tile: switch to generic sigaltstack

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

arch/tile/Kconfig

@@ -21,6 +21,7 @@ config TILE
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select GENERIC_CLOCKEVENTS
 	select MODULES_USE_ELF_RELA
+	select GENERIC_SIGALTSTACK
 
 # FIXME: investigate whether we need/want these options.
 #	select HAVE_IOREMAP_PROT

arch/tile/include/asm/compat.h

@@ -281,8 +281,6 @@ long compat_sys_rt_sigaction(int sig, struct compat_sigaction __user *act,
 long compat_sys_rt_sigqueueinfo(int pid, int sig,
 				struct compat_siginfo __user *uinfo);
 long compat_sys_rt_sigreturn(void);
-long compat_sys_sigaltstack(const struct compat_sigaltstack __user *uss_ptr,
-			    struct compat_sigaltstack __user *uoss_ptr);
 long compat_sys_truncate64(char __user *filename, u32 dummy, u32 low, u32 high);
 long compat_sys_ftruncate64(unsigned int fd, u32 dummy, u32 low, u32 high);
 long compat_sys_pread64(unsigned int fd, char __user *ubuf, size_t count,

arch/tile/include/asm/syscalls.h

@@ -64,9 +64,7 @@ long sys_ftruncate64(unsigned int fd, loff_t length);
 
 /* Provide versions of standard syscalls that use current_pt_regs(). */
 long sys_rt_sigreturn(void);
-long sys_sigaltstack(const stack_t __user *, stack_t __user *);
 #define sys_rt_sigreturn sys_rt_sigreturn
-#define sys_sigaltstack sys_sigaltstack
 
 /* These are the intvec*.S trampolines. */
 long _sys_rt_sigreturn(void);

arch/tile/kernel/compat_signal.c

@@ -41,12 +41,6 @@ struct compat_sigaction {
 	sigset_t sa_mask __packed;
 };
 
-struct compat_sigaltstack {
-	compat_uptr_t ss_sp;
-	int ss_flags;
-	compat_size_t ss_size;
-};
-
 struct compat_ucontext {
 	compat_ulong_t	  uc_flags;
 	compat_uptr_t     uc_link;
@@ -196,40 +190,6 @@ int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
 	return err;
 }
 
-long compat_sys_sigaltstack(const struct compat_sigaltstack __user *uss_ptr,
-			    struct compat_sigaltstack __user *uoss_ptr)
-{
-	stack_t uss, uoss;
-	int ret;
-	mm_segment_t seg;
-
-	if (uss_ptr) {
-		u32 ptr;
-
-		memset(&uss, 0, sizeof(stack_t));
-		if (!access_ok(VERIFY_READ, uss_ptr, sizeof(*uss_ptr)) ||
-			    __get_user(ptr, &uss_ptr->ss_sp) ||
-			    __get_user(uss.ss_flags, &uss_ptr->ss_flags) ||
-			    __get_user(uss.ss_size, &uss_ptr->ss_size))
-			return -EFAULT;
-		uss.ss_sp = compat_ptr(ptr);
-	}
-	seg = get_fs();
-	set_fs(KERNEL_DS);
-	ret = do_sigaltstack(uss_ptr ? (stack_t __user __force *)&uss : NULL,
-			     (stack_t __user __force *)&uoss,
-			     (unsigned long)compat_ptr(current_pt_regs()->sp));
-	set_fs(seg);
-	if (ret >= 0 && uoss_ptr)  {
-		if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(*uoss_ptr)) ||
-		    __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
-		    __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
-		    __put_user(uoss.ss_size, &uoss_ptr->ss_size))
-			ret = -EFAULT;
-	}
-	return ret;
-}
-
 /* The assembly shim for this function arranges to ignore the return value. */
 long compat_sys_rt_sigreturn(void)
 {
@@ -248,7 +208,7 @@ long compat_sys_rt_sigreturn(void)
 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 		goto badframe;
 
-	if (compat_sys_sigaltstack(&frame->uc.uc_stack, NULL) == -EFAULT)
+	if (compat_restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
 
 	return 0;
@@ -325,11 +285,7 @@ int compat_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(0, &frame->uc.uc_link);
-	err |= __put_user(ptr_to_compat((void *)(current->sas_ss_sp)),
-			  &frame->uc.uc_stack.ss_sp);
-	err |= __put_user(sas_ss_flags(regs->sp),
-			  &frame->uc.uc_stack.ss_flags);
-	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+	err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
 	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)

arch/tile/kernel/signal.c

@@ -37,13 +37,6 @@
 
 #define DEBUG_SIG 0
 
-SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
-		stack_t __user *, uoss)
-{
-	return do_sigaltstack(uss, uoss, current_pt_regs()->sp);
-}
-
-
 /*
  * Do a signal return; undo the signal stack.
  */
@@ -100,7 +93,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 		goto badframe;
 
-	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
+	if (restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
 
 	return 0;
@@ -191,11 +184,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(NULL, &frame->uc.uc_link);
-	err |= __put_user((void __user *)(current->sas_ss_sp),
-			  &frame->uc.uc_stack.ss_sp);
-	err |= __put_user(sas_ss_flags(regs->sp),
-			  &frame->uc.uc_stack.ss_flags);
-	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+	err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)