x86: get rid of get_user_ex() in ia32_restore_sigcontext()

Just do copyin into a local struct and be done with that - we are
on a shallow stack here.

[reworked by tglx, removing the macro horrors while we are touching that]

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

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index c72025d..23e2c55 100644 (file)
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -36,70 +36,56 @@
 #include <asm/sighandling.h>
 #include <asm/smap.h>
 
+static inline void reload_segments(struct sigcontext_32 *sc)
+{
+       unsigned int cur;
+
+       savesegment(gs, cur);
+       if ((sc->gs | 0x03) != cur)
+               load_gs_index(sc->gs | 0x03);
+       savesegment(fs, cur);
+       if ((sc->fs | 0x03) != cur)
+               loadsegment(fs, sc->fs | 0x03);
+       savesegment(ds, cur);
+       if ((sc->ds | 0x03) != cur)
+               loadsegment(ds, sc->ds | 0x03);
+       savesegment(es, cur);
+       if ((sc->es | 0x03) != cur)
+               loadsegment(es, sc->es | 0x03);
+}
+
 /*
  * Do a signal return; undo the signal stack.
  */
-#define loadsegment_gs(v)      load_gs_index(v)
-#define loadsegment_fs(v)      loadsegment(fs, v)
-#define loadsegment_ds(v)      loadsegment(ds, v)
-#define loadsegment_es(v)      loadsegment(es, v)
-
-#define get_user_seg(seg)      ({ unsigned int v; savesegment(seg, v); v; })
-#define set_user_seg(seg, v)   loadsegment_##seg(v)
-
-#define COPY(x)                        {               \
-       get_user_ex(regs->x, &sc->x);           \
-}
-
-#define GET_SEG(seg)           ({                      \
-       unsigned short tmp;                             \
-       get_user_ex(tmp, &sc->seg);                     \
-       tmp;                                            \
-})
-
-#define COPY_SEG_CPL3(seg)     do {                    \
-       regs->seg = GET_SEG(seg) | 3;                   \
-} while (0)
-
-#define RELOAD_SEG(seg)                {               \
-       unsigned int pre = (seg) | 3;           \
-       unsigned int cur = get_user_seg(seg);   \
-       if (pre != cur)                         \
-               set_user_seg(seg, pre);         \
-}
-
 static int ia32_restore_sigcontext(struct pt_regs *regs,
-                                  struct sigcontext_32 __user *sc)
+                                  struct sigcontext_32 __user *usc)
 {
-       unsigned int tmpflags, err = 0;
-       u16 gs, fs, es, ds;
-       void __user *buf;
-       u32 tmp;
+       struct sigcontext_32 sc;
 
        /* Always make any pending restarted system calls return -EINTR */
        current->restart_block.fn = do_no_restart_syscall;
 
-       get_user_try {
-               gs = GET_SEG(gs);
-               fs = GET_SEG(fs);
-               ds = GET_SEG(ds);
-               es = GET_SEG(es);
-
-               COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
-               COPY(dx); COPY(cx); COPY(ip); COPY(ax);
-               /* Don't touch extended registers */
-
-               COPY_SEG_CPL3(cs);
-               COPY_SEG_CPL3(ss);
-
-               get_user_ex(tmpflags, &sc->flags);
-               regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
-               /* disable syscall checks */
-               regs->orig_ax = -1;
+       if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
+               return -EFAULT;
 
-               get_user_ex(tmp, &sc->fpstate);
-               buf = compat_ptr(tmp);
-       } get_user_catch(err);
+       /* Get only the ia32 registers. */
+       regs->bx = sc.bx;
+       regs->cx = sc.cx;
+       regs->dx = sc.dx;
+       regs->si = sc.si;
+       regs->di = sc.di;
+       regs->bp = sc.bp;
+       regs->ax = sc.ax;
+       regs->sp = sc.sp;
+       regs->ip = sc.ip;
+
+       /* Get CS/SS and force CPL3 */
+       regs->cs = sc.cs | 0x03;
+       regs->ss = sc.ss | 0x03;
+
+       regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
+       /* disable syscall checks */
+       regs->orig_ax = -1;
 
        /*
         * Reload fs and gs if they have changed in the signal
@@ -107,14 +93,8 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
         * the handler, but does not clobber them at least in the
         * normal case.
         */
-       RELOAD_SEG(gs);
-       RELOAD_SEG(fs);
-       RELOAD_SEG(ds);
-       RELOAD_SEG(es);
-
-       err |= fpu__restore_sig(buf, 1);
-
-       return err;
+       reload_segments(&sc);
+       return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
 }
 
 COMPAT_SYSCALL_DEFINE0(sigreturn)
@@ -172,6 +152,8 @@ badframe:
  * Set up a signal frame.
  */
 
+#define get_user_seg(seg)      ({ unsigned int v; savesegment(seg, v); v; })
+
 static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
                                 void __user *fpstate,
                                 struct pt_regs *regs, unsigned int mask)