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