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
  ...

1 files changed, 30 insertions, 7 deletions

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index b9ff83c7135b..44e0bff38e72 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -57,6 +57,7 @@
 #include <asm/switch_to.h>
 
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
+asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");
 
 /*
  * Return saved PC of a blocked thread.
@@ -127,23 +128,39 @@ void release_thread(struct task_struct *dead_task)
 }
 
 int copy_thread(unsigned long clone_flags, unsigned long sp,
-        unsigned long unused,
+        unsigned long arg,
         struct task_struct *p, struct pt_regs *regs)
 {
-        struct pt_regs *childregs;
+        struct pt_regs *childregs = task_pt_regs(p);
         struct task_struct *tsk;
         int err;
 
-        childregs = task_pt_regs(p);
+        p->thread.sp = (unsigned long) childregs;
+        p->thread.sp0 = (unsigned long) (childregs+1);
+
+        if (unlikely(!regs)) {
+                /* kernel thread */
+                memset(childregs, 0, sizeof(struct pt_regs));
+                p->thread.ip = (unsigned long) ret_from_kernel_thread;
+                task_user_gs(p) = __KERNEL_STACK_CANARY;
+                childregs->ds = __USER_DS;
+                childregs->es = __USER_DS;
+                childregs->fs = __KERNEL_PERCPU;
+                childregs->bx = sp;     /* function */
+                childregs->bp = arg;
+                childregs->orig_ax = -1;
+                childregs->cs = __KERNEL_CS | get_kernel_rpl();
+                childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_BIT1;
+                p->fpu_counter = 0;
+                p->thread.io_bitmap_ptr = NULL;
+                memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
+                return 0;
+        }
         *childregs = *regs;
         childregs->ax = 0;
         childregs->sp = sp;
 
-        p->thread.sp = (unsigned long) childregs;
-        p->thread.sp0 = (unsigned long) (childregs+1);
-
         p->thread.ip = (unsigned long) ret_from_fork;
-
         task_user_gs(p) = get_user_gs(regs);
 
         p->fpu_counter = 0;
@@ -190,6 +207,12 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
         regs->cs                = __USER_CS;
         regs->ip                = new_ip;
         regs->sp                = new_sp;
+        regs->flags             = X86_EFLAGS_IF;
+        /*
+         * force it to the iret return path by making it look as if there was
+         * some work pending.
+         */
+        set_thread_flag(TIF_NOTIFY_RESUME);
 }
 EXPORT_SYMBOL_GPL(start_thread);