4 files changed, 38 insertions, 131 deletions

diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index e337879595e5..831cd38c8d99 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -20,7 +20,7 @@
                 CALL(sys_creat)
                 CALL(sys_link)
 /* 10 */        CALL(sys_unlink)
-                CALL(sys_execve_wrapper)
+                CALL(sys_execve)
                 CALL(sys_chdir)
                 CALL(OBSOLETE(sys_time))        /* used by libc4 */
                 CALL(sys_mknod)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f45987037bf1..e340fa1db203 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -91,6 +91,30 @@ ENTRY(ret_from_fork)
         b       ret_slow_syscall
 ENDPROC(ret_from_fork)
 
+ENTRY(ret_from_kernel_thread)
+ UNWIND(.fnstart)
+ UNWIND(.cantunwind)
+        bl      schedule_tail
+        mov     r0, r4
+        adr     lr, BSYM(1f)    @ kernel threads should not exit
+        mov     pc, r5
+1:      bl      do_exit
+        nop
+ UNWIND(.fnend)
+ENDPROC(ret_from_kernel_thread)
+
+/*
+ * turn a kernel thread into userland process
+ * use: ret_from_kernel_execve(struct pt_regs *normal)
+ */
+ENTRY(ret_from_kernel_execve)
+        mov     why, #0                 @ not a syscall
+        str     why, [r0, #S_R0]        @ ... and we want 0 in ->ARM_r0 as well
+        get_thread_info tsk             @ thread structure
+        mov     sp, r0                  @ stack pointer just under pt_regs
+        b       ret_slow_syscall
+ENDPROC(ret_from_kernel_execve)
+
         .equ NR_syscalls,0
 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
 #include "calls.S"
@@ -517,11 +541,6 @@ sys_vfork_wrapper:
                 b       sys_vfork
 ENDPROC(sys_vfork_wrapper)
 
-sys_execve_wrapper:
-                add     r3, sp, #S_OFF
-                b       sys_execve
-ENDPROC(sys_execve_wrapper)
-
 sys_clone_wrapper:
                 add     ip, sp, #S_OFF
                 str     ip, [sp, #4]
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 04eea22d7958..f98c17ff1957 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -373,6 +373,7 @@ void release_thread(struct task_struct *dead_task)
 }
 
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
+asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");
 
 int
 copy_thread(unsigned long clone_flags, unsigned long stack_start,
@@ -381,13 +382,20 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start,
         struct thread_info *thread = task_thread_info(p);
         struct pt_regs *childregs = task_pt_regs(p);
 
-        *childregs = *regs;
-        childregs->ARM_r0 = 0;
-        childregs->ARM_sp = stack_start;
-
         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
+
+        if (likely(regs)) {
+                *childregs = *regs;
+                childregs->ARM_r0 = 0;
+                childregs->ARM_sp = stack_start;
+                thread->cpu_context.pc = (unsigned long)ret_from_fork;
+        } else {
+                thread->cpu_context.r4 = stk_sz;
+                thread->cpu_context.r5 = stack_start;
+                thread->cpu_context.pc = (unsigned long)ret_from_kernel_thread;
+                childregs->ARM_cpsr = SVC_MODE;
+        }
         thread->cpu_context.sp = (unsigned long)childregs;
-        thread->cpu_context.pc = (unsigned long)ret_from_fork;
 
         clear_ptrace_hw_breakpoint(p);
 
@@ -423,63 +431,6 @@ int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
 }
 EXPORT_SYMBOL(dump_fpu);
 
-/*
- * Shuffle the argument into the correct register before calling the
- * thread function.  r4 is the thread argument, r5 is the pointer to
- * the thread function, and r6 points to the exit function.
- */
-extern void kernel_thread_helper(void);
-asm(    ".pushsection .text\n"
-"       .align\n"
-"       .type   kernel_thread_helper, #function\n"
-"kernel_thread_helper:\n"
-#ifdef CONFIG_TRACE_IRQFLAGS
-"       bl      trace_hardirqs_on\n"
-#endif
-"       msr     cpsr_c, r7\n"
-"       mov     r0, r4\n"
-"       mov     lr, r6\n"
-"       mov     pc, r5\n"
-"       .size   kernel_thread_helper, . - kernel_thread_helper\n"
-"       .popsection");
-
-#ifdef CONFIG_ARM_UNWIND
-extern void kernel_thread_exit(long code);
-asm(    ".pushsection .text\n"
-"       .align\n"
-"       .type   kernel_thread_exit, #function\n"
-"kernel_thread_exit:\n"
-"       .fnstart\n"
-"       .cantunwind\n"
-"       bl      do_exit\n"
-"       nop\n"
-"       .fnend\n"
-"       .size   kernel_thread_exit, . - kernel_thread_exit\n"
-"       .popsection");
-#else
-#define kernel_thread_exit      do_exit
-#endif
-
-/*
- * Create a kernel thread.
- */
-pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-
-        regs.ARM_r4 = (unsigned long)arg;
-        regs.ARM_r5 = (unsigned long)fn;
-        regs.ARM_r6 = (unsigned long)kernel_thread_exit;
-        regs.ARM_r7 = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;
-        regs.ARM_pc = (unsigned long)kernel_thread_helper;
-        regs.ARM_cpsr = regs.ARM_r7 | PSR_I_BIT;
-
-        return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
 unsigned long get_wchan(struct task_struct *p)
 {
         struct stackframe frame;
diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c
index 76cbb055dd05..c2a898aa57aa 100644
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -59,69 +59,6 @@ asmlinkage int sys_vfork(struct pt_regs *regs)
         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->ARM_sp, regs, 0, NULL, NULL);
 }
 
-/* sys_execve() executes a new program.
- * This is called indirectly via a small wrapper
- */
-asmlinkage int sys_execve(const char __user *filenamei,
-                          const char __user *const __user *argv,
-                          const char __user *const __user *envp, struct pt_regs *regs)
-{
-        int error;
-        char * filename;
-
-        filename = getname(filenamei);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                goto out;
-        error = do_execve(filename, argv, envp, regs);
-        putname(filename);
-out:
-        return error;
-}
-
-int kernel_execve(const char *filename,
-                  const char *const argv[],
-                  const char *const envp[])
-{
-        struct pt_regs regs;
-        int ret;
-
-        memset(&regs, 0, sizeof(struct pt_regs));
-        ret = do_execve(filename,
-                        (const char __user *const __user *)argv,
-                        (const char __user *const __user *)envp, &regs);
-        if (ret < 0)
-                goto out;
-
-        /*
-         * Save argc to the register structure for userspace.
-         */
-        regs.ARM_r0 = ret;
-
-        /*
-         * We were successful.  We won't be returning to our caller, but
-         * instead to user space by manipulating the kernel stack.
-         */
-        asm(    "add    r0, %0, %1\n\t"
-                "mov    r1, %2\n\t"
-                "mov    r2, %3\n\t"
-                "bl     memmove\n\t"    /* copy regs to top of stack */
-                "mov    r8, #0\n\t"     /* not a syscall */
-                "mov    r9, %0\n\t"     /* thread structure */
-                "mov    sp, r0\n\t"     /* reposition stack pointer */
-                "b      ret_to_user"
-                :
-                : "r" (current_thread_info()),
-                  "Ir" (THREAD_START_SP - sizeof(regs)),
-                  "r" (&regs),
-                  "Ir" (sizeof(regs))
-                : "r0", "r1", "r2", "r3", "r8", "r9", "ip", "lr", "memory");
-
- out:
-        return ret;
-}
-EXPORT_SYMBOL(kernel_execve);
-
 /*
  * Since loff_t is a 64 bit type we avoid a lot of ABI hassle
  * with a different argument ordering.