v4.19.13 snapshot.
diff --git a/arch/um/kernel/skas/Makefile b/arch/um/kernel/skas/Makefile
new file mode 100644
index 0000000..0b76d88
--- /dev/null
+++ b/arch/um/kernel/skas/Makefile
@@ -0,0 +1,15 @@
+#
+# Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+# Licensed under the GPL
+#
+
+obj-y := clone.o mmu.o process.o syscall.o uaccess.o
+
+# clone.o is in the stub, so it can't be built with profiling
+# GCC hardened also auto-enables -fpic, but we need %ebx so it can't work ->
+# disable it
+
+CFLAGS_clone.o := $(CFLAGS_NO_HARDENING)
+UNPROFILE_OBJS := clone.o
+
+include arch/um/scripts/Makefile.rules
diff --git a/arch/um/kernel/skas/clone.c b/arch/um/kernel/skas/clone.c
new file mode 100644
index 0000000..0f25d41
--- /dev/null
+++ b/arch/um/kernel/skas/clone.c
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
+ * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <signal.h>
+#include <sched.h>
+#include <asm/unistd.h>
+#include <sys/time.h>
+#include <as-layout.h>
+#include <ptrace_user.h>
+#include <stub-data.h>
+#include <sysdep/stub.h>
+
+/*
+ * This is in a separate file because it needs to be compiled with any
+ * extraneous gcc flags (-pg, -fprofile-arcs, -ftest-coverage) disabled
+ *
+ * Use UM_KERN_PAGE_SIZE instead of PAGE_SIZE because that calls getpagesize
+ * on some systems.
+ */
+
+void __attribute__ ((__section__ (".__syscall_stub")))
+stub_clone_handler(void)
+{
+ struct stub_data *data = (struct stub_data *) STUB_DATA;
+ long err;
+
+ err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
+ STUB_DATA + UM_KERN_PAGE_SIZE / 2 - sizeof(void *));
+ if (err != 0)
+ goto out;
+
+ err = stub_syscall4(__NR_ptrace, PTRACE_TRACEME, 0, 0, 0);
+ if (err)
+ goto out;
+
+ remap_stack(data->fd, data->offset);
+ goto done;
+
+ out:
+ /*
+ * save current result.
+ * Parent: pid;
+ * child: retcode of mmap already saved and it jumps around this
+ * assignment
+ */
+ data->err = err;
+ done:
+ trap_myself();
+}
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
new file mode 100644
index 0000000..7a1f2a9
--- /dev/null
+++ b/arch/um/kernel/skas/mmu.c
@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/sections.h>
+#include <as-layout.h>
+#include <os.h>
+#include <skas.h>
+
+static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
+ unsigned long kernel)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pgd = pgd_offset(mm, proc);
+ pud = pud_alloc(mm, pgd, proc);
+ if (!pud)
+ goto out;
+
+ pmd = pmd_alloc(mm, pud, proc);
+ if (!pmd)
+ goto out_pmd;
+
+ pte = pte_alloc_map(mm, pmd, proc);
+ if (!pte)
+ goto out_pte;
+
+ *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
+ *pte = pte_mkread(*pte);
+ return 0;
+
+ out_pte:
+ pmd_free(mm, pmd);
+ out_pmd:
+ pud_free(mm, pud);
+ out:
+ return -ENOMEM;
+}
+
+int init_new_context(struct task_struct *task, struct mm_struct *mm)
+{
+ struct mm_context *from_mm = NULL;
+ struct mm_context *to_mm = &mm->context;
+ unsigned long stack = 0;
+ int ret = -ENOMEM;
+
+ stack = get_zeroed_page(GFP_KERNEL);
+ if (stack == 0)
+ goto out;
+
+ to_mm->id.stack = stack;
+ if (current->mm != NULL && current->mm != &init_mm)
+ from_mm = ¤t->mm->context;
+
+ block_signals();
+ if (from_mm)
+ to_mm->id.u.pid = copy_context_skas0(stack,
+ from_mm->id.u.pid);
+ else to_mm->id.u.pid = start_userspace(stack);
+ unblock_signals();
+
+ if (to_mm->id.u.pid < 0) {
+ ret = to_mm->id.u.pid;
+ goto out_free;
+ }
+
+ ret = init_new_ldt(to_mm, from_mm);
+ if (ret < 0) {
+ printk(KERN_ERR "init_new_context_skas - init_ldt"
+ " failed, errno = %d\n", ret);
+ goto out_free;
+ }
+
+ return 0;
+
+ out_free:
+ if (to_mm->id.stack != 0)
+ free_page(to_mm->id.stack);
+ out:
+ return ret;
+}
+
+void uml_setup_stubs(struct mm_struct *mm)
+{
+ int err, ret;
+
+ ret = init_stub_pte(mm, STUB_CODE,
+ (unsigned long) __syscall_stub_start);
+ if (ret)
+ goto out;
+
+ ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
+ if (ret)
+ goto out;
+
+ mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
+ mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
+
+ /* dup_mmap already holds mmap_sem */
+ err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
+ VM_READ | VM_MAYREAD | VM_EXEC |
+ VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
+ mm->context.stub_pages);
+ if (err) {
+ printk(KERN_ERR "install_special_mapping returned %d\n", err);
+ goto out;
+ }
+ return;
+
+out:
+ force_sigsegv(SIGSEGV, current);
+}
+
+void arch_exit_mmap(struct mm_struct *mm)
+{
+ pte_t *pte;
+
+ pte = virt_to_pte(mm, STUB_CODE);
+ if (pte != NULL)
+ pte_clear(mm, STUB_CODE, pte);
+
+ pte = virt_to_pte(mm, STUB_DATA);
+ if (pte == NULL)
+ return;
+
+ pte_clear(mm, STUB_DATA, pte);
+}
+
+void destroy_context(struct mm_struct *mm)
+{
+ struct mm_context *mmu = &mm->context;
+
+ /*
+ * If init_new_context wasn't called, this will be
+ * zero, resulting in a kill(0), which will result in the
+ * whole UML suddenly dying. Also, cover negative and
+ * 1 cases, since they shouldn't happen either.
+ */
+ if (mmu->id.u.pid < 2) {
+ printk(KERN_ERR "corrupt mm_context - pid = %d\n",
+ mmu->id.u.pid);
+ return;
+ }
+ os_kill_ptraced_process(mmu->id.u.pid, 1);
+
+ free_page(mmu->id.stack);
+ free_ldt(mmu);
+}
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
new file mode 100644
index 0000000..d4dbf08
--- /dev/null
+++ b/arch/um/kernel/skas/process.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/init.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/task_stack.h>
+#include <linux/sched/task.h>
+
+#include <as-layout.h>
+#include <kern.h>
+#include <os.h>
+#include <skas.h>
+
+extern void start_kernel(void);
+
+static int __init start_kernel_proc(void *unused)
+{
+ int pid;
+
+ block_signals();
+ pid = os_getpid();
+
+ cpu_tasks[0].pid = pid;
+ cpu_tasks[0].task = current;
+
+ start_kernel();
+ return 0;
+}
+
+extern int userspace_pid[];
+
+extern char cpu0_irqstack[];
+
+int __init start_uml(void)
+{
+ stack_protections((unsigned long) &cpu0_irqstack);
+ set_sigstack(cpu0_irqstack, THREAD_SIZE);
+
+ init_new_thread_signals();
+
+ init_task.thread.request.u.thread.proc = start_kernel_proc;
+ init_task.thread.request.u.thread.arg = NULL;
+ return start_idle_thread(task_stack_page(&init_task),
+ &init_task.thread.switch_buf);
+}
+
+unsigned long current_stub_stack(void)
+{
+ if (current->mm == NULL)
+ return 0;
+
+ return current->mm->context.id.stack;
+}
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
new file mode 100644
index 0000000..b783ac8
--- /dev/null
+++ b/arch/um/kernel/skas/syscall.c
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+#include <linux/seccomp.h>
+#include <kern_util.h>
+#include <sysdep/ptrace.h>
+#include <sysdep/ptrace_user.h>
+#include <sysdep/syscalls.h>
+
+void handle_syscall(struct uml_pt_regs *r)
+{
+ struct pt_regs *regs = container_of(r, struct pt_regs, regs);
+ int syscall;
+
+ /* Initialize the syscall number and default return value. */
+ UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+ PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
+
+ if (syscall_trace_enter(regs))
+ goto out;
+
+ /* Do the seccomp check after ptrace; failures should be fast. */
+ if (secure_computing(NULL) == -1)
+ goto out;
+
+ syscall = UPT_SYSCALL_NR(r);
+ if (syscall >= 0 && syscall <= __NR_syscall_max)
+ PT_REGS_SET_SYSCALL_RETURN(regs,
+ EXECUTE_SYSCALL(syscall, regs));
+
+out:
+ syscall_trace_leave(regs);
+}
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
new file mode 100644
index 0000000..d450797
--- /dev/null
+++ b/arch/um/kernel/skas/uaccess.c
@@ -0,0 +1,246 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/err.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <asm/current.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <kern_util.h>
+#include <os.h>
+
+pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ if (mm == NULL)
+ return NULL;
+
+ pgd = pgd_offset(mm, addr);
+ if (!pgd_present(*pgd))
+ return NULL;
+
+ pud = pud_offset(pgd, addr);
+ if (!pud_present(*pud))
+ return NULL;
+
+ pmd = pmd_offset(pud, addr);
+ if (!pmd_present(*pmd))
+ return NULL;
+
+ return pte_offset_kernel(pmd, addr);
+}
+
+static pte_t *maybe_map(unsigned long virt, int is_write)
+{
+ pte_t *pte = virt_to_pte(current->mm, virt);
+ int err, dummy_code;
+
+ if ((pte == NULL) || !pte_present(*pte) ||
+ (is_write && !pte_write(*pte))) {
+ err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
+ if (err)
+ return NULL;
+ pte = virt_to_pte(current->mm, virt);
+ }
+ if (!pte_present(*pte))
+ pte = NULL;
+
+ return pte;
+}
+
+static int do_op_one_page(unsigned long addr, int len, int is_write,
+ int (*op)(unsigned long addr, int len, void *arg), void *arg)
+{
+ jmp_buf buf;
+ struct page *page;
+ pte_t *pte;
+ int n, faulted;
+
+ pte = maybe_map(addr, is_write);
+ if (pte == NULL)
+ return -1;
+
+ page = pte_page(*pte);
+ addr = (unsigned long) kmap_atomic(page) +
+ (addr & ~PAGE_MASK);
+
+ current->thread.fault_catcher = &buf;
+
+ faulted = UML_SETJMP(&buf);
+ if (faulted == 0)
+ n = (*op)(addr, len, arg);
+ else
+ n = -1;
+
+ current->thread.fault_catcher = NULL;
+
+ kunmap_atomic((void *)addr);
+
+ return n;
+}
+
+static long buffer_op(unsigned long addr, int len, int is_write,
+ int (*op)(unsigned long, int, void *), void *arg)
+{
+ long size, remain, n;
+
+ size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
+ remain = len;
+
+ n = do_op_one_page(addr, size, is_write, op, arg);
+ if (n != 0) {
+ remain = (n < 0 ? remain : 0);
+ goto out;
+ }
+
+ addr += size;
+ remain -= size;
+ if (remain == 0)
+ goto out;
+
+ while (addr < ((addr + remain) & PAGE_MASK)) {
+ n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
+ if (n != 0) {
+ remain = (n < 0 ? remain : 0);
+ goto out;
+ }
+
+ addr += PAGE_SIZE;
+ remain -= PAGE_SIZE;
+ }
+ if (remain == 0)
+ goto out;
+
+ n = do_op_one_page(addr, remain, is_write, op, arg);
+ if (n != 0) {
+ remain = (n < 0 ? remain : 0);
+ goto out;
+ }
+
+ return 0;
+ out:
+ return remain;
+}
+
+static int copy_chunk_from_user(unsigned long from, int len, void *arg)
+{
+ unsigned long *to_ptr = arg, to = *to_ptr;
+
+ memcpy((void *) to, (void *) from, len);
+ *to_ptr += len;
+ return 0;
+}
+
+unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ if (uaccess_kernel()) {
+ memcpy(to, (__force void*)from, n);
+ return 0;
+ }
+
+ return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to);
+}
+EXPORT_SYMBOL(raw_copy_from_user);
+
+static int copy_chunk_to_user(unsigned long to, int len, void *arg)
+{
+ unsigned long *from_ptr = arg, from = *from_ptr;
+
+ memcpy((void *) to, (void *) from, len);
+ *from_ptr += len;
+ return 0;
+}
+
+unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+ if (uaccess_kernel()) {
+ memcpy((__force void *) to, from, n);
+ return 0;
+ }
+
+ return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from);
+}
+EXPORT_SYMBOL(raw_copy_to_user);
+
+static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
+{
+ char **to_ptr = arg, *to = *to_ptr;
+ int n;
+
+ strncpy(to, (void *) from, len);
+ n = strnlen(to, len);
+ *to_ptr += n;
+
+ if (n < len)
+ return 1;
+ return 0;
+}
+
+long __strncpy_from_user(char *dst, const char __user *src, long count)
+{
+ long n;
+ char *ptr = dst;
+
+ if (uaccess_kernel()) {
+ strncpy(dst, (__force void *) src, count);
+ return strnlen(dst, count);
+ }
+
+ n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
+ &ptr);
+ if (n != 0)
+ return -EFAULT;
+ return strnlen(dst, count);
+}
+EXPORT_SYMBOL(__strncpy_from_user);
+
+static int clear_chunk(unsigned long addr, int len, void *unused)
+{
+ memset((void *) addr, 0, len);
+ return 0;
+}
+
+unsigned long __clear_user(void __user *mem, unsigned long len)
+{
+ if (uaccess_kernel()) {
+ memset((__force void*)mem, 0, len);
+ return 0;
+ }
+
+ return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
+}
+EXPORT_SYMBOL(__clear_user);
+
+static int strnlen_chunk(unsigned long str, int len, void *arg)
+{
+ int *len_ptr = arg, n;
+
+ n = strnlen((void *) str, len);
+ *len_ptr += n;
+
+ if (n < len)
+ return 1;
+ return 0;
+}
+
+long __strnlen_user(const void __user *str, long len)
+{
+ int count = 0, n;
+
+ if (uaccess_kernel())
+ return strnlen((__force char*)str, len) + 1;
+
+ n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
+ if (n == 0)
+ return count + 1;
+ return 0;
+}
+EXPORT_SYMBOL(__strnlen_user);