x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers

What's left is just a sequence of stores to userland addresses, with all
error handling, etc. done out of line.  Calling that from user_access block
is safe, but rather than teaching objtool to recognize it as such we can
just make it always_inline - it is small enough and has few enough callers,
for the space savings not to be an issue.

	Rename the sucker to __unsafe_setup_sigcontext32() and provide
unsafe_put_sigcontext32() with usual kind of semantics.

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 a96995a..799ca5b 100644 (file)
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -154,13 +154,11 @@ badframe:
 
 #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)
+static __always_inline int
+__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
+                           void __user *fpstate,
+                           struct pt_regs *regs, unsigned int mask)
 {
-       if (!user_access_begin(sc, sizeof(struct sigcontext_32)))
-               return -EFAULT;
-
        unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
        unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
        unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
@@ -187,13 +185,18 @@ static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
        /* non-iBCS2 extensions.. */
        unsafe_put_user(mask, &sc->oldmask, Efault);
        unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
-       user_access_end();
        return 0;
+
 Efault:
-       user_access_end();
        return -EFAULT;
 }
 
+#define unsafe_put_sigcontext32(sc, fp, regs, set, label)              \
+do {                                                                   \
+       if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0]))     \
+               goto label;                                             \
+} while(0)
+
 /*
  * Determine which stack to use..
  */
@@ -234,7 +237,7 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
        struct sigframe_ia32 __user *frame;
        void __user *restorer;
        int err = 0;
-       void __user *fpstate = NULL;
+       void __user *fp = NULL;
 
        /* copy_to_user optimizes that into a single 8 byte store */
        static const struct {
@@ -247,7 +250,7 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
                0x80cd,         /* int $0x80 */
        };
 
-       frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
+       frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
 
        if (!access_ok(frame, sizeof(*frame)))
                return -EFAULT;
@@ -255,9 +258,12 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
        if (__put_user(sig, &frame->sig))
                return -EFAULT;
 
-       if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
+       if (!user_access_begin(&frame->sc, sizeof(struct sigcontext_32)))
                return -EFAULT;
 
+       unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
+       user_access_end();
+
        if (__put_user(set->sig[1], &frame->extramask[0]))
                return -EFAULT;
 
@@ -301,6 +307,9 @@ int ia32_setup_frame(int sig, struct ksignal *ksig,
        regs->ss = __USER32_DS;
 
        return 0;
+Efault:
+       user_access_end();
+       return -EFAULT;
 }
 
 int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
@@ -309,7 +318,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
        struct rt_sigframe_ia32 __user *frame;
        void __user *restorer;
        int err = 0;
-       void __user *fpstate = NULL;
+       void __user *fp = NULL;
 
        /* __copy_to_user optimizes that into a single 8 byte store */
        static const struct {
@@ -324,7 +333,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
                0,
        };
 
-       frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
+       frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
 
        if (!user_access_begin(frame, sizeof(*frame)))
                return -EFAULT;
@@ -355,9 +364,12 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
        unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
        user_access_end();
 
-       err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false);
-       err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
-                                    regs, set->sig[0]);
+       if (__copy_siginfo_to_user32(&frame->info, &ksig->info, false))
+               return -EFAULT;
+       if (!user_access_begin(&frame->uc.uc_mcontext, sizeof(struct sigcontext_32)))
+               return -EFAULT;
+       unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
+       user_access_end();
        err |= __put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask);
 
        if (err)