x86: get rid of put_user_try in __setup_rt_frame() (both 32bit and 64bit)

Straightforward, except for save_altstack_ex() stuck in those.
Replace that thing with an analogue that would use unsafe_put_user()
instead of put_user_ex() (called compat_save_altstack()) and be done
with 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 29abad2..8b879fd 100644 (file)
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -365,38 +365,37 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
 
        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 
-       if (!access_ok(frame, sizeof(*frame)))
+       if (!user_access_begin(frame, sizeof(*frame)))
                return -EFAULT;
 
-       put_user_try {
-               put_user_ex(sig, &frame->sig);
-               put_user_ex(&frame->info, &frame->pinfo);
-               put_user_ex(&frame->uc, &frame->puc);
+       unsafe_put_user(sig, &frame->sig, Efault);
+       unsafe_put_user(&frame->info, &frame->pinfo, Efault);
+       unsafe_put_user(&frame->uc, &frame->puc, Efault);
 
-               /* Create the ucontext.  */
-               if (static_cpu_has(X86_FEATURE_XSAVE))
-                       put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
-               else
-                       put_user_ex(0, &frame->uc.uc_flags);
-               put_user_ex(0, &frame->uc.uc_link);
-               save_altstack_ex(&frame->uc.uc_stack, regs->sp);
+       /* Create the ucontext.  */
+       if (static_cpu_has(X86_FEATURE_XSAVE))
+               unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
+       else
+               unsafe_put_user(0, &frame->uc.uc_flags, Efault);
+       unsafe_put_user(0, &frame->uc.uc_link, Efault);
+       unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
 
-               /* Set up to return from userspace.  */
-               restorer = current->mm->context.vdso +
-                       vdso_image_32.sym___kernel_rt_sigreturn;
-               if (ksig->ka.sa.sa_flags & SA_RESTORER)
-                       restorer = ksig->ka.sa.sa_restorer;
-               put_user_ex(restorer, &frame->pretcode);
+       /* Set up to return from userspace.  */
+       restorer = current->mm->context.vdso +
+               vdso_image_32.sym___kernel_rt_sigreturn;
+       if (ksig->ka.sa.sa_flags & SA_RESTORER)
+               restorer = ksig->ka.sa.sa_restorer;
+       unsafe_put_user(restorer, &frame->pretcode, Efault);
 
-               /*
-                * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
-                *
-                * WE DO NOT USE IT ANY MORE! It's only left here for historical
-                * reasons and because gdb uses it as a signature to notice
-                * signal handler stack frames.
-                */
-               put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
-       } put_user_catch(err);
+       /*
+        * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
+        *
+        * WE DO NOT USE IT ANY MORE! It's only left here for historical
+        * reasons and because gdb uses it as a signature to notice
+        * signal handler stack frames.
+        */
+       unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
+       user_access_end();
        
        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
@@ -419,6 +418,9 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
        regs->cs = __USER_CS;
 
        return 0;
+Efault:
+       user_access_end();
+       return -EFAULT;
 }
 #else /* !CONFIG_X86_32 */
 static unsigned long frame_uc_flags(struct pt_regs *regs)
@@ -444,6 +446,10 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
        unsigned long uc_flags;
        int err = 0;
 
+       /* x86-64 should always use SA_RESTORER. */
+       if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
+               return -EFAULT;
+
        frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
 
        if (!access_ok(frame, sizeof(*frame)))
@@ -455,23 +461,18 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
        }
 
        uc_flags = frame_uc_flags(regs);
+       if (!user_access_begin(frame, sizeof(*frame)))
+               return -EFAULT;
 
-       put_user_try {
-               /* Create the ucontext.  */
-               put_user_ex(uc_flags, &frame->uc.uc_flags);
-               put_user_ex(0, &frame->uc.uc_link);
-               save_altstack_ex(&frame->uc.uc_stack, regs->sp);
-
-               /* Set up to return from userspace.  If provided, use a stub
-                  already in userspace.  */
-               /* x86-64 should always use SA_RESTORER. */
-               if (ksig->ka.sa.sa_flags & SA_RESTORER) {
-                       put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
-               } else {
-                       /* could use a vstub here */
-                       err |= -EFAULT;
-               }
-       } put_user_catch(err);
+       /* Create the ucontext.  */
+       unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
+       unsafe_put_user(0, &frame->uc.uc_link, Efault);
+       unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
+
+       /* Set up to return from userspace.  If provided, use a stub
+          already in userspace.  */
+       unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
+       user_access_end();
 
        err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
        err |= __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
@@ -515,6 +516,10 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
                force_valid_ss(regs);
 
        return 0;
+
+Efault:
+       user_access_end();
+       return -EFAULT;
 }
 #endif /* CONFIG_X86_32 */
 

diff --git a/include/linux/signal.h b/include/linux/signal.h
index 1a5f883..05bacd2 100644 (file)
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -444,12 +444,12 @@ void signals_init(void);
 int restore_altstack(const stack_t __user *);
 int __save_altstack(stack_t __user *, unsigned long);
 
-#define save_altstack_ex(uss, sp) do { \
+#define unsafe_save_altstack(uss, sp, label) do { \
        stack_t __user *__uss = uss; \
        struct task_struct *t = current; \
-       put_user_ex((void __user *)t->sas_ss_sp, &__uss->ss_sp); \
-       put_user_ex(t->sas_ss_flags, &__uss->ss_flags); \
-       put_user_ex(t->sas_ss_size, &__uss->ss_size); \
+       unsafe_put_user((void __user *)t->sas_ss_sp, &__uss->ss_sp, label); \
+       unsafe_put_user(t->sas_ss_flags, &__uss->ss_flags, label); \
+       unsafe_put_user(t->sas_ss_size, &__uss->ss_size, label); \
        if (t->sas_ss_flags & SS_AUTODISARM) \
                sas_ss_reset(t); \
 } while (0);