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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /arch/x86/kernel/cpu/sgx/encl.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/kernel/cpu/sgx/encl.c')
-rw-r--r--arch/x86/kernel/cpu/sgx/encl.c1325
1 files changed, 1325 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
new file mode 100644
index 0000000000..279148e724
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -0,0 +1,1325 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2016-20 Intel Corporation. */
+
+#include <linux/lockdep.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/shmem_fs.h>
+#include <linux/suspend.h>
+#include <linux/sched/mm.h>
+#include <asm/sgx.h>
+#include "encl.h"
+#include "encls.h"
+#include "sgx.h"
+
+static int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing);
+
+#define PCMDS_PER_PAGE (PAGE_SIZE / sizeof(struct sgx_pcmd))
+/*
+ * 32 PCMD entries share a PCMD page. PCMD_FIRST_MASK is used to
+ * determine the page index associated with the first PCMD entry
+ * within a PCMD page.
+ */
+#define PCMD_FIRST_MASK GENMASK(4, 0)
+
+/**
+ * reclaimer_writing_to_pcmd() - Query if any enclave page associated with
+ * a PCMD page is in process of being reclaimed.
+ * @encl: Enclave to which PCMD page belongs
+ * @start_addr: Address of enclave page using first entry within the PCMD page
+ *
+ * When an enclave page is reclaimed some Paging Crypto MetaData (PCMD) is
+ * stored. The PCMD data of a reclaimed enclave page contains enough
+ * information for the processor to verify the page at the time
+ * it is loaded back into the Enclave Page Cache (EPC).
+ *
+ * The backing storage to which enclave pages are reclaimed is laid out as
+ * follows:
+ * Encrypted enclave pages:SECS page:PCMD pages
+ *
+ * Each PCMD page contains the PCMD metadata of
+ * PAGE_SIZE/sizeof(struct sgx_pcmd) enclave pages.
+ *
+ * A PCMD page can only be truncated if it is (a) empty, and (b) not in the
+ * process of getting data (and thus soon being non-empty). (b) is tested with
+ * a check if an enclave page sharing the PCMD page is in the process of being
+ * reclaimed.
+ *
+ * The reclaimer sets the SGX_ENCL_PAGE_BEING_RECLAIMED flag when it
+ * intends to reclaim that enclave page - it means that the PCMD page
+ * associated with that enclave page is about to get some data and thus
+ * even if the PCMD page is empty, it should not be truncated.
+ *
+ * Context: Enclave mutex (&sgx_encl->lock) must be held.
+ * Return: 1 if the reclaimer is about to write to the PCMD page
+ * 0 if the reclaimer has no intention to write to the PCMD page
+ */
+static int reclaimer_writing_to_pcmd(struct sgx_encl *encl,
+ unsigned long start_addr)
+{
+ int reclaimed = 0;
+ int i;
+
+ /*
+ * PCMD_FIRST_MASK is based on number of PCMD entries within
+ * PCMD page being 32.
+ */
+ BUILD_BUG_ON(PCMDS_PER_PAGE != 32);
+
+ for (i = 0; i < PCMDS_PER_PAGE; i++) {
+ struct sgx_encl_page *entry;
+ unsigned long addr;
+
+ addr = start_addr + i * PAGE_SIZE;
+
+ /*
+ * Stop when reaching the SECS page - it does not
+ * have a page_array entry and its reclaim is
+ * started and completed with enclave mutex held so
+ * it does not use the SGX_ENCL_PAGE_BEING_RECLAIMED
+ * flag.
+ */
+ if (addr == encl->base + encl->size)
+ break;
+
+ entry = xa_load(&encl->page_array, PFN_DOWN(addr));
+ if (!entry)
+ continue;
+
+ /*
+ * VA page slot ID uses same bit as the flag so it is important
+ * to ensure that the page is not already in backing store.
+ */
+ if (entry->epc_page &&
+ (entry->desc & SGX_ENCL_PAGE_BEING_RECLAIMED)) {
+ reclaimed = 1;
+ break;
+ }
+ }
+
+ return reclaimed;
+}
+
+/*
+ * Calculate byte offset of a PCMD struct associated with an enclave page. PCMD's
+ * follow right after the EPC data in the backing storage. In addition to the
+ * visible enclave pages, there's one extra page slot for SECS, before PCMD
+ * structs.
+ */
+static inline pgoff_t sgx_encl_get_backing_page_pcmd_offset(struct sgx_encl *encl,
+ unsigned long page_index)
+{
+ pgoff_t epc_end_off = encl->size + sizeof(struct sgx_secs);
+
+ return epc_end_off + page_index * sizeof(struct sgx_pcmd);
+}
+
+/*
+ * Free a page from the backing storage in the given page index.
+ */
+static inline void sgx_encl_truncate_backing_page(struct sgx_encl *encl, unsigned long page_index)
+{
+ struct inode *inode = file_inode(encl->backing);
+
+ shmem_truncate_range(inode, PFN_PHYS(page_index), PFN_PHYS(page_index) + PAGE_SIZE - 1);
+}
+
+/*
+ * ELDU: Load an EPC page as unblocked. For more info, see "OS Management of EPC
+ * Pages" in the SDM.
+ */
+static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
+ struct sgx_epc_page *epc_page,
+ struct sgx_epc_page *secs_page)
+{
+ unsigned long va_offset = encl_page->desc & SGX_ENCL_PAGE_VA_OFFSET_MASK;
+ struct sgx_encl *encl = encl_page->encl;
+ pgoff_t page_index, page_pcmd_off;
+ unsigned long pcmd_first_page;
+ struct sgx_pageinfo pginfo;
+ struct sgx_backing b;
+ bool pcmd_page_empty;
+ u8 *pcmd_page;
+ int ret;
+
+ if (secs_page)
+ page_index = PFN_DOWN(encl_page->desc - encl_page->encl->base);
+ else
+ page_index = PFN_DOWN(encl->size);
+
+ /*
+ * Address of enclave page using the first entry within the PCMD page.
+ */
+ pcmd_first_page = PFN_PHYS(page_index & ~PCMD_FIRST_MASK) + encl->base;
+
+ page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index);
+
+ ret = sgx_encl_lookup_backing(encl, page_index, &b);
+ if (ret)
+ return ret;
+
+ pginfo.addr = encl_page->desc & PAGE_MASK;
+ pginfo.contents = (unsigned long)kmap_local_page(b.contents);
+ pcmd_page = kmap_local_page(b.pcmd);
+ pginfo.metadata = (unsigned long)pcmd_page + b.pcmd_offset;
+
+ if (secs_page)
+ pginfo.secs = (u64)sgx_get_epc_virt_addr(secs_page);
+ else
+ pginfo.secs = 0;
+
+ ret = __eldu(&pginfo, sgx_get_epc_virt_addr(epc_page),
+ sgx_get_epc_virt_addr(encl_page->va_page->epc_page) + va_offset);
+ if (ret) {
+ if (encls_failed(ret))
+ ENCLS_WARN(ret, "ELDU");
+
+ ret = -EFAULT;
+ }
+
+ memset(pcmd_page + b.pcmd_offset, 0, sizeof(struct sgx_pcmd));
+ set_page_dirty(b.pcmd);
+
+ /*
+ * The area for the PCMD in the page was zeroed above. Check if the
+ * whole page is now empty meaning that all PCMD's have been zeroed:
+ */
+ pcmd_page_empty = !memchr_inv(pcmd_page, 0, PAGE_SIZE);
+
+ kunmap_local(pcmd_page);
+ kunmap_local((void *)(unsigned long)pginfo.contents);
+
+ get_page(b.pcmd);
+ sgx_encl_put_backing(&b);
+
+ sgx_encl_truncate_backing_page(encl, page_index);
+
+ if (pcmd_page_empty && !reclaimer_writing_to_pcmd(encl, pcmd_first_page)) {
+ sgx_encl_truncate_backing_page(encl, PFN_DOWN(page_pcmd_off));
+ pcmd_page = kmap_local_page(b.pcmd);
+ if (memchr_inv(pcmd_page, 0, PAGE_SIZE))
+ pr_warn("PCMD page not empty after truncate.\n");
+ kunmap_local(pcmd_page);
+ }
+
+ put_page(b.pcmd);
+
+ return ret;
+}
+
+static struct sgx_epc_page *sgx_encl_eldu(struct sgx_encl_page *encl_page,
+ struct sgx_epc_page *secs_page)
+{
+
+ unsigned long va_offset = encl_page->desc & SGX_ENCL_PAGE_VA_OFFSET_MASK;
+ struct sgx_encl *encl = encl_page->encl;
+ struct sgx_epc_page *epc_page;
+ int ret;
+
+ epc_page = sgx_alloc_epc_page(encl_page, false);
+ if (IS_ERR(epc_page))
+ return epc_page;
+
+ ret = __sgx_encl_eldu(encl_page, epc_page, secs_page);
+ if (ret) {
+ sgx_encl_free_epc_page(epc_page);
+ return ERR_PTR(ret);
+ }
+
+ sgx_free_va_slot(encl_page->va_page, va_offset);
+ list_move(&encl_page->va_page->list, &encl->va_pages);
+ encl_page->desc &= ~SGX_ENCL_PAGE_VA_OFFSET_MASK;
+ encl_page->epc_page = epc_page;
+
+ return epc_page;
+}
+
+/*
+ * Ensure the SECS page is not swapped out. Must be called with encl->lock
+ * to protect the enclave states including SECS and ensure the SECS page is
+ * not swapped out again while being used.
+ */
+static struct sgx_epc_page *sgx_encl_load_secs(struct sgx_encl *encl)
+{
+ struct sgx_epc_page *epc_page = encl->secs.epc_page;
+
+ if (!epc_page)
+ epc_page = sgx_encl_eldu(&encl->secs, NULL);
+
+ return epc_page;
+}
+
+static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
+ struct sgx_encl_page *entry)
+{
+ struct sgx_epc_page *epc_page;
+
+ /* Entry successfully located. */
+ if (entry->epc_page) {
+ if (entry->desc & SGX_ENCL_PAGE_BEING_RECLAIMED)
+ return ERR_PTR(-EBUSY);
+
+ return entry;
+ }
+
+ epc_page = sgx_encl_load_secs(encl);
+ if (IS_ERR(epc_page))
+ return ERR_CAST(epc_page);
+
+ epc_page = sgx_encl_eldu(entry, encl->secs.epc_page);
+ if (IS_ERR(epc_page))
+ return ERR_CAST(epc_page);
+
+ encl->secs_child_cnt++;
+ sgx_mark_page_reclaimable(entry->epc_page);
+
+ return entry;
+}
+
+static struct sgx_encl_page *sgx_encl_load_page_in_vma(struct sgx_encl *encl,
+ unsigned long addr,
+ unsigned long vm_flags)
+{
+ unsigned long vm_prot_bits = vm_flags & VM_ACCESS_FLAGS;
+ struct sgx_encl_page *entry;
+
+ entry = xa_load(&encl->page_array, PFN_DOWN(addr));
+ if (!entry)
+ return ERR_PTR(-EFAULT);
+
+ /*
+ * Verify that the page has equal or higher build time
+ * permissions than the VMA permissions (i.e. the subset of {VM_READ,
+ * VM_WRITE, VM_EXECUTE} in vma->vm_flags).
+ */
+ if ((entry->vm_max_prot_bits & vm_prot_bits) != vm_prot_bits)
+ return ERR_PTR(-EFAULT);
+
+ return __sgx_encl_load_page(encl, entry);
+}
+
+struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
+ unsigned long addr)
+{
+ struct sgx_encl_page *entry;
+
+ entry = xa_load(&encl->page_array, PFN_DOWN(addr));
+ if (!entry)
+ return ERR_PTR(-EFAULT);
+
+ return __sgx_encl_load_page(encl, entry);
+}
+
+/**
+ * sgx_encl_eaug_page() - Dynamically add page to initialized enclave
+ * @vma: VMA obtained from fault info from where page is accessed
+ * @encl: enclave accessing the page
+ * @addr: address that triggered the page fault
+ *
+ * When an initialized enclave accesses a page with no backing EPC page
+ * on a SGX2 system then the EPC can be added dynamically via the SGX2
+ * ENCLS[EAUG] instruction.
+ *
+ * Returns: Appropriate vm_fault_t: VM_FAULT_NOPAGE when PTE was installed
+ * successfully, VM_FAULT_SIGBUS or VM_FAULT_OOM as error otherwise.
+ */
+static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
+ struct sgx_encl *encl, unsigned long addr)
+{
+ vm_fault_t vmret = VM_FAULT_SIGBUS;
+ struct sgx_pageinfo pginfo = {0};
+ struct sgx_encl_page *encl_page;
+ struct sgx_epc_page *epc_page;
+ struct sgx_va_page *va_page;
+ unsigned long phys_addr;
+ u64 secinfo_flags;
+ int ret;
+
+ if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
+ return VM_FAULT_SIGBUS;
+
+ /*
+ * Ignore internal permission checking for dynamically added pages.
+ * They matter only for data added during the pre-initialization
+ * phase. The enclave decides the permissions by the means of
+ * EACCEPT, EACCEPTCOPY and EMODPE.
+ */
+ secinfo_flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_X;
+ encl_page = sgx_encl_page_alloc(encl, addr - encl->base, secinfo_flags);
+ if (IS_ERR(encl_page))
+ return VM_FAULT_OOM;
+
+ mutex_lock(&encl->lock);
+
+ epc_page = sgx_encl_load_secs(encl);
+ if (IS_ERR(epc_page)) {
+ if (PTR_ERR(epc_page) == -EBUSY)
+ vmret = VM_FAULT_NOPAGE;
+ goto err_out_unlock;
+ }
+
+ epc_page = sgx_alloc_epc_page(encl_page, false);
+ if (IS_ERR(epc_page)) {
+ if (PTR_ERR(epc_page) == -EBUSY)
+ vmret = VM_FAULT_NOPAGE;
+ goto err_out_unlock;
+ }
+
+ va_page = sgx_encl_grow(encl, false);
+ if (IS_ERR(va_page)) {
+ if (PTR_ERR(va_page) == -EBUSY)
+ vmret = VM_FAULT_NOPAGE;
+ goto err_out_epc;
+ }
+
+ if (va_page)
+ list_add(&va_page->list, &encl->va_pages);
+
+ ret = xa_insert(&encl->page_array, PFN_DOWN(encl_page->desc),
+ encl_page, GFP_KERNEL);
+ /*
+ * If ret == -EBUSY then page was created in another flow while
+ * running without encl->lock
+ */
+ if (ret)
+ goto err_out_shrink;
+
+ pginfo.secs = (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page);
+ pginfo.addr = encl_page->desc & PAGE_MASK;
+ pginfo.metadata = 0;
+
+ ret = __eaug(&pginfo, sgx_get_epc_virt_addr(epc_page));
+ if (ret)
+ goto err_out;
+
+ encl_page->encl = encl;
+ encl_page->epc_page = epc_page;
+ encl_page->type = SGX_PAGE_TYPE_REG;
+ encl->secs_child_cnt++;
+
+ sgx_mark_page_reclaimable(encl_page->epc_page);
+
+ phys_addr = sgx_get_epc_phys_addr(epc_page);
+ /*
+ * Do not undo everything when creating PTE entry fails - next #PF
+ * would find page ready for a PTE.
+ */
+ vmret = vmf_insert_pfn(vma, addr, PFN_DOWN(phys_addr));
+ if (vmret != VM_FAULT_NOPAGE) {
+ mutex_unlock(&encl->lock);
+ return VM_FAULT_SIGBUS;
+ }
+ mutex_unlock(&encl->lock);
+ return VM_FAULT_NOPAGE;
+
+err_out:
+ xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc));
+
+err_out_shrink:
+ sgx_encl_shrink(encl, va_page);
+err_out_epc:
+ sgx_encl_free_epc_page(epc_page);
+err_out_unlock:
+ mutex_unlock(&encl->lock);
+ kfree(encl_page);
+
+ return vmret;
+}
+
+static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
+{
+ unsigned long addr = (unsigned long)vmf->address;
+ struct vm_area_struct *vma = vmf->vma;
+ struct sgx_encl_page *entry;
+ unsigned long phys_addr;
+ struct sgx_encl *encl;
+ vm_fault_t ret;
+
+ encl = vma->vm_private_data;
+
+ /*
+ * It's very unlikely but possible that allocating memory for the
+ * mm_list entry of a forked process failed in sgx_vma_open(). When
+ * this happens, vm_private_data is set to NULL.
+ */
+ if (unlikely(!encl))
+ return VM_FAULT_SIGBUS;
+
+ /*
+ * The page_array keeps track of all enclave pages, whether they
+ * are swapped out or not. If there is no entry for this page and
+ * the system supports SGX2 then it is possible to dynamically add
+ * a new enclave page. This is only possible for an initialized
+ * enclave that will be checked for right away.
+ */
+ if (cpu_feature_enabled(X86_FEATURE_SGX2) &&
+ (!xa_load(&encl->page_array, PFN_DOWN(addr))))
+ return sgx_encl_eaug_page(vma, encl, addr);
+
+ mutex_lock(&encl->lock);
+
+ entry = sgx_encl_load_page_in_vma(encl, addr, vma->vm_flags);
+ if (IS_ERR(entry)) {
+ mutex_unlock(&encl->lock);
+
+ if (PTR_ERR(entry) == -EBUSY)
+ return VM_FAULT_NOPAGE;
+
+ return VM_FAULT_SIGBUS;
+ }
+
+ phys_addr = sgx_get_epc_phys_addr(entry->epc_page);
+
+ ret = vmf_insert_pfn(vma, addr, PFN_DOWN(phys_addr));
+ if (ret != VM_FAULT_NOPAGE) {
+ mutex_unlock(&encl->lock);
+
+ return VM_FAULT_SIGBUS;
+ }
+
+ sgx_encl_test_and_clear_young(vma->vm_mm, entry);
+ mutex_unlock(&encl->lock);
+
+ return VM_FAULT_NOPAGE;
+}
+
+static void sgx_vma_open(struct vm_area_struct *vma)
+{
+ struct sgx_encl *encl = vma->vm_private_data;
+
+ /*
+ * It's possible but unlikely that vm_private_data is NULL. This can
+ * happen in a grandchild of a process, when sgx_encl_mm_add() had
+ * failed to allocate memory in this callback.
+ */
+ if (unlikely(!encl))
+ return;
+
+ if (sgx_encl_mm_add(encl, vma->vm_mm))
+ vma->vm_private_data = NULL;
+}
+
+
+/**
+ * sgx_encl_may_map() - Check if a requested VMA mapping is allowed
+ * @encl: an enclave pointer
+ * @start: lower bound of the address range, inclusive
+ * @end: upper bound of the address range, exclusive
+ * @vm_flags: VMA flags
+ *
+ * Iterate through the enclave pages contained within [@start, @end) to verify
+ * that the permissions requested by a subset of {VM_READ, VM_WRITE, VM_EXEC}
+ * do not contain any permissions that are not contained in the build time
+ * permissions of any of the enclave pages within the given address range.
+ *
+ * An enclave creator must declare the strongest permissions that will be
+ * needed for each enclave page. This ensures that mappings have the identical
+ * or weaker permissions than the earlier declared permissions.
+ *
+ * Return: 0 on success, -EACCES otherwise
+ */
+int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
+ unsigned long end, unsigned long vm_flags)
+{
+ unsigned long vm_prot_bits = vm_flags & VM_ACCESS_FLAGS;
+ struct sgx_encl_page *page;
+ unsigned long count = 0;
+ int ret = 0;
+
+ XA_STATE(xas, &encl->page_array, PFN_DOWN(start));
+
+ /* Disallow mapping outside enclave's address range. */
+ if (test_bit(SGX_ENCL_INITIALIZED, &encl->flags) &&
+ (start < encl->base || end > encl->base + encl->size))
+ return -EACCES;
+
+ /*
+ * Disallow READ_IMPLIES_EXEC tasks as their VMA permissions might
+ * conflict with the enclave page permissions.
+ */
+ if (current->personality & READ_IMPLIES_EXEC)
+ return -EACCES;
+
+ mutex_lock(&encl->lock);
+ xas_lock(&xas);
+ xas_for_each(&xas, page, PFN_DOWN(end - 1)) {
+ if (~page->vm_max_prot_bits & vm_prot_bits) {
+ ret = -EACCES;
+ break;
+ }
+
+ /* Reschedule on every XA_CHECK_SCHED iteration. */
+ if (!(++count % XA_CHECK_SCHED)) {
+ xas_pause(&xas);
+ xas_unlock(&xas);
+ mutex_unlock(&encl->lock);
+
+ cond_resched();
+
+ mutex_lock(&encl->lock);
+ xas_lock(&xas);
+ }
+ }
+ xas_unlock(&xas);
+ mutex_unlock(&encl->lock);
+
+ return ret;
+}
+
+static int sgx_vma_mprotect(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, unsigned long newflags)
+{
+ return sgx_encl_may_map(vma->vm_private_data, start, end, newflags);
+}
+
+static int sgx_encl_debug_read(struct sgx_encl *encl, struct sgx_encl_page *page,
+ unsigned long addr, void *data)
+{
+ unsigned long offset = addr & ~PAGE_MASK;
+ int ret;
+
+
+ ret = __edbgrd(sgx_get_epc_virt_addr(page->epc_page) + offset, data);
+ if (ret)
+ return -EIO;
+
+ return 0;
+}
+
+static int sgx_encl_debug_write(struct sgx_encl *encl, struct sgx_encl_page *page,
+ unsigned long addr, void *data)
+{
+ unsigned long offset = addr & ~PAGE_MASK;
+ int ret;
+
+ ret = __edbgwr(sgx_get_epc_virt_addr(page->epc_page) + offset, data);
+ if (ret)
+ return -EIO;
+
+ return 0;
+}
+
+/*
+ * Load an enclave page to EPC if required, and take encl->lock.
+ */
+static struct sgx_encl_page *sgx_encl_reserve_page(struct sgx_encl *encl,
+ unsigned long addr,
+ unsigned long vm_flags)
+{
+ struct sgx_encl_page *entry;
+
+ for ( ; ; ) {
+ mutex_lock(&encl->lock);
+
+ entry = sgx_encl_load_page_in_vma(encl, addr, vm_flags);
+ if (PTR_ERR(entry) != -EBUSY)
+ break;
+
+ mutex_unlock(&encl->lock);
+ }
+
+ if (IS_ERR(entry))
+ mutex_unlock(&encl->lock);
+
+ return entry;
+}
+
+static int sgx_vma_access(struct vm_area_struct *vma, unsigned long addr,
+ void *buf, int len, int write)
+{
+ struct sgx_encl *encl = vma->vm_private_data;
+ struct sgx_encl_page *entry = NULL;
+ char data[sizeof(unsigned long)];
+ unsigned long align;
+ int offset;
+ int cnt;
+ int ret = 0;
+ int i;
+
+ /*
+ * If process was forked, VMA is still there but vm_private_data is set
+ * to NULL.
+ */
+ if (!encl)
+ return -EFAULT;
+
+ if (!test_bit(SGX_ENCL_DEBUG, &encl->flags))
+ return -EFAULT;
+
+ for (i = 0; i < len; i += cnt) {
+ entry = sgx_encl_reserve_page(encl, (addr + i) & PAGE_MASK,
+ vma->vm_flags);
+ if (IS_ERR(entry)) {
+ ret = PTR_ERR(entry);
+ break;
+ }
+
+ align = ALIGN_DOWN(addr + i, sizeof(unsigned long));
+ offset = (addr + i) & (sizeof(unsigned long) - 1);
+ cnt = sizeof(unsigned long) - offset;
+ cnt = min(cnt, len - i);
+
+ ret = sgx_encl_debug_read(encl, entry, align, data);
+ if (ret)
+ goto out;
+
+ if (write) {
+ memcpy(data + offset, buf + i, cnt);
+ ret = sgx_encl_debug_write(encl, entry, align, data);
+ if (ret)
+ goto out;
+ } else {
+ memcpy(buf + i, data + offset, cnt);
+ }
+
+out:
+ mutex_unlock(&encl->lock);
+
+ if (ret)
+ break;
+ }
+
+ return ret < 0 ? ret : i;
+}
+
+const struct vm_operations_struct sgx_vm_ops = {
+ .fault = sgx_vma_fault,
+ .mprotect = sgx_vma_mprotect,
+ .open = sgx_vma_open,
+ .access = sgx_vma_access,
+};
+
+/**
+ * sgx_encl_release - Destroy an enclave instance
+ * @ref: address of a kref inside &sgx_encl
+ *
+ * Used together with kref_put(). Frees all the resources associated with the
+ * enclave and the instance itself.
+ */
+void sgx_encl_release(struct kref *ref)
+{
+ struct sgx_encl *encl = container_of(ref, struct sgx_encl, refcount);
+ unsigned long max_page_index = PFN_DOWN(encl->base + encl->size - 1);
+ struct sgx_va_page *va_page;
+ struct sgx_encl_page *entry;
+ unsigned long count = 0;
+
+ XA_STATE(xas, &encl->page_array, PFN_DOWN(encl->base));
+
+ xas_lock(&xas);
+ xas_for_each(&xas, entry, max_page_index) {
+ if (entry->epc_page) {
+ /*
+ * The page and its radix tree entry cannot be freed
+ * if the page is being held by the reclaimer.
+ */
+ if (sgx_unmark_page_reclaimable(entry->epc_page))
+ continue;
+
+ sgx_encl_free_epc_page(entry->epc_page);
+ encl->secs_child_cnt--;
+ entry->epc_page = NULL;
+ }
+
+ kfree(entry);
+ /*
+ * Invoke scheduler on every XA_CHECK_SCHED iteration
+ * to prevent soft lockups.
+ */
+ if (!(++count % XA_CHECK_SCHED)) {
+ xas_pause(&xas);
+ xas_unlock(&xas);
+
+ cond_resched();
+
+ xas_lock(&xas);
+ }
+ }
+ xas_unlock(&xas);
+
+ xa_destroy(&encl->page_array);
+
+ if (!encl->secs_child_cnt && encl->secs.epc_page) {
+ sgx_encl_free_epc_page(encl->secs.epc_page);
+ encl->secs.epc_page = NULL;
+ }
+
+ while (!list_empty(&encl->va_pages)) {
+ va_page = list_first_entry(&encl->va_pages, struct sgx_va_page,
+ list);
+ list_del(&va_page->list);
+ sgx_encl_free_epc_page(va_page->epc_page);
+ kfree(va_page);
+ }
+
+ if (encl->backing)
+ fput(encl->backing);
+
+ cleanup_srcu_struct(&encl->srcu);
+
+ WARN_ON_ONCE(!list_empty(&encl->mm_list));
+
+ /* Detect EPC page leak's. */
+ WARN_ON_ONCE(encl->secs_child_cnt);
+ WARN_ON_ONCE(encl->secs.epc_page);
+
+ kfree(encl);
+}
+
+/*
+ * 'mm' is exiting and no longer needs mmu notifications.
+ */
+static void sgx_mmu_notifier_release(struct mmu_notifier *mn,
+ struct mm_struct *mm)
+{
+ struct sgx_encl_mm *encl_mm = container_of(mn, struct sgx_encl_mm, mmu_notifier);
+ struct sgx_encl_mm *tmp = NULL;
+ bool found = false;
+
+ /*
+ * The enclave itself can remove encl_mm. Note, objects can't be moved
+ * off an RCU protected list, but deletion is ok.
+ */
+ spin_lock(&encl_mm->encl->mm_lock);
+ list_for_each_entry(tmp, &encl_mm->encl->mm_list, list) {
+ if (tmp == encl_mm) {
+ list_del_rcu(&encl_mm->list);
+ found = true;
+ break;
+ }
+ }
+ spin_unlock(&encl_mm->encl->mm_lock);
+
+ if (found) {
+ synchronize_srcu(&encl_mm->encl->srcu);
+ mmu_notifier_put(mn);
+ }
+}
+
+static void sgx_mmu_notifier_free(struct mmu_notifier *mn)
+{
+ struct sgx_encl_mm *encl_mm = container_of(mn, struct sgx_encl_mm, mmu_notifier);
+
+ /* 'encl_mm' is going away, put encl_mm->encl reference: */
+ kref_put(&encl_mm->encl->refcount, sgx_encl_release);
+
+ kfree(encl_mm);
+}
+
+static const struct mmu_notifier_ops sgx_mmu_notifier_ops = {
+ .release = sgx_mmu_notifier_release,
+ .free_notifier = sgx_mmu_notifier_free,
+};
+
+static struct sgx_encl_mm *sgx_encl_find_mm(struct sgx_encl *encl,
+ struct mm_struct *mm)
+{
+ struct sgx_encl_mm *encl_mm = NULL;
+ struct sgx_encl_mm *tmp;
+ int idx;
+
+ idx = srcu_read_lock(&encl->srcu);
+
+ list_for_each_entry_rcu(tmp, &encl->mm_list, list) {
+ if (tmp->mm == mm) {
+ encl_mm = tmp;
+ break;
+ }
+ }
+
+ srcu_read_unlock(&encl->srcu, idx);
+
+ return encl_mm;
+}
+
+int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm)
+{
+ struct sgx_encl_mm *encl_mm;
+ int ret;
+
+ /*
+ * Even though a single enclave may be mapped into an mm more than once,
+ * each 'mm' only appears once on encl->mm_list. This is guaranteed by
+ * holding the mm's mmap lock for write before an mm can be added or
+ * remove to an encl->mm_list.
+ */
+ mmap_assert_write_locked(mm);
+
+ /*
+ * It's possible that an entry already exists in the mm_list, because it
+ * is removed only on VFS release or process exit.
+ */
+ if (sgx_encl_find_mm(encl, mm))
+ return 0;
+
+ encl_mm = kzalloc(sizeof(*encl_mm), GFP_KERNEL);
+ if (!encl_mm)
+ return -ENOMEM;
+
+ /* Grab a refcount for the encl_mm->encl reference: */
+ kref_get(&encl->refcount);
+ encl_mm->encl = encl;
+ encl_mm->mm = mm;
+ encl_mm->mmu_notifier.ops = &sgx_mmu_notifier_ops;
+
+ ret = __mmu_notifier_register(&encl_mm->mmu_notifier, mm);
+ if (ret) {
+ kfree(encl_mm);
+ return ret;
+ }
+
+ spin_lock(&encl->mm_lock);
+ list_add_rcu(&encl_mm->list, &encl->mm_list);
+ /* Pairs with smp_rmb() in sgx_zap_enclave_ptes(). */
+ smp_wmb();
+ encl->mm_list_version++;
+ spin_unlock(&encl->mm_lock);
+
+ return 0;
+}
+
+/**
+ * sgx_encl_cpumask() - Query which CPUs might be accessing the enclave
+ * @encl: the enclave
+ *
+ * Some SGX functions require that no cached linear-to-physical address
+ * mappings are present before they can succeed. For example, ENCLS[EWB]
+ * copies a page from the enclave page cache to regular main memory but
+ * it fails if it cannot ensure that there are no cached
+ * linear-to-physical address mappings referring to the page.
+ *
+ * SGX hardware flushes all cached linear-to-physical mappings on a CPU
+ * when an enclave is exited via ENCLU[EEXIT] or an Asynchronous Enclave
+ * Exit (AEX). Exiting an enclave will thus ensure cached linear-to-physical
+ * address mappings are cleared but coordination with the tracking done within
+ * the SGX hardware is needed to support the SGX functions that depend on this
+ * cache clearing.
+ *
+ * When the ENCLS[ETRACK] function is issued on an enclave the hardware
+ * tracks threads operating inside the enclave at that time. The SGX
+ * hardware tracking require that all the identified threads must have
+ * exited the enclave in order to flush the mappings before a function such
+ * as ENCLS[EWB] will be permitted
+ *
+ * The following flow is used to support SGX functions that require that
+ * no cached linear-to-physical address mappings are present:
+ * 1) Execute ENCLS[ETRACK] to initiate hardware tracking.
+ * 2) Use this function (sgx_encl_cpumask()) to query which CPUs might be
+ * accessing the enclave.
+ * 3) Send IPI to identified CPUs, kicking them out of the enclave and
+ * thus flushing all locally cached linear-to-physical address mappings.
+ * 4) Execute SGX function.
+ *
+ * Context: It is required to call this function after ENCLS[ETRACK].
+ * This will ensure that if any new mm appears (racing with
+ * sgx_encl_mm_add()) then the new mm will enter into the
+ * enclave with fresh linear-to-physical address mappings.
+ *
+ * It is required that all IPIs are completed before a new
+ * ENCLS[ETRACK] is issued so be sure to protect steps 1 to 3
+ * of the above flow with the enclave's mutex.
+ *
+ * Return: cpumask of CPUs that might be accessing @encl
+ */
+const cpumask_t *sgx_encl_cpumask(struct sgx_encl *encl)
+{
+ cpumask_t *cpumask = &encl->cpumask;
+ struct sgx_encl_mm *encl_mm;
+ int idx;
+
+ cpumask_clear(cpumask);
+
+ idx = srcu_read_lock(&encl->srcu);
+
+ list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
+ if (!mmget_not_zero(encl_mm->mm))
+ continue;
+
+ cpumask_or(cpumask, cpumask, mm_cpumask(encl_mm->mm));
+
+ mmput_async(encl_mm->mm);
+ }
+
+ srcu_read_unlock(&encl->srcu, idx);
+
+ return cpumask;
+}
+
+static struct page *sgx_encl_get_backing_page(struct sgx_encl *encl,
+ pgoff_t index)
+{
+ struct address_space *mapping = encl->backing->f_mapping;
+ gfp_t gfpmask = mapping_gfp_mask(mapping);
+
+ return shmem_read_mapping_page_gfp(mapping, index, gfpmask);
+}
+
+/**
+ * __sgx_encl_get_backing() - Pin the backing storage
+ * @encl: an enclave pointer
+ * @page_index: enclave page index
+ * @backing: data for accessing backing storage for the page
+ *
+ * Pin the backing storage pages for storing the encrypted contents and Paging
+ * Crypto MetaData (PCMD) of an enclave page.
+ *
+ * Return:
+ * 0 on success,
+ * -errno otherwise.
+ */
+static int __sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing)
+{
+ pgoff_t page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index);
+ struct page *contents;
+ struct page *pcmd;
+
+ contents = sgx_encl_get_backing_page(encl, page_index);
+ if (IS_ERR(contents))
+ return PTR_ERR(contents);
+
+ pcmd = sgx_encl_get_backing_page(encl, PFN_DOWN(page_pcmd_off));
+ if (IS_ERR(pcmd)) {
+ put_page(contents);
+ return PTR_ERR(pcmd);
+ }
+
+ backing->contents = contents;
+ backing->pcmd = pcmd;
+ backing->pcmd_offset = page_pcmd_off & (PAGE_SIZE - 1);
+
+ return 0;
+}
+
+/*
+ * When called from ksgxd, returns the mem_cgroup of a struct mm stored
+ * in the enclave's mm_list. When not called from ksgxd, just returns
+ * the mem_cgroup of the current task.
+ */
+static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl)
+{
+ struct mem_cgroup *memcg = NULL;
+ struct sgx_encl_mm *encl_mm;
+ int idx;
+
+ /*
+ * If called from normal task context, return the mem_cgroup
+ * of the current task's mm. The remainder of the handling is for
+ * ksgxd.
+ */
+ if (!current_is_ksgxd())
+ return get_mem_cgroup_from_mm(current->mm);
+
+ /*
+ * Search the enclave's mm_list to find an mm associated with
+ * this enclave to charge the allocation to.
+ */
+ idx = srcu_read_lock(&encl->srcu);
+
+ list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
+ if (!mmget_not_zero(encl_mm->mm))
+ continue;
+
+ memcg = get_mem_cgroup_from_mm(encl_mm->mm);
+
+ mmput_async(encl_mm->mm);
+
+ break;
+ }
+
+ srcu_read_unlock(&encl->srcu, idx);
+
+ /*
+ * In the rare case that there isn't an mm associated with
+ * the enclave, set memcg to the current active mem_cgroup.
+ * This will be the root mem_cgroup if there is no active
+ * mem_cgroup.
+ */
+ if (!memcg)
+ return get_mem_cgroup_from_mm(NULL);
+
+ return memcg;
+}
+
+/**
+ * sgx_encl_alloc_backing() - create a new backing storage page
+ * @encl: an enclave pointer
+ * @page_index: enclave page index
+ * @backing: data for accessing backing storage for the page
+ *
+ * When called from ksgxd, sets the active memcg from one of the
+ * mms in the enclave's mm_list prior to any backing page allocation,
+ * in order to ensure that shmem page allocations are charged to the
+ * enclave. Create a backing page for loading data back into an EPC page with
+ * ELDU. This function takes a reference on a new backing page which
+ * must be dropped with a corresponding call to sgx_encl_put_backing().
+ *
+ * Return:
+ * 0 on success,
+ * -errno otherwise.
+ */
+int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing)
+{
+ struct mem_cgroup *encl_memcg = sgx_encl_get_mem_cgroup(encl);
+ struct mem_cgroup *memcg = set_active_memcg(encl_memcg);
+ int ret;
+
+ ret = __sgx_encl_get_backing(encl, page_index, backing);
+
+ set_active_memcg(memcg);
+ mem_cgroup_put(encl_memcg);
+
+ return ret;
+}
+
+/**
+ * sgx_encl_lookup_backing() - retrieve an existing backing storage page
+ * @encl: an enclave pointer
+ * @page_index: enclave page index
+ * @backing: data for accessing backing storage for the page
+ *
+ * Retrieve a backing page for loading data back into an EPC page with ELDU.
+ * It is the caller's responsibility to ensure that it is appropriate to use
+ * sgx_encl_lookup_backing() rather than sgx_encl_alloc_backing(). If lookup is
+ * not used correctly, this will cause an allocation which is not accounted for.
+ * This function takes a reference on an existing backing page which must be
+ * dropped with a corresponding call to sgx_encl_put_backing().
+ *
+ * Return:
+ * 0 on success,
+ * -errno otherwise.
+ */
+static int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,
+ struct sgx_backing *backing)
+{
+ return __sgx_encl_get_backing(encl, page_index, backing);
+}
+
+/**
+ * sgx_encl_put_backing() - Unpin the backing storage
+ * @backing: data for accessing backing storage for the page
+ */
+void sgx_encl_put_backing(struct sgx_backing *backing)
+{
+ put_page(backing->pcmd);
+ put_page(backing->contents);
+}
+
+static int sgx_encl_test_and_clear_young_cb(pte_t *ptep, unsigned long addr,
+ void *data)
+{
+ pte_t pte;
+ int ret;
+
+ ret = pte_young(*ptep);
+ if (ret) {
+ pte = pte_mkold(*ptep);
+ set_pte_at((struct mm_struct *)data, addr, ptep, pte);
+ }
+
+ return ret;
+}
+
+/**
+ * sgx_encl_test_and_clear_young() - Test and reset the accessed bit
+ * @mm: mm_struct that is checked
+ * @page: enclave page to be tested for recent access
+ *
+ * Checks the Access (A) bit from the PTE corresponding to the enclave page and
+ * clears it.
+ *
+ * Return: 1 if the page has been recently accessed and 0 if not.
+ */
+int sgx_encl_test_and_clear_young(struct mm_struct *mm,
+ struct sgx_encl_page *page)
+{
+ unsigned long addr = page->desc & PAGE_MASK;
+ struct sgx_encl *encl = page->encl;
+ struct vm_area_struct *vma;
+ int ret;
+
+ ret = sgx_encl_find(mm, addr, &vma);
+ if (ret)
+ return 0;
+
+ if (encl != vma->vm_private_data)
+ return 0;
+
+ ret = apply_to_page_range(vma->vm_mm, addr, PAGE_SIZE,
+ sgx_encl_test_and_clear_young_cb, vma->vm_mm);
+ if (ret < 0)
+ return 0;
+
+ return ret;
+}
+
+struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
+ unsigned long offset,
+ u64 secinfo_flags)
+{
+ struct sgx_encl_page *encl_page;
+ unsigned long prot;
+
+ encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL);
+ if (!encl_page)
+ return ERR_PTR(-ENOMEM);
+
+ encl_page->desc = encl->base + offset;
+ encl_page->encl = encl;
+
+ prot = _calc_vm_trans(secinfo_flags, SGX_SECINFO_R, PROT_READ) |
+ _calc_vm_trans(secinfo_flags, SGX_SECINFO_W, PROT_WRITE) |
+ _calc_vm_trans(secinfo_flags, SGX_SECINFO_X, PROT_EXEC);
+
+ /*
+ * TCS pages must always RW set for CPU access while the SECINFO
+ * permissions are *always* zero - the CPU ignores the user provided
+ * values and silently overwrites them with zero permissions.
+ */
+ if ((secinfo_flags & SGX_SECINFO_PAGE_TYPE_MASK) == SGX_SECINFO_TCS)
+ prot |= PROT_READ | PROT_WRITE;
+
+ /* Calculate maximum of the VM flags for the page. */
+ encl_page->vm_max_prot_bits = calc_vm_prot_bits(prot, 0);
+
+ return encl_page;
+}
+
+/**
+ * sgx_zap_enclave_ptes() - remove PTEs mapping the address from enclave
+ * @encl: the enclave
+ * @addr: page aligned pointer to single page for which PTEs will be removed
+ *
+ * Multiple VMAs may have an enclave page mapped. Remove the PTE mapping
+ * @addr from each VMA. Ensure that page fault handler is ready to handle
+ * new mappings of @addr before calling this function.
+ */
+void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr)
+{
+ unsigned long mm_list_version;
+ struct sgx_encl_mm *encl_mm;
+ struct vm_area_struct *vma;
+ int idx, ret;
+
+ do {
+ mm_list_version = encl->mm_list_version;
+
+ /* Pairs with smp_wmb() in sgx_encl_mm_add(). */
+ smp_rmb();
+
+ idx = srcu_read_lock(&encl->srcu);
+
+ list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
+ if (!mmget_not_zero(encl_mm->mm))
+ continue;
+
+ mmap_read_lock(encl_mm->mm);
+
+ ret = sgx_encl_find(encl_mm->mm, addr, &vma);
+ if (!ret && encl == vma->vm_private_data)
+ zap_vma_ptes(vma, addr, PAGE_SIZE);
+
+ mmap_read_unlock(encl_mm->mm);
+
+ mmput_async(encl_mm->mm);
+ }
+
+ srcu_read_unlock(&encl->srcu, idx);
+ } while (unlikely(encl->mm_list_version != mm_list_version));
+}
+
+/**
+ * sgx_alloc_va_page() - Allocate a Version Array (VA) page
+ * @reclaim: Reclaim EPC pages directly if none available. Enclave
+ * mutex should not be held if this is set.
+ *
+ * Allocate a free EPC page and convert it to a Version Array (VA) page.
+ *
+ * Return:
+ * a VA page,
+ * -errno otherwise
+ */
+struct sgx_epc_page *sgx_alloc_va_page(bool reclaim)
+{
+ struct sgx_epc_page *epc_page;
+ int ret;
+
+ epc_page = sgx_alloc_epc_page(NULL, reclaim);
+ if (IS_ERR(epc_page))
+ return ERR_CAST(epc_page);
+
+ ret = __epa(sgx_get_epc_virt_addr(epc_page));
+ if (ret) {
+ WARN_ONCE(1, "EPA returned %d (0x%x)", ret, ret);
+ sgx_encl_free_epc_page(epc_page);
+ return ERR_PTR(-EFAULT);
+ }
+
+ return epc_page;
+}
+
+/**
+ * sgx_alloc_va_slot - allocate a VA slot
+ * @va_page: a &struct sgx_va_page instance
+ *
+ * Allocates a slot from a &struct sgx_va_page instance.
+ *
+ * Return: offset of the slot inside the VA page
+ */
+unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page)
+{
+ int slot = find_first_zero_bit(va_page->slots, SGX_VA_SLOT_COUNT);
+
+ if (slot < SGX_VA_SLOT_COUNT)
+ set_bit(slot, va_page->slots);
+
+ return slot << 3;
+}
+
+/**
+ * sgx_free_va_slot - free a VA slot
+ * @va_page: a &struct sgx_va_page instance
+ * @offset: offset of the slot inside the VA page
+ *
+ * Frees a slot from a &struct sgx_va_page instance.
+ */
+void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset)
+{
+ clear_bit(offset >> 3, va_page->slots);
+}
+
+/**
+ * sgx_va_page_full - is the VA page full?
+ * @va_page: a &struct sgx_va_page instance
+ *
+ * Return: true if all slots have been taken
+ */
+bool sgx_va_page_full(struct sgx_va_page *va_page)
+{
+ int slot = find_first_zero_bit(va_page->slots, SGX_VA_SLOT_COUNT);
+
+ return slot == SGX_VA_SLOT_COUNT;
+}
+
+/**
+ * sgx_encl_free_epc_page - free an EPC page assigned to an enclave
+ * @page: EPC page to be freed
+ *
+ * Free an EPC page assigned to an enclave. It does EREMOVE for the page, and
+ * only upon success, it puts the page back to free page list. Otherwise, it
+ * gives a WARNING to indicate page is leaked.
+ */
+void sgx_encl_free_epc_page(struct sgx_epc_page *page)
+{
+ int ret;
+
+ WARN_ON_ONCE(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED);
+
+ ret = __eremove(sgx_get_epc_virt_addr(page));
+ if (WARN_ONCE(ret, EREMOVE_ERROR_MESSAGE, ret, ret))
+ return;
+
+ sgx_free_epc_page(page);
+}