diff options
Diffstat (limited to 'arch/sparc/kernel/adi_64.c')
| -rw-r--r-- | arch/sparc/kernel/adi_64.c | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/arch/sparc/kernel/adi_64.c b/arch/sparc/kernel/adi_64.c new file mode 100644 index 0000000000..ce332942de --- /dev/null +++ b/arch/sparc/kernel/adi_64.c @@ -0,0 +1,396 @@ +// 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 (khalid.aziz@oracle.com) + */ +#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; +} |