ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/marvell/linux/arch/x86/kernel/ldt.c b/marvell/linux/arch/x86/kernel/ldt.c
new file mode 100644
index 0000000..b2463fc
--- /dev/null
+++ b/marvell/linux/arch/x86/kernel/ldt.c
@@ -0,0 +1,582 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
+ * Copyright (C) 2002 Andi Kleen
+ *
+ * This handles calls from both 32bit and 64bit mode.
+ *
+ * Lock order:
+ * contex.ldt_usr_sem
+ * mmap_sem
+ * context.lock
+ */
+
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/syscalls.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/uaccess.h>
+
+#include <asm/ldt.h>
+#include <asm/tlb.h>
+#include <asm/desc.h>
+#include <asm/mmu_context.h>
+#include <asm/syscalls.h>
+
+static void refresh_ldt_segments(void)
+{
+#ifdef CONFIG_X86_64
+ unsigned short sel;
+
+ /*
+ * Make sure that the cached DS and ES descriptors match the updated
+ * LDT.
+ */
+ savesegment(ds, sel);
+ if ((sel & SEGMENT_TI_MASK) == SEGMENT_LDT)
+ loadsegment(ds, sel);
+
+ savesegment(es, sel);
+ if ((sel & SEGMENT_TI_MASK) == SEGMENT_LDT)
+ loadsegment(es, sel);
+#endif
+}
+
+/* context.lock is held by the task which issued the smp function call */
+static void flush_ldt(void *__mm)
+{
+ struct mm_struct *mm = __mm;
+
+ if (this_cpu_read(cpu_tlbstate.loaded_mm) != mm)
+ return;
+
+ load_mm_ldt(mm);
+
+ refresh_ldt_segments();
+}
+
+/* The caller must call finalize_ldt_struct on the result. LDT starts zeroed. */
+static struct ldt_struct *alloc_ldt_struct(unsigned int num_entries)
+{
+ struct ldt_struct *new_ldt;
+ unsigned int alloc_size;
+
+ if (num_entries > LDT_ENTRIES)
+ return NULL;
+
+ new_ldt = kmalloc(sizeof(struct ldt_struct), GFP_KERNEL);
+ if (!new_ldt)
+ return NULL;
+
+ BUILD_BUG_ON(LDT_ENTRY_SIZE != sizeof(struct desc_struct));
+ alloc_size = num_entries * LDT_ENTRY_SIZE;
+
+ /*
+ * Xen is very picky: it requires a page-aligned LDT that has no
+ * trailing nonzero bytes in any page that contains LDT descriptors.
+ * Keep it simple: zero the whole allocation and never allocate less
+ * than PAGE_SIZE.
+ */
+ if (alloc_size > PAGE_SIZE)
+ new_ldt->entries = vzalloc(alloc_size);
+ else
+ new_ldt->entries = (void *)get_zeroed_page(GFP_KERNEL);
+
+ if (!new_ldt->entries) {
+ kfree(new_ldt);
+ return NULL;
+ }
+
+ /* The new LDT isn't aliased for PTI yet. */
+ new_ldt->slot = -1;
+
+ new_ldt->nr_entries = num_entries;
+ return new_ldt;
+}
+
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+
+static void do_sanity_check(struct mm_struct *mm,
+ bool had_kernel_mapping,
+ bool had_user_mapping)
+{
+ if (mm->context.ldt) {
+ /*
+ * We already had an LDT. The top-level entry should already
+ * have been allocated and synchronized with the usermode
+ * tables.
+ */
+ WARN_ON(!had_kernel_mapping);
+ if (boot_cpu_has(X86_FEATURE_PTI))
+ WARN_ON(!had_user_mapping);
+ } else {
+ /*
+ * This is the first time we're mapping an LDT for this process.
+ * Sync the pgd to the usermode tables.
+ */
+ WARN_ON(had_kernel_mapping);
+ if (boot_cpu_has(X86_FEATURE_PTI))
+ WARN_ON(had_user_mapping);
+ }
+}
+
+#ifdef CONFIG_X86_PAE
+
+static pmd_t *pgd_to_pmd_walk(pgd_t *pgd, unsigned long va)
+{
+ p4d_t *p4d;
+ pud_t *pud;
+
+ if (pgd->pgd == 0)
+ return NULL;
+
+ p4d = p4d_offset(pgd, va);
+ if (p4d_none(*p4d))
+ return NULL;
+
+ pud = pud_offset(p4d, va);
+ if (pud_none(*pud))
+ return NULL;
+
+ return pmd_offset(pud, va);
+}
+
+static void map_ldt_struct_to_user(struct mm_struct *mm)
+{
+ pgd_t *k_pgd = pgd_offset(mm, LDT_BASE_ADDR);
+ pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd);
+ pmd_t *k_pmd, *u_pmd;
+
+ k_pmd = pgd_to_pmd_walk(k_pgd, LDT_BASE_ADDR);
+ u_pmd = pgd_to_pmd_walk(u_pgd, LDT_BASE_ADDR);
+
+ if (boot_cpu_has(X86_FEATURE_PTI) && !mm->context.ldt)
+ set_pmd(u_pmd, *k_pmd);
+}
+
+static void sanity_check_ldt_mapping(struct mm_struct *mm)
+{
+ pgd_t *k_pgd = pgd_offset(mm, LDT_BASE_ADDR);
+ pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd);
+ bool had_kernel, had_user;
+ pmd_t *k_pmd, *u_pmd;
+
+ k_pmd = pgd_to_pmd_walk(k_pgd, LDT_BASE_ADDR);
+ u_pmd = pgd_to_pmd_walk(u_pgd, LDT_BASE_ADDR);
+ had_kernel = (k_pmd->pmd != 0);
+ had_user = (u_pmd->pmd != 0);
+
+ do_sanity_check(mm, had_kernel, had_user);
+}
+
+#else /* !CONFIG_X86_PAE */
+
+static void map_ldt_struct_to_user(struct mm_struct *mm)
+{
+ pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR);
+
+ if (boot_cpu_has(X86_FEATURE_PTI) && !mm->context.ldt)
+ set_pgd(kernel_to_user_pgdp(pgd), *pgd);
+}
+
+static void sanity_check_ldt_mapping(struct mm_struct *mm)
+{
+ pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR);
+ bool had_kernel = (pgd->pgd != 0);
+ bool had_user = (kernel_to_user_pgdp(pgd)->pgd != 0);
+
+ do_sanity_check(mm, had_kernel, had_user);
+}
+
+#endif /* CONFIG_X86_PAE */
+
+/*
+ * If PTI is enabled, this maps the LDT into the kernelmode and
+ * usermode tables for the given mm.
+ */
+static int
+map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
+{
+ unsigned long va;
+ bool is_vmalloc;
+ spinlock_t *ptl;
+ int i, nr_pages;
+
+ if (!boot_cpu_has(X86_FEATURE_PTI))
+ return 0;
+
+ /*
+ * Any given ldt_struct should have map_ldt_struct() called at most
+ * once.
+ */
+ WARN_ON(ldt->slot != -1);
+
+ /* Check if the current mappings are sane */
+ sanity_check_ldt_mapping(mm);
+
+ is_vmalloc = is_vmalloc_addr(ldt->entries);
+
+ nr_pages = DIV_ROUND_UP(ldt->nr_entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+
+ for (i = 0; i < nr_pages; i++) {
+ unsigned long offset = i << PAGE_SHIFT;
+ const void *src = (char *)ldt->entries + offset;
+ unsigned long pfn;
+ pgprot_t pte_prot;
+ pte_t pte, *ptep;
+
+ va = (unsigned long)ldt_slot_va(slot) + offset;
+ pfn = is_vmalloc ? vmalloc_to_pfn(src) :
+ page_to_pfn(virt_to_page(src));
+ /*
+ * Treat the PTI LDT range as a *userspace* range.
+ * get_locked_pte() will allocate all needed pagetables
+ * and account for them in this mm.
+ */
+ ptep = get_locked_pte(mm, va, &ptl);
+ if (!ptep)
+ return -ENOMEM;
+ /*
+ * Map it RO so the easy to find address is not a primary
+ * target via some kernel interface which misses a
+ * permission check.
+ */
+ pte_prot = __pgprot(__PAGE_KERNEL_RO & ~_PAGE_GLOBAL);
+ /* Filter out unsuppored __PAGE_KERNEL* bits: */
+ pgprot_val(pte_prot) &= __supported_pte_mask;
+ pte = pfn_pte(pfn, pte_prot);
+ set_pte_at(mm, va, ptep, pte);
+ pte_unmap_unlock(ptep, ptl);
+ }
+
+ /* Propagate LDT mapping to the user page-table */
+ map_ldt_struct_to_user(mm);
+
+ ldt->slot = slot;
+ return 0;
+}
+
+static void unmap_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt)
+{
+ unsigned long va;
+ int i, nr_pages;
+
+ if (!ldt)
+ return;
+
+ /* LDT map/unmap is only required for PTI */
+ if (!boot_cpu_has(X86_FEATURE_PTI))
+ return;
+
+ nr_pages = DIV_ROUND_UP(ldt->nr_entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+
+ for (i = 0; i < nr_pages; i++) {
+ unsigned long offset = i << PAGE_SHIFT;
+ spinlock_t *ptl;
+ pte_t *ptep;
+
+ va = (unsigned long)ldt_slot_va(ldt->slot) + offset;
+ ptep = get_locked_pte(mm, va, &ptl);
+ pte_clear(mm, va, ptep);
+ pte_unmap_unlock(ptep, ptl);
+ }
+
+ va = (unsigned long)ldt_slot_va(ldt->slot);
+ flush_tlb_mm_range(mm, va, va + nr_pages * PAGE_SIZE, PAGE_SHIFT, false);
+}
+
+#else /* !CONFIG_PAGE_TABLE_ISOLATION */
+
+static int
+map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
+{
+ return 0;
+}
+
+static void unmap_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt)
+{
+}
+#endif /* CONFIG_PAGE_TABLE_ISOLATION */
+
+static void free_ldt_pgtables(struct mm_struct *mm)
+{
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+ struct mmu_gather tlb;
+ unsigned long start = LDT_BASE_ADDR;
+ unsigned long end = LDT_END_ADDR;
+
+ if (!boot_cpu_has(X86_FEATURE_PTI))
+ return;
+
+ tlb_gather_mmu(&tlb, mm, start, end);
+ free_pgd_range(&tlb, start, end, start, end);
+ tlb_finish_mmu(&tlb, start, end);
+#endif
+}
+
+/* After calling this, the LDT is immutable. */
+static void finalize_ldt_struct(struct ldt_struct *ldt)
+{
+ paravirt_alloc_ldt(ldt->entries, ldt->nr_entries);
+}
+
+static void install_ldt(struct mm_struct *mm, struct ldt_struct *ldt)
+{
+ mutex_lock(&mm->context.lock);
+
+ /* Synchronizes with READ_ONCE in load_mm_ldt. */
+ smp_store_release(&mm->context.ldt, ldt);
+
+ /* Activate the LDT for all CPUs using currents mm. */
+ on_each_cpu_mask(mm_cpumask(mm), flush_ldt, mm, true);
+
+ mutex_unlock(&mm->context.lock);
+}
+
+static void free_ldt_struct(struct ldt_struct *ldt)
+{
+ if (likely(!ldt))
+ return;
+
+ paravirt_free_ldt(ldt->entries, ldt->nr_entries);
+ if (ldt->nr_entries * LDT_ENTRY_SIZE > PAGE_SIZE)
+ vfree_atomic(ldt->entries);
+ else
+ free_page((unsigned long)ldt->entries);
+ kfree(ldt);
+}
+
+/*
+ * Called on fork from arch_dup_mmap(). Just copy the current LDT state,
+ * the new task is not running, so nothing can be installed.
+ */
+int ldt_dup_context(struct mm_struct *old_mm, struct mm_struct *mm)
+{
+ struct ldt_struct *new_ldt;
+ int retval = 0;
+
+ if (!old_mm)
+ return 0;
+
+ mutex_lock(&old_mm->context.lock);
+ if (!old_mm->context.ldt)
+ goto out_unlock;
+
+ new_ldt = alloc_ldt_struct(old_mm->context.ldt->nr_entries);
+ if (!new_ldt) {
+ retval = -ENOMEM;
+ goto out_unlock;
+ }
+
+ memcpy(new_ldt->entries, old_mm->context.ldt->entries,
+ new_ldt->nr_entries * LDT_ENTRY_SIZE);
+ finalize_ldt_struct(new_ldt);
+
+ retval = map_ldt_struct(mm, new_ldt, 0);
+ if (retval) {
+ free_ldt_pgtables(mm);
+ free_ldt_struct(new_ldt);
+ goto out_unlock;
+ }
+ mm->context.ldt = new_ldt;
+
+out_unlock:
+ mutex_unlock(&old_mm->context.lock);
+ return retval;
+}
+
+/*
+ * No need to lock the MM as we are the last user
+ *
+ * 64bit: Don't touch the LDT register - we're already in the next thread.
+ */
+void destroy_context_ldt(struct mm_struct *mm)
+{
+ free_ldt_struct(mm->context.ldt);
+ mm->context.ldt = NULL;
+}
+
+void ldt_arch_exit_mmap(struct mm_struct *mm)
+{
+ free_ldt_pgtables(mm);
+}
+
+static int read_ldt(void __user *ptr, unsigned long bytecount)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long entries_size;
+ int retval;
+
+ down_read(&mm->context.ldt_usr_sem);
+
+ if (!mm->context.ldt) {
+ retval = 0;
+ goto out_unlock;
+ }
+
+ if (bytecount > LDT_ENTRY_SIZE * LDT_ENTRIES)
+ bytecount = LDT_ENTRY_SIZE * LDT_ENTRIES;
+
+ entries_size = mm->context.ldt->nr_entries * LDT_ENTRY_SIZE;
+ if (entries_size > bytecount)
+ entries_size = bytecount;
+
+ if (copy_to_user(ptr, mm->context.ldt->entries, entries_size)) {
+ retval = -EFAULT;
+ goto out_unlock;
+ }
+
+ if (entries_size != bytecount) {
+ /* Zero-fill the rest and pretend we read bytecount bytes. */
+ if (clear_user(ptr + entries_size, bytecount - entries_size)) {
+ retval = -EFAULT;
+ goto out_unlock;
+ }
+ }
+ retval = bytecount;
+
+out_unlock:
+ up_read(&mm->context.ldt_usr_sem);
+ return retval;
+}
+
+static int read_default_ldt(void __user *ptr, unsigned long bytecount)
+{
+ /* CHECKME: Can we use _one_ random number ? */
+#ifdef CONFIG_X86_32
+ unsigned long size = 5 * sizeof(struct desc_struct);
+#else
+ unsigned long size = 128;
+#endif
+ if (bytecount > size)
+ bytecount = size;
+ if (clear_user(ptr, bytecount))
+ return -EFAULT;
+ return bytecount;
+}
+
+static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
+{
+ struct mm_struct *mm = current->mm;
+ struct ldt_struct *new_ldt, *old_ldt;
+ unsigned int old_nr_entries, new_nr_entries;
+ struct user_desc ldt_info;
+ struct desc_struct ldt;
+ int error;
+
+ error = -EINVAL;
+ if (bytecount != sizeof(ldt_info))
+ goto out;
+ error = -EFAULT;
+ if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
+ goto out;
+
+ error = -EINVAL;
+ if (ldt_info.entry_number >= LDT_ENTRIES)
+ goto out;
+ if (ldt_info.contents == 3) {
+ if (oldmode)
+ goto out;
+ if (ldt_info.seg_not_present == 0)
+ goto out;
+ }
+
+ if ((oldmode && !ldt_info.base_addr && !ldt_info.limit) ||
+ LDT_empty(&ldt_info)) {
+ /* The user wants to clear the entry. */
+ memset(&ldt, 0, sizeof(ldt));
+ } else {
+ if (!IS_ENABLED(CONFIG_X86_16BIT) && !ldt_info.seg_32bit) {
+ error = -EINVAL;
+ goto out;
+ }
+
+ fill_ldt(&ldt, &ldt_info);
+ if (oldmode)
+ ldt.avl = 0;
+ }
+
+ if (down_write_killable(&mm->context.ldt_usr_sem))
+ return -EINTR;
+
+ old_ldt = mm->context.ldt;
+ old_nr_entries = old_ldt ? old_ldt->nr_entries : 0;
+ new_nr_entries = max(ldt_info.entry_number + 1, old_nr_entries);
+
+ error = -ENOMEM;
+ new_ldt = alloc_ldt_struct(new_nr_entries);
+ if (!new_ldt)
+ goto out_unlock;
+
+ if (old_ldt)
+ memcpy(new_ldt->entries, old_ldt->entries, old_nr_entries * LDT_ENTRY_SIZE);
+
+ new_ldt->entries[ldt_info.entry_number] = ldt;
+ finalize_ldt_struct(new_ldt);
+
+ /*
+ * If we are using PTI, map the new LDT into the userspace pagetables.
+ * If there is already an LDT, use the other slot so that other CPUs
+ * will continue to use the old LDT until install_ldt() switches
+ * them over to the new LDT.
+ */
+ error = map_ldt_struct(mm, new_ldt, old_ldt ? !old_ldt->slot : 0);
+ if (error) {
+ /*
+ * This only can fail for the first LDT setup. If an LDT is
+ * already installed then the PTE page is already
+ * populated. Mop up a half populated page table.
+ */
+ if (!WARN_ON_ONCE(old_ldt))
+ free_ldt_pgtables(mm);
+ free_ldt_struct(new_ldt);
+ goto out_unlock;
+ }
+
+ install_ldt(mm, new_ldt);
+ unmap_ldt_struct(mm, old_ldt);
+ free_ldt_struct(old_ldt);
+ error = 0;
+
+out_unlock:
+ up_write(&mm->context.ldt_usr_sem);
+out:
+ return error;
+}
+
+SYSCALL_DEFINE3(modify_ldt, int , func , void __user * , ptr ,
+ unsigned long , bytecount)
+{
+ int ret = -ENOSYS;
+
+ switch (func) {
+ case 0:
+ ret = read_ldt(ptr, bytecount);
+ break;
+ case 1:
+ ret = write_ldt(ptr, bytecount, 1);
+ break;
+ case 2:
+ ret = read_default_ldt(ptr, bytecount);
+ break;
+ case 0x11:
+ ret = write_ldt(ptr, bytecount, 0);
+ break;
+ }
+ /*
+ * The SYSCALL_DEFINE() macros give us an 'unsigned long'
+ * return type, but tht ABI for sys_modify_ldt() expects
+ * 'int'. This cast gives us an int-sized value in %rax
+ * for the return code. The 'unsigned' is necessary so
+ * the compiler does not try to sign-extend the negative
+ * return codes into the high half of the register when
+ * taking the value from int->long.
+ */
+ return (unsigned int)ret;
+}