linux how code gets into the kernel

Release 4.14 arch/tile/mm/homecache.c

Directory: arch/tile/mm
/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 *
 * This code maintains the "home" for each page in the system.
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/bootmem.h>
#include <linux/rmap.h>
#include <linux/pagemap.h>
#include <linux/mutex.h>
#include <linux/interrupt.h>
#include <linux/sysctl.h>
#include <linux/pagevec.h>
#include <linux/ptrace.h>
#include <linux/timex.h>
#include <linux/cache.h>
#include <linux/smp.h>
#include <linux/module.h>
#include <linux/hugetlb.h>

#include <asm/page.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/pgalloc.h>
#include <asm/homecache.h>

#include <arch/sim.h>

#include "migrate.h"


/*
 * The noallocl2 option suppresses all use of the L2 cache to cache
 * locally from a remote home.
 */

static int __ro_after_init noallocl2;

static int __init set_noallocl2(char *str) { noallocl2 = 1; return 0; }

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early_param("noallocl2", set_noallocl2); /* * Update the irq_stat for cpus that we are going to interrupt * with TLB or cache flushes. Also handle removing dataplane cpus * from the TLB flush set, and setting dataplane_tlb_state instead. */
static void hv_flush_update(const struct cpumask *cache_cpumask, struct cpumask *tlb_cpumask, unsigned long tlb_va, unsigned long tlb_length, HV_Remote_ASID *asids, int asidcount) { struct cpumask mask; int i, cpu; cpumask_clear(&mask); if (cache_cpumask) cpumask_or(&mask, &mask, cache_cpumask); if (tlb_cpumask && tlb_length) { cpumask_or(&mask, &mask, tlb_cpumask); } for (i = 0; i < asidcount; ++i) cpumask_set_cpu(asids[i].y * smp_width + asids[i].x, &mask); /* * Don't bother to update atomically; losing a count * here is not that critical. */ for_each_cpu(cpu, &mask) ++per_cpu(irq_stat, cpu).irq_hv_flush_count; }

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/* * This wrapper function around hv_flush_remote() does several things: * * - Provides a return value error-checking panic path, since * there's never any good reason for hv_flush_remote() to fail. * - Accepts a 32-bit PFN rather than a 64-bit PA, which generally * is the type that Linux wants to pass around anyway. * - Canonicalizes that lengths of zero make cpumasks NULL. * - Handles deferring TLB flushes for dataplane tiles. * - Tracks remote interrupts in the per-cpu irq_cpustat_t. * * Note that we have to wait until the cache flush completes before * updating the per-cpu last_cache_flush word, since otherwise another * concurrent flush can race, conclude the flush has already * completed, and start to use the page while it's still dirty * remotely (running concurrently with the actual evict, presumably). */
void flush_remote(unsigned long cache_pfn, unsigned long cache_control, const struct cpumask *cache_cpumask_orig, HV_VirtAddr tlb_va, unsigned long tlb_length, unsigned long tlb_pgsize, const struct cpumask *tlb_cpumask_orig, HV_Remote_ASID *asids, int asidcount) { int rc; struct cpumask cache_cpumask_copy, tlb_cpumask_copy; struct cpumask *cache_cpumask, *tlb_cpumask; HV_PhysAddr cache_pa; mb(); /* provided just to simplify "magic hypervisor" mode */ /* * Canonicalize and copy the cpumasks. */ if (cache_cpumask_orig && cache_control) { cpumask_copy(&cache_cpumask_copy, cache_cpumask_orig); cache_cpumask = &cache_cpumask_copy; } else { cpumask_clear(&cache_cpumask_copy); cache_cpumask = NULL; } if (cache_cpumask == NULL) cache_control = 0; if (tlb_cpumask_orig && tlb_length) { cpumask_copy(&tlb_cpumask_copy, tlb_cpumask_orig); tlb_cpumask = &tlb_cpumask_copy; } else { cpumask_clear(&tlb_cpumask_copy); tlb_cpumask = NULL; } hv_flush_update(cache_cpumask, tlb_cpumask, tlb_va, tlb_length, asids, asidcount); cache_pa = (HV_PhysAddr)cache_pfn << PAGE_SHIFT; rc = hv_flush_remote(cache_pa, cache_control, cpumask_bits(cache_cpumask), tlb_va, tlb_length, tlb_pgsize, cpumask_bits(tlb_cpumask), asids, asidcount); if (rc == 0) return; pr_err("hv_flush_remote(%#llx, %#lx, %p [%*pb], %#lx, %#lx, %#lx, %p [%*pb], %p, %d) = %d\n", cache_pa, cache_control, cache_cpumask, cpumask_pr_args(&cache_cpumask_copy), (unsigned long)tlb_va, tlb_length, tlb_pgsize, tlb_cpumask, cpumask_pr_args(&tlb_cpumask_copy), asids, asidcount, rc); panic("Unsafe to continue."); }

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static void homecache_finv_page_va(void* va, int home) { int cpu = get_cpu(); if (home == cpu) { finv_buffer_local(va, PAGE_SIZE); } else if (home == PAGE_HOME_HASH) { finv_buffer_remote(va, PAGE_SIZE, 1); } else { BUG_ON(home < 0 || home >= NR_CPUS); finv_buffer_remote(va, PAGE_SIZE, 0); } put_cpu(); }

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void homecache_finv_map_page(struct page *page, int home) { unsigned long flags; unsigned long va; pte_t *ptep; pte_t pte; if (home == PAGE_HOME_UNCACHED) return; local_irq_save(flags); #ifdef CONFIG_HIGHMEM va = __fix_to_virt(FIX_KMAP_BEGIN + kmap_atomic_idx_push() + (KM_TYPE_NR * smp_processor_id())); #else va = __fix_to_virt(FIX_HOMECACHE_BEGIN + smp_processor_id()); #endif ptep = virt_to_kpte(va); pte = pfn_pte(page_to_pfn(page), PAGE_KERNEL); __set_pte(ptep, pte_set_home(pte, home)); homecache_finv_page_va((void *)va, home); __pte_clear(ptep); hv_flush_page(va, PAGE_SIZE); #ifdef CONFIG_HIGHMEM kmap_atomic_idx_pop(); #endif local_irq_restore(flags); }

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static void homecache_finv_page_home(struct page *page, int home) { if (!PageHighMem(page) && home == page_home(page)) homecache_finv_page_va(page_address(page), home); else homecache_finv_map_page(page, home); }

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static inline bool incoherent_home(int home) { return home == PAGE_HOME_IMMUTABLE || home == PAGE_HOME_INCOHERENT; }

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static void homecache_finv_page_internal(struct page *page, int force_map) { int home = page_home(page); if (home == PAGE_HOME_UNCACHED) return; if (incoherent_home(home)) { int cpu; for_each_cpu(cpu, &cpu_cacheable_map) homecache_finv_map_page(page, cpu); } else if (force_map) { /* Force if, e.g., the normal mapping is migrating. */ homecache_finv_map_page(page, home); } else { homecache_finv_page_home(page, home); } sim_validate_lines_evicted(PFN_PHYS(page_to_pfn(page)), PAGE_SIZE); }

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void homecache_finv_page(struct page *page) { homecache_finv_page_internal(page, 0); }

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void homecache_evict(const struct cpumask *mask) { flush_remote(0, HV_FLUSH_EVICT_L2, mask, 0, 0, 0, NULL, NULL, 0); }

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/* Report the home corresponding to a given PTE. */
static int pte_to_home(pte_t pte) { if (hv_pte_get_nc(pte)) return PAGE_HOME_IMMUTABLE; switch (hv_pte_get_mode(pte)) { case HV_PTE_MODE_CACHE_TILE_L3: return get_remote_cache_cpu(pte); case HV_PTE_MODE_CACHE_NO_L3: return PAGE_HOME_INCOHERENT; case HV_PTE_MODE_UNCACHED: return PAGE_HOME_UNCACHED; case HV_PTE_MODE_CACHE_HASH_L3: return PAGE_HOME_HASH; } panic("Bad PTE %#llx\n", pte.val); }

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/* Update the home of a PTE if necessary (can also be used for a pgprot_t). */
pte_t pte_set_home(pte_t pte, int home) { #if CHIP_HAS_MMIO() /* Check for MMIO mappings and pass them through. */ if (hv_pte_get_mode(pte) == HV_PTE_MODE_MMIO) return pte; #endif /* * Only immutable pages get NC mappings. If we have a * non-coherent PTE, but the underlying page is not * immutable, it's likely the result of a forced * caching setting running up against ptrace setting * the page to be writable underneath. In this case, * just keep the PTE coherent. */ if (hv_pte_get_nc(pte) && home != PAGE_HOME_IMMUTABLE) { pte = hv_pte_clear_nc(pte); pr_err("non-immutable page incoherently referenced: %#llx\n", pte.val); } switch (home) { case PAGE_HOME_UNCACHED: pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED); break; case PAGE_HOME_INCOHERENT: pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3); break; case PAGE_HOME_IMMUTABLE: /* * We could home this page anywhere, since it's immutable, * but by default just home it to follow "hash_default". */ BUG_ON(hv_pte_get_writable(pte)); if (pte_get_forcecache(pte)) { /* Upgrade "force any cpu" to "No L3" for immutable. */ if (hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_TILE_L3 && pte_get_anyhome(pte)) { pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3); } } else if (hash_default) pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3); else pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3); pte = hv_pte_set_nc(pte); break; case PAGE_HOME_HASH: pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3); break; default: BUG_ON(home < 0 || home >= NR_CPUS || !cpu_is_valid_lotar(home)); pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3); pte = set_remote_cache_cpu(pte, home); break; } if (noallocl2) pte = hv_pte_set_no_alloc_l2(pte); /* Simplify "no local and no l3" to "uncached" */ if (hv_pte_get_no_alloc_l2(pte) && hv_pte_get_no_alloc_l1(pte) && hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_NO_L3) { pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED); } /* Checking this case here gives a better panic than from the hv. */ BUG_ON(hv_pte_get_mode(pte) == 0); return pte; }

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EXPORT_SYMBOL(pte_set_home); /* * The routines in this section are the "static" versions of the normal * dynamic homecaching routines; they just set the home cache * of a kernel page once, and require a full-chip cache/TLB flush, * so they're not suitable for anything but infrequent use. */
int page_home(struct page *page) { if (PageHighMem(page)) { return PAGE_HOME_HASH; } else { unsigned long kva = (unsigned long)page_address(page); return pte_to_home(*virt_to_kpte(kva)); } }

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EXPORT_SYMBOL(page_home);
void homecache_change_page_home(struct page *page, int order, int home) { int i, pages = (1 << order); unsigned long kva; BUG_ON(PageHighMem(page)); BUG_ON(page_count(page) > 1); BUG_ON(page_mapcount(page) != 0); kva = (unsigned long) page_address(page); flush_remote(0, HV_FLUSH_EVICT_L2, &cpu_cacheable_map, kva, pages * PAGE_SIZE, PAGE_SIZE, cpu_online_mask, NULL, 0); for (i = 0; i < pages; ++i, kva += PAGE_SIZE) { pte_t *ptep = virt_to_kpte(kva); pte_t pteval = *ptep; BUG_ON(!pte_present(pteval) || pte_huge(pteval)); __set_pte(ptep, pte_set_home(pteval, home)); } }

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EXPORT_SYMBOL(homecache_change_page_home);
struct page *homecache_alloc_pages(gfp_t gfp_mask, unsigned int order, int home) { struct page *page; BUG_ON(gfp_mask & __GFP_HIGHMEM); /* must be lowmem */ page = alloc_pages(gfp_mask, order); if (page) homecache_change_page_home(page, order, home); return page; }

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EXPORT_SYMBOL(homecache_alloc_pages);
struct page *homecache_alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order, int home) { struct page *page; BUG_ON(gfp_mask & __GFP_HIGHMEM); /* must be lowmem */ page = alloc_pages_node(nid, gfp_mask, order); if (page) homecache_change_page_home(page, order, home); return page; }

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void __homecache_free_pages(struct page *page, unsigned int order) { if (put_page_testzero(page)) { homecache_change_page_home(page, order, PAGE_HOME_HASH); if (order == 0) { free_hot_cold_page(page, false); } else { init_page_count(page); __free_pages(page, order); } } }

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EXPORT_SYMBOL(__homecache_free_pages);
void homecache_free_pages(unsigned long addr, unsigned int order) { if (addr != 0) { VM_BUG_ON(!virt_addr_valid((void *)addr)); __homecache_free_pages(virt_to_page((void *)addr), order); } }

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EXPORT_SYMBOL(homecache_free_pages);

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