Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal

Pull generic execve() changes from Al Viro:
 "This introduces the generic kernel_thread() and kernel_execve()
  functions, and switches x86, arm, alpha, um and s390 over to them."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (26 commits)
  s390: convert to generic kernel_execve()
  s390: switch to generic kernel_thread()
  s390: fold kernel_thread_helper() into ret_from_fork()
  s390: fold execve_tail() into start_thread(), convert to generic sys_execve()
  um: switch to generic kernel_thread()
  x86, um/x86: switch to generic sys_execve and kernel_execve
  x86: split ret_from_fork
  alpha: introduce ret_from_kernel_execve(), switch to generic kernel_execve()
  alpha: switch to generic kernel_thread()
  alpha: switch to generic sys_execve()
  arm: get rid of execve wrapper, switch to generic execve() implementation
  arm: optimized current_pt_regs()
  arm: introduce ret_from_kernel_execve(), switch to generic kernel_execve()
  arm: split ret_from_fork, simplify kernel_thread() [based on patch by rmk]
  generic sys_execve()
  generic kernel_execve()
  new helper: current_pt_regs()
  preparation for generic kernel_thread()
  um: kill thread->forking
  um: let signal_delivered() do SIGTRAP on singlestepping into handler
  ...

fs/exec.c

@@ -59,7 +59,6 @@
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
 #include <asm/tlb.h>
-#include <asm/exec.h>
 
 #include <trace/events/task.h>
 #include "internal.h"
@@ -392,7 +391,7 @@ struct user_arg_ptr {
 	union {
 		const char __user *const __user *native;
 #ifdef CONFIG_COMPAT
-		compat_uptr_t __user *compat;
+		const compat_uptr_t __user *compat;
 #endif
 	} ptr;
 };
@@ -1574,9 +1573,9 @@ int do_execve(const char *filename,
 }
 
 #ifdef CONFIG_COMPAT
-int compat_do_execve(char *filename,
-	compat_uptr_t __user *__argv,
-	compat_uptr_t __user *__envp,
+int compat_do_execve(const char *filename,
+	const compat_uptr_t __user *__argv,
+	const compat_uptr_t __user *__envp,
 	struct pt_regs *regs)
 {
 	struct user_arg_ptr argv = {
@@ -1658,3 +1657,55 @@ int get_dumpable(struct mm_struct *mm)
 {
 	return __get_dumpable(mm->flags);
 }
+
+#ifdef __ARCH_WANT_SYS_EXECVE
+SYSCALL_DEFINE3(execve,
+		const char __user *, filename,
+		const char __user *const __user *, argv,
+		const char __user *const __user *, envp)
+{
+	const char *path = getname(filename);
+	int error = PTR_ERR(path);
+	if (!IS_ERR(path)) {
+		error = do_execve(path, argv, envp, current_pt_regs());
+		putname(path);
+	}
+	return error;
+}
+#ifdef CONFIG_COMPAT
+asmlinkage long compat_sys_execve(const char __user * filename,
+	const compat_uptr_t __user * argv,
+	const compat_uptr_t __user * envp)
+{
+	const char *path = getname(filename);
+	int error = PTR_ERR(path);
+	if (!IS_ERR(path)) {
+		error = compat_do_execve(path, argv, envp, current_pt_regs());
+		putname(path);
+	}
+	return error;
+}
+#endif
+#endif
+
+#ifdef __ARCH_WANT_KERNEL_EXECVE
+int kernel_execve(const char *filename,
+		  const char *const argv[],
+		  const char *const envp[])
+{
+	struct pt_regs *p = current_pt_regs();
+	int ret;
+
+	ret = do_execve(filename,
+			(const char __user *const __user *)argv,
+			(const char __user *const __user *)envp, p);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * We were successful.  We won't be returning to our caller, but
+	 * instead to user space by manipulating the kernel stack.
+	 */
+	ret_from_kernel_execve(p);
+}
+#endif