arm: introduce ret_from_kernel_execve(), switch to generic kernel_execve()

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

3 files changed, 13 insertions, 42 deletions

diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 0cab47d4a83f..2c9b7a87e64b 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -469,6 +469,7 @@
 #define __ARCH_WANT_OLD_READDIR
 #define __ARCH_WANT_SYS_SOCKETCALL
 #endif
+#define __ARCH_WANT_KERNEL_EXECVE
 
 /*
  * "Conditional" syscalls
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 9a48b7a577e7..4a6e46a9a3d7 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -103,6 +103,18 @@ ENTRY(ret_from_kernel_thread)
  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/sys_arm.c b/arch/arm/kernel/sys_arm.c
index 3ba62e3cd1a2..c8e729efc187 100644
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -79,48 +79,6 @@ 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;
-}
-
 /*
  * Since loff_t is a 64 bit type we avoid a lot of ABI hassle
  * with a different argument ordering.