397 lines
11 KiB
C
397 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* adi_64.c: support for ADI (Application Data Integrity) feature on
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* sparc m7 and newer processors. This feature is also known as
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* SSM (Silicon Secured Memory).
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*
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* Copyright (C) 2016 Oracle and/or its affiliates. All rights reserved.
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* Author: Khalid Aziz (khalid.aziz@oracle.com)
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*/
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/mm_types.h>
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#include <asm/mdesc.h>
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#include <asm/adi_64.h>
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#include <asm/mmu_64.h>
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#include <asm/pgtable_64.h>
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/* Each page of storage for ADI tags can accommodate tags for 128
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* pages. When ADI enabled pages are being swapped out, it would be
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* prudent to allocate at least enough tag storage space to accommodate
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* SWAPFILE_CLUSTER number of pages. Allocate enough tag storage to
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* store tags for four SWAPFILE_CLUSTER pages to reduce need for
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* further allocations for same vma.
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*/
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#define TAG_STORAGE_PAGES 8
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struct adi_config adi_state;
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EXPORT_SYMBOL(adi_state);
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/* mdesc_adi_init() : Parse machine description provided by the
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* hypervisor to detect ADI capabilities
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*
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* Hypervisor reports ADI capabilities of platform in "hwcap-list" property
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* for "cpu" node. If the platform supports ADI, "hwcap-list" property
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* contains the keyword "adp". If the platform supports ADI, "platform"
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* node will contain "adp-blksz", "adp-nbits" and "ue-on-adp" properties
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* to describe the ADI capabilities.
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*/
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void __init mdesc_adi_init(void)
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{
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struct mdesc_handle *hp = mdesc_grab();
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const char *prop;
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u64 pn, *val;
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int len;
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if (!hp)
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goto adi_not_found;
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pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
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if (pn == MDESC_NODE_NULL)
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goto adi_not_found;
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prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
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if (!prop)
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goto adi_not_found;
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/*
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* Look for "adp" keyword in hwcap-list which would indicate
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* ADI support
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*/
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adi_state.enabled = false;
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while (len) {
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int plen;
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if (!strcmp(prop, "adp")) {
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adi_state.enabled = true;
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break;
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}
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plen = strlen(prop) + 1;
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prop += plen;
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len -= plen;
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}
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if (!adi_state.enabled)
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goto adi_not_found;
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/* Find the ADI properties in "platform" node. If all ADI
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* properties are not found, ADI support is incomplete and
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* do not enable ADI in the kernel.
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*/
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pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
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if (pn == MDESC_NODE_NULL)
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goto adi_not_found;
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val = (u64 *) mdesc_get_property(hp, pn, "adp-blksz", &len);
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if (!val)
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goto adi_not_found;
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adi_state.caps.blksz = *val;
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val = (u64 *) mdesc_get_property(hp, pn, "adp-nbits", &len);
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if (!val)
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goto adi_not_found;
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adi_state.caps.nbits = *val;
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val = (u64 *) mdesc_get_property(hp, pn, "ue-on-adp", &len);
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if (!val)
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goto adi_not_found;
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adi_state.caps.ue_on_adi = *val;
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/* Some of the code to support swapping ADI tags is written
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* assumption that two ADI tags can fit inside one byte. If
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* this assumption is broken by a future architecture change,
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* that code will have to be revisited. If that were to happen,
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* disable ADI support so we do not get unpredictable results
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* with programs trying to use ADI and their pages getting
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* swapped out
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*/
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if (adi_state.caps.nbits > 4) {
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pr_warn("WARNING: ADI tag size >4 on this platform. Disabling AADI support\n");
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adi_state.enabled = false;
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}
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mdesc_release(hp);
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return;
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adi_not_found:
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adi_state.enabled = false;
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adi_state.caps.blksz = 0;
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adi_state.caps.nbits = 0;
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if (hp)
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mdesc_release(hp);
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}
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tag_storage_desc_t *find_tag_store(struct mm_struct *mm,
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struct vm_area_struct *vma,
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unsigned long addr)
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{
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tag_storage_desc_t *tag_desc = NULL;
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unsigned long i, max_desc, flags;
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/* Check if this vma already has tag storage descriptor
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* allocated for it.
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*/
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max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
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if (mm->context.tag_store) {
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tag_desc = mm->context.tag_store;
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spin_lock_irqsave(&mm->context.tag_lock, flags);
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for (i = 0; i < max_desc; i++) {
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if ((addr >= tag_desc->start) &&
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((addr + PAGE_SIZE - 1) <= tag_desc->end))
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break;
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tag_desc++;
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}
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spin_unlock_irqrestore(&mm->context.tag_lock, flags);
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/* If no matching entries were found, this must be a
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* freshly allocated page
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*/
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if (i >= max_desc)
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tag_desc = NULL;
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}
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return tag_desc;
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}
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tag_storage_desc_t *alloc_tag_store(struct mm_struct *mm,
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struct vm_area_struct *vma,
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unsigned long addr)
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{
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unsigned char *tags;
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unsigned long i, size, max_desc, flags;
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tag_storage_desc_t *tag_desc, *open_desc;
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unsigned long end_addr, hole_start, hole_end;
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max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
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open_desc = NULL;
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hole_start = 0;
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hole_end = ULONG_MAX;
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end_addr = addr + PAGE_SIZE - 1;
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/* Check if this vma already has tag storage descriptor
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* allocated for it.
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*/
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spin_lock_irqsave(&mm->context.tag_lock, flags);
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if (mm->context.tag_store) {
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tag_desc = mm->context.tag_store;
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/* Look for a matching entry for this address. While doing
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* that, look for the first open slot as well and find
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* the hole in already allocated range where this request
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* will fit in.
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*/
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for (i = 0; i < max_desc; i++) {
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if (tag_desc->tag_users == 0) {
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if (open_desc == NULL)
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open_desc = tag_desc;
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} else {
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if ((addr >= tag_desc->start) &&
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(tag_desc->end >= (addr + PAGE_SIZE - 1))) {
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tag_desc->tag_users++;
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goto out;
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}
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}
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if ((tag_desc->start > end_addr) &&
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(tag_desc->start < hole_end))
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hole_end = tag_desc->start;
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if ((tag_desc->end < addr) &&
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(tag_desc->end > hole_start))
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hole_start = tag_desc->end;
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tag_desc++;
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}
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} else {
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size = sizeof(tag_storage_desc_t)*max_desc;
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mm->context.tag_store = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
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if (mm->context.tag_store == NULL) {
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tag_desc = NULL;
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goto out;
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}
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tag_desc = mm->context.tag_store;
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for (i = 0; i < max_desc; i++, tag_desc++)
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tag_desc->tag_users = 0;
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open_desc = mm->context.tag_store;
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i = 0;
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}
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/* Check if we ran out of tag storage descriptors */
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if (open_desc == NULL) {
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tag_desc = NULL;
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goto out;
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}
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/* Mark this tag descriptor slot in use and then initialize it */
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tag_desc = open_desc;
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tag_desc->tag_users = 1;
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/* Tag storage has not been allocated for this vma and space
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* is available in tag storage descriptor. Since this page is
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* being swapped out, there is high probability subsequent pages
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* in the VMA will be swapped out as well. Allocate pages to
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* store tags for as many pages in this vma as possible but not
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* more than TAG_STORAGE_PAGES. Each byte in tag space holds
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* two ADI tags since each ADI tag is 4 bits. Each ADI tag
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* covers adi_blksize() worth of addresses. Check if the hole is
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* big enough to accommodate full address range for using
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* TAG_STORAGE_PAGES number of tag pages.
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*/
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size = TAG_STORAGE_PAGES * PAGE_SIZE;
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end_addr = addr + (size*2*adi_blksize()) - 1;
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/* Check for overflow. If overflow occurs, allocate only one page */
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if (end_addr < addr) {
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size = PAGE_SIZE;
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end_addr = addr + (size*2*adi_blksize()) - 1;
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/* If overflow happens with the minimum tag storage
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* allocation as well, adjust ending address for this
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* tag storage.
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*/
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if (end_addr < addr)
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end_addr = ULONG_MAX;
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}
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if (hole_end < end_addr) {
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/* Available hole is too small on the upper end of
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* address. Can we expand the range towards the lower
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* address and maximize use of this slot?
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*/
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unsigned long tmp_addr;
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end_addr = hole_end - 1;
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tmp_addr = end_addr - (size*2*adi_blksize()) + 1;
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/* Check for underflow. If underflow occurs, allocate
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* only one page for storing ADI tags
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*/
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if (tmp_addr > addr) {
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size = PAGE_SIZE;
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tmp_addr = end_addr - (size*2*adi_blksize()) - 1;
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/* If underflow happens with the minimum tag storage
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* allocation as well, adjust starting address for
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* this tag storage.
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*/
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if (tmp_addr > addr)
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tmp_addr = 0;
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}
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if (tmp_addr < hole_start) {
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/* Available hole is restricted on lower address
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* end as well
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*/
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tmp_addr = hole_start + 1;
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}
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addr = tmp_addr;
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size = (end_addr + 1 - addr)/(2*adi_blksize());
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size = (size + (PAGE_SIZE-adi_blksize()))/PAGE_SIZE;
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size = size * PAGE_SIZE;
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}
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tags = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
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if (tags == NULL) {
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tag_desc->tag_users = 0;
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tag_desc = NULL;
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goto out;
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}
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tag_desc->start = addr;
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tag_desc->tags = tags;
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tag_desc->end = end_addr;
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out:
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spin_unlock_irqrestore(&mm->context.tag_lock, flags);
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return tag_desc;
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}
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void del_tag_store(tag_storage_desc_t *tag_desc, struct mm_struct *mm)
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{
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unsigned long flags;
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unsigned char *tags = NULL;
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spin_lock_irqsave(&mm->context.tag_lock, flags);
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tag_desc->tag_users--;
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if (tag_desc->tag_users == 0) {
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tag_desc->start = tag_desc->end = 0;
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/* Do not free up the tag storage space allocated
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* by the first descriptor. This is persistent
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* emergency tag storage space for the task.
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*/
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if (tag_desc != mm->context.tag_store) {
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tags = tag_desc->tags;
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tag_desc->tags = NULL;
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}
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}
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spin_unlock_irqrestore(&mm->context.tag_lock, flags);
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kfree(tags);
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}
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#define tag_start(addr, tag_desc) \
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((tag_desc)->tags + ((addr - (tag_desc)->start)/(2*adi_blksize())))
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/* Retrieve any saved ADI tags for the page being swapped back in and
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* restore these tags to the newly allocated physical page.
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*/
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void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long addr, pte_t pte)
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{
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unsigned char *tag;
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tag_storage_desc_t *tag_desc;
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unsigned long paddr, tmp, version1, version2;
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/* Check if the swapped out page has an ADI version
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* saved. If yes, restore version tag to the newly
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* allocated page.
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*/
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tag_desc = find_tag_store(mm, vma, addr);
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if (tag_desc == NULL)
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return;
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tag = tag_start(addr, tag_desc);
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paddr = pte_val(pte) & _PAGE_PADDR_4V;
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for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
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version1 = (*tag) >> 4;
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version2 = (*tag) & 0x0f;
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*tag++ = 0;
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asm volatile("stxa %0, [%1] %2\n\t"
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:
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: "r" (version1), "r" (tmp),
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"i" (ASI_MCD_REAL));
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tmp += adi_blksize();
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asm volatile("stxa %0, [%1] %2\n\t"
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:
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: "r" (version2), "r" (tmp),
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"i" (ASI_MCD_REAL));
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}
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asm volatile("membar #Sync\n\t");
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/* Check and mark this tag space for release later if
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* the swapped in page was the last user of tag space
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*/
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del_tag_store(tag_desc, mm);
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}
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/* A page is about to be swapped out. Save any ADI tags associated with
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* this physical page so they can be restored later when the page is swapped
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* back in.
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*/
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int adi_save_tags(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long addr, pte_t oldpte)
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{
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unsigned char *tag;
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tag_storage_desc_t *tag_desc;
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unsigned long version1, version2, paddr, tmp;
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tag_desc = alloc_tag_store(mm, vma, addr);
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if (tag_desc == NULL)
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return -1;
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tag = tag_start(addr, tag_desc);
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paddr = pte_val(oldpte) & _PAGE_PADDR_4V;
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for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
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asm volatile("ldxa [%1] %2, %0\n\t"
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: "=r" (version1)
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: "r" (tmp), "i" (ASI_MCD_REAL));
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tmp += adi_blksize();
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asm volatile("ldxa [%1] %2, %0\n\t"
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: "=r" (version2)
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: "r" (tmp), "i" (ASI_MCD_REAL));
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*tag = (version1 << 4) | version2;
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tag++;
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}
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return 0;
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}
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