ia64: don't mess with ar_bspstore in kernel_thread()

the only thing we use that for is in copy_thread(), where the way
we set it will result in rbs_size being 0.  Just move that calculating
rbs_size and copying rbs to non-kernel-thread side of
if (user_mode(regs)) in copy_thread() and set rbs_size to 0 on
kernel thread side.

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

1 files changed, 4 insertions, 5 deletions

diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index 63a77b8b5cfa..6a48775d9363 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -411,12 +411,11 @@ copy_thread(unsigned long clone_flags,
 
         rbs = (unsigned long) current + IA64_RBS_OFFSET;
         child_rbs = (unsigned long) p + IA64_RBS_OFFSET;
-        rbs_size = stack->ar_bspstore - rbs;
-
-        /* copy the parent's register backing store to the child: */
-        memcpy((void *) child_rbs, (void *) rbs, rbs_size);
 
         if (likely(user_mode(child_ptregs))) {
+                /* copy the parent's register backing store to the child: */
+                rbs_size = stack->ar_bspstore - rbs;
+                memcpy((void *) child_rbs, (void *) rbs, rbs_size);
                 if (clone_flags & CLONE_SETTLS)
                         child_ptregs->r13 = regs->r16;  /* see sys_clone2() in entry.S */
                 if (user_stack_base) {
@@ -433,6 +432,7 @@ copy_thread(unsigned long clone_flags,
                  * been taken care of by the caller of sys_clone()
                  * already.
                  */
+                rbs_size = 0;
                 child_ptregs->r12 = (unsigned long) child_ptregs - 16; /* kernel sp */
                 child_ptregs->r13 = (unsigned long) p;          /* set `current' pointer */
         }
@@ -637,7 +637,6 @@ kernel_thread (int (*fn)(void *), void *arg, unsigned long flags)
         regs.pt.cr_ipsr = ia64_getreg(_IA64_REG_PSR) | IA64_PSR_BN;
         regs.pt.cr_ifs = 1UL << 63;             /* mark as valid, empty frame */
         regs.sw.ar_fpsr = regs.pt.ar_fpsr = ia64_getreg(_IA64_REG_AR_FPSR);
-        regs.sw.ar_bspstore = (unsigned long) current + IA64_RBS_OFFSET;
         regs.sw.pr = (1 << PRED_KERNEL_STACK);
         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs.pt, 0, NULL, NULL);
 }