// 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);
}
static 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;
}
static 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;
}
static 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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