x86: get rid of get_user_ex() in 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/kernel/signal.c b/arch/x86/kernel/signal.c
index 53ac66b3fd9be3a896dab53dbdb0e296895d2982..83563e98f0be9463bf24ba6c51ceb5f397457986 100644 (file)
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -47,24 +47,6 @@
 #include <asm/sigframe.h>
 #include <asm/signal.h>
 
-#define COPY(x)                        do {                    \
-       get_user_ex(regs->x, &sc->x);                   \
-} while (0)
-
-#define GET_SEG(seg)           ({                      \
-       unsigned short tmp;                             \
-       get_user_ex(tmp, &sc->seg);                     \
-       tmp;                                            \
-})
-
-#define COPY_SEG(seg)          do {                    \
-       regs->seg = GET_SEG(seg);                       \
-} while (0)
-
-#define COPY_SEG_CPL3(seg)     do {                    \
-       regs->seg = GET_SEG(seg) | 3;                   \
-} while (0)
-
 #ifdef CONFIG_X86_64
 /*
  * If regs->ss will cause an IRET fault, change it.  Otherwise leave it
@@ -92,53 +74,58 @@ static void force_valid_ss(struct pt_regs *regs)
            ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
                regs->ss = __USER_DS;
 }
+# define CONTEXT_COPY_SIZE     offsetof(struct sigcontext, reserved1)
+#else
+# define CONTEXT_COPY_SIZE     sizeof(struct sigcontext)
 #endif
 
 static int restore_sigcontext(struct pt_regs *regs,
-                             struct sigcontext __user *sc,
+                             struct sigcontext __user *usc,
                              unsigned long uc_flags)
 {
-       unsigned long buf_val;
-       void __user *buf;
-       unsigned int tmpflags;
-       unsigned int err = 0;
+       struct sigcontext sc;
 
        /* Always make any pending restarted system calls return -EINTR */
        current->restart_block.fn = do_no_restart_syscall;
 
-       get_user_try {
+       if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE))
+               return -EFAULT;
 
 #ifdef CONFIG_X86_32
-               set_user_gs(regs, GET_SEG(gs));
-               COPY_SEG(fs);
-               COPY_SEG(es);
-               COPY_SEG(ds);
+       set_user_gs(regs, sc.gs);
+       regs->fs = sc.fs;
+       regs->es = sc.es;
+       regs->ds = sc.ds;
 #endif /* CONFIG_X86_32 */
 
-               COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
-               COPY(dx); COPY(cx); COPY(ip); COPY(ax);
+       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;
 
 #ifdef CONFIG_X86_64
-               COPY(r8);
-               COPY(r9);
-               COPY(r10);
-               COPY(r11);
-               COPY(r12);
-               COPY(r13);
-               COPY(r14);
-               COPY(r15);
+       regs->r8 = sc.r8;
+       regs->r9 = sc.r9;
+       regs->r10 = sc.r10;
+       regs->r11 = sc.r11;
+       regs->r12 = sc.r12;
+       regs->r13 = sc.r13;
+       regs->r14 = sc.r14;
+       regs->r15 = sc.r15;
 #endif /* CONFIG_X86_64 */
 
-               COPY_SEG_CPL3(cs);
-               COPY_SEG_CPL3(ss);
-
-               get_user_ex(tmpflags, &sc->flags);
-               regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
-               regs->orig_ax = -1;             /* disable syscall checks */
+       /* Get CS/SS and force CPL3 */
+       regs->cs = sc.cs | 0x03;
+       regs->ss = sc.ss | 0x03;
 
-               get_user_ex(buf_val, &sc->fpstate);
-               buf = (void __user *)buf_val;
-       } get_user_catch(err);
+       regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
+       /* disable syscall checks */
+       regs->orig_ax = -1;
 
 #ifdef CONFIG_X86_64
        /*
@@ -149,9 +136,8 @@ static int restore_sigcontext(struct pt_regs *regs,
                force_valid_ss(regs);
 #endif
 
-       err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
-
-       return err;
+       return fpu__restore_sig((void __user *)sc.fpstate,
+                              IS_ENABLED(CONFIG_X86_32));
 }
 
 int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,