Fixed MTP to work with TWRP

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

arch/um/kernel/skas/clone.c

@@ -0,0 +1,56 @@
+/*
+ * 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;
+
+	err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
+			    (long) &data->timer, 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();
+}

arch/um/kernel/skas/mmu.c

@@ -0,0 +1,178 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <as-layout.h>
+#include <os.h>
+#include <skas.h>
+
+extern int __syscall_stub_start;
+
+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, NULL, 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;
+
+	if (skas_needs_stub) {
+		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 = &current->mm->context;
+
+	if (proc_mm) {
+		ret = new_mm(stack);
+		if (ret < 0) {
+			printk(KERN_ERR "init_new_context_skas - "
+			       "new_mm failed, errno = %d\n", ret);
+			goto out_free;
+		}
+		to_mm->id.u.mm_fd = ret;
+	}
+	else {
+		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);
+
+		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;
+
+	if (!skas_needs_stub)
+		return;
+
+	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 (proc_mm)
+		os_close_file(mmu->id.u.mm_fd);
+	else {
+		/*
+		 * 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);
+	}
+
+	if (skas_needs_stub)
+		free_page(mmu->id.stack);
+
+	free_ldt(mmu);
+}

arch/um/kernel/skas/process.c

@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <as-layout.h>
+#include <kern.h>
+#include <os.h>
+#include <skas.h>
+
+int new_mm(unsigned long stack)
+{
+	int fd, err;
+
+	fd = os_open_file("/proc/mm", of_cloexec(of_write(OPENFLAGS())), 0);
+	if (fd < 0)
+		return fd;
+
+	if (skas_needs_stub) {
+		err = map_stub_pages(fd, STUB_CODE, STUB_DATA, stack);
+		if (err) {
+			os_close_file(fd);
+			return err;
+		}
+	}
+
+	return fd;
+}
+
+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;
+#ifdef CONFIG_SMP
+	init_cpu_online(get_cpu_mask(0));
+#endif
+	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);
+	if (proc_mm) {
+		userspace_pid[0] = start_userspace(0);
+		if (userspace_pid[0] < 0) {
+			printf("start_uml - start_userspace returned %d\n",
+			       userspace_pid[0]);
+			exit(1);
+		}
+	}
+
+	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;
+}

arch/um/kernel/skas/syscall.c

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+#include <kern_util.h>
+#include <sysdep/ptrace.h>
+#include <sysdep/syscalls.h>
+
+extern int syscall_table_size;
+#define NR_SYSCALLS (syscall_table_size / sizeof(void *))
+
+void handle_syscall(struct uml_pt_regs *r)
+{
+	struct pt_regs *regs = container_of(r, struct pt_regs, regs);
+	long result;
+	int syscall;
+
+	syscall_trace_enter(regs);
+
+	/*
+	 * This should go in the declaration of syscall, but when I do that,
+	 * strace -f -c bash -c 'ls ; ls' breaks, sometimes not tracing
+	 * children at all, sometimes hanging when bash doesn't see the first
+	 * ls exit.
+	 * The assembly looks functionally the same to me.  This is
+	 *     gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)
+	 * in case it's a compiler bug.
+	 */
+	syscall = UPT_SYSCALL_NR(r);
+	if ((syscall >= NR_SYSCALLS) || (syscall < 0))
+		result = -ENOSYS;
+	else result = EXECUTE_SYSCALL(syscall, regs);
+
+	PT_REGS_SET_SYSCALL_RETURN(regs, result);
+
+	syscall_trace_leave(regs);
+}

arch/um/kernel/skas/uaccess.c

@@ -0,0 +1,259 @@
+/*
+ * 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 int buffer_op(unsigned long addr, int len, int is_write,
+		     int (*op)(unsigned long, int, void *), void *arg)
+{
+	int 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;
+}
+
+int copy_from_user(void *to, const void __user *from, int n)
+{
+	if (segment_eq(get_fs(), KERNEL_DS)) {
+		memcpy(to, (__force void*)from, n);
+		return 0;
+	}
+
+	return access_ok(VERIFY_READ, from, n) ?
+	       buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
+	       n;
+}
+EXPORT_SYMBOL(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;
+}
+
+int copy_to_user(void __user *to, const void *from, int n)
+{
+	if (segment_eq(get_fs(), KERNEL_DS)) {
+		memcpy((__force void *) to, from, n);
+		return 0;
+	}
+
+	return access_ok(VERIFY_WRITE, to, n) ?
+	       buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
+	       n;
+}
+EXPORT_SYMBOL(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;
+}
+
+int strncpy_from_user(char *dst, const char __user *src, int count)
+{
+	int n;
+	char *ptr = dst;
+
+	if (segment_eq(get_fs(), KERNEL_DS)) {
+		strncpy(dst, (__force void *) src, count);
+		return strnlen(dst, count);
+	}
+
+	if (!access_ok(VERIFY_READ, src, 1))
+		return -EFAULT;
+
+	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;
+}
+
+int __clear_user(void __user *mem, int len)
+{
+	return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
+}
+
+int clear_user(void __user *mem, int len)
+{
+	if (segment_eq(get_fs(), KERNEL_DS)) {
+		memset((__force void*)mem, 0, len);
+		return 0;
+	}
+
+	return access_ok(VERIFY_WRITE, mem, len) ?
+	       buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len;
+}
+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;
+}
+
+int strnlen_user(const void __user *str, int len)
+{
+	int count = 0, n;
+
+	if (segment_eq(get_fs(), KERNEL_DS))
+		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);