x86, ptrace: Simplify xstateregs_get()

48 bytes (bytes 464..511) of the xstateregs payload come from the
kernel defined structure (xstate_fx_sw_bytes). Rest comes from the
xstate regs structure in the thread struct. Instead of having multiple
user_regset_copyout()'s, simplify the xstateregs_get() by first
copying the SW bytes into the xstate regs structure in the thread structure
and then using one user_regset_copyout() to copyout the xstateregs.

Requested-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20100222225240.494688491@sbs-t61.sc.intel.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Oleg Nesterov <oleg@redhat.com>

1 files changed, 7 insertions, 23 deletions

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 7a8a193b5144..81e23bf12c12 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -243,34 +243,18 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
                 return ret;
 
         /*
-         * First copy the fxsave bytes 0..463.
+         * Copy the 48bytes defined by the software first into the xstate
+         * memory layout in the thread struct, so that we can copy the entire
+         * xstateregs to the user using one user_regset_copyout().
          */
-        ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-                                  &target->thread.xstate->xsave, 0,
-                                  offsetof(struct user_xstateregs,
-                                           i387.xstate_fx_sw));
-        if (ret)
-                return ret;
-
-        /*
-         * Copy the 48bytes defined by software.
-         */
-        ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-                                  xstate_fx_sw_bytes,
-                                  offsetof(struct user_xstateregs,
-                                           i387.xstate_fx_sw),
-                                  offsetof(struct user_xstateregs,
-                                           xsave_hdr));
-        if (ret)
-                return ret;
+        memcpy(&target->thread.xstate->fxsave.sw_reserved,
+               xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
 
         /*
-         * Copy the rest of xstate memory layout.
+         * Copy the xstate memory layout.
          */
         ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-                                  &target->thread.xstate->xsave.xsave_hdr,
-                                  offsetof(struct user_xstateregs,
-                                           xsave_hdr), -1);
+                                  &target->thread.xstate->xsave, 0, -1);
         return ret;
 }