arm: switch to saner kernel_execve() semantics

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 7 insertions, 29 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a949eec22861..ea3ad0641952 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -50,6 +50,7 @@ config ARM
         select GENERIC_STRNLEN_USER
         select DCACHE_WORD_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && !CPU_BIG_ENDIAN
         select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
         help
           The ARM series is a line of low-power-consumption RISC chip designs
           licensed by ARM Ltd and targeted at embedded applications and
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 6a70aa42debb..984ad42ed0af 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -470,7 +470,6 @@
 #define __ARCH_WANT_SYS_SOCKETCALL
 #endif
 #define __ARCH_WANT_SYS_EXECVE
-#define __ARCH_WANT_KERNEL_EXECVE
 
 /*
  * "Conditional" syscalls
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index ed7941277ca2..91069666af9f 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -86,35 +86,14 @@ ENDPROC(ret_to_user)
  */
 ENTRY(ret_from_fork)
         bl      schedule_tail
+        cmp     r5, #0
+        movne   r0, r4
+        movne   lr, pc
+        movne   pc, r5
         get_thread_info tsk
-        mov     why, #1
         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"
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index c10e4395bc47..0f83fa2e58e3 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -373,7 +373,6 @@ 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,
@@ -388,13 +387,13 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start,
                 *childregs = *regs;
                 childregs->ARM_r0 = 0;
                 childregs->ARM_sp = stack_start;
-                thread->cpu_context.pc = (unsigned long)ret_from_fork;
         } else {
+                memset(childregs, 0, sizeof(struct pt_regs));
                 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.pc = (unsigned long)ret_from_fork;
         thread->cpu_context.sp = (unsigned long)childregs;
 
         clear_ptrace_hw_breakpoint(p);