/* * Handle caching attributes in page tables (PAT) * * Authors: Venkatesh Pallipadi * Suresh B Siddha * * Loosely based on earlier PAT patchset from Eric Biederman and Andi Kleen. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "pat_internal.h" #ifdef CONFIG_X86_PAT int __read_mostly pat_enabled = 1; static inline void pat_disable(const char *reason) { pat_enabled = 0; printk(KERN_INFO "%s\n", reason); } static int __init nopat(char *str) { pat_disable("PAT support disabled."); return 0; } early_param("nopat", nopat); #else static inline void pat_disable(const char *reason) { (void)reason; } #endif int pat_debug_enable; static int __init pat_debug_setup(char *str) { pat_debug_enable = 1; return 0; } __setup("debugpat", pat_debug_setup); static u64 __read_mostly boot_pat_state; enum { PAT_UC = 0, /* uncached */ PAT_WC = 1, /* Write combining */ PAT_WT = 4, /* Write Through */ PAT_WP = 5, /* Write Protected */ PAT_WB = 6, /* Write Back (default) */ PAT_UC_MINUS = 7, /* UC, but can be overriden by MTRR */ }; #define PAT(x, y) ((u64)PAT_ ## y << ((x)*8)) void pat_init(void) { u64 pat; bool boot_cpu = !boot_pat_state; if (!pat_enabled) return; if (!cpu_has_pat) { if (!boot_pat_state) { pat_disable("PAT not supported by CPU."); return; } else { /* * If this happens we are on a secondary CPU, but * switched to PAT on the boot CPU. We have no way to * undo PAT. */ printk(KERN_ERR "PAT enabled, " "but not supported by secondary CPU\n"); BUG(); } } /* Set PWT to Write-Combining. All other bits stay the same */ /* * PTE encoding used in Linux: * PAT * |PCD * ||PWT * ||| * 000 WB _PAGE_CACHE_WB * 001 WC _PAGE_CACHE_WC * 010 UC- _PAGE_CACHE_UC_MINUS * 011 UC _PAGE_CACHE_UC * PAT bit unused */ pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) | PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC); /* Boot CPU check */ if (!boot_pat_state) rdmsrl(MSR_IA32_CR_PAT, boot_pat_state); wrmsrl(MSR_IA32_CR_PAT, pat); if (boot_cpu) printk(KERN_INFO "x86 PAT enabled: cpu %d, old 0x%Lx, new 0x%Lx\n", smp_processor_id(), boot_pat_state, pat); } #undef PAT static DEFINE_SPINLOCK(memtype_lock); /* protects memtype accesses */ /* * Does intersection of PAT memory type and MTRR memory type and returns * the resulting memory type as PAT understands it. * (Type in pat and mtrr will not have same value) * The intersection is based on "Effective Memory Type" tables in IA-32 * SDM vol 3a */ static unsigned long pat_x_mtrr_type(u64 start, u64 end, unsigned long req_type) { /* * Look for MTRR hint to get the effective type in case where PAT * request is for WB. */ if (req_type == _PAGE_CACHE_WB) { u8 mtrr_type; mtrr_type = mtrr_type_lookup(start, end); if (mtrr_type != MTRR_TYPE_WRBACK) return _PAGE_CACHE_UC_MINUS; return _PAGE_CACHE_WB; } return req_type; } struct pagerange_state { unsigned long cur_pfn; int ram; int not_ram; }; static int pagerange_is_ram_callback(unsigned long initial_pfn, unsigned long total_nr_pages, void *arg) { struct pagerange_state *state = arg; state->not_ram |= initial_pfn > state->cur_pfn; state->ram |= total_nr_pages > 0; state->cur_pfn = initial_pfn + total_nr_pages; return state->ram && state->not_ram; } static int pat_pagerange_is_ram(resource_size_t start, resource_size_t end) { int ret = 0; unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long end_pfn = (end + PAGE_SIZE - 1) >> PAGE_SHIFT; struct pagerange_state state = {start_pfn, 0, 0}; /* * For legacy reasons, physical address range in the legacy ISA * region is tracked as non-RAM. This will allow users of * /dev/mem to map portions of legacy ISA region, even when * some of those portions are listed(or not even listed) with * different e820 types(RAM/reserved/..) */ if (start_pfn < ISA_END_ADDRESS >> PAGE_SHIFT) start_pfn = ISA_END_ADDRESS >> PAGE_SHIFT; if (start_pfn < end_pfn) { ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &state, pagerange_is_ram_callback); } return (ret > 0) ? -1 : (state.ram ? 1 : 0); } /* * For RAM pages, we use page flags to mark the pages with appropriate type. * Here we do two pass: * - Find the memtype of all the pages in the range, look for any conflicts * - In case of no conflicts, set the new memtype for pages in the range */ static int reserve_ram_pages_type(u64 start, u64 end, unsigned long req_type, unsigned long *new_type) { struct page *page; u64 pfn; if (req_type == _PAGE_CACHE_UC) { /* We do not support strong UC */ WARN_ON_ONCE(1); req_type = _PAGE_CACHE_UC_MINUS; } for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) { unsigned long type; page = pfn_to_page(pfn); type = get_page_memtype(page); if (type != -1) { printk(KERN_INFO "reserve_ram_pages_type failed [mem %#010Lx-%#010Lx], track 0x%lx, req 0x%lx\n", start, end - 1, type, req_type); if (new_type) *new_type = type; return -EBUSY; } } if (new_type) *new_type = req_type; for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) { page = pfn_to_page(pfn); set_page_memtype(page, req_type); } return 0; } static int free_ram_pages_type(u64 start, u64 end) { struct page *page; u64 pfn; for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) { page = pfn_to_page(pfn); set_page_memtype(page, -1); } return 0; } /* * req_type typically has one of the: * - _PAGE_CACHE_WB * - _PAGE_CACHE_WC * - _PAGE_CACHE_UC_MINUS * - _PAGE_CACHE_UC * * If new_type is NULL, function will return an error if it cannot reserve the * region with req_type. If new_type is non-NULL, function will return * available type in new_type in case of no error. In case of any error * it will return a negative return value. */ int reserve_memtype(u64 start, u64 end, unsigned long req_type, unsigned long *new_type) { struct memtype *new; unsigned long actual_type; int is_range_ram; int err = 0; BUG_ON(start >= end); /* end is exclusive */ if (!pat_enabled) { /* This is identical to page table setting without PAT */ if (new_type) { if (req_type == _PAGE_CACHE_WC) *new_type = _PAGE_CACHE_UC_MINUS; else *new_type = req_type & _PAGE_CACHE_MASK; } return 0; } /* Low ISA region is always mapped WB in page table. No need to track */ if (x86_platform.is_untracked_pat_range(start, end)) { if (new_type) *new_type = _PAGE_CACHE_WB; return 0; } /* * Call mtrr_lookup to get the type hint. This is an * optimization for /dev/mem mmap'ers into WB memory (BIOS * tools and ACPI tools). Use WB request for WB memory and use * UC_MINUS otherwise. */ actual_type = pat_x_mtrr_type(start, end, req_type & _PAGE_CACHE_MASK); if (new_type) *new_type = actual_type; is_range_ram = pat_pagerange_is_ram(start, end); if (is_range_ram == 1) { err = reserve_ram_pages_type(start, end, req_type, new_type); return err; } else if (is_range_ram < 0) { return -EINVAL; } new = kzalloc(sizeof(struct memtype), GFP_KERNEL); if (!new) return -ENOMEM; new->start = start; new->end = end; new->type = actual_type; spin_lock(&memtype_lock); err = rbt_memtype_check_insert(new, new_type); if (err) { printk(KERN_INFO "reserve_memtype failed [mem %#010Lx-%#010Lx], track %s, req %s\n", start, end - 1, cattr_name(new->type), cattr_name(req_type)); kfree(new); spin_unlock(&memtype_lock); return err; } spin_unlock(&memtype_lock); dprintk("reserve_memtype added [mem %#010Lx-%#010Lx], track %s, req %s, ret %s\n", start, end - 1, cattr_name(new->type), cattr_name(req_type), new_type ? cattr_name(*new_type) : "-"); return err; } int free_memtype(u64 start, u64 end) { int err = -EINVAL; int is_range_ram; struct memtype *entry; if (!pat_enabled) return 0; /* Low ISA region is always mapped WB. No need to track */ if (x86_platform.is_untracked_pat_range(start, end)) return 0; is_range_ram = pat_pagerange_is_ram(start, end); if (is_range_ram == 1) { err = free_ram_pages_type(start, end); return err; } else if (is_range_ram < 0) { return -EINVAL; } spin_lock(&memtype_lock); entry = rbt_memtype_erase(start, end); spin_unlock(&memtype_lock); if (!entry) { printk(KERN_INFO "%s:%d freeing invalid memtype [mem %#010Lx-%#010Lx]\n", current->comm, current->pid, start, end - 1); return -EINVAL; } kfree(entry); dprintk("free_memtype request [mem %#010Lx-%#010Lx]\n", start, end - 1); return 0; } /** * lookup_memtype - Looksup the memory type for a physical address * @paddr: physical address of which memory type needs to be looked up * * Only to be called when PAT is enabled * * Returns _PAGE_CACHE_WB, _PAGE_CACHE_WC, _PAGE_CACHE_UC_MINUS or * _PAGE_CACHE_UC */ static unsigned long lookup_memtype(u64 paddr) { int rettype = _PAGE_CACHE_WB; struct memtype *entry; if (x86_platform.is_untracked_pat_range(paddr, paddr + PAGE_SIZE)) return rettype; if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) { struct page *page; page = pfn_to_page(paddr >> PAGE_SHIFT); rettype = get_page_memtype(page); /* * -1 from get_page_memtype() implies RAM page is in its * default state and not reserved, and hence of type WB */ if (rettype == -1) rettype = _PAGE_CACHE_WB; return rettype; } spin_lock(&memtype_lock); entry = rbt_memtype_lookup(paddr); if (entry != NULL) rettype = entry->type; else rettype = _PAGE_CACHE_UC_MINUS; spin_unlock(&memtype_lock); return rettype; } /** * io_reserve_memtype - Request a memory type mapping for a region of memory * @start: start (physical address) of the region * @end: end (physical address) of the region * @type: A pointer to memtype, with requested type. On success, requested * or any other compatible type that was available for the region is returned * * On success, returns 0 * On failure, returns non-zero */ int io_reserve_memtype(resource_size_t start, resource_size_t end, unsigned long *type) { resource_size_t size = end - start; unsigned long req_type = *type; unsigned long new_type; int ret; WARN_ON_ONCE(iomem_map_sanity_check(start, size)); ret = reserve_memtype(start, end, req_type, &new_type); if (ret) goto out_err; if (!is_new_memtype_allowed(start, size, req_type, new_type)) goto out_free; if (kernel_map_sync_memtype(start, size, new_type) < 0) goto out_free; *type = new_type; return 0; out_free: free_memtype(start, end); ret = -EBUSY; out_err: return ret; } /** * io_free_memtype - Release a memory type mapping for a region of memory * @start: start (physical address) of the region * @end: end (physical address) of the region */ void io_free_memtype(resource_size_t start, resource_size_t end) { free_memtype(start, end); } pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { return vma_prot; } #ifdef CONFIG_STRICT_DEVMEM /* This check is done in drivers/char/mem.c in case of STRICT_DEVMEM*/ static inline int range_is_allowed(unsigned long pfn, unsigned long size) { return 1; } #else /* This check is needed to avoid cache aliasing when PAT is enabled */ static inline int range_is_allowed(unsigned long pfn, unsigned long size) { u64 from = ((u64)pfn) << PAGE_SHIFT; u64 to = from + size; u64 cursor = from; if (!pat_enabled) return 1; while (cursor < to) { if (!devmem_is_allowed(pfn)) { printk(KERN_INFO "Program %s tried to access /dev/mem between [mem %#010Lx-%#010Lx]\n", current->comm, from, to - 1); return 0; } cursor += PAGE_SIZE; pfn++; } return 1; } #endif /* CONFIG_STRICT_DEVMEM */ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, unsigned long size, pgprot_t *vma_prot) { unsigned long flags = _PAGE_CACHE_WB; if (!range_is_allowed(pfn, size)) return 0; if (file->f_flags & O_DSYNC) flags = _PAGE_CACHE_UC_MINUS; #ifdef CONFIG_X86_32 /* * On the PPro and successors, the MTRRs are used to set * memory types for physical addresses outside main memory, * so blindly setting UC or PWT on those pages is wrong. * For Pentiums and earlier, the surround logic should disable * caching for the high addresses through the KEN pin, but * we maintain the tradition of paranoia in this code. */ if (!pat_enabled && !(boot_cpu_has(X86_FEATURE_MTRR) || boot_cpu_has(X86_FEATURE_K6_MTRR) || boot_cpu_has(X86_FEATURE_CYRIX_ARR) || boot_cpu_has(X86_FEATURE_CENTAUR_MCR)) && (pfn << PAGE_SHIFT) >= __pa(high_memory)) { flags = _PAGE_CACHE_UC; } #endif *vma_prot = __pgprot((pgprot_val(*vma_prot) & ~_PAGE_CACHE_MASK) | flags); return 1; } /* * Change the memory type for the physial address range in kernel identity * mapping space if that range is a part of identity map. */ int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags) { unsigned long id_sz; if (base >= __pa(high_memory)) return 0; id_sz = (__pa(high_memory) < base + size) ? __pa(high_memory) - base : size; if (ioremap_change_attr((unsigned long)__va(base), id_sz, flags) < 0) { printk(KERN_INFO "%s:%d ioremap_change_attr failed %s " "for [mem %#010Lx-%#010Lx]\n", current->comm, current->pid, cattr_name(flags), base, (unsigned long long)(base + size-1)); return -EINVAL; } return 0; } /* * Internal interface to reserve a range of physical memory with prot. * Reserved non RAM regions only and after successful reserve_memtype, * this func also keeps identity mapping (if any) in sync with this new prot. */ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot, int strict_prot) { int is_ram = 0; int ret; unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK); unsigned long flags = want_flags; is_ram = pat_pagerange_is_ram(paddr, paddr + size); /* * reserve_pfn_range() for RAM pages. We do not refcount to keep * track of number of mappings of RAM pages. We can assert that * the type requested matches the type of first page in the range. */ if (is_ram) { if (!pat_enabled) return 0; flags = lookup_memtype(paddr); if (want_flags != flags) { printk(KERN_WARNING "%s:%d map pfn RAM range req %s for [mem %#010Lx-%#010Lx], got %s\n", current->comm, current->pid, cattr_name(want_flags), (unsigned long long)paddr, (unsigned long long)(paddr + size - 1), cattr_name(flags)); *vma_prot = __pgprot((pgprot_val(*vma_prot) & (~_PAGE_CACHE_MASK)) | flags); } return 0; } ret = reserve_memtype(paddr, paddr + size, want_flags, &flags); if (ret) return ret; if (flags != want_flags) { if (strict_prot || !is_new_memtype_allowed(paddr, size, want_flags, flags)) { free_memtype(paddr, paddr + size); printk(KERN_ERR "%s:%d map pfn expected mapping type %s" " for [mem %#010Lx-%#010Lx], got %s\n", current->comm, current->pid, cattr_name(want_flags), (unsigned long long)paddr, (unsigned long long)(paddr + size - 1), cattr_name(flags)); return -EINVAL; } /* * We allow returning different type than the one requested in * non strict case. */ *vma_prot = __pgprot((pgprot_val(*vma_prot) & (~_PAGE_CACHE_MASK)) | flags); } if (kernel_map_sync_memtype(paddr, size, flags) < 0) { free_memtype(paddr, paddr + size); return -EINVAL; } return 0; } /* * Internal interface to free a range of physical memory. * Frees non RAM regions only. */ static void free_pfn_range(u64 paddr, unsigned long size) { int is_ram; is_ram = pat_pagerange_is_ram(paddr, paddr + size); if (is_ram == 0) free_memtype(paddr, paddr + size); } /* * track_pfn_copy is called when vma that is covering the pfnmap gets * copied through copy_page_range(). * * If the vma has a linear pfn mapping for the entire range, we get the prot * from pte and reserve the entire vma range with single reserve_pfn_range call. */ int track_pfn_copy(struct vm_area_struct *vma) { resource_size_t paddr; unsigned long prot; unsigned long vma_size = vma->vm_end - vma->vm_start; pgprot_t pgprot; if (is_linear_pfn_mapping(vma)) { /* * reserve the whole chunk covered by vma. We need the * starting address and protection from pte. */ if (follow_phys(vma, vma->vm_start, 0, &prot, &paddr)) { WARN_ON_ONCE(1); return -EINVAL; } pgprot = __pgprot(prot); return reserve_pfn_range(paddr, vma_size, &pgprot, 1); } return 0; } /* * prot is passed in as a parameter for the new mapping. If the vma has a * linear pfn mapping for the entire range reserve the entire vma range with * single reserve_pfn_range call. */ int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot, unsigned long pfn, unsigned long size) { resource_size_t paddr = (resource_size_t)pfn << PAGE_SHIFT; unsigned long flags; /* reserve the whole chunk starting from paddr */ if (is_linear_pfn_mapping(vma)) return reserve_pfn_range(paddr, size, prot, 0); if (!pat_enabled) return 0; /* * For anything smaller than the vma size we set prot based on the * lookup. */ flags = lookup_memtype(paddr); /* Check memtype for the remaining pages */ while (size > PAGE_SIZE) { size -= PAGE_SIZE; paddr += PAGE_SIZE; if (flags != lookup_memtype(paddr)) return -EINVAL; } *prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) | flags); return 0; } int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, unsigned long pfn) { unsigned long flags; if (!pat_enabled) return 0; /* Set prot based on lookup */ flags = lookup_memtype((resource_size_t)pfn << PAGE_SHIFT); *prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) | flags); return 0; } /* * untrack_pfn is called while unmapping a pfnmap for a region. * untrack can be called for a specific region indicated by pfn and size or * can be for the entire vma (in which case pfn, size are zero). */ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, unsigned long size) { resource_size_t paddr; unsigned long prot; if (!is_linear_pfn_mapping(vma)) return; /* free the chunk starting from pfn or the whole chunk */ paddr = (resource_size_t)pfn << PAGE_SHIFT; if (!paddr && !size) { if (follow_phys(vma, vma->vm_start, 0, &prot, &paddr)) { WARN_ON_ONCE(1); return; } size = vma->vm_end - vma->vm_start; } free_pfn_range(paddr, size); } pgprot_t pgprot_writecombine(pgprot_t prot) { if (pat_enabled) return __pgprot(pgprot_val(prot) | _PAGE_CACHE_WC); else return pgprot_noncached(prot); } EXPORT_SYMBOL_GPL(pgprot_writecombine); #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT) static struct memtype *memtype_get_idx(loff_t pos) { struct memtype *print_entry; int ret; print_entry = kzalloc(sizeof(struct memtype), GFP_KERNEL); if (!print_entry) return NULL; spin_lock(&memtype_lock); ret = rbt_memtype_copy_nth_element(print_entry, pos); spin_unlock(&memtype_lock); if (!ret) { return print_entry; } else { kfree(print_entry); return NULL; } } static void *memtype_seq_start(struct seq_file *seq, loff_t *pos) { if (*pos == 0) { ++*pos; seq_printf(seq, "PAT memtype list:\n"); } return memtype_get_idx(*pos); } static void *memtype_seq_next(struct seq_file *seq, void *v, loff_t *pos) { ++*pos; return memtype_get_idx(*pos); } static void memtype_seq_stop(struct seq_file *seq, void *v) { } static int memtype_seq_show(struct seq_file *seq, void *v) { struct memtype *print_entry = (struct memtype *)v; seq_printf(seq, "%s @ 0x%Lx-0x%Lx\n", cattr_name(print_entry->type), print_entry->start, print_entry->end); kfree(print_entry); return 0; } static const struct seq_operations memtype_seq_ops = { .start = memtype_seq_start, .next = memtype_seq_next, .stop = memtype_seq_stop, .show = memtype_seq_show, }; static int memtype_seq_open(struct inode *inode, struct file *file) { return seq_open(file, &memtype_seq_ops); } static const struct file_operations memtype_fops = { .open = memtype_seq_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; static int __init pat_memtype_list_init(void) { if (pat_enabled) { debugfs_create_file("pat_memtype_list", S_IRUSR, arch_debugfs_dir, NULL, &memtype_fops); } return 0; } late_initcall(pat_memtype_list_init); #endif /* CONFIG_DEBUG_FS && CONFIG_X86_PAT */